Acrylaldehyde

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well documented study report which meets basic scientific principles

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1974

Report date:

1974

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Study performance before implementation of the corresponding international (OECD or EC) guidelines. However, study performance and documentation complies to a large extent to the later implemented international guidelines.

GLP compliance:

no

Remarks:

study performance before implementation of GLP

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Acrylaldehyde

EC Number:

203-453-4

EC Name:

Acrylaldehyde

Cas Number:

107-02-8

Molecular formula:

C3H4O

IUPAC Name:

acrylaldehyde

Details on test material:

- Name of test material (as cited in study report): acrolein
- Analytical purity: no data
- Impurities (identity and concentrations): no data
- Lot/batch No.: freshly prepared at the test institute´s section of organic synthesis

Test animals

Species:

hamster, Syrian

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Central Institute for the Breeding of Laboratory Animals TNO, Zeist, The Netherlands
- Age at study initiation: young adults
- Weight at study initiation: males: 106 g, females: 105 g
- Fasting period before study: no data
- Housing: five per cage when not exposed, individual housing during exposure
- Diet: ad libitum, pelleted stock diet Muracon I
- Water: ad libitum, tap water
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS: no data

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

other: dry nitrogen

Remarks on MMAD:

MMAD / GSD: not measured

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
Acrolein was freshly prepared by the Institute´s Section of Organic Synthesis and added in small amounts to a glass evaporation column filled with chromosorb N grains (45-60 mesh, Johns-Hanvilla, New York, NY, USA) as an inert carrier. The liquid was evaporated at a constant rat by passing through the column a flow of dry nitrogen of ca. 50 ml/min at a temperature of -10°C. The high concentration acrolein/nitrogen mixture thus produced was diluted with a filtered, compressed air-derived auxiliary flow and transported through glass and copper tubing to a 2.5 m³ cylindrical, stainless steel/glass exposure chamber as described by Kruysse et al. (1970), in which the acrolein vapour dilution was mixed with a flow of conditioned air of 40 m³/h. Thus 4.9 ppm test atmosphere was prepared.
In a similar evaporation column another high concentration acrolein/nitrogen mixture was generated. After dilution with air part of this mixture was used to restore the atmospheres containg the intermediate and low dose levels, being 1.4 and 0.4 ppm, respectively.

CONTROLS: One exposure chamber of the same type as those used for exposing the test animals was supplied with air only and contained the control animals.

TEST ATMOSPHERE ANALYSIS
To monitor the acrolein concentration in each test atmosphere samples were taken automatically at regular intervals by means of a stainless steel sampling tube and sample loop using a membrane pump and a timer-controlled 7-port linear gas-sampling valve (Varian Aerograph, Wallnut Creek, Calif., USA) and analysed by GLC. The gaschromatograph were built by the Technical Service department of the test institute and each consists of a Terranisi furnace with a 3.00 x 4 mm helical Al column, filled with LAC 1-R 296 (Cambridge Industries Co. Inc., Cambridge, Miss. USA) on Gaschrom S (60-80 mesh), and a flame ionization detector (Becker, Delft, The Netherlands). Nitrogen was used as carrier gas. The temperature of the column was ca. 80°C.

VEHICLE: dry nitrogen

Tested concentrations reported by the study authors in ppm (0.4, 1.4 and 4.9 ppm) corresond to 0.932, 3.262 and 11.417 µg/l, respectively, by using the conversion factor (1013 hPa (760 mmg Hg), 20 °C) of 1 ppm = 2.33 mg/m³ reported in the European Union Risk Assessment Report (2001).

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

6 hours a day

Frequency of treatment:

5 days a week for 13 weeks

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0.4 ppm
Basis:
analytical conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
1.4 ppm
Basis:
analytical conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
4.9 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

10

Control animals:

yes, sham-exposed

Details on study design:

no further data given

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: not given, however at least during exposure

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: not given, however at least during exposure

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: No data

FOOD EFFICIENCY: No data

WATER CONSUMPTION: No data

OPHTHALMOSCOPIC EXAMINATION: No data

HAEMATOLOGY: Yes
- Time schedule for collection of blood: during week 12
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: all
- Parameters examined: haemoglobin content, haematocrit value, erythrocyte count, total and differential leucocyte counts

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: terminally (week 13)
- Animals fasted: No data
- How many animals: all
- Parameters examined: serum activities of glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase, alkaline phosphatase

URINALYSIS: Yes
- Time schedule for collection of urine: during week 12
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters examined: in pooled samples of each group: glucose, ketones, protein content using Labstix test stripes (Ames, Epernon, France)

