Allyl methacrylate

Endpoint summary

Description of key information

- oral, rat, subacute: NOAEL = 15 mg/kg bw, LOAEL = 60 mg/kg bw (according to OECD 422)

- dermal, subacute (28 days), rabbit: NOAEL: 25 mg/kg/d

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-10-19 to 2004-12-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study, GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Version / remarks:

adopted on 22 March 1996

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: US EPA guideline OPPTS 870.3650, July 2000

Deviations:

no

Principles of method if other than guideline:

The study was conducted as a combined repeated dose toxicity study with Reproduction / Developmental Toxicity Screening Test. In this part all parameters concerning systemic toxicity were considered.

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories France, L’Arbresle, France
- Age at study initiation: males were 8 weeks old and the females were 10 weeks old
- Weight at study initiation: 303 g (range: 280 g to 332 g) for the males and 229 g (range: 199 g to 273 g) for the females
- Fasting period before study: no
- Housing: The animals were housed individually (except during mating) in suspended wire-mesh cages (43.0 x 21.5 x 18.0 cm). A metal tray, containing autoclaved sawdust was placed under each cage. Shortly before parturition, the females were moved to polycarbonate cages (43.0 x 21.5 x 20.0 cm) with autoclaved sawdust and wood shavings as nesting material (SICSA, Alfortville, France).
- Diet: The animals had free access to SSNIFF R/M-H pelleted maintenance diet, Batch Nos. 2764132 and 4764439 (SNIFF Spezialdiäten GmbH, Soest, Germany) distributed weekly.
- Water: The animals had free access to bottles containing tap water (filtered with a 0.22 μm filter).
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 50 ± 20
- Air changes (per hr): approximately 12 cycles/hour of filtered, non-recycled air.
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 2004-10-12 To: 2004-12-07

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

Vehicle
The vehicle was corn oil, Batch No. 103K0107, supplied by Sigma (Saint-Quentin-Fallavier, France).

Dosage formulation preparation
The test item dosage formulations were prepared by suspending Allyl Methacrylate (AMA) in corn oil in order to achieve the concentrations of 0.6, 3 and 12 mg/mL and were stored at +4°C or up to 9 days protected from light.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Chemical analysis of the dosage formulations
Homogeneity
Two dosage formulations were prepared at 0.2 and 15 mg/mL of AMA (in corn oil) in order to cover all the concentrations intended for use in this study. From both dosage formulations, duplicate samples were taken at three different levels of the container (top, middle, bottom) and analyzed for concentration of the test item just after preparation (day 0) and after 9 days of storage at +4°C (protected from light).
Stability
The two dosage formulations prepared at 0.2 and 15 mg/mL of AMA in corn oil for homogeneity analysis were sampled after 0 (just after preparation), 4 and 9 days storage at +4°C (protected from light). The aliquots (n = 2) sampled on day 4 were stored frozen at -20°C pending analysis on the last sampling occasion, when all samples were assayed. The mean concentrations measured on days 0 and 9 for homogeneity were taken as the initial and final values for the stability test.
Concentration
The concentration of samples taken from each dosage formulation (including the control) prepared for use in weeks 1, 2, 4 and 7 was determined.

Results
A satisfactory agreement was observed between the nominal and actual concentrations of the test item in the dosage formulations analyzed since the deviations from nominal concentration remained in an acceptable range of ± 10%. Furthermore, there was a satisfactory correspondence between the nominal and the measured concentrations of the test item in the vehicle.

Duration of treatment / exposure:

Males: 15 days before mating, through mating and post-mating periods through sacrifice (minimum 4 weeks);
Females: 15 days before mating, through mating period, pregnancy and lactation, until day 5 post-partum inclusive (or until sacrifice, for unmated females);

Frequency of treatment:

once daily

Dose / conc.:

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

Remarks:

analytical concentration

Dose / conc.:

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

Remarks:

analytical concentration

Dose / conc.:

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

Remarks:

analytical concentration

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The dose-levels were selected following the results of a previously conducted study CIT/Study No. 28198 TSR in which rats were dosed (gavage) withAllyl Methacrylate (AMA), Batch. 00216X, at 0, 25, 75 and 150 mg/kg/day for 10 consecutive days. In this study, 150 mg/kg/day resulted in morbidity and mortality, both sexes in the 25 and 75 mg/kg/day groups showed signs of hypersalivation during the dosing period, males showed signs of piloerection at 75 mg/kg/day, and the females in the 75 mg/kg/day group had increased liver weight.
Taking into account that the duration of the dosing period for this study was nearly 6 weeks in females, the high dose-level was set at 60 mg/kg/day. The intermediate and low dose-levels were selected in order to identify a No Effect Level.

