Acrylic acid

Endpoint summary

Description of key information

Oral

In a subchronic study with Fischer 344 rats following administration of acrylic acid in the drinking water for 90 days, the NOAEL was determined to be 83 mg/kg bw/day. Following chronic exposure to acrylic acid in the drinking water, the NOAEL for male Wistar rats was 40 mg/kg bw/day, and for female rats 375 mg/kg bw/day.

Inhalation

In a 90-days subchronic study in rats and mice by the inhalation route, the NOAEC for local effects on the nasal epithelium was 74 mg/m3 in rats. No NOAEC for local effects was derived in mice, the respective LOAEC was 15 mg/m3. The systemic NOAEC in rats and male mice was 221 mg/m3, and in female mice 15 mg/m3.

Dermal

Skin irritation become prevalent with higher incidence and severity in mice treated with 4 % acrylic acid compared to 1 % acrylic acid or vehicle control (acetone) after 13 weeks of dermal application (3 d/wk). No irritant effect was evident after long-term application of 1 % acrylic acid in acetone in mice (see Section 7.7 Carcinogencity).

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Aug 1983 - 22 Nov 1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

Acrylic acid was administered by gavage to 50 Wistar rats (20 males, 20 females) for 3 months. For comparison a group of untreated animals (10 males, 10 females) was used as a control. Doses were 150 and 375 mg test substance per kg body weight/day.

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid, pure
- Analytical purity: > 99 %
- Impurities (identity and concentrations): stabilized with 200 ppm MEHQ
- Test Substance No.: 82/380

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Karl THOMAE, Biberach an der Riss, Germany
- Age at study initiation: 42 days old
- Weight at study initiation:
- male animals: 183 .3 (166 - 202) g
- female animals: 146.9 (133 - 162) g
- Fasting period before study: no
- Housing: singly in Type DK III stainless steel wire cages
- Diet (ad libitum): ground Kliba 343 rat/mouse/hamster "A" food supplied by KLINGENTALMUHLE AG, CH-4303, Kaiseraugst, Switzerland
- Water (ad libitum): tap water
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70 % (80 % only for short periods)
- Photoperiod (hrs dark / hrs light): 12 hours

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
For preparation of the test substance preparations the substance was weighed in a measuring flask in a varying amount according to dose group, the flask made up to the mark with doubly distilled water, and then shaken. The solutions were prepared in such a way that 5 mL of solution contained 150 or 375 mg of acrylic acid. The animals of the control group received the solvent doubly distilled water as a control, also by gavage.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

In order to check the correctness of the amounts of acrylic acid weighed, control analyses of the concentrations of each dose were carried out before the beginning of the study, after 4 and 8 weeks of the study, and toward the end of the study. The corresponding determinations were effected by gas chromatography.
Results of analytical dose verification: 147.5 - 151.21 mg/5 mL water and 359.3 - 375.21 mg/5 mL water were determined.

Duration of treatment / exposure:

90 days

Frequency of treatment:

5 days/week

Dose / conc.:

150 mg/kg bw/day (actual dose received)

Dose / conc.:

375 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
In a parallel study (Project No. 74C0380/8239) in connection with the testing for chronic toxicity, Wistar rats received the substance with the drinking water in various doses (0, 120, 800, 2000 and 5000 ppm) over a period of 3 months (satellite groups) or 12 months (main groups).
The present study was intended to be able to compare between continuous administration with the drinking water and single (bolus) administration by gavage on working days, the study being designed in particular to investigate the extend of the irritating effect of acrylic acid on the digestive tract. For this study, therefore, doses were chosen which roughly corresponded to the two highest doses in the drinking water study. At 150 mg/kg body weight (= approx. 2000 ppm - factor 13.3) effects on the body weight gain and on the feed and drinking water consumption were expected. 375 mg/kg body weight (= approx. 5000 ppm - factor 13.3) should additionally lead to organ alterations (among others kidney and digestive tract).

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

WATER CONSUMPTION: Yes
- Time schedule for examinations: weekly

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
After sacrifice, the animals were weighed, necropsied, assessed by gross pathology, and the organs weighed.
In addition to the weight of the exsanguinated animal bodies the absolute and relative weights (organ weight/100 g body weight) of the following organs were determined:
liver, kidneys, spleen, testes, ovaries, adrenals, brain.

HISTOPATHOLOGY: Yes
All the organs listed below were fixed in toto or in representative parts depending on their size in a 4 % buffered formaldehyde solution at room temperature:
all gross lesions, head, heart, thoracic aorta, trachea (with larynx), lung with stem bronchi (right and left), esophagus, stomach (forestomach and glandular stomach), small intestines (duodenum, jejunum, ileum), large intestines (cecum, colon, rectum), salivary glands, liver, pancreas, spleen, thymus, sternum with sternal marrow, kidney, urinary bladder, testes, prostate, seminal vesicle, ovaries, uterus in toto, pituitary, adrenals, thyroids (with parathyroids), brain, skeletal muscle (m. massetor), eye with optic nerve, skin, mesenteric lymph nodes, mammary gland, tongue, buccal mucosa, nasal mucosa.

In the case of the tongue a medial longitudinal section was examined.
The buccal mucosa was removed from the region of the molars and examined as longitudinal section.
In the case of the esophagus a cross-section from the segment in the vicinity of the stomach was examined.
In the case of the liver and kidneys a slide for fat demonstration was prepared in extension of the study protocol. After decalcification of the facial part of the skull a section was removed at the level of the 2nd crista palatinae and the 1st molar. The side facing the molar was intended to be the area of section. This level contains ectoturbinals, endoturbinals with nasal septum, maxillary sinus, nasopharyngeal duct, and to some extent also sections of the molars.

Statistics:

Clinical examinations and pathology: The statistical significance of body and organ weights was carried out using a t-test generalized by Williams for simultaneous comparison of several dose groups with a control group.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Whereas the control animals did not exhibit any clinically evident signs, severe findings attributable to the administration of the test substance were caused in many but not all of the animals that received 150 or 375 mg of test substance/kg body weight. In a number of animals a premature death was the result. From about the 3rd week of the study onward, an increasing number of animals manifested pronounced tympania (gaseous distention of the stomach or abdomen), frequently accompanied by dyspnoea and cyanosis. In addition, several animals began as early as in the first week of the study to make unphysiological utterances, which most closely resembled those made by ducklings. Finally, in some animals - usually shortly before
death occurred - appearances typical of agony, such as hypothermia, apathy and piloerection, were seen; moreover, numerous rats that died prematurely showed a reduced general state of health. Overall, the clinical signs in the animals of test group 2 (375 mg/kg bw) were considerably more pronounced than in those in test group 1 (150 mg/kg bw), as was also shown by a comparison of the respective mortality rates. However, in test group 2 (375 mg/kg bw) one female animal was to be found which was free from clinical signs for the whole period of the study, and furthermore in 4 male rats of this group only temporary signs were observed, which had disappeared by the end of the study.

Mortality:

mortality observed, treatment-related

Description (incidence):

Numerous animals of test groups 1 and 2 (150 and 375 mg/kg bw) died before the end of the period planned for the study. The mortality rate was between 50 and 90 % depending on group and sex, and the intercurrent deaths occurred between the 14th and 81st day of the study.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Whereas the change in body weight in the animals of test group 1 (150 mg/kg bw) took a similar course to that of the corresponding control animals, the male animals of test group 2 (375 mg/kg bw) exhibited a slightly or moderately retarded weight gain. In the female animals of the latter group a corresponding trend was only barely perceptible during the first 3 weeks of the study. Therefore an evaluation of the parameter is no longer rational
because of the intercurrent deaths (see Mortality).

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Neither the male nor the female rats of test groups 1 and 2 (150 and 375 mg/kg bw) exhibited any marked differences with respect to the mean daily feed consumption in comparison with the corresponding control groups.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

The altogether greatly varying mean daily drinking water consumption of the rats used did not reveal any clearly dose-dependent trend; moreover, opposing trends were at times detectable in the male and female animals. Thus, for example, after 21 days of the study the male rats of the control group exhibited a markedly higher drinking water consumption than those of test groups 1 and 2 (150 and 375 mg/kg bw), whereas at this point the female rats of the two test groups consumed more water than the corresponding control group. Hence, all in all no clear effect of the test substance on the drinking water consumption was observed.

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not specified

Description (incidence and severity):

Of the organ weights of the animals sacrificed at the end of the study only the relative liver weight of the female animals of group 1 (150 mg/kg bw) was significantly increased (level of significance 5%). The increase was very slight and without relevance, the more so as a similar change was not observed in the male animals in group 2 (375 mg/kg bw). Also due to the small number of weights available for evaluation (group 1: 5 males, 5 females; group 2: 4 males, 1 female) no clear statement on adverse effects can be made.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Of the animals of dose groups 1 and 2 sacrificed at the end of the study, only 1 male and 3 female animals of group 1 did not exhibit any pathological changes. In the remaining animals, including those from group 2, there were findings suggesting an irritation of the stomach; in several animals the plica marginata was slightly or markedly thickened, in 2 animals the gastric mucosa was hyperemic, and 1 animal had hemorrhagic erosions/ulcerations in the glandular stomach. The other findings in the animals sacrificed are to be assessed as isolated findings independent of the administration of the test substance.
The gastrointestinal tracts of the animals that died intercurrently were usually empty or, in a few instances, exhibited a minimal content of feed or fluid. In all of the animals, the stomach and the entire or parts of the intestinal tract were distended with tympania. Since tympania had been observed clinically and intra vitam before, a postmortal genesis is to be excluded so that in the animals that died prematurely tympania has to be assumed as the cause of death in connection with the clinical signs.
The findings in the lungs (emphysema, edema, etc.) are also to be regarded as a consequence of the tympania and a resulting elevation of the diaphragm (Roehmheld's syndrome). The findings in the stomachs of the animals that died intercurrently corresponded to those in the animals sacrificed at the end of the study, but the cases with hemorrhagic erosions/ulcerations in the glandular stomach were relatively more frequent. Involutions of the spleen were seen in 6 animals and sharp liver margins in one animal, indicating the poor nutritional state of these animals that died intercurrently.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

The gross-pathological findings were largely confirmed on histopathological evaluation of the animals sacrificed and those that died intercurrently, and additional cases usually diagnosed; in the stomach a pronounced hyperemia of the mucosal apices and erosions in the glandular stomach with/without cellular reactions were frequently observed. Under the microscope, the thickening of the plica marginata represented a submucosal edema or a slight degree of epithelial hyperplasia in this region. The fact that, particularly in the case of the male animals, the slight thickenings of the plica marginata seen on grosspathological inspection could not always be confirmed histopathologically, may be due to a shrinking process as a result of the fixation. On the other hand, thickenings which are perhaps still to be regarded as physiological borderline cases were noticed before during gross pathology.

For the tympania in the gastrointestinal tract, there was no histopathological equivalent suggesting a bacterial participation with morphological changes. The histopathological findings in the lungs were also equivalent to those in gross pathology (alveolar hyperemia, alveolar edema, alveolar emphysema, dystelectases). Unexpected findings were observed at examination of the nasal mucosa. Catarrhal and/or catarrhal- purulent rhinites were found in the nasal cavities and/or in the naso-pharyngeal duct of more than half of the animals of the dose groups and in individual animals also in the sinus maxillaris; in four of the animals they were even of a necrotizing character. In many animals there was in addition atrophy/metaplasia of the
mucosa in the ventral region of the nasopharyngeal duct and, in isolated cases, also in the regions of the respiratory epithelium of the nasal cavities. In 2 animals the submucosa of the nasal mucosa was thickened or fibrosed, and an increased goblet cell activity was determined in 3 animals. It must therefore be assumed that the changes are associated with the administration of the test substance, since a corresponding state of inflammation was not seen in any of the control animals. However, it may be said that it is rather improbable that these findings were due to a systemic effect of the substance. It is more likely that they are directly related to the administration by gavage because portions of the test substance were regurgitated during introduction into or withdrawal of the tube from the stomach, or drops adhering to the tube got into the pharyngeal duct on withdrawal. The ventral localization of the changes and the purulent mucus in the pharynx of one animal, diagnosed during gross pathology, also support this assumption.

The most noteworthy histopathological finding, however, was seen in the kidneys of the majority of the animals that died intercurrently. Thus, in 10 out of 11 male animals in the two dose groups a necrotizing tubular nephrosis on the basis of a ballooning degeneration with subsequent fragmentation of the epithelia in the cortical region was diagnosed. With the female animals this was the case in 11 out of 14. Wíth the animals of the dose groups sacrificed at the end of the study this finding was remarkably enough absent and not even suggested. The extent to which this finding is related to a
primary nephrotoxic effect of the substance, or whether it is of a secondary ischemic nature, was not to be derived from the morphological picture. However, a tubulonecrosis on the basis of an ischemia could be explained by the tympania, beginning with a respiratory hypoxidosis intra vitam (see clinical dyspnoea) and, with progressing tympania, by a direct compression of the afferent and/or efferent renal vessels. This is indicated by the fact
that the kidney findings were only obtained in animals that died intercurrently having tympania in the gastrointestinal tract. Out of the 4 animals that died and exhibited no tubulonecrosis, 2 animals showed pronounced cloudy swelling of the epithelia and the other 2 animals moderately increased tubular dilatation. These findings may similarly be interpreted as a consequence of ischemia. The pronounced fatty degeneration of tubular epithelia in individual female animals is a further indicator for damage. Although the degenerative renal changes were to some extent considerably masked by postmortal autolytic tissue alterations, they could still be distinguished from the latter relatively clearly as having occurred intra vitam.