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
The day after the last exposure the hamsters were killed by exsanguination from abdominal aorta after anaesthesia with Brietal sodium (Lilly & Co., Indianapolis, Ind., USA), injected i.p..
All animals were autopsied, and the heart, kidneys, liver, spleen, brain, gonads, lung and adrenals were weighed.
Tissue samples of the organs weighed and also of the gastro-intestinal tract, thymus, thyroid, aorta, uterus, pancreas, mesenteric lymph nodes, skin, skeletal muscle, cheek pouch, urinary bladder, salivary glands and head (after removal of the skin, brain and lower jaw) were fixed in 10 % neutral formalin.
The lungs were removed and fixed according to the method described in detail by Saffiotti et al (1968).
Following fixation the heads were decalcified in nitric acid.
The head, larynx, trachea and pulmonary lobes of all animals were embedded in paraffin, sectioned at 5 µm (3 transverse sections across the nasal cavity and 3 longitudinal sections through the larynx, trachea with main bronchi and each of the pulmonary lobes), stained with haematoxylin and eosin, and examined microscopically.
The preparation of paraffin sections and the microscopic examination of the other tissues preserved, were restricted to all male and female hamsters of the highest concentration group and the control group.

Statistics:

Statistical analysis of body weight changes and organ-to-body weight ratios were carried out using the Student´s t-test, whereas the haematological and biochemical data were evaluated statistically by means of the test of Wilcoxon.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

MORTALITY:
All animals survived except one male of the highest concentration group that had to be killed in week 12 of the experimental period in moribund conditions.

CLINICAL SIGNS:
- 4.9 ppm dose group: During the exposure all males and females of the 4.9 ppm group showed eye irritation, nasal discharge and salivation. These animals were restless and did not sleep during the exposures.
- 1.4 ppm dose group: In the intermediate level (1.4 ppm) the hamsters showed signs of slight irritation. After a few minutes of excitement at the start of the exposure they usually fell asleep but remained restless while sleeping.
- 0.4 ppm dose group: At he lowest level (0.4 ppm) no abnormal behaviour was observed, the animals were sleeping as a rule.

BODY WEIGHT AND WEIGHT GAIN:
- 4.9 ppm dose group: Body weights were significantly decreased at 4.9 ppm in both sexes throughout the experiment.
- 1.4 and 0.4 ppm dose groups: no statistically significant effect

FOOD CONSUMPTION: no data

FOOD EFFICIENCY: no data

WATER CONSUMPTION: no data

OPHTHALMOSCOPIC EXAMINATION: not examined

HAEMATOLOGY:
- 4.9 ppm dose group:
-- females: The haemoglobin and haematocrit values as well as the erythrocyte count in females of the highest level group were significantly higher than those of controls. The differential count showed a significantly increased lymphocyte value accompanied by a significantly decreased neutrophile value.
-- males: No significant differences occured in males.
- 1.4 and 0.4 ppm dose groups: no statistically significant effect

CLINICAL CHEMISTRY:
- all dose groups: The average biochemical serum values of terminal blood samples did not show marked or statistically significant differences between the various groups.

URINALYSIS:
- all dose groups: The analysis of pooled urine samples showed slight differences between some of the test groups and the controls with respect to the occurence of occult blood and amorph crystals, but all gradings were within the normal range. The ketone levels were very high in males of the 1.4 ppm dosage group. This effect was not present in the highest dosage group and did not occur at all in females. None of these changes in the composition of the urine was considered to be treatment-related.

NEUROBEHAVIOUR: not examined

ORGAN WEIGHTS:
- 4.9 ppm dose group: The relative weights of the kidneys, brain, gonads and lung were significantly increased in both sexes at the 4.9 ppm level. The relative heart weight was significantly increased in females in this level. However, no histopathological changes attributed to the acrolein exposure were found, except the respiration tract.
- 1.4 and 0.4 ppm dose groups: In addition, a few deviations in relative organ weights were noted in the various test groups, but there was no dosis-effect relationship.

GROSS PATHOLOGY:
- all dose groups: Upon gross examination the lungs of both the test and control animals looked normal and there was no evidence of treatment-related changes in any of the other organs. Infrequently occuring gross changes unrelated to the inhalation of acrolein included splenomegalia, renal infarot, swollen axillary lymph nodes and absence of one of the testicles.
- The male animal of the highest dose group that had to be killed in week 12, showed subcutaneous oedema, ascites, abscesses in both epididymides, a small ulcer in the stomach and strikingly pale kidneys and liver.