Positive control:

not required

Observations and examinations performed and frequency:

- CLINICAL OBSERVATIONS: Clinical observations were conducted daily throughout the study period.

- DETAILE CLINICAL OBSERVATIONS (DCO): Conducted on all rats pre-exposure and weekly throughout the study. The DCOs included cage-side, handheld and open-field observations that were recorded categorically or using explicitly defined scales.

- FUNCTIONAL TESTS: The functional tests included reactivity to manipulation or different stimuli and motor activity.

BODY WEIGHT: Yes
- Time schedule for examinations: Male body weights were recorded weekly throughout the study. Female body weights were performed weekly for the premating and mating periods. Maternal body weights were recorded on gd 0, 7, 14, 17 and 20. Females that delivered were weighed on ld 1 and 5. Females that failed to mate or deliver were weighed on a weekly basis for the study duration.

FOOD CONSUMPTION AND COMPOUND INTAKE:
Food consumption was determined weekly for males and females during the pre-mating period. Due to co-housing, food consumption was not measured during mating. During gestation, food consumption for the females was measured on gd 0, 7, 10, 14, 17 and 20. After parturition, food consumption was measured on ld 1 and 5.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At necropsy, blood samples were removed from the orbital sinus.
- Anaesthetic used for blood collection: Yes
- Animals fasted: Yes
- How many animals: all
- Parameters: erythrocytes, hemoglobin, packed cell volume, thrombocytes, leucocytes (WBC), differential WBC count with morphology, mean cell hemoglobin (MCH), mean cell volume (MCV), and mean cell hemoglobin concentration (MCHC); Coagulation Assay: prothrombin time, activated partial thromboplastin time and fibrinogen;

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At necropsy, blood samples were removed from the orbital sinus.
- Animals fasted: Yes
- How many animals: all
- Parameters: Enzyme activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, triglyceride, albumin, cholesterol, creatinine, sodium, potassium, inorganic phosphorous, chloride, calcium, glucose, total bilirubin, albumin/globulin ratio, total protein, bile acids and urea

URINALYSIS: Yes
- Time schedule for collection of urine: Urine was collected from the first 5 surviving male rats in each dose group during the week prior to necropsy.
- Metabolism cages used for collection of urine: Yes
- Parameters: Color, appearance, specific gravity, urine volume, pH, bilirubin, glucose, proteins, ketones, blood, nitrates and urobilinogen;

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
A complete necropsy of all animals was performed. Male rats were sacrificed at the end of the mating period (total treatment was at least 40 days). The females and their pups were sacrificed on ld 6. The necropsy included an examination of: the external tissues and all orifices, the cranial, nasal, thoracic and abdominal cavities, and all viscera. Selected tissues of the viscera were incised. On the day prior to necropsy, all animals were fasted overnight. At necropsy, animals were anesthetized and blood samples were removed from the orbital sinus.
In five males and five females from each group, the following tissues were harvested and preserved in appropriate materials: macroscopic lesions, adrenals, brain, cecum, colon, duodenum, epididymis, heart, ileum, jejunum, kidneys, liver, lungs with bronchi, lymph nodes, ovaries, prostate, rectum, sciatic nerve, seminal vesicles, spinal cord, spleen, sternum with bone marrow, stomach with forestomach, testes, thymus, thyroids, trachea, urinary bladder, and uterus. Weights were also recorded for the adrenals, brain, epididymis, heart, kidneys, liver, spleen, testes and thymus.

Statistics:

The following sequence was used for the statistical analyses of body weight, food consumption, hematology, blood biochemistry, urinalysis and organ weight data. If there were 3 or less animals/sex/group remaining, no statistical analysis was performed. If there were 5 or less animals/sex/group remaining for 3 or more groups, the data were analyzed using the Dunn test. If there were 5 or less animals/sex/group remaining for less than 3 groups, the data were analyzed using the Mann-Whitney/Wilcoxon test. If there were 5 or more animals/sex/group, the data were analyzed by Kolmogorov-Lillefors test to test for the normality of the distribution of the data. If it was not normal, the values were logarithmically transformed and retested for normality. If it still did not meet the criteria for normality, the original values were analyzed by the Dunn test. If the data were normal, and there were 3 or more groups, the data were assessed for homogeneity of variance between groups with the Bartlett test. If not homogeneous, the data were analyzed by the Dunn test; if homogeneous, the data were assessed by the Dunnett test. If the data were normal, and there were less than 3 groups, the data were assessed for homogeneity of variance between groups with the Fisher test. If not homogeneous, the data were assessed using the Mann-Whitney/Wilcoxon test; if homogeneous, the data were analyzed by the Student test. The statistical comparison of results of motor activity (horizontal and rearing movements recorded from five males and five females per group) was performed, according to the following steps: step 1: normality and homogeneity of variances (Kolmogorov-Smirnov and Bartlett test respectively), step 2: parametric (ANOVA plus Dunnett test if necessary) or non-parametric (Kruskal-Wallis plus Dunn test if necessary) tests was conducted based on the results obtained at step 1. These statistics were performed using the software SAS Enterprise Guide V2 (2.0.0.417, SAS Institute Inc).

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Hypersalivation was observed in a dose-related manner in males and females given 15 or 60 mg/kg/day during the premating period (from week 2) and then in females during gestation and lactation. One female given 60 mg/kg/day experienced hypotonia and half closed eyes (on day 5 p.p.);

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

There was no effect of treatment on group mean male body weight gain during the premating phase. The marginal reduction in body weight gain observed at 15 and 60 mg/kg/day (p<0.05)
during the mating period was not considered to be biologically significant based on lack of clear dose response and lack of effects at other time periods.
All female groups given Allyl Methacrylate gained less weight than the controls during the premating phase. During gestation, no clear effect was observed on the body weight gain, although females given the lowest dose-level continued to have low body weight gain. Females
given 60 mg/kg/day had lower body weight gain than controls during the lactation period. But none of these variations reached statistical significance when compared to control mean values.
Based on the lack of dose response and consistency across periods, none of these differences was considered to be related to treatment.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

There was no effect of treatment on group mean male food consumption during the study.
All female groups given Allyl Methacrylate had marginally lower food consumption during the premating period. These differences reached statistically significance at 3 and 15 mg/kg/day only
although all values were similar in the three treated groups. Food consumption was comparable with the controls during gestation and marginally reduced during lactation. Based on the lack of
dose response, the small magnitude of the changes, and lack of consistency across periods, none of these differences was considered to be related to treatment.

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

There was no effect of treatment on any male or female hematological parameters. There was a lower value of white cell counts recorded in males given 15 or 60 mg/kg/day (13% and 19% lower, respectively) that did not attain statistical significance. When compared to the mean control values, increased values of fibrinogen plasmatic levels were noted in all male-treated groups (3.31, p<0.05, 3.15 and 3.28 g/L at 3, 15 and 60 mg/kg/day respectively, vs. 2.62 g/l in controls). However, there was no dose-response.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

There was no effect of treatment on any male or female hematological parameters.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There was no effect of treatment on pH, specific gravity or volume or urine produced by the males in any group.

Behaviour (functional findings):

effects observed, non-treatment-related

Description (incidence and severity):

Reactivity to manipulation or to different stimuli: There was no evidence of disturbance of either autonomal or physiological functions at any dose level.
Motor Activity: When compared to the control values, a significant increase in the mean total number of rearing movements was recorded in the female group given 60 mg/kg/day. No other differences in the measured motor activity were noted in any group.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

details see below

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Yellowish areas were noted in the liver of 2/5 females given 60 mg/kg/day. This was considered to be treatment-related and correlated with microscopic findings. All other necropsy findings reported at the end of treatment period were those which commonly occur in the rat of this strain and age when kept under laboratory conditions, and were considered to be of no toxicological importance.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

At histopathology, several foci of degenerated/necrotic hepatocytes, together with slight periportal fibrosis, slight biliary proliferation, and greenish-pigment-laden macrophages, were noted in 3/5 females given 60 mg/kg/day. There were no other treatment-related histopathological changes for either sex at any dose.