In the liver no pathological differences between the control and the dose groups were seen, with the exception of one animal with vacuolar degeneration. In this connection, special mention is to be made of the fatty deposits; they were not increased in the sense of an ischemic fatty degeneration of liver cells. This, too, would substantiate the assumption that the kidney findings occurred within a relatively short time and mechanically as a result of a local compression ischemia and not as a result of a general hypoxidosis. A third possibility to be discussed would be the question of a slight nephrotoxic effect of the test substance being enhanced by the effect of the compression ischemia.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

LOAEL

Effect level:

150 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: overall effects

Key result

Critical effects observed:

no

Summary:

375 mg/kg body weight group:

Body weight change:

- slightly to moderately retarded growth of the male rats, also suggested in the female rats during the first 3 weeks of the study

Clinical signs:

- in most of the animals employed, from the 3rd week of administration onwards tympania of the gastrointestinal tract, frequently accompanied by cyanosis and dyspnoea

- in the case of individual animals unphysiological utterances

Mortality:

- premature death of 6 out of 10 male and 9 out of 10 female rats

Gross-pathological and histopathological findings:

- irritations of the stomach such as thickening of the plica marginata, hyperemia and hemorrhagic erosions/ ulcerations of the gastric mucosa

- elevation of the diaphragm (Roemheld syndrome), pulmonary edema/emphysema and alveolar hyperemia and dystelectases as a consequence of the already clinically evident tympania

- catarrhal or catarrhal purulent rhinites in some of the animals

- necrotizing tubular nephroses mostly in the animals that died prematurely

150 mg/kg body weight group:

Clinical signs:

- in some animals from the 3rd week of administration onward tympania of the gastrointestinal tract, accompanied in some animals by cyanoais and dyspnoea

Mortality:

- premature death of 5 out of 10 animals used per sex

Gross-pathological and histopathological findings:

- as for test group 2 (375 mg/kg body weight) but frequently less pronounced and in a smaller number of animals

Reference 2

Endpoint:

chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Aug 1983 - 24 Aug 1984

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 452 (Chronic Toxicity Studies)

Principles of method if other than guideline:

Acrylic acid was administered in 4 different doses (120, 800, 2000 and 5000 ppm corresponding to about 9, 61, 140 and 331 mg/kg body weight/day, respectively) in the drinking water to male and female Wistar rats for 3 (satellite groups) or 12 (main groups) months.

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid, pure
- Analytical purity: > 99 %
- Impurities (identity and concentrations): stabilized with 200 ppm MEHQ
- Test Substance No.: 82/380

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Strain: Wistar (Chbb = THOM (SPF))
- Source: Karl THOMAE, Biberach an der Riss, Germany
- Age at study initiation: 42 days old
- Weight at study initiation:
- male animals (main groups): 181.3 (155-202) g
- male animals (sat. groups): 180 .9 (163-199) g
- female animals (main groups): 145.3 (127-177) g
- female animals (sat. groups): 146.9 ( 131-169) g
- Fasting period before study: no
- Housing: singly in Type DK III stainless steel wire cages
- Diet (ad libitum): ground Kliba 343 rat/mouse/hamster "A" food supplied by KLINGENTALMUHLE AG, CH-4303, Kaiseraugst, Switzerland
- Water (ad libitum): tap water
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70 %
- Photoperiod (hrs dark / hrs light): 12 hours/ 12 hours

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

The test substance preparations were freshly prepared 3 times a week. The test substance was weighed out for each test group and added to the appropriate amount of drinking water. The drinking water was agitated with a magnetic stirrer until the test substance had completely dissolved, which took about 3 minutes.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses to check the concentrations were carried out on each dose at the start of the study and after 3, 6 and 12 months. The determinations were carried out by gas chromatography.
The actual concentrations in the test solutions were found to be in the ranges 95 to 107, 90 to 96, 95 to 100 and 94 to 100 % of the target concentrations of 120, 800, 2000 and 5000 ppm, respectively.

Duration of treatment / exposure:

3 (satellite groups) and 12 months (main groups)

Frequency of treatment:

continuously

Dose / conc.:

120 ppm

Remarks:

nominal in water

Dose / conc.:

800 ppm

Remarks:

nominal in water

Dose / conc.:

2 000 ppm

Remarks:

nominal in water

Dose / conc.:

5 000 ppm

Remarks:

nominal in water

No. of animals per sex per dose:

10 (satellite groups) or 20 (main groups) animals

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice a day (Monday to Friday) or once a day (Saturdays, Sundays and public holidays)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly during the first three months, then every 4 weeks

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: weekly during the first three months, at intervals of 3 months after the third month of the study

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: about 4, 12, 26 and 51 weeks after the start of administration
- Anaesthetic used for blood collection: No
- Animals fasted: No
- How many animals: 10
- Parameters examined:
Hemoglobin, Erythrocytes, Hematocrit, Mean hemoglobin content per erythrocyte, Mean cell volume, Mean corpuscular hemoglobin concentration, Platelets, Leukocytes, Prothrombin time (Hepato Quick's Test)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: about 4, 12, 26 and 51 weeks after the start of administration
- Animals fasted: No
- How many animals: 10
- Parameters examined:
Blood chemistry: Total bilirubin, Creatinine, Urea, Sodium, Potassium, Total protein, Glucose, Inorganic phosphate, Calcium, Chloride, Triglycerides, Cholesterol, Albumin
Enzyme activities: Glutamic-pyruvic transaminase, Alkaline phosphatase, Glutamic-oxalacetic transaminase


URINALYSIS: Yes
- Time schedule for collection of urine: about 3, 11, 25 and 50 weeks after the start of treatment
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No
- Parameters were examined:
pH, protein, glucose, ketones, bilirubin, blood, nitrite, urobilinogen, sediment


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
The animals were exsanguinated, dissected and the gross pathology was assessed. The exsanguinated animals, and the liver, kidneys, testes/ovaries, spleen, brain and adrenals were weighed and the relative organ weights were determined.

HISTOPATHOLOGY: Yes
The following organs/tissues were fixed in 4% formaldehyde solution:
- liver, kidneys, adrenals, heart, lungs, thymus, esophagus, jejunum, colon, urinary, bladder, salivary glands, aorta, eyes, brain, thyroids/parathyroids, stomach, ileum, rectum, uterus, representative lymph nodes, accessory genital organs, skin, femur with articular surface, buccal mucosa, cervical/
thoracic/ lumbar cord, nasal mucosa, spleen, testes/epididymides, ovaries, pituitary, trachea, duodenum, cecum, pancreas, sternum with marrow, peripheral nerve, skeletal muscles, female mammary gland, tongue, all gross lesions

A medial longitudinal section of the tongue (satellite groups) was examined.
The buccal mucosa ( satellite groups) was removed from the region of the molars and examined as a longitudinal section.
After the facial bones had been decalcified (satellite groups) a fragment at the level of the 2nd palatine ridge and of the 1st molar was removed. The side facing the molars was intended to be the cut surface. The section contains the ectoturbinates, endoturbinates with nasal septum, maxillary sinus, nasopharyngeal duct as well as, in some cases, parts of the molars.

Other examinations:

The mean amount of test substance consumed each day (in mg per kg body weight) was calculated by way of example for weeks 1, 13, 25, 37 and
52 of the study (main groups) and for the entire duration of the study (satellite groups) at weekly intervals.

Statistics:

Clinical examination and pathology: Statistical significance was determined by analysis of variance (ANOVA) followed by a Dunnett Test or a t-test generalized by WILLIAMS (pathology) for the simultaneous comparison of several dose groups with a control group.
Clinical chemistry/haematology: To test for significance, the t-test was used to compare the individual dose groups with the control group.
Urinanalysis: A chi2 test was carried out in appropriate 2 x 2 contingency tables to assess whether particular features differed between the control and test groups.

Clinical signs:

no effects observed

Description (incidence and severity):

The 4 doses administered by addition to the drinking water (120, 800, 2000 and 5000 ppm) resulted in no impairment of general wellbeing of any of the animals in this study.

Mortality:

no mortality observed

Description (incidence):

Apart from one male animal in main group (120 ppm) which, having previously attracted attention due to a marked increase in the consumption of drinking water and an anemic appearance, died after 326 days of the study, no animal in the main or satellite groups died prematurely. The gross-pathological findings of this animal indicated chronic progressive nephropathy.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The mean body weights of the male rats in main and satellite groups (2000 and 5000 ppm) were up to about 9 % below those of the control animals from 1 week after the start of administration up to the end of the study. In contrast, the mean body weights of the other males and of all the females treated with acrylic acid corresponded to those of the relevant controls. The rather marginal effect on the body weights of the male rats in the 2000 and 5000 ppm groups has to be viewed in the context of the reduction in the consumption of food and/or drinking water by these animals and must be attributed to the administration of the test substance.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Only the male rats in the main and satellite group at the highest dose of 5000 ppm showed reduced food consumption throughout the study. In contrast, the food consumptions of the other animals treated with acrylic acid solutions were comparable with those of the relevant control groups. The reduction in food consumption by the male animals in highest dose group (5000 ppm; main and satellite groups), although slight, was seen throughout the study and must be regarded as connected with administration of the test substance.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

The consumption of drinking water by the male animals in the main and satellite groups receiving 120 and 800 ppm was the same or somewhat higher than that of the relevant control groups; in contrast, the corresponding figures for the animals in the 5000 ppm group were distinctly (up to about 20 %) lower, and for the rats in the 2000 ppm were less markedly lower (not more than about 13 %) than the figures for the controls.
The consumption of drinking water by the female rats in the main and satellite groups (120 and 800 ppm) showed nothing abnormal on comparison with the controls. The differences found, which were mainly slight and independent of the dose, are of an incidental nature. In contrast, the drinking water consumption by the animals in the highest dose main and satellite groups (5000 ppm) was reduced, although only slightly, throughout the study. At times, the female rats in the 2000 ppm group also showed a tendency to this.
The marked reduction in the drinking water consumed by the male animals in test group (5000 ppm) and the less pronounced reduction in the drinking water consumption of the male rats in test group (2000 ppm) and the female animals in test groups (2000 and 5000 ppm) are attributed to the test substance.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

Administration of acrylic acid in doses of 120, 800, 2000 and 5000 ppm in the drinking water to rats for 12 months resulted in no changes in the haematology which were unambiguously attributable to the test substance administration.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

Administration of acrylic acid in doses of 120, 800, 2000 and 5000 ppm in the drinking water to rats for 12 months resulted in no changes in the clinical chemistry which were unambiguously attributable to the test substance administration.

Urinalysis findings:

no effects observed

Description (incidence and severity):

Administration of acrylic acid in doses of 120, 800, 2000 and 5000 ppm in the drinking water to rats for 12 months resulted in no changes in the urinanalysis which were unambiguously attributable to the test substance administration.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

At 5000 ppm in the male animals a fall in the absolute adrenal weight, and increased relative kidney, brain and testes weight were observed. In the female animals of the highest dose group (5000 ppm) a fall in the relative spleen weight was found. The changes are very slight and there is no similar change in the other sex. Furthermore, the computed increases in the relative weights are regarded as the consequence of the reduction in the body weight while the absolute weights of the relevant organs remained unchanged. Thus, the weight changes are not regarded as having pathognomonic relevance.

Gross pathological findings:

no effects observed

Description (incidence and severity):

None of the individual findings from the grosspathological assessment showed any relevant connection with the administration of the test substance.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

None of the individual findings from the histopathological assessment showed any relevant connection with the administration of the test substance.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

40 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

other: Based on the reduced body weight gain in males and lower water consumption in both sexes, the NOAEL of this study was considered to be 800 ppm in male rats (corresponding to 40 mg/kg bw).

Key result

Dose descriptor:

NOAEL

Effect level:

375 mg/kg bw/day (nominal)

Sex:

female

Basis for effect level:

other: In females the NOAEL was considered to be 5000 ppm (corresponding to 375 mg/kg bw) since reduced water consumption was not interpreted as a clear adverse health effect.

Key result

Dose descriptor:

LOAEL

Effect level:

100 mg/kg bw/day (nominal)

Sex:

male

Basis for effect level:

other: body weight; water consumption and compound intake

Key result

Critical effects observed:

no

Conclusions:

The following findings were obtained and assessed as being related to the test substance:

5000 ppm group:

- reduced food consumption by the male rats (main and satellite groups)

- distinctly reduced drinking water consumption (main and satellite groups) by the males, and to a slight extent also by the female rats

- retarded body weight gain of the male rats (main and satellite groups)

2000 ppm group:

- slight reduction in drinking water consumption by both sexes (main and satellite groups)

- marginal effect on body weight gain of the male rats (main and satellite groups)

120 and 800 ppm groups:

- no changes which could be connected with the test substance administered.

In conclusion, it can be said that administration of various doses of acrylic acid in the drinking water for up to 12 months to male and female Wistar rats produced nothing in the clinical chemistry, haematology, urinanalysis or gross-pathological or histopathological findings, or changes in organ weights, which was unambiguously connected with administration of the test substance. Only at the two higher doses (2000 and 5000 ppm) did the animals show clinical signs (reduced consumption of drinking water and/or food, retarded body weight gain) which has to be regarded as related to the test substance. The reaction of the male animals was more sensitive than that of the females.

Acrylic acid at 2000 ppm (corresponding to 140 mg/kg bw) was unpalatable to rats. Thus, for the carcinogenicity study, a lower maximum dose of 1200 ppm was selected.

Reference 3

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Groups of 15 Fischer 344 rats/sex/dose were administered acrylic acid in the drinking-water at doses of 83, 250, and 750 mg/kg bw/day over a study period of 3 months.

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid
- Analytical purity: 97.75 %
- Impurities (identity and concentrations):
- Dimer, Wt % 0.15
- Acetic Acid, Wt % 0.18
- Propionic Acid, Wt % 0.20
- Acrolein, ppm < 25
- Ethyl Acrylate, ppm < 25
- Iron, ppm < 1
- Phenothiazine, ppm 0.4
- Proto-anemonin, ppm < 20
- Furfural, ppm < 20
- Source: Celanese Chemical Company, Houston, Texas
- Analytical Results Reference: No.: MRS-159-78
- Analysis: The sample was analyzed for concentration of acrylic acid, total acid and dimer using a titration method at regular intervals during the study. The concentrations of acrylic acid (by weight) were found to be 97.75 % and 96.55 % at the start and end, respectively, of the study. An increase
in dimer concentration from 1.1 % at the start to 2.3 % at the end of the 90-day-study was observed.

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Microbiological Associates, Inc., Walkersville, MD
- Age at study initiation: 41 days
- Weight at study initiation: males: 105-142 g; females: 81-110 g
- Housing: 3 males or 5 females/cage
- Diet (ad libitum): Zeigler Brothers NIH-07 Rat and Mouse Ration
- Water (ad libitum): tap water originating from the Beaver Run Reservoir, Westmoreland County, PA

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
Fresh test solutions were prepared each week, with the percentage of acrylic acid in the water adjusted to maintain a relatively constant dosage level in g/kg bw.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability of aqueous solutions of acrylic acid was determined using a gas chromatographic procedure. Samples were stored for up to 3 weeks at room temperature with aliquots tested for acrylic acid content at frequent intervals. Stability of acrylic acid was determined for solutions stored in standard glass bottles as well as dosing solutions stored in water bottles under actual study conditions. In addition, the concentration of acrylic acid in the dosing preparations was determined monthly during the study.
Aqueous solutions of acrylic acid were found to be stable for at least 3 weeks when stored at room temperature. Solutions stored in animal water bottles were stable for at least 1 week.