HISTOPATHOLOGY: NON-NEOPLASTIC

- RESPIRATION TRACT: Histopathological changes, which could be attributed to the inhalation of acrolein, were observed in the nasal cavity, larynx and trachea:
- nasal cavity:
-- 4.9 ppm dose group: The injuries observed in the nasal cavity of animals exposed to 4.9 ppm of acrolein (highest dase level) consisted of moderate rhinitis, necrosis and hyper- and metaplasia of respiratory and olfactory epithelium. A necrotizing rhinitis was occasionally visible in the dorsomedial region of the anterior half of the nasal cavity. In this area the epithelium was necrotic and the submucosa was thickened due to the presence of an increased amount of loosely arranged fibrous tissue. In the nasomaxillary region the normal epithelium was partly replaced by low cuboidal or stratified squamous epithilium; keratinisation was a requent finding. Neutrophilic infiltration of the mucosa and lamina propria was invariably observed, whereas substantial neutrophilic exudation in the lumen of the nasal cavity was seen only in a few animals.
-- 1.4 ppm dose group: In hamsters exposed to 1.4 ppm of acrolein (intermediate exposure level) the degree and frequency of neutrophilic infiltration of the mucosa and lamina propria was slightly higher than in controls and in the low dose animals.
-- 0.4 ppm dose group: no effects

- larynx:
--4.9 ppm dose group females: The epithelium covering the vocal cords and the region caudal to the vocal cords locked slightly hyperplastic in a few females of the top dose group.
-- 4.9 ppm dose group males: In males the laryngeal epithelium of the test animals were indistinguishable from that iof the controls.
-- 1.4 and 0.4 dose groups: no effects

- trachea:
-- 4.9 ppm dose group: Focal hyper- and metaplasia of the tracheal epithelium was found in a few males and nearly all females of the top dose group. Stratification of the epithelium was a common finding, but keratinization could not be demonstrated unequivocally.
-- 1.4 and 0.4 dose groups: no effects

- bronchi and lungs:
-- all dose grouos: In the bronchi and lungs no histopathological changes were observed, which could be ascribed to the acrolein exposure.

- OTHER ORGANS: The histopathological changes, which were found outside the respiratory tract, occured only in single animals or in a few animals, or were about equally disributed between control and test animals. Therefore, none of these alterations could be realted to the test material.

The male animal of the top dose group which had to be killed because of its bad condition, showed amyloidosis in the kidney, liver and adrenals, testicular atrophy and inflammatory changes in the organs and was excluded from effect evaluation.

HISTOPATHOLOGY: NEOPLASTIC: not examined

HISTORICAL CONTROL DATA: no data

Effect levels

1

Dose descriptor:

NOEC

Effect level:

0.4 ppm

Sex:

male/female

Basis for effect level:

other: overall effects

2

Dose descriptor:

LOEC

Effect level:

1.4 ppm

Sex:

male/female

Basis for effect level:

other: Mortality: none Clinical signs: Slight signs of irritation Bodyweight: no effects Histopathology: Minimal inflammatory changes in the nasal cavity

3

Dose descriptor:

conc. level: highest exposure level

Effect level:

4.9 ppm

Sex:

male/female

Basis for effect level:

other: Mortality: none, however one male had to be killed in week 12 in moribund conditions Clinical signs: Eye irritation, nasal discharge and salivation Bodyweight: decreased Histopathology: Changes occured in the nasal cavity, larynx and trachea

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Executive summary:

In a subchronic inhalation toxicity study Acrolein (no data on a.i., however freshly prepared at the test institute´s section of organic synthesis) was administered to 10 Syrian golden hamsters/sex/concentration by whole body exposure at concentrations of 0 (control), 0.4, 1.4, and 4.9 ppm (corresponding to 0 (control), 0.932, 3.262, and 11.417 µg/l at 20 °C) for 6 hours per day, 5 days/week for a total of  13 weeks.

 

The histological observations indicate that acrolein vapour, when inhaled, mainly attacts the upper part of the respiraton tract

At the highest exposure level (4.9 ppm) eye irritaion, nasal discharge and salivation were observed. Body weights were decreased and histopatological changes occured in the nasal cavity, larynx and trachea. At the intermediate level (1.4 ppm) the animals showed slight signs of irritation and minimal inflammatory changes in the nasal cavity. The lowest level tested (0.4 ppm) was found to be a no-toxic effect level.

The LOAEL is 1.4 ppm (corresponding to 3.262 µg/l at 20 °C), based on  slight clinical signs of irritation and minimal histopathological changes, attributed to irritation, in the nasal cavity.  The NOEC is 0.4 ppm (corresponding to 0.932 µg/l at 20 °C).

 

This subchronic inhalation study in the Syrian golden hamster is acceptable. Study performance was before implementation of the corresponding international (OECD or EC) guidelines. However, study performance and documentation complies to a large extent to the later implemented international guideline.