Duration of treatment / exposure:

90 days

Frequency of treatment:

continuously

Dose / conc.:

83 mg/kg bw/day (nominal)

Remarks:

in water

Dose / conc.:

250 mg/kg bw/day (nominal)

Remarks:

in water

Dose / conc.:

750 mg/kg bw/day (nominal)

Remarks:

in water

No. of animals per sex per dose:

15

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: Yes
- Food consumption for cage determined: weekly

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: weekly

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: approx. 2 weeks before sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes
- How many animals: 15
- Parameters examined: red and white blood cell counts (RBC and WBC), measurement of hemoglobin, calculation of hematocrit and differential and reticulocyte counts.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: approx. 2 weeks before sacrifice
- Animals fasted: Yes
- How many animals: 15
- Parameters examined: measurement of serum concentration of total cholesterol (CHOL), serum urea nitrogen, glucose, alkaline phosphatase (ALP), aspaitate transaminase (AST), alanine transaminase (ALT) and creatine phosphokinase (CPR).

URINALYSIS: Yes
- Time schedule for collection of urine: approx. 2 weeks before sacrifice
- Metabolism cages used for collection of urine: Yes
- Animals fasted: No data
- Parameters examined: specific gravity, pH, protein, glucose, ketone, bilirubin, occult blood, nitrite, color and turbidity.


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
All rats were given a complete gross necropsy examination and organ weights were recorded for the liver, kidneys, heart, spleen, brain and testes.

HISTOPATHOLOGY: Yes
The following tissues were taken and fixed in 10 % neutral buffered formalin:
Pituitary*, Thyroids*, Parathyroids*, Adrenals*, Heart*, Great vessels - Aorta, Thymus*, Spleen*, Cervical lymph node, Uterus, Cervix, Vagina, Vulva, Testes*, Epididymides*, Prostate, Seminal vesicles, Rectum, Kidneys*, Bronchial lymph node, Mesenteric lymph node*, Mediastinal lymph node, Nasal cavity*, Larynx, Trachea*, Lungs*, Ovaries*, Oviduct*, Liver*, Pancreas*, Brain*, Spinal cord, Sciatic nerve, Eyes*, Extraorbital lacrimal gland, Harderian gland, Inner and middle ears, Skin*, Urinary bladder*, Mammary gland*, Tongue*, External ear, Submandibular salivary gland, Adipose tissue, Parotid salivary gland, Sternal bone marrow, Sublingual salivary gland, Gastrocnemius muscle, Esophagus*, Stomach*, Duodenum*, Jejunum, Ileum, Cecum, Colon*, Anterior thigh muscle, Knee joint, Femur, Costochondral junction, Sternum*, Vertebrae, Any lesions*.

The tissues marked with *, as well as any other tissues with gross lesions, were etamined microscopically on all high dose and control animals. Only those tissues with gross lesions were examined microscopically from the intermediate and low level animals.

Statistics:

For every experimental parameter measured, the results of each of the three test levels (high, medium, low) were compared with the control group. To evaluate the statistical significance of possible changes in continuous data, the analysis of variance (ANOVA) validated by Bartlett's test for homogeneity of variance, was used. Individual mean differences were identified by Duncan's multiple range test when indicated by a significant F value for ANOVA. In the case of heterogenous variances, as indicated by Bartlett's test, the Paired group F test, and either the Cochran or the Student t-test were used to identify significant differences. Enumerative data were evaluated statistically by NxR Chi Square test; differences between groups were delineated by Fisher's Exact test. Non-parametric data were compared by a distribution-free multiple comparison method. The fiducial limit of 0.05 was employed as the critical level of difference not attributable to chance.

Clinical signs:

no effects observed

Description (incidence and severity):

No clinical signs were observed in any of the animals.

Mortality:

no mortality observed

Description (incidence):

There were no deaths in the three-month study period.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Body weight gain was depressed markedly for both sexes at the high dosage level. This effect was statistically highly significant in these groups throughout the study. Further examination shows statistical reduction of body weight gain for the intermediate level males at 4 of the 10 comparison intervals and for the females from 41 through 90 doses.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Significant reductions in diet consumption were observed for both sexes at the high dosage level.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

effects observed, treatment-related

Description (incidence and severity):

There was a dose-related reduction in water consumption for all male test animals and for females at the high and intermediate levels as well. Water consumption for the low level males, while statistically significant, was numerically close to that of the controls. Furthermore, in a previous study by the same laboratory (Report 42-558), water consumption in male rats receiving as much as 420 mg/kg bw/day of acrylic acid in the drinking water was numerically and statistically equivalent to the controls. Therefore, the change in water consumption observed for the low level male rats is not considered to be toxicologically important.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

The only significant finding was an elevation of the red blood cell count for the low level females. This change was not dose-related and is not considered biologically important; it is probably an artifact.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

An increase in serum urea nitrogen was noted for the high level male rats. In the females, a decrease of serum cholesterol and increases of serum urea nitrogen, glucose, alkaline phosphatase and aspartate transaminase were observed among the high dosage level animals. In addition, dosage-related increases of serum urea nitrogen and alkaline phosphatase and a decrease in serum cholesterol were observed at the intermediate dosage level for the females.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

In both sexes at the high and intermediate levels, increases of urine specific gravity and urine protein were observed. A decrease in urine pH was noted for the high level female rats as well. Alterations in fluid balance resulting from decreased fluid intake may underlie the changes in serum urea nitrogen, urine specific gravity and urine protein. An alternate explanation of direct or indirect renal toxicity supported by increased relative kidney weights in both sexes at the high and intermediate levels is possible.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The effect of acrylic acid on the organ weights of the rats was obvious in the high dosage level in both sexes.

In the male rats this effect included:
(1) Significant reduction in absolute liver, spleen, heart and brain weights.
(2) Significant increase in relative (as % of body weight) liver, kidney, spleen, brain and testes weights.

In the female rats, the effects on the organ weights at the high dose level included:
(1) Significant reduction in absolute liver, spleen and heart weights.
(2) Significant increase in absolute kidney weight and relative kidney and brain weights.

Furthermore, the significant increases in relative kidney and testes weights for the intermediate level males and absolute and relative kidney weights for the intermediate level females are dose-related deleterious effects.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No significant treatment related gross lesions were noted in any animal on the study.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No significant difference in prevalence of microscopic lesions was noted between animals treated with acrylic acid and controls. Malacia within the optic nerves was observed in 2/15 high dose males versus 0/15 control males (P = 0.48) and 1/15 high dose females versus 0/15 control females (P = 1.00). The true prevalence of this lesion in the study could not be determined. However, the unilaterality of this lesion concomitant with absence of lesions within the spinal cord and sciatic nerve indicate that this lesion is not attributable to the treatment with acrylic acid.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

83 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: no toxicological significant changes observed

Key result

Dose descriptor:

LOAEL

Effect level:

250 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: Diet and water consumption, body and organ weight changes and abnormal clinical chemical and urine analysis parameters

Key result

Critical effects observed:

no

Deleterious effects were observed at the high dosage level (750 mg/kg bw/day) and at the intermediate level (250 mg/kg bw/day) in both sexes. These effects included diet and water consumption, body and organ weight changes and abnormal clinical chemical and urinalysis parameters. At the low dosage level (83 mg/kg bw/day), a significant reduction in water consumption was noted for the male rats. Since this effect is only a moderate reduction of water intake and since the variance is relatively small, the toxicological significance is considered minimal. The slight increase in red blood cells noted for the low dosage level females is considered to be an artifact. Accordingly, the maximum no ill-effect level for three-month ingestion of acrylic acid in the rat is estimated to be at or slightly lower than 83 mg/kg bw/day. Based on this consideration and the findings concerning the effect of acrylic acid at the intermediate and high levels, the minimum effect level is estimated to be 250 mg/kg bw/day.

Summary of results of 90 days of inclusion of Acrylic acid in the drinking water of male rats:

 

Dosage goal [mg/kg bw/d]	750		250		83		control
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Dosage attained [mg/kg bw/d]	740	50	250	10	84	4	0	0
Diet consumption [g/kg bw/d]	14.0***	0.6	16.2	0.6	16.4	0.9	16.9	0.6
Water consumption [mL/rat/d]	13.0***	0.7	17.5***	0.8	19.4**	1.3	21.4	0.7
Body weight gain [g]	141.5***	21.5	188.2	23.5	196.7	17.3	200.6	20.2
Liver weight [g]	9.33***	1.25	11.30	1.64	11.17	0.85	11.08	0.89
Liver wt as % bw	3.52*	0.15	3.61	0.38	3.50	0.15	3.40	0.14
Kidney weight [g]	2.06	0.22	2.20	0.18	2.14	0.16	2.15	0.13
Kidney wt as % bw	0.78***	0.04	0.71***	0.03	0.67	0.03	0.66	0.02
Spleen weight [g]	0.53**	0.05	0.60	0.08	0.61	0.06	0.60	0.06
Spleen wt as % bw	0.20**	0.02	0.19	0.02	0.19	0.02	0.18	0.01
Heart weight [g]	0.71**	0.09	0.81	0.10	0.83	0.08	0.82	0.10
Heart wt as % bw	0.27	0.02	0.26	0.02	0.26	0.02	0.25	0.03
Brain weight [g]	1.74**	0.08	1.81	0.08	1.81	0.08	1.84	0.06
Brain wt as % bw	0.66***	0.05	0.58	0.04	0.57	0.03	0.57	0.03
Testes weight [g]	2.72	0.17	2.82	0.14	2.73	0.14	2.72	0.32
Testes wt as % bw	1.04***	0.06	0.91*	0.07	0.86	0.07	0.84	0.11

* p< 0.05, ** p< 0.01, *** p< 0.001

Summary of results of 90 days of inclusion of Acrylic acid in the drinking water of female rats:

 

Dosage goal [mg/kg bw/d]	750		250		83		control
	Mean	SD	Mean	SD	Mean	SD	Mean	SD
Dosage attained [mg/kg bw/d]	720	50	250	10	84	3	0	0
Diet consumption [g/kg bw/d]	8.7**	0.3	10.2	0.6	10.6	0.2	10.4	0.4
Water consumption [mL/rat/d]	8.6***	0.5	11.8***	0.7	14.9	0.8	15.0	0.7
Body weight gain [g]	48.0***	8.2	68.4*	9.8	82.1	11.1	78.0	10.8
Liver weight [g]	4.91***	0.50	5.61	0.47	5.84	0.57	5.70	0.45
Liver wt as % bw	3.27	0.22	3.29	0.18	3.16	0.14	3.19	0.13
Kidney weight [g]	1.34**	0.10	1.37***	0.07	1.29	0.08	1.24	0.08
Kidney wt as % bw	0.89***	0.04	0.80***	0.06	0.70	0.04	0.69	0.03
Spleen weight [g]	0.37***	0.04	0.43	0.04	0.46	0.05	0.43	0.05
Spleen wt as % bw	0.24	0.02	0.25	0.02	0.25	0.02	0.24	0.02
Heart weight [g]	0.45***	0.04	0.54	0.05	0.55	0.06	0.54	0.07
Heart wt as % bw	0.30	0.02	0.32	0.02	0.30	0.02	0.30	0.03
Brain weight [g]	1.61	0.12	1.68	0.08	1.66	0.10	1.65	0.14
Brain wt as % bw	1.07***	0.09	0.99	0.08	0.90	0.08	0.93	0.10

* p< 0.05, ** p< 0.01, *** p< 0.001

 

 

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

40 mg/kg bw/day

Study duration:

chronic

Species:

rat

Quality of whole database:

similar to OECD TG 452

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Principles of method if other than guideline:

Male and female 66C3F1 mice were exposed to 0, 5 , 25 or 75 ppm acrylic acid vapours (corresponding to 0, 0.015, 0.074, 0.221 mg/L) 6 hours per day, 5 days per week, for 13 weeks.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid
- Analytical purity: 99.7 %
- Impurities (identity and concentrations):
- water wt% 0.08,
- monomethyl ether of hydroquione 218 ppm
- Dimer wt% 0.23
- Acetic Acid wt% 0.12
- Propionic Acid wt% 0.15
- Acrolein ppm <25
- Ethyl Acrylate ppm <25
- Phenothiazine ppm 0.10
- Proto-anemonin ppm <20
- Furfural ppm <20
- Source: Celanese Chemical Company

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Wilmington, MA
- Age at study initiation: 3 weeks
- Fasting period before study: no
- Housing: single
- Diet (ad libitum): standard laboratory diet (Purina Laboratory Chow, Ralston Purina Co., St. Louis, MO) except during exposure
- Water: ad libitum
- Acclimation period: 16 days

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: inhalation chambers (14500 liters) with stainless steel pyramidal-shaped ceilings and epoxy resin-coated walls and floors with dynamic airflow conditions
- Source and rate of air: Exposure levels of acrylic acid were generated by pumping liquid acrylic acid at calculated rates into glass vaporization flasks heated to approximately 130°C. Vapours from the flasks were swept into the chamber air supply duct with compressed air and mixed with incoming air by turbulence.
- Temperature, humidity, pressure in air chamber: 21 °C, 50 %, slight negative pressure
- Air flow rate: 2500 liters per minute
- Air change rate: 10 air changes per hour


TEST ATMOSPHERE
- Brief description of analytical method used: The actual concentration of acrylic acid in each chamber was measured 2-3 times per hour (12-15 times daily) by infrared spectrophotometry using a Miran I Infrared Analyzer at a wavelength of 8.9 µm. Prior to initiating exposures, distribution of acrylic acid vapours within the chambers was determined to be uniform within 10 % of the target concentrations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Percent dimer in the liquid acrylic acid monomer varied between 0.4% and 3.7% during the exposure interval.
Analytical concentrations (mean ± SD): 5.0 ± 0.3 ppm; 25 ± 1 ppm; 75 ± 1 ppm

Duration of treatment / exposure:

90 days

Frequency of treatment:

6 hours/day; 5 days/week

Dose / conc.:

5 ppm

Remarks:

analytical concentration

Dose / conc.:

25 ppm

Remarks:

analytical concentration

Dose / conc.:

75 ppm

Remarks:

analytical concentration

No. of animals per sex per dose:

15

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily


BODY WEIGHT: Yes
- Time schedule for examinations: on the 1st day of exposure and weekly thereafter


OPHTHALMOSCOPIC EXAMINATION: YES


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 1 week prior to sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes / No / No data
- How many animals: 10/sex/dose group
- Parameters examined: Packed Cell Volume (PCV), Hemoglobin (Hgb), Erythrocyte count and morphology, Total and differential leukocyte counts


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: immediately prior to sacrifice
- Animals fasted: Yes
- How many animals: 10/sex/dose group
- Parameters examined: Glucose, Blood urea nitrogen (BUN), Alkaline Phosphatase (AP), Glutamic-pyruvic transaminase (SGPT)


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Approximately 18 hours after the final exposure, animals were sacrificed and submitted to necropsy. Animals were fasted overnight prior to sacrifice. Each animal was examined externally and internally for gross pathologic alterations. Immediately after decapitation, the eyes of each animal were examined by a glass slide technique with fluorescent illumination. Weights of brain, heart, liver, kidneys and testes were determined and recorded. Lungs and trachea were removed as a unit and the lungs were expanded to approximately their normal inspiratory volume with buffered 10 % formalin.
Animals which died spontaneously or which were sacrificed in a moribund condition during the course of the study were given a complete gross pathological examination. In general, representative portions of the organs and tissues listed below from each animal were preserved in buffered 10 % formalin.


HISTOPATHOLOGY: Yes
Slides (hematoxylin and eosin stained) were prepared and histopathologic examinations performed on tissues listed below for 10 animals of each
sex in the control and 75 ppm exposure groups. Similar histopathologic examinations were conducted on all animals that died spontaneously during the course of the study. Target organs identified in the 75 ppm exposure group were also examined for 10 animals in the 5 ppm and 25 ppm exposure groups.

Organs/Tissues:
adipose tissue, adrenals, aorta, brain, cecum, esophagus, eyes, gall bladder, gonads, gross lesions, heart, small intestine, large intestine, kidneys, lacrimal gland, larynx, liver, lungs, lymph nodes (mesenteric & thoracic), mammary gland, nasal turbinates, pancreas, peripheral nerve, pituitary, prostate, salivary gland, seminal vesicles & coagulating glands, skeletal muscle, skin, spinal cord, spleen, stomach, trachea, thymus, thyroid/parathyroid, urinary bladder, uterus, vertebrae with bone marrow

Statistics:

Variances of group body weight changes were analyzed for Bartlett's test for homogeneity of variances (Snedecor and Cochran, 1967). Body weight changes, organ weights, organ-to-body weight ratios, haematology values, clinical chemistry values and urinary specific gravity were evaluated by analysis of variance; differences between control and treatment groups were delineated by Dunnett's test (Steel and Torrie, 1960). The level of significance chosen in all cases was p<0.05.

Clinical signs:

no effects observed

Description (incidence and severity):

Animal observations revealed no discernible effects on appearance or demeanor of mice which were related to exposure.

Mortality:

no mortality observed

Description (incidence):

A female mouse in the 75 ppm group and a male mouse in the 25 ppm group died as a result of traumatic injury. An additional female mouse in the 75 ppm group was sent to pathology in a moribund condition after 5-6 weeks of exposure.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weight gains of male mice in the 5 ppm exposure group were in general significantly higher than for controls during the study. Likewise, mean body weight gains of male mice in the two higher exposure groups (25 and 75 ppm) were generally either higher than for controls or were not different from controls. The mean body weight gains of female mice in the 25 and 75 ppm groups were significantly lower than for controls after 12 weeks of exposure but not at any of the previous weekly weighings. These statistical differences may have resulted from the unusually high mean body weight gain of female mice in the control group (the mean body weight gain of female control mice was even higher than for male control mice). It was concluded that exposure to acrylic acid vapours had no adverse effect on growth of male mice, and a very slight effect, if any, on the growth of female mice.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Mean hemoglobin values of male mice in the 25 and 75 ppm exposure groups and for female mice in the 75 ppm group were significantly lower than for controls; these effects on hemoglobin of mice were probably related to exposure to the test material, but they were considered to be of only minor toxicologic significance. The reduced white cell count for male mice in the 25 ppm group was considered to be a spontaneous statistical difference.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

The mean alkaline phosphatase values of female mice in the 25 and 75 ppm exposure groups were significantly lower than for controls but decreases in alkaline phosphatase have no known toxicologic significance. All other differences in clinical chemistry parameters of mice (blood urea nitrogen values in male mice) were considered to be spontaneous statistical differences unrelated to exposure due to the absence of a dose-response relationship.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no effects on organ weights or organ-to-body weight ratios of male or female mice which were considered to be related to exposure. All statistical differences in absolute and relative organ weights between control and exposure groups of mice, including relative brain and kidney weights of female mice in the 25 pqm group, and relative heart weights of female mice in the 75 ppm group were considered spontaneous in nature and unrelated to exposure to the test material.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no gross pathologic alterations that were considered to be related to treatment with the test material. Alopecia of variable distribution was the only frequently occurring observation and was observed in nearly all groups including the male and female control groups. Two mice, one female in the 75 ppm exposure group and one male in the 25 ppm exposure group, died spontaneously as a result of traumatic injury incurred while handling. One additional female mouse in the 75 ppm group was sacrificed in a moribund condition. Gross pathological examination of this animal revealed depletion of the abdominal adipose tissue and absence of ingesta in the gastrointestinal tract, suggesting that possibly the animal did not have access to either food or water.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathologic lesions of the olfactory portion of the nasal mucosa were detected in all male and female mice in the 75 ppm exposure group, in all males and nine of ten females in the 25 ppm group, and in one of ten males and four of ten females in the 5 ppm group. These lesions of the nasal mucosa were considered to be a result of treatment with the test material. Similar lesions were not observed in any of the male or female mice in the control group. The nasal lesions of all affected mice were confined to the olfactory portion of the nasal mucosa on the dorsomedial aspect of the nasal passages. However, there was a clearcut dose-response relationship based upon the size of the affected area; the severity of the lesions within the affected area; and the numbers of animals affected. The lesions in mice in the 75 ppm exposure group consisted of: focal degeneration of the olfactory epithelium with partial replacement by an epithelium resembling respiratory epithelium; very slight focal infiltration of principally mononuclear inflammatory cells in the mucosa and submucosa of the affected regions; and very slight focal hyperplasia of the submucosal glands within some of the affected area. Overall, the lesions in these mice were graded as slight to moderate. The lesions of affected mice in the 25 ppm exposure group were limited to slight focal degeneration of the olfactory epithelium, usually without evidence of an inflammatory response. Only very slight focal degeneration of the olfactory mucosa was observed in affected mice in the 5 ppm exposure group. As noted previously, the nasal lesions observed in the mice in this study were confined to the olfactory portions of the nasal mucosa. This distribution of the lesions and their microscopic appearance indicated that the olfactory epithelium of the nasal mucosa is more vulnerable than the respiratory epithelium to the irritant properties of acrylic acid vapour. All other histopathologic observations were considered to be spontaneous in nature and unrelated to treatment with the test material.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEC

Effect level:

0.221 mg/L air (analytical)

Sex:

male

Basis for effect level:

other: Systemic toxicity

Key result

Dose descriptor:

NOAEC

Effect level:

0.015 mg/L air (analytical)

Sex:

female

Basis for effect level:

other: Systemic toxicity

Key result

Dose descriptor:

LOAEC

Effect level:

0.015 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Local effects: focal degeneration of the olfactory epithelium

Critical effects observed:

not specified

For local effects no NOAEC was identified.

Reference 2

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Principles of method if other than guideline:

Male and female Fischer 344 rats were exposed to 0, 5 , 25 or 75 ppm acrylic acid vapours (corresponding to 0, 0.015, 0.074, 0.221 mg/L) 6 hours per day, 5 days per week, for 13 weeks.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid
- Analytical purity: 99.7 %
- Impurities (identity and concentrations):
- water wt% 0.08,
- monomethyl ether of hydroquione 218 ppm
- Dimer wt% 0.23
- Acetic Acid wt% 0.12
- Propionic Acid wt% 0.15
- Acrolein ppm <25
- Ethyl Acrylate ppm <25
- Phenothiazine ppm 0.10
- Proto-anemonin ppm <20
- Furfural ppm <20
- Source: Celanese Chemical Company

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Wilmington, MA
- Age at study initiation: 3 weeks
- Fasting period before study: no
- Housing: 22-3/cage
- Diet (ad libitum): standard laboratory diet (Purina Laboratory Chow, Ralston Purina Co., St. Louis, MO) except during exposure
- Water: ad libitum
- Acclimation period: 16 days

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: inhalation chambers (14500 liters) with stainless steel pyramidal-shaped ceilings and epoxy resin-coated walls and floors dynamic airflow conditions
- Source and rate of air: Exposure levels of acrylic acid were generated by pumping liquid acrylic acid at calculated rates into glass vaporization flasks heated to approximately 130°C. Vapours from the flasks were swept into the chamber air supply duct with compressed air and mixed with incoming air by turbulence.
- Temperature, humidity, pressure in air chamber: 21 °C, 50 %, slight negative pressure
- Air flow rate: 2500 liters per minute
- Air change rate: 10 air changes per hour


TEST ATMOSPHERE
- Brief description of analytical method used: The actual concentration of acrylic acid in each chamber was measured 2-3 times per hour (12-15 times daily) by infrared spectrophotometry using a Miran I Infrared Analyzer at a wavelength of 8.9 µm. Prior to initiating exposures, distribution of acrylic acid vapours within the chambers was determined to be uniform within 10 % of the target concentrations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Percent dimer in the liquid acrylic acid monomer varied between 0.4% and 3.7% during the exposure interval.
Analytical concentrations (mean ± SD): 5.0 ± 0.3 ppm; 25 ± 1 ppm; 75 ± 1 ppm

Duration of treatment / exposure:

90 days

Frequency of treatment:

6 hours/day; 5 days/week

Dose / conc.:

5 ppm

Remarks:

analytical concentration

Dose / conc.:

25 ppm

Remarks:

analytical concentration

Dose / conc.:

75 ppm

Remarks:

analytical concentration

No. of animals per sex per dose:

15

Control animals:

yes, sham-exposed

Details on study design:

Post-exposure period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily


BODY WEIGHT: Yes
- Time schedule for examinations: on the 1st day of exposure and weekly thereafter


OPHTHALMOSCOPIC EXAMINATION: YES


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 1 week prior to sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes / No / No data
- How many animals: 10/sex/dose group
- Parameters examined: Packed Cell Volume (PCV), Hemoglobin (Hgb), Erythrocyte count and morphology, Total and differential leukocyte counts


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the time of sacrifice
- Animals fasted: Yes
- How many animals: 10/sex/dose group
- Parameters examined: Glucose, Blood urea nitrogen (BUN), Alkaline Phosphatase (AP), Glutamic-pyruvic transaminase (SGPT), Total Protein, Albumin, Albumin/Globulin (A/G) Ratio


URINALYSIS: Yes
- Time schedule for collection of urine: 1 week prior to sacrifice
- Metabolism cages used for collection of urine: No
- Animals fasted: No
- Parameters examined: Bilirubin, pH, Glucose, Protein, Ketone, Urobilinogen, Occult Blood, Specific Gravity (refractive ìndex)


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Approximately 18 hours after the final exposure, animals were sacrificed and submitted to necropsy. Animals were fasted overnight prior to sacrifice. Each animal was examined externally and internally for gross pathologic alterations. Immediately after decapitation, the eyes of each animal were examined by a glass slide technique with fluorescent illumination. Weights of brain, heart, liver, kidneys and testes were determined and recorded. Lungs and trachea were removed as a unit and the lungs were expanded to approximately their normal inspiratory volume with buffered 10 % formalin.
Animals which died spontaneously or which were sacrificed in a moribund condition during the course of the study were given a complete gross pathological examination. In general, representative portions of the organs and tissues listed below from each animal were preserved in buffered 10 % formalin.


HISTOPATHOLOGY: Yes
Slides (hematoxylin and eosin stained) were prepared and histopathologic examinations performed on tissues listed below for 10 animals of each
sex in the control and 75 ppm exposure groups. Similar histopathologic examinations were conducted on all animals that died spontaneously during the course of the study. Target organs identified in the 75 ppm exposure group were also examined for 10 animals in the 5 ppm and 25 ppm exposure groups.

Organs/Tissues:
adipose tissue, adrenals, aorta, brain, cecum, esophagus, eyes, gonads, gross lesions, heart, small intestine, large intestine, kidneys, lacrimal gland, larynx, liver, lungs, lymph nodes (mesenteric & thoracic), mammary gland, nasal turbinates, pancreas, peripheral nerve, pituitary, prostate, salivary gland, seminal vesicles & coagulating glands, skeletal muscle, skin, spinal cord, spleen, stomach, tongue, trachea, thymus, thyroid/parathyroid, urinary bladder, uterus, vertebrae with bone marrow, zymbal gland

Statistics:

Variances of group body weight changes were analyzed for Bartlett's test for homogeneity of variances (Snedecor and Cochran, 1967). Body weight changes, organ weights, organ-to-body weight ratios, haematology values, clinical chemistry values and urinary specific gravity were evaluated by analysis of variance; differences between control and treatment groups were delineated by Dunnett's test (Steel and Torrie, 1960). The level of significance chosen in all cases was p<0.05.

Clinical signs:

no effects observed

Description (incidence and severity):

Animal observations revealed no discernible effects on appearance or demeanor of rats which were related to exposure.

Mortality:

no mortality observed

Description (incidence):

There were no spontaneous deaths of rats during the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weight gains of male and female rats in the 5, 25 and 75 ppm exposure groups were not different from controls except during the first
two weeks of exposure when the body weight gains of female rats in the 5 and 25 ppm groups were statistically higher than for controls. Thus exposure to 5, 25 or 75 ppm acrylic acid vapors had no adverse effect on growth of male or female rats.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

There were no statistical differences, in hematologic values of male rats or female rats exposed to acrylic acid vapours which were considered
to be related to exposure. The reduced white cell count for male rats in the 25 ppm group was considered to be a spontaneous statistical difference unrelated to exposure in view of the absence of any effect on white cell count for animals in the higher (75 ppm) exposure group.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Mean alkaline phosphatase values of female rats in the 75 ppm group were significantly higher than for controls; this effect may have been related to exposure but is of uncertain toxicologic significance. All other differences in clinical chemistry parameters of rats (glucose values) were considered to be spontaneous statistical differences unrelated to exposure due to the absence of a dose-response relationship.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no discernible effects on urinalysis parameters of male or female rats. Statistical analyses of urinary specific gravity values revealed no significant differences between control and exposure groups of rats.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no effects on organ weights or organ-to-body weight ratios of male or female rats which were considered to be related to exposure. All statistical differences in absolute and relative organ weights between control and exposure groups of rats, including absolute and relative liver weights of male rats in the 5 ppm group and relative liver weights of female rats in the 5 ppm group were considered spontaneous in nature and unrelated to exposure to the test material.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no gross pathologic observations which were considered to be related to treatment with the test material. All gross pathologic observations on the male and female rats in this study were considered to be spontaneous in nature and typical of those usually encountered in rats of this strain and age.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathologic lesions of the nasal mucosa were observed in 7/10 male and 10/10 female rats in the 75 ppm exposure group but not in rats in the 25 or 5 ppm exposure groups; these were the only lesions considered to be related to treatment. In affected rats in the 75 ppm exposure group, the nasal lesions consisted of slight focal degeneration of the olfactory epithelium on the dorsomedial aspect of the nasal passages. The nasal lesions in most affected rats were detected only in the most rostral of four cross sections obtained through the nasal. However, lesions were observed in the more caudal sections in a few cases. The lesions were characterized principally by disorganization of the normal arrangement of the nuclei of the olfactory epithelium and associated mild degenerative alterations of the epithelial cells in the affected regions. No lesions of the nasal mucosa were observed in 3/10 male rats in the 75 ppm group. Since it was possible that the original sections prepared for these rats were not through the proper portion of the nasal passages, additional sections were prepared. Examination of these additional sections also failed to reveal any discernible lesions. As indicated above, no lesions of the nasal mucosa were observed in either male or female rats in the groups exposed to 25 or 5 ppm acrylic acid. Slight subacute inflammatory lesions were observed in the nasal mucosa of one female rat in the control group. These lesions were unlike the lesions observed in the rats in the 75 ppm group. All other observations were considered to be spontaneous in nature and unrelated to treatment with the test material.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEC

Effect level:

0.074 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Local effects

Key result

Dose descriptor:

NOAEC

Effect level:

0.221 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Systemic toxicity

Dose descriptor:

LOAEC

Effect level:

0.221 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Local effects: focal degeneration of the olfactory epithelium

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

15 mg/m³

Study duration:

subchronic

Species:

mouse

Quality of whole database:

similar to OECD TG 413

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Principles of method if other than guideline:

Male and female 66C3F1 mice were exposed to 0, 5 , 25 or 75 ppm acrylic acid vapours (corresponding to 0, 0.015, 0.074, 0.221 mg/L) 6 hours per day, 5 days per week, for 13 weeks.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid
- Analytical purity: 99.7 %
- Impurities (identity and concentrations):
- water wt% 0.08,
- monomethyl ether of hydroquione 218 ppm
- Dimer wt% 0.23
- Acetic Acid wt% 0.12
- Propionic Acid wt% 0.15
- Acrolein ppm <25
- Ethyl Acrylate ppm <25
- Phenothiazine ppm 0.10
- Proto-anemonin ppm <20
- Furfural ppm <20
- Source: Celanese Chemical Company

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Wilmington, MA
- Age at study initiation: 3 weeks
- Fasting period before study: no
- Housing: single
- Diet (ad libitum): standard laboratory diet (Purina Laboratory Chow, Ralston Purina Co., St. Louis, MO) except during exposure
- Water: ad libitum
- Acclimation period: 16 days

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: inhalation chambers (14500 liters) with stainless steel pyramidal-shaped ceilings and epoxy resin-coated walls and floors with dynamic airflow conditions
- Source and rate of air: Exposure levels of acrylic acid were generated by pumping liquid acrylic acid at calculated rates into glass vaporization flasks heated to approximately 130°C. Vapours from the flasks were swept into the chamber air supply duct with compressed air and mixed with incoming air by turbulence.
- Temperature, humidity, pressure in air chamber: 21 °C, 50 %, slight negative pressure
- Air flow rate: 2500 liters per minute
- Air change rate: 10 air changes per hour


TEST ATMOSPHERE
- Brief description of analytical method used: The actual concentration of acrylic acid in each chamber was measured 2-3 times per hour (12-15 times daily) by infrared spectrophotometry using a Miran I Infrared Analyzer at a wavelength of 8.9 µm. Prior to initiating exposures, distribution of acrylic acid vapours within the chambers was determined to be uniform within 10 % of the target concentrations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Percent dimer in the liquid acrylic acid monomer varied between 0.4% and 3.7% during the exposure interval.
Analytical concentrations (mean ± SD): 5.0 ± 0.3 ppm; 25 ± 1 ppm; 75 ± 1 ppm

Duration of treatment / exposure:

90 days

Frequency of treatment:

6 hours/day; 5 days/week

Dose / conc.:

5 ppm

Remarks:

analytical concentration

Dose / conc.:

25 ppm

Remarks:

analytical concentration

Dose / conc.:

75 ppm

Remarks:

analytical concentration

No. of animals per sex per dose:

15

Control animals:

yes, concurrent no treatment

Details on study design:

Post-exposure period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily


BODY WEIGHT: Yes
- Time schedule for examinations: on the 1st day of exposure and weekly thereafter


OPHTHALMOSCOPIC EXAMINATION: YES


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 1 week prior to sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes / No / No data
- How many animals: 10/sex/dose group
- Parameters examined: Packed Cell Volume (PCV), Hemoglobin (Hgb), Erythrocyte count and morphology, Total and differential leukocyte counts


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: immediately prior to sacrifice
- Animals fasted: Yes
- How many animals: 10/sex/dose group
- Parameters examined: Glucose, Blood urea nitrogen (BUN), Alkaline Phosphatase (AP), Glutamic-pyruvic transaminase (SGPT)


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Approximately 18 hours after the final exposure, animals were sacrificed and submitted to necropsy. Animals were fasted overnight prior to sacrifice. Each animal was examined externally and internally for gross pathologic alterations. Immediately after decapitation, the eyes of each animal were examined by a glass slide technique with fluorescent illumination. Weights of brain, heart, liver, kidneys and testes were determined and recorded. Lungs and trachea were removed as a unit and the lungs were expanded to approximately their normal inspiratory volume with buffered 10 % formalin.
Animals which died spontaneously or which were sacrificed in a moribund condition during the course of the study were given a complete gross pathological examination. In general, representative portions of the organs and tissues listed below from each animal were preserved in buffered 10 % formalin.


HISTOPATHOLOGY: Yes
Slides (hematoxylin and eosin stained) were prepared and histopathologic examinations performed on tissues listed below for 10 animals of each
sex in the control and 75 ppm exposure groups. Similar histopathologic examinations were conducted on all animals that died spontaneously during the course of the study. Target organs identified in the 75 ppm exposure group were also examined for 10 animals in the 5 ppm and 25 ppm exposure groups.

Organs/Tissues:
adipose tissue, adrenals, aorta, brain, cecum, esophagus, eyes, gall bladder, gonads, gross lesions, heart, small intestine, large intestine, kidneys, lacrimal gland, larynx, liver, lungs, lymph nodes (mesenteric & thoracic), mammary gland, nasal turbinates, pancreas, peripheral nerve, pituitary, prostate, salivary gland, seminal vesicles & coagulating glands, skeletal muscle, skin, spinal cord, spleen, stomach, trachea, thymus, thyroid/parathyroid, urinary bladder, uterus, vertebrae with bone marrow

Statistics:

Variances of group body weight changes were analyzed for Bartlett's test for homogeneity of variances (Snedecor and Cochran, 1967). Body weight changes, organ weights, organ-to-body weight ratios, haematology values, clinical chemistry values and urinary specific gravity were evaluated by analysis of variance; differences between control and treatment groups were delineated by Dunnett's test (Steel and Torrie, 1960). The level of significance chosen in all cases was p<0.05.

Clinical signs:

no effects observed

Description (incidence and severity):

Animal observations revealed no discernible effects on appearance or demeanor of mice which were related to exposure.

Mortality:

no mortality observed

Description (incidence):

A female mouse in the 75 ppm group and a male mouse in the 25 ppm group died as a result of traumatic injury. An additional female mouse in the 75 ppm group was sent to pathology in a moribund condition after 5-6 weeks of exposure.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weight gains of male mice in the 5 ppm exposure group were in general significantly higher than for controls during the study. Likewise, mean body weight gains of male mice in the two higher exposure groups (25 and 75 ppm) were generally either higher than for controls or were not different from controls. The mean body weight gains of female mice in the 25 and 75 ppm groups were significantly lower than for controls after 12 weeks of exposure but not at any of the previous weekly weighings. These statistical differences may have resulted from the unusually high mean body weight gain of female mice in the control group (the mean body weight gain of female control mice was even higher than for male control mice). It was concluded that exposure to acrylic acid vapours had no adverse effect on growth of male mice, and a very slight effect, if any, on the growth of female mice.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

Mean hemoglobin values of male mice in the 25 and 75 ppm exposure groups and for female mice in the 75 ppm group were significantly lower than for controls; these effects on hemoglobin of mice were probably related to exposure to the test material, but they were considered to be of only minor toxicologic significance. The reduced white cell count for male mice in the 25 ppm group was considered to be a spontaneous statistical difference.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

The mean alkaline phosphatase values of female mice in the 25 and 75 ppm exposure groups were significantly lower than for controls but decreases in alkaline phosphatase have no known toxicologic significance. All other differences in clinical chemistry parameters of mice (blood urea nitrogen values in male mice) were considered to be spontaneous statistical differences unrelated to exposure due to the absence of a dose-response relationship.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no effects on organ weights or organ-to-body weight ratios of male or female mice which were considered to be related to exposure. All statistical differences in absolute and relative organ weights between control and exposure groups of mice, including relative brain and kidney weights of female mice in the 25 pqm group, and relative heart weights of female mice in the 75 ppm group were considered spontaneous in nature and unrelated to exposure to the test material.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no gross pathologic alterations that were considered to be related to treatment with the test material. Alopecia of variable distribution was the only frequently occurring observation and was observed in nearly all groups including the male and female control groups. Two mice, one female in the 75 ppm exposure group and one male in the 25 ppm exposure group, died spontaneously as a result of traumatic injury incurred while handling. One additional female mouse in the 75 ppm group was sacrificed in a moribund condition. Gross pathological examination of this animal revealed depletion of the abdominal adipose tissue and absence of ingesta in the gastrointestinal tract, suggesting that possibly the animal did not have access to either food or water.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathologic lesions of the olfactory portion of the nasal mucosa were detected in all male and female mice in the 75 ppm exposure group, in all males and nine of ten females in the 25 ppm group, and in one of ten males and four of ten females in the 5 ppm group. These lesions of the nasal mucosa were considered to be a result of treatment with the test material. Similar lesions were not observed in any of the male or female mice in the control group. The nasal lesions of all affected mice were confined to the olfactory portion of the nasal mucosa on the dorsomedial aspect of the nasal passages. However, there was a clearcut dose-response relationship based upon the size of the affected area; the severity of the lesions within the affected area; and the numbers of animals affected. The lesions in mice in the 75 ppm exposure group consisted of: focal degeneration of the olfactory epithelium with partial replacement by an epithelium resembling respiratory epithelium; very slight focal infiltration of principally mononuclear inflammatory cells in the mucosa and submucosa of the affected regions; and very slight focal hyperplasia of the submucosal glands within some of the affected area. Overall, the lesions in these mice were graded as slight to moderate. The lesions of affected mice in the 25 ppm exposure group were limited to slight focal degeneration of the olfactory epithelium, usually without evidence of an inflammatory response. Only very slight focal degeneration of the olfactory mucosa was observed in affected mice in the 5 ppm exposure group. As noted previously, the nasal lesions observed in the mice in this study were confined to the olfactory portions of the nasal mucosa. This distribution of the lesions and their microscopic appearance indicated that the olfactory epithelium of the nasal mucosa is more vulnerable than the respiratory epithelium to the irritant properties of acrylic acid vapour. All other histopathologic observations were considered to be spontaneous in nature and unrelated to treatment with the test material.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEC

Effect level:

0.221 mg/L air (analytical)

Sex:

male

Basis for effect level:

other: Systemic toxicity

Key result

Dose descriptor:

NOAEC

Effect level:

0.015 mg/L air (analytical)

Sex:

female

Basis for effect level:

other: Systemic toxicity

Key result

Dose descriptor:

LOAEC

Effect level:

0.015 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Local effects: focal degeneration of the olfactory epithelium

Critical effects observed:

not specified

For local effects no NOAEC was identified.

Reference 2

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Principles of method if other than guideline:

Male and female Fischer 344 rats were exposed to 0, 5 , 25 or 75 ppm acrylic acid vapours (corresponding to 0, 0.015, 0.074, 0.221 mg/L) 6 hours per day, 5 days per week, for 13 weeks.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): Acrylic acid
- Analytical purity: 99.7 %
- Impurities (identity and concentrations):
- water wt% 0.08,
- monomethyl ether of hydroquione 218 ppm
- Dimer wt% 0.23
- Acetic Acid wt% 0.12
- Propionic Acid wt% 0.15
- Acrolein ppm <25
- Ethyl Acrylate ppm <25
- Phenothiazine ppm 0.10
- Proto-anemonin ppm <20
- Furfural ppm <20
- Source: Celanese Chemical Company

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Wilmington, MA
- Age at study initiation: 3 weeks
- Fasting period before study: no
- Housing: 22-3/cage
- Diet (ad libitum): standard laboratory diet (Purina Laboratory Chow, Ralston Purina Co., St. Louis, MO) except during exposure
- Water: ad libitum
- Acclimation period: 16 days

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: inhalation chambers (14500 liters) with stainless steel pyramidal-shaped ceilings and epoxy resin-coated walls and floors dynamic airflow conditions
- Source and rate of air: Exposure levels of acrylic acid were generated by pumping liquid acrylic acid at calculated rates into glass vaporization flasks heated to approximately 130°C. Vapours from the flasks were swept into the chamber air supply duct with compressed air and mixed with incoming air by turbulence.
- Temperature, humidity, pressure in air chamber: 21 °C, 50 %, slight negative pressure
- Air flow rate: 2500 liters per minute
- Air change rate: 10 air changes per hour


TEST ATMOSPHERE
- Brief description of analytical method used: The actual concentration of acrylic acid in each chamber was measured 2-3 times per hour (12-15 times daily) by infrared spectrophotometry using a Miran I Infrared Analyzer at a wavelength of 8.9 µm. Prior to initiating exposures, distribution of acrylic acid vapours within the chambers was determined to be uniform within 10 % of the target concentrations.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Percent dimer in the liquid acrylic acid monomer varied between 0.4% and 3.7% during the exposure interval.
Analytical concentrations (mean ± SD): 5.0 ± 0.3 ppm; 25 ± 1 ppm; 75 ± 1 ppm

Duration of treatment / exposure:

90 days

Frequency of treatment:

6 hours/day; 5 days/week

Dose / conc.:

5 ppm

Remarks:

analytical concentration

Dose / conc.:

25 ppm

Remarks:

analytical concentration

Dose / conc.:

75 ppm

Remarks:

analytical concentration

No. of animals per sex per dose:

15

Control animals:

yes, sham-exposed

Details on study design:

Post-exposure period: none

Positive control:

none

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily


BODY WEIGHT: Yes
- Time schedule for examinations: on the 1st day of exposure and weekly thereafter


OPHTHALMOSCOPIC EXAMINATION: YES


HAEMATOLOGY: Yes
- Time schedule for collection of blood: 1 week prior to sacrifice
- Anaesthetic used for blood collection: No
- Animals fasted: Yes / No / No data
- How many animals: 10/sex/dose group
- Parameters examined: Packed Cell Volume (PCV), Hemoglobin (Hgb), Erythrocyte count and morphology, Total and differential leukocyte counts


CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the time of sacrifice
- Animals fasted: Yes
- How many animals: 10/sex/dose group
- Parameters examined: Glucose, Blood urea nitrogen (BUN), Alkaline Phosphatase (AP), Glutamic-pyruvic transaminase (SGPT), Total Protein, Albumin, Albumin/Globulin (A/G) Ratio


URINALYSIS: Yes
- Time schedule for collection of urine: 1 week prior to sacrifice
- Metabolism cages used for collection of urine: No
- Animals fasted: No
- Parameters examined: Bilirubin, pH, Glucose, Protein, Ketone, Urobilinogen, Occult Blood, Specific Gravity (refractive ìndex)


NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Approximately 18 hours after the final exposure, animals were sacrificed and submitted to necropsy. Animals were fasted overnight prior to sacrifice. Each animal was examined externally and internally for gross pathologic alterations. Immediately after decapitation, the eyes of each animal were examined by a glass slide technique with fluorescent illumination. Weights of brain, heart, liver, kidneys and testes were determined and recorded. Lungs and trachea were removed as a unit and the lungs were expanded to approximately their normal inspiratory volume with buffered 10 % formalin.
Animals which died spontaneously or which were sacrificed in a moribund condition during the course of the study were given a complete gross pathological examination. In general, representative portions of the organs and tissues listed below from each animal were preserved in buffered 10 % formalin.


HISTOPATHOLOGY: Yes
Slides (hematoxylin and eosin stained) were prepared and histopathologic examinations performed on tissues listed below for 10 animals of each
sex in the control and 75 ppm exposure groups. Similar histopathologic examinations were conducted on all animals that died spontaneously during the course of the study. Target organs identified in the 75 ppm exposure group were also examined for 10 animals in the 5 ppm and 25 ppm exposure groups.

Organs/Tissues:
adipose tissue, adrenals, aorta, brain, cecum, esophagus, eyes, gonads, gross lesions, heart, small intestine, large intestine, kidneys, lacrimal gland, larynx, liver, lungs, lymph nodes (mesenteric & thoracic), mammary gland, nasal turbinates, pancreas, peripheral nerve, pituitary, prostate, salivary gland, seminal vesicles & coagulating glands, skeletal muscle, skin, spinal cord, spleen, stomach, tongue, trachea, thymus, thyroid/parathyroid, urinary bladder, uterus, vertebrae with bone marrow, zymbal gland

Statistics:

Variances of group body weight changes were analyzed for Bartlett's test for homogeneity of variances (Snedecor and Cochran, 1967). Body weight changes, organ weights, organ-to-body weight ratios, haematology values, clinical chemistry values and urinary specific gravity were evaluated by analysis of variance; differences between control and treatment groups were delineated by Dunnett's test (Steel and Torrie, 1960). The level of significance chosen in all cases was p<0.05.

Clinical signs:

no effects observed

Description (incidence and severity):

Animal observations revealed no discernible effects on appearance or demeanor of rats which were related to exposure.

Mortality:

no mortality observed

Description (incidence):

There were no spontaneous deaths of rats during the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weight gains of male and female rats in the 5, 25 and 75 ppm exposure groups were not different from controls except during the first
two weeks of exposure when the body weight gains of female rats in the 5 and 25 ppm groups were statistically higher than for controls. Thus exposure to 5, 25 or 75 ppm acrylic acid vapors had no adverse effect on growth of male or female rats.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

There were no statistical differences, in hematologic values of male rats or female rats exposed to acrylic acid vapours which were considered
to be related to exposure. The reduced white cell count for male rats in the 25 ppm group was considered to be a spontaneous statistical difference unrelated to exposure in view of the absence of any effect on white cell count for animals in the higher (75 ppm) exposure group.

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Mean alkaline phosphatase values of female rats in the 75 ppm group were significantly higher than for controls; this effect may have been related to exposure but is of uncertain toxicologic significance. All other differences in clinical chemistry parameters of rats (glucose values) were considered to be spontaneous statistical differences unrelated to exposure due to the absence of a dose-response relationship.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no discernible effects on urinalysis parameters of male or female rats. Statistical analyses of urinary specific gravity values revealed no significant differences between control and exposure groups of rats.

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no effects on organ weights or organ-to-body weight ratios of male or female rats which were considered to be related to exposure. All statistical differences in absolute and relative organ weights between control and exposure groups of rats, including absolute and relative liver weights of male rats in the 5 ppm group and relative liver weights of female rats in the 5 ppm group were considered spontaneous in nature and unrelated to exposure to the test material.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no gross pathologic observations which were considered to be related to treatment with the test material. All gross pathologic observations on the male and female rats in this study were considered to be spontaneous in nature and typical of those usually encountered in rats of this strain and age.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathologic lesions of the nasal mucosa were observed in 7/10 male and 10/10 female rats in the 75 ppm exposure group but not in rats in the 25 or 5 ppm exposure groups; these were the only lesions considered to be related to treatment. In affected rats in the 75 ppm exposure group, the nasal lesions consisted of slight focal degeneration of the olfactory epithelium on the dorsomedial aspect of the nasal passages. The nasal lesions in most affected rats were detected only in the most rostral of four cross sections obtained through the nasal. However, lesions were observed in the more caudal sections in a few cases. The lesions were characterized principally by disorganization of the normal arrangement of the nuclei of the olfactory epithelium and associated mild degenerative alterations of the epithelial cells in the affected regions. No lesions of the nasal mucosa were observed in 3/10 male rats in the 75 ppm group. Since it was possible that the original sections prepared for these rats were not through the proper portion of the nasal passages, additional sections were prepared. Examination of these additional sections also failed to reveal any discernible lesions. As indicated above, no lesions of the nasal mucosa were observed in either male or female rats in the groups exposed to 25 or 5 ppm acrylic acid. Slight subacute inflammatory lesions were observed in the nasal mucosa of one female rat in the control group. These lesions were unlike the lesions observed in the rats in the 75 ppm group. All other observations were considered to be spontaneous in nature and unrelated to treatment with the test material.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEC

Effect level:

0.074 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Local effects

Key result

Dose descriptor:

NOAEC

Effect level:

0.221 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Systemic toxicity

Dose descriptor:

LOAEC

Effect level:

0.221 mg/L air (analytical)

Sex:

male/female

Basis for effect level:

other: Local effects: focal degeneration of the olfactory epithelium

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LOAEC

15 mg/m³

Study duration:

subchronic

Species:

mouse

Quality of whole database:

similar to OECD TG 413

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 Dec 1986 - 03 Mar 1987 (experimental)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

Principles of method if other than guideline:

13-week dermal irritation study conducted in three strains of mice to assess the MTD.

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): acrylic acid
- Source: Celanese
- Analytical purity: 99.5 %
- Impurities (identity and concentrations): 220 ppm of the inhibitor monomethyl ether of hydroquinone (maximum concentration)

Species:

mouse

Strain:

other: ICR, C3H, B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hilltop Lab Animals, Inc. Scottdale, Pennsylvania
- Age at study initiation: 42 days old
- Weight at study initiation:
- female ICR mice: 18.8 - 27.2 g,
- male C3H: 22.0 - 26.5 g,
- female B6C3F1: 18.4 - 24.2 g
- Housing: singly
- Diet (ad libitum): Purina Rodent Chow #5002, Purina Company, Richmond, Indiana
- Water (ad libitum): tap water
- Acclimation period: 1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 40 to 70 %
- Air changes (per hr): 8-10
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To:

Type of coverage:

open

Vehicle:

acetone

Details on exposure:

Route of Administration: dermal
At weekly intervals for each dose, dosing solutions were prepared from a pre-calculated volume of test article mixed with a predetermined set volume of acetone.

TEST SITE
- Area of exposure: shaved dorsal area (dorsal mid-line midway between the caudal margin of the scapulae and the last rib); approx. 1 cm2
- Time intervals for shavings or clipplings: more than 20 hours before treatment

REMOVAL OF TEST SUBSTANCE
- Washing: no

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 µL
- Concentration (if solution): 1 and 4 %
- Constant volume or concentration used: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were taken for analysis weekly, but only week 1, 4, 8 and 12 samples were analyzed for acrylic acid and dimer content. The 1 % solution varied from 95 to 134 % of target with an average of 108 %. The 4 % solutions varied from 97 to 121 % of target with an average of 103 %. The dimer content of the test article varied from 0.81 to 1.91 %. Dimer content in the dosing solutions did not vary over the one week dosing period.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

3 days/week

Dose / conc.:

52 mg/kg bw/day

Dose / conc.:

208 mg/kg bw/day

No. of animals per sex per dose:

30

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: no

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily during dosing period

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily during dosing period

DERMAL IRRITATION: Yes
- Time schedule for examinations: daily
All animals were observed daily for grading of skin reaction. The six parameters observed were erythema, edema, desquamation, fissuring, eschar and exfoliation.

BODY WEIGHT: Yes
- Time schedule for examinations: two days prior to dosing, on the first day of dosing, at weekly intervals thereafter for the duration of dosing and at terminal necropsy.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Gross examinations were performed and a skin section of approximately 2 cm X 1.5 cm was taken from the test site and an untreated section of skin from the scored area as well as the carcass were placed in 10 % neutral buffered formalin. The treated skin section was divided into three sections
oriented transversely and embedded in glycol methacrylate (Pathology Associates, Inc. Durham, NC). These were stained with hematoxylin and eosin and examined microscopically by a veterinary pathologist.

Clinical signs:

no effects observed

Description (incidence and severity):

The only clinical signs observed other than shaving injuries were a swollen anus during week 7 in a control mouse, hunched posture and thinness prior to death of a control (0%) ICR mouse. All the above signs are considered incidental findings and unrelated to the test article.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

In the ICR mice receiving 1% solutions, dermal desquamation was observed in 2 of 25 mice on day 14 only. Erythema was noted in B6C3FI mice receiving control and 1% solutions during weeks 2, 3 or 4. No other reactions were seen in the control and 1% dose level groups. The predominant reactions observed occurred predominately in the mice receiving 4% solutions on the dorsal thorax.
Minimal erythema changes scored as a 1 (slight or barely perceptible) were observed predominantly in the B6C3F1 strain during the first five weeks. Erythema was first observed as early as day 4.
Edema was observed at the end of the first week but only in the C3H strain. The maximum score was 1.
The major reactions of the skin were desquamation, fissuring and eschar seen in all strains of mice at the 4% dose level.
Desquamation was observed during the first week. The onset of marked desquamation (score of 3) occurred with a higher frequency with the C3H strain. This was followed by the B6C3F1 strain. After peaking at 21 days, the C3H strain remained the more severely affected group until day 35. Using chi-square to determine if a strain difference existed, significances were noted on days 7, 11, 14, 18, 25, 28 and 32. No differences were noted on days 21, 35, 39 and 42. Therefore, it was observed that desquamation occurred in all strains and was at its peak approximately on day 21 but the onset varied.
Fissuring was first observed after the first week. On day 18 the frequency of slight fissuring (score of 1) was greater in the ICR strain yet on days 32 and 35 the range (0 to 3) and frequency was greater in the C3H strain. Using chi-square, strain differences existed on days 18, 32 and 35.
Eschar was observed during the first week initially in the C3H strain. During the second week the B6C3F1 strain displayed this reaction. At no time interval did the ICR strain mice show any eschar.
Exfoliation followed the same time course and strain difference as eschar.
Therefore, there were strain differences within the six parameters of skin reactions evaluated but there were no consistent strain differences across the six parameters.

Mortality:

no mortality observed

Description (incidence):

Five mice died during the study. Of these, three (4% ICR, 1% C3H and 0% B6C3F1) were accidental deaths due to animals getting caught in feeders, watering opening or cage openings. The cause of death of two mice were undetermined; one of these mice was a control (0%) ICR mouse and one was a 1% C3H mouse. All other animals survived to terminal necropsy.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weights of control and compound-treated mice were comparable throughout the 13-week dosing period.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

The gross lesions observed were in the lungs, kidneys, adrenals, ovary/uterus, lymph nodes and skin. In the lungs and kidneys, reddening or white-grey foci were noted in various dose groups. Darkened adrenals were observed in all dose groups of the C3H mice beginning at the 4-week interim necropsy. Enlarged or cystic ovary or uterus and enlarged lymph nodes were observed in the 1% groups of all strains. Alopecia in a 1 % mouse was noted on the abdomen of one B6C3F1 mouse at terminal necropsy.
All lesions except the skin reactions noted in the treated area did not appear to be related to compound treatment.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Microscopic findings in the dermis and epidermis described as proliferative degenerative or inflammatory changes were seen predominantly in the 4% treatment level in all mouse strains; similar findings were seen occasionally in the 1% dose groups but rarely in the control groups. Dysplasia and hyperplasia were not seen in tissues from any of the groups.
The proliferative changes involving the epidermis and, to a lesser degree, the dermis were characterized as parakeratosis, granulosis and acanthosis of moderate degree and were consistent findings throughout all the 4% groups. Minimal to mild fibroplasia were almost entirely confined to the 4% groups. Sebaceous gland hyperplasia was recognized in the pilosebaceous apparatus of most of the animals in the 4% dose level. Necrosis was the most frequent degenerative change observed in the 4% level. This lesion was characterized by large eosinophilic changes resembling edema in the dermis; however, the squamous cells could be seen faintly as ghost cells. These areas could often be traced out to areas that were transformed into early parakeratosis. Crusts and ulcers were occasionally observed but with no constant feature. Inflammatory changes in the epidermis consisted of occasional pustules and exocytosis. Dermal infiltrates were almost entirely leukocytic predominantly with neutrophils and eosinophils. Macrophages and mast cells appeared to a minimal or lesser degree in most sections.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEL

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Critical effects observed:

not specified

Summary

Results of the present study with three strains of mice receiving acrylic acid dermally at levels of 4, 1 and 0% for 13 weeks caused comparable skin irritation to ICR, C3H and B6C3F1 mice at the 4% dose level. Minimal skin reactions were observed in all strains at the 1% dose level. Gross lesions other than skin reactions were incidental to treatment. Microscopic findings characterized as proliferative, degenerative or inflammatory changes were seen predominantly at the 4% level in all strains, occasionally at the 1% level and only rarely in controls. Body weights of all strains at all dose levels were similar.

Current guidelines for dose selection in chronic dermal studies retrospectively were applied to this study to ascertain MTD. Using proposed MTD criteria established in the EPA Workshops on dermal carcinogenesis bioassays, microscopic and gross changes to the skin in subchronic studies can easily be used to classify skin response as exceeding the MTD, reaching the MTD, or tolerating the treatment dose. However, one must be aware of certain hazards to interpretation. The present work shows that microscopic examination alone at the end of 13 wk of treatment could adequately categorize tolerated doses from those exceeding the MTD. Similarily, gross examination of the skin throughout the whole course of exposure could be used to identify concentrations in excess of a tolerated dose. However, gross examination alone, performed only at final autopsy, would miss early skin lesions that would trigger 'exceeding MTD' classification. There appears to be a 'hardening' or accommodation of the skin to irritants such as acrylic acid with repeated insult, reflected by the apparent refractoriness to irritation that developed after 8 wk in this study. Data collected during visual examination prior to wk 8 indicate that the MTD had been reached or exceeded. Data collected by gross examination after 8 wk of exposure suggest that the 4% acrylic acid would be tolerated in a long-term exposure. However, microscopic examination after 13 wk showed that 4% acrylic acid clearly exceeds MTD. Thus, microscopic findings provided a more sensitive index for exceeding MTD than gross observations taken only at autopsy, but generally correlated well for MTD if gross observations were taken at regular intervals during treatment. Gross examination at study termination alone would be insufficient to predict doses for use in a chronic dermal study. Acrylic acid at 1% in acetone was fairly well tolerated by all mice in all strains, although signs suggest that the MTD was approached. Thus, 1% acrylic acid in acetone, one-quarter of that concentration in clear excess of MTD, would be the appropriate dose concentration for lifetime skin studies, based on MTD criteria.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Study duration:

subchronic

Species:

mouse

Quality of whole database:

similar to OECD TG 411

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03 Dec 1986 - 03 Mar 1987 (experimental)

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

Principles of method if other than guideline:

13-week dermal irritation study conducted in three strains of mice to assess the MTD.

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): acrylic acid
- Source: Celanese
- Analytical purity: 99.5 %
- Impurities (identity and concentrations): 220 ppm of the inhibitor monomethyl ether of hydroquinone (maximum concentration)

Species:

mouse

Strain:

other: ICR, C3H, B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hilltop Lab Animals, Inc. Scottdale, Pennsylvania
- Age at study initiation: 42 days old
- Weight at study initiation:
- female ICR mice: 18.8 - 27.2 g,
- male C3H: 22.0 - 26.5 g,
- female B6C3F1: 18.4 - 24.2 g
- Housing: singly
- Diet (ad libitum): Purina Rodent Chow #5002, Purina Company, Richmond, Indiana
- Water (ad libitum): tap water
- Acclimation period: 1 week


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 40 to 70 %
- Air changes (per hr): 8-10
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To:

Type of coverage:

open

Vehicle:

acetone

Details on exposure:

Route of Administration: dermal
At weekly intervals for each dose, dosing solutions were prepared from a pre-calculated volume of test article mixed with a predetermined set volume of acetone.

TEST SITE
- Area of exposure: shaved dorsal area (dorsal mid-line midway between the caudal margin of the scapulae and the last rib); approx. 1 cm2
- Time intervals for shavings or clipplings: more than 20 hours before treatment

REMOVAL OF TEST SUBSTANCE
- Washing: no

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 µL
- Concentration (if solution): 1 and 4 %
- Constant volume or concentration used: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples were taken for analysis weekly, but only week 1, 4, 8 and 12 samples were analyzed for acrylic acid and dimer content. The 1 % solution varied from 95 to 134 % of target with an average of 108 %. The 4 % solutions varied from 97 to 121 % of target with an average of 103 %. The dimer content of the test article varied from 0.81 to 1.91 %. Dimer content in the dosing solutions did not vary over the one week dosing period.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

3 days/week

Dose / conc.:

52 mg/kg bw/day

Dose / conc.:

208 mg/kg bw/day

No. of animals per sex per dose:

30

Control animals:

yes, concurrent vehicle

Details on study design:

Post-exposure period: no

Positive control:

no

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily during dosing period

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily during dosing period

DERMAL IRRITATION: Yes
- Time schedule for examinations: daily
All animals were observed daily for grading of skin reaction. The six parameters observed were erythema, edema, desquamation, fissuring, eschar and exfoliation.

BODY WEIGHT: Yes
- Time schedule for examinations: two days prior to dosing, on the first day of dosing, at weekly intervals thereafter for the duration of dosing and at terminal necropsy.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes

Gross examinations were performed and a skin section of approximately 2 cm X 1.5 cm was taken from the test site and an untreated section of skin from the scored area as well as the carcass were placed in 10 % neutral buffered formalin. The treated skin section was divided into three sections
oriented transversely and embedded in glycol methacrylate (Pathology Associates, Inc. Durham, NC). These were stained with hematoxylin and eosin and examined microscopically by a veterinary pathologist.

Clinical signs:

no effects observed

Description (incidence and severity):

The only clinical signs observed other than shaving injuries were a swollen anus during week 7 in a control mouse, hunched posture and thinness prior to death of a control (0%) ICR mouse. All the above signs are considered incidental findings and unrelated to the test article.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

In the ICR mice receiving 1% solutions, dermal desquamation was observed in 2 of 25 mice on day 14 only. Erythema was noted in B6C3FI mice receiving control and 1% solutions during weeks 2, 3 or 4. No other reactions were seen in the control and 1% dose level groups. The predominant reactions observed occurred predominately in the mice receiving 4% solutions on the dorsal thorax.
Minimal erythema changes scored as a 1 (slight or barely perceptible) were observed predominantly in the B6C3F1 strain during the first five weeks. Erythema was first observed as early as day 4.
Edema was observed at the end of the first week but only in the C3H strain. The maximum score was 1.
The major reactions of the skin were desquamation, fissuring and eschar seen in all strains of mice at the 4% dose level.
Desquamation was observed during the first week. The onset of marked desquamation (score of 3) occurred with a higher frequency with the C3H strain. This was followed by the B6C3F1 strain. After peaking at 21 days, the C3H strain remained the more severely affected group until day 35. Using chi-square to determine if a strain difference existed, significances were noted on days 7, 11, 14, 18, 25, 28 and 32. No differences were noted on days 21, 35, 39 and 42. Therefore, it was observed that desquamation occurred in all strains and was at its peak approximately on day 21 but the onset varied.
Fissuring was first observed after the first week. On day 18 the frequency of slight fissuring (score of 1) was greater in the ICR strain yet on days 32 and 35 the range (0 to 3) and frequency was greater in the C3H strain. Using chi-square, strain differences existed on days 18, 32 and 35.
Eschar was observed during the first week initially in the C3H strain. During the second week the B6C3F1 strain displayed this reaction. At no time interval did the ICR strain mice show any eschar.
Exfoliation followed the same time course and strain difference as eschar.
Therefore, there were strain differences within the six parameters of skin reactions evaluated but there were no consistent strain differences across the six parameters.

Mortality:

no mortality observed

Description (incidence):

Five mice died during the study. Of these, three (4% ICR, 1% C3H and 0% B6C3F1) were accidental deaths due to animals getting caught in feeders, watering opening or cage openings. The cause of death of two mice were undetermined; one of these mice was a control (0%) ICR mouse and one was a 1% C3H mouse. All other animals survived to terminal necropsy.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weights of control and compound-treated mice were comparable throughout the 13-week dosing period.

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

The gross lesions observed were in the lungs, kidneys, adrenals, ovary/uterus, lymph nodes and skin. In the lungs and kidneys, reddening or white-grey foci were noted in various dose groups. Darkened adrenals were observed in all dose groups of the C3H mice beginning at the 4-week interim necropsy. Enlarged or cystic ovary or uterus and enlarged lymph nodes were observed in the 1% groups of all strains. Alopecia in a 1 % mouse was noted on the abdomen of one B6C3F1 mouse at terminal necropsy.
All lesions except the skin reactions noted in the treated area did not appear to be related to compound treatment.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Microscopic findings in the dermis and epidermis described as proliferative degenerative or inflammatory changes were seen predominantly in the 4% treatment level in all mouse strains; similar findings were seen occasionally in the 1% dose groups but rarely in the control groups. Dysplasia and hyperplasia were not seen in tissues from any of the groups.
The proliferative changes involving the epidermis and, to a lesser degree, the dermis were characterized as parakeratosis, granulosis and acanthosis of moderate degree and were consistent findings throughout all the 4% groups. Minimal to mild fibroplasia were almost entirely confined to the 4% groups. Sebaceous gland hyperplasia was recognized in the pilosebaceous apparatus of most of the animals in the 4% dose level. Necrosis was the most frequent degenerative change observed in the 4% level. This lesion was characterized by large eosinophilic changes resembling edema in the dermis; however, the squamous cells could be seen faintly as ghost cells. These areas could often be traced out to areas that were transformed into early parakeratosis. Crusts and ulcers were occasionally observed but with no constant feature. Inflammatory changes in the epidermis consisted of occasional pustules and exocytosis. Dermal infiltrates were almost entirely leukocytic predominantly with neutrophils and eosinophils. Macrophages and mast cells appeared to a minimal or lesser degree in most sections.

Histopathological findings: neoplastic:

no effects observed

Key result

Dose descriptor:

NOAEL

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Critical effects observed:

not specified

Summary

Results of the present study with three strains of mice receiving acrylic acid dermally at levels of 4, 1 and 0% for 13 weeks caused comparable skin irritation to ICR, C3H and B6C3F1 mice at the 4% dose level. Minimal skin reactions were observed in all strains at the 1% dose level. Gross lesions other than skin reactions were incidental to treatment. Microscopic findings characterized as proliferative, degenerative or inflammatory changes were seen predominantly at the 4% level in all strains, occasionally at the 1% level and only rarely in controls. Body weights of all strains at all dose levels were similar.

Current guidelines for dose selection in chronic dermal studies retrospectively were applied to this study to ascertain MTD. Using proposed MTD criteria established in the EPA Workshops on dermal carcinogenesis bioassays, microscopic and gross changes to the skin in subchronic studies can easily be used to classify skin response as exceeding the MTD, reaching the MTD, or tolerating the treatment dose. However, one must be aware of certain hazards to interpretation. The present work shows that microscopic examination alone at the end of 13 wk of treatment could adequately categorize tolerated doses from those exceeding the MTD. Similarily, gross examination of the skin throughout the whole course of exposure could be used to identify concentrations in excess of a tolerated dose. However, gross examination alone, performed only at final autopsy, would miss early skin lesions that would trigger 'exceeding MTD' classification. There appears to be a 'hardening' or accommodation of the skin to irritants such as acrylic acid with repeated insult, reflected by the apparent refractoriness to irritation that developed after 8 wk in this study. Data collected during visual examination prior to wk 8 indicate that the MTD had been reached or exceeded. Data collected by gross examination after 8 wk of exposure suggest that the 4% acrylic acid would be tolerated in a long-term exposure. However, microscopic examination after 13 wk showed that 4% acrylic acid clearly exceeds MTD. Thus, microscopic findings provided a more sensitive index for exceeding MTD than gross observations taken only at autopsy, but generally correlated well for MTD if gross observations were taken at regular intervals during treatment. Gross examination at study termination alone would be insufficient to predict doses for use in a chronic dermal study. Acrylic acid at 1% in acetone was fairly well tolerated by all mice in all strains, although signs suggest that the MTD was approached. Thus, 1% acrylic acid in acetone, one-quarter of that concentration in clear excess of MTD, would be the appropriate dose concentration for lifetime skin studies, based on MTD criteria.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Study duration:

subchronic

Species:

mouse

Quality of whole database:

similar to OECD TG 411

Additional information

Repeated dose toxicity: Oral administration

In an oral 90-day study (BASF AG, 1987; Hellwig et al., 1993) acrylic acid (purity: approx. 99 %) was administered by gavage in two dosages (150 and 375 mg/kg bw/d) to Wistar rats. The testing parameters did not include hematology, clinical chemistry, urinalysis.

The clinical examinations revealed vocalization beginning after the first week of treatment and tympania of the gastrointestinal tract, which was frequently accompanied with cyanosis and dyspnoea, in most of the animals from week 3 onwards. 6 males and 9 females of the high-dose group and 5 males and 5 females of the low-dose group died prematurely (day 14-81 of the treatment) showing apathy, hypothermia and piloerection before death. Dose-related severe toxic effects were recorded in both dose groups consisting of reduced body weight gain, thickening of the plica marginata and hyperaemia or erosions/ulcerations of the gastric mucosa. Degeneration/necrosis of renal tubules were observed in the five males in each of both dose groups and four and seven females of the low and high dose groups, respectively, that died during the study. Other gross- and histopathological findings were: catarrhal or catarrhal purulent rhinitis in some of the animals, elevations of the diaphragma (Roemheld syndrome), pulmonary edema/emphysema and alveolar hyperemia and dystelectases as a consequence of the already clinically evident tympania.

The LOAEL of this study was 150 mg/kg bw, no NOAEL was derived.

 

Wistar rats which received acrylic acid in the drinking water at doses of 120, 800, 2000 or 5000 ppm (corresponding to approx. 6, 40, 100 or 200 mg/kg bw/d in males, and 10, 66, 150 or 375 mg/kg bw/d in females) for 3 months (10 rats/group/sex) and 12 months (20 rats/group/sex) showed reduced water consumption at 2000 ppm and 5000 ppm dosages (BASF AG, 1987; Hellwig et al., 1993). No treatment-related premature deaths occurred. Lower food consumption was seen in high dose males and reduced body weight gain was observed in males from 2000 ppm and 5000 ppm groups. No treatment-related effects on haematology, clinical chemistry, and urine parameters were found. No substance-related toxic effect could be microscopically demonstrated in a comprehensive list of organs examined in the two high doses. Obviously due to the bad palatability treated animals had lower drinking water uptake, which was considered to result in lower food consumption and body weight gain. Mortality and toxic effects in the kidney and the stomach found in the gavage study were not confirmed in this study at comparable doses indicating that these effects were attributable to high local and blood peak values after bolus administration by gavage.

Based on the reduced body weight gain in males and lower water consumption in both sexes, the NOAEL of this study was considered to be 800 ppm in male rats (corresponding to 40 mg/kg bw/day). In females the NOAEL was considered to be 5000 ppm (corresponding to 375 mg/kg bw/day) since reduced water consumption was not interpreted as a clear adverse health effect.

 

Fischer 344 rats (15 animals/sex/group) in another 90-day drinking water study (Inter-Company Acrylate Study Group, 1980; DePass et al., 1983) were administered doses of 83, 250, or 750 mg/kg bw/d of acrylic acid. No deaths occurred during the treatment period. However, clear dose-related effects were observed. At the high-dose level there was reduced food and water consumption, reduced body weight gain, lower organ weights of liver, kidneys, spleen, heart, brain, and elevated testes weight and some altered clinical chemistry parameters (increased levels of serum urea nitrogen, glucose, alkaline phosphatase and aspartate transaminase). Furthermore, there was a statistically significant decrease in total serum cholesterol noted for the high level females. In both sexes increases of urinary protein and specific gravity and a decrease in urinary pH values were noted. No significant prevalence of microscopic lesions was found in any of the animals. At 250 mg/kg bw, a decrease in water consumption was noted for both sexes. Body weight gain was lower in females. Kidney weights were increased in both sexes and relative testes weights were increased in males. Effects on serum urea nitrogen, cholesterol and alkaline phosphatase in female rats and urinary specific gravity and protein in both sexes were similar, but less pronounced than those observed at the high dose level.

At 83 mg/kg bw the only effects noted were a reduction of water consumption by male rats and a slight increase in red blood cells in female rats. Both findings were not considered to be of toxicological relevance, therefore 83 mg/kg bw was the NOAEL of this study.

Groups of Fischer 344 rats were administered acrylic acid in the diet or drinking water in various doses (IATG, 1979). Body weight depression was observed at <0.18% AA in drinking water and <2% in diet.

Young adult albino rats were treated with 400 ppm of sodium acrylate (with the diet) for 10 weeks followed by three weeks at 800 ppm treatment. Four rats were given seven successive doses of 100 mg/kg over the next nine days. No adverse effect on behaviour was observed (Barnes, 1970).

23 rabbits were administered acrylic acid orally at doses of 0.025, 0.25, 2.5 mg/kg bw. The LOAEL was 0.25 mg/kg bw/day due to variations in the biochemical indices (alkalinity, chlorides), increased extension of sugar in the urine and certain histopathological changes in the liver, kidneys and suprarenal glands (Klimkina, 1969). However, the documentation was insufficient and therefore the study was not used for assessment of repeated dose toxicity.

In a further study 10 male rats were administered acrylic acid (10% aqueous solution) by gavage (according to the modified method of Limy, R. K. S. et al. (Arch int. pharmacodyn., 130, 336) over a study period of 20 days. The administered dose increased of up to 50% every 4 days and varied from 135 mg/kg bw to 684 mg/kg bw. Only changes in the stomach of the treated animals were observed (e.g. thickening of the squamous epithelium and proliferation of the germ layer as well as subepithelial inflammation). No NOAEL could be determined due to insufficient documentation.

Two probe studies were performed to determine the best exposure route to use (diet or drinking water) for a sub-chronic study and to determine the dose level for a sub-chronic study (BASF AG, 1981). After administration in drinking water for 7 days a NOAEL of ca. 410 mg/kg bw/day was determined and after administration in diet a NOAEL of ca. 650 mg/kg bw/day was reported. No further information is available.

Repeated dose toxicity: Inhalation route

A 90-day inhalation study on Fischer 344 rats and B6C3F1 mice (Industry Acrylate Testing Group, 1979; Miller et al., 1981) using 15 animals/sex/group exposed to doses of 5, 25 or 75 ppm (corresponding to approx. 0.015, 0.074 or 0.221 mg/L) of acrylic acid vapour on 6 hours/day on 5 days/week had no adverse effect on the growth of male and female rats and male mice. However, the mean body weight gains of female mice in the 25 and 75 ppm exposure groups were statistically lower than for controls after 12 weeks of exposure. There were no effects on absolute or relative weights of brain, heart, liver, kidneys or testes for either rats or mice which were considered to be related to exposure. Hematologic values of male and female rats were unaffected by exposure to acrylic acid vapours except for slight, although statistically significant, reductions in mean hemoglobin values for male mice in the 25 and 75 ppm exposure groups as well as for female mice in the 75 ppm exposure groups. Although these reductions in hemoglobin of mice were probably related to exposure, they were considered of only minor toxicologic significance. Serum alkaline phosphatase values of female rats in the 75 ppm exposure group were higher than for controls; possibly as a result of exposure to the test material. Urinalysis parameters of male and female rats were not altered by the exposures. Gross pathologic examinations revealed no alterations in either rats or mice which were considered to be related to exposure to the test material. Histopathologic examination of an extensive list of tissues from 10 rats per sex in the 0 and 75 ppm exposure groups and of the nasal turbinates of 10 rats per sex in the 25 and 5 ppm groups revealed slight degenerative lesions of the nasal mucosa of 7/10 male and 10/10 female rats in the 75 ppm exposure group that were attributed to treatment with the test material. No histopathologic alterations that could be attributed to treatment were detected in any of the male or female rats in the 25 and 5 ppm exposure groups.

Histopathologic examination of an extensive list of tissues of 10 mice per sex from the control and 75 ppm groups and of the nasal turbinate tissue of 10 mice per sex from the 5 and 25 ppm groups revealed lesions of the nasal mucosa of some or all mice at each treatment level that were considered to be related to treatment. The nasal lesions observed at all exposure levels were limited to the olfactory portions of the nasal mucosa. Mice in the 75 ppm exposure group had slight to moderate focal degeneration of the olfactory epithelium which was accompanied by very slight inflammatory cell infiltration and very slight hyperplasia of the submucosal glands in the affected areas. In some of the affected regions, the olfactory epithelium had been replaced by an epithelium that resembled respiratory epithelium. Slight focal degeneration of the olfactory nasal mucosa was observed in ten of ten male and nine of ten female mice in the 25 ppm exposure group. Only very slight focal degeneration of the olfactory mucosa was detected in one of ten males and four of ten females in the 5 ppm group. Three mice, one male in the 25 ppm group and two females in the 75 ppm group, died during the course of the study. None of these early deaths appeared to be related to treatment with the test material.

It was concluded that the nasal lesions observed in the mice in this study were a result of the irritant properties of acrylic acid vapour and that the olfactory epithelium of the nasal passages was more susceptible than the respiratory epithelium to the irritant properties of this vapour. Results of the study indicate that mice are more susceptible than rats to acrylic acid vapours.

In this study, histopathology of four cross-sections were examined in 10 animals/sex/group at different levels of the nasal turbinates, being the target organ identified. For local effects, this study revealed a NOAEC of 25 ppm (corresponding to approx. 0.074 mg/L) for rats. No local NOAEC was derived in mice, the LOAEC (local) was 5 ppm (corresponding to approx. 0.015 mg/L). There was no systemic toxicity in rats and male mice and the systemic NOAEC was therefore 75 ppm (corresponding to approx. 0.221 mgL). Because of lower body weight gain, the NOAEC for female mice was 5 ppm (corresponding to approx. 0.015 mg/L).

 

 

Male F-344 rats (180-280 g) and male B6C3F1 mice (20-30 g) were used in studies designed to quantify the nasal dose of acrylic acid after vapour exposure (Barrow, 1986). The animals were first pretreated by whole-body exposure to a target concentration of 75 ppm acrylic acid 6 h/day for 4 days. On the fifth day, groups of two rats or two mice were exposed to these same target concentrations of AA for 6 h in a glass, head-only chamber. Respiratory rates and tidal volumes were measured before and during exposure to AA by a body plethysmograph technique.Since this study was designed to quantify the amount of chemical inhaled, only the inspiratory tidal volume was recorded. From the tidal volume and respiratory rate recordings, minute volume was calculated. A total of 7-10 rats or mice were studied.

Respiratory function (respiratory minute volumes (-23% in rats, -27-34% in mice) and respiratory rates (-17% in rats, -32-37% in mice) were slightly depressed after inhalation of 75 ppm acrylic acid vapour by male rats and male mice for 5 days (6 h/d). Assuming an even distribution of acrylic acid, the dose expressed as acrylic acid concentration (µL/L)/minute volume (L/min)/nasal cavity surface area (cm²) was nearly twice in mice (3.5-3.8 µL/min/cm²) than in rats (1.8-2.1 µL/min/cm²). Histopathology of sections from four levels of the nasal cavity was characterised by severe lesions in both species. Mice had more severe lesions, as seen by the presence of more cellular exudate in the lumen of the nose and a much greater loss of sensory cells. Under the assumption of an evenly distributed chemical the damage of the tissue should be distributed regularly throughout the nasal cavity. However, the principal location of the lesions was on the dorsal meatus of level 3, where epithelial cell counts indicated a 50 percent decrease in mice versus 15 percent in rats. Cell proliferation studies showed a statistically significant increase in cell turnover of the olfactory epithelium in the dorsal meatus of both species. Turnover rate was 4 percent in treated rats (versus 0.9 percent in controls) and 1.7 percent in treated mice (versus 0.1 percent in controls).

 

Evaluation of various daily exposure periods on the nasal irritation observed in mice following sub-acute inhalation exposure to acrylic acid was investigated by Rohm& Haas and Lomax 1994. No adverse effects resulting from 5 ppm for 6 hr/day acrylic acid exposure of female mice were detected histopathologically .The toxic effects induced by Acrylic Acid in the nasal cavity were fully reversible for the dose groups exposed to 25 ppm x 6 hr/day or less of acrylic acid based on histopathological analysis. The more severe toxic effects observed at 25 ppm for 22 hr/day exposure induce a change in which regions of sensitive olfactory epithelium are replaced with an epithelium that appears morphologically identical to resistant respiratory epithelium. This process has previously been described as respiratory metaplasia.

In a further test, the animals (2 female, 2 male rats) were exposed to dynamic atmospheres, at acrylic acid vapour concentrations of 1500, 300, and 80 ppm (corresponding to approx. 4.49, 0.90, and 0.24 mg/L) 6h/day for a period of 4 (high dose) and 20 days (mid and low dose), respectively. The LOAEC was 0.9 mg/L due to nasal irritation (Gage 1970).

In a sub-acute inhalation study with 10 Wistar rats, which were exposed to an test atmosphere of 0.7 mg/L acrylic acid for 4 h/d on 6 d/w for 5 weeks reduced body weight and food consumption, increased number of reticulocyte, lower specific urine weight; lower relative and absolute liver weight; inflammable lung tissue infiltrations, inflammations of the bronchial mucosa, serous/ulcerous exudates in the bronchial lumen, proliferations in the lymphatic peribronchial tissue, infiltrations in the broncheoli and oedema of the connective tissue were observed (Majka, 1974).

Repeated dose toxicity: Dermal route

Skin irritation become prevalent with higher incidence and severity in mice treated with 4 % acrylic acid compared to 1 % acrylic acid or vehicle control (acetone) after 13 weeks of dermal application (3 d/wk) (Basic Acrylate Monomer Manufacturers, 1987; Tegeris et al., 1988). No irritant effect was evident after long-term application of 1 % acrylic acid in acetone in mice Basic Acrylate Monomer Manufacturers, 1990, see Section 7.7 Carcinogencity).

The application of 5, 6 or 7% test substance resulted in skin lesions in female mice and changes of varying degree. A “No effect level” could not be determined after 90 days. Based on the clinical results, the skin findings caused by the 5 % aqueous solution of acrylic acid were consistent with the EPA recommendation for the determination of the MTD. The higher test substance concentrations exceeded the MTD (BASF AG, 1990). At concentrations of 5%, acrylic acid caused peeling and flaking of the skin in mice after 14 days exposure. At 1.0% there were no adverse effects observed (IATG, 1982).

 

Conclusions

Overall, the toxic profile of acrylic acid is dominated by its local irritation effects irrespective of the way of application. Prolonged inhalation of concentrations from 5 ppm or higher in mice and 75 ppm in rats induced degeneration of the olfactory mucosa. It causes severe mucosal damage to the stomach after repeated gavage administration of > 150 mg/kg bw/d, but not after application via drinking water at similar or higher doses. Long-term exposure of the skin to acrylic acid at a concentration of >1 % resulted in irritation whereas no effect on the skin was evident at 1 % (see also dermal carcinogenicity studies in Section 7.7). Following oral, dermal or inhalation administrations no other systemic toxic effects were detected except premature deaths and tubular degeneration/necrosis in the kidneys which were evident after gavage administration of dosages >150 mg/kg bw/d in a 3-month study in rats. Effects were attributed to the high peak concentrations and did not occur in drinking water studies at similar or higher doses. Some studies with repeated application revealed minimal changes of single red blood cell parameters, however no clear hematotoxic effect was found. Changes in clinical chemistry parameters, observed in drinking water studies, were assumed to be associated with reduced consumption of water and/or food.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. The substance is not considered to be classified for repeated dose toxicity according to Regulation (EC) No 1272/2008 (CLP), as amended for the twelfth time in Regulation (EU) 2019/521.