Histopathological findings: neoplastic:

not specified

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

Blood chemistry:
Decreased triglyceride concentration was noted in all male test item-treated groups, but without clear dose-relationship or statistical significance (0.37, 0.39 and 0.31 mmol/L at 3, 15 and 60 mg/kg/day respectively, vs. 0.57 mmol/L in controls). Therefore, these differences were not
considered to be treatment-related.
In females, the differences recorded in blood biochemistry parameters were considered not to be toxicologically relevant since they were slight and/or without clear dose-relationship and great inter-animal variability was noted or no correlation could be clearly made with other parameters (e.g. increased in Alanine aminotransferase activity in the high dose group females). However, the total bilirubin concentration in female G21411 (10 µmol/L, vs. 3 to 4 µmol/L
in controls) and the high concentration of biliary acids recorded in female G21415 (402 µmol/L, vs. 56.6 µmol/L in controls) were considered to be related to the treatment with the test item at 60 mg/kg/day, as these changes correlated with histopathological findings in the liver.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

female

Basis for effect level:

other: liver effects

Key result

Dose descriptor:

LOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: hyperrsalivation

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: parental toxicity

Critical effects observed:

not specified

Salient Male Clinical Observations
# Animals Affected	Dose Level (mg/kg/day)
	0	3	15	60
Hypersalivation (Premating)	0	1	9	10
Salient Female Clinical Observations
# Animals Affected	Dose Level (mg/kg/day)
	0	3	15	60
Hypersalivation (Premating)	0	0	8	10
Hypersalivation (Gestation)	0	0	8	10
Hypersalivation (Lactation)	0	0	8	10
Food Consumption in the Pre-mating period
Sex	Males				Females
Dose (mg/kg/day)	0	3	15	60	0	3	15	60
Pre-mating period (g/rat/d)
Days 1-8	26	26	26	26	20	18*	18*	18
Days 8-15	26	26	26	27	20	18*	17**	18
* = p < 0.05; ** = p< 0.01
Motor Activity
Sex	Males				Females
Dose (mg/kg/day)	0	3	15	60	0	3	15	60
Horizontal Movements (mean +/- SD)	808 105	628 121	683 93	577 221	303 116	377 95	359 88	415 73
Rearing (mean +/- SD)	314 68	252 70	294 99	214 91	82 35	107 29	155 52	157* 36
SD: Standard Deviation
*: p<0.05 (Dunnett test, comparison with the mean control value)
-Organ Weights:
Sex	Males			Females
Dose (mg/kg/day)	3	15	60	3	15	60
Adrenals
absolute	+4	+6	-10	+1	-2	-12
relative	+1	+2	-15	+6	-1	-8
Thymus
absolute	+19	+24*	+28*	-1	-1	-17
relative	+15	+20	+20	+2	-1	-14
*: p<0.05 (Dunnett test, comparison with the mean control value)

Conclusions:

In this study, the NOAEL was found to be 15 mg/kg/day parental to liver damage in the female rats.

Executive summary:

In an OECD 422 study, three groups of 10 male and 10 female Sprague-Dawley rats received the test item, allyl methacylate (AMA), by daily oral (gavage) administration for 15 days before mating, through mating, gestation and the beginning of the lactation period (until day 5 post-partum (p.p.)). The dose-levels were 3, 15 and 60 mg/kg bw/day. Another group of 10 males and 10 females received the vehicle, corn oil, alone, under the same experimental conditions and served as a control group. The dosing volume was 5 mL/kg.

Clinical signs and mortality were checked daily. Body weight and food consumption were recorded at designated intervals throughout the study. Detailed clinical observations, reactivity to different stimuli (Functional Observational Battery, (FOB)) and motor activity were also recorded. Blood was taken from five males and five females for hematological and blood biochemical investigations at terminal sacrifice (i.e. in week 5 for males and week 7 for females). At the same time, urine was collected from five males for analysis. Males were sacrificed approximately one week after the end of the mating period, females on day 6 p.p. The animals were sacrificed and subjected to a macroscopic examination of the principal thoracic and abdominal organs. Designated organs were weighed and examined microscopically. In addition, the numbers of corpora lutea and implantation sites were recorded for each female. Due to potentially treatment-related microscopic findings observed in the livers of some animals in the 60 mg/kg bw/day treatment group, the retained livers of the males and females in the low- and intermediate-dose groups also were examined microscopically. The pups were observed daily for clinical signs, sexed and weighed on days 1 and 5 p.p.. After sacrifice on day 6 p.p., the pups were examined for gross abnormalities and discarded.

Hypersalivation was observed in a dose-related manner in males and females given 15 or 60 mg/kg bw/day during the premating period (from week 2) and then in females during gestation and lactation. This clinical sign was not considered to be adverse as it likely represents a reaction to the dosing procedure and not a direct effect of AMA toxicity. At 60 mg/kg bw/day, one female experienced hypotonia and half-closed eyes on day 5 p.p.. There was no disturbance of autonomal or physiological functions at any dose-levels and the motor activity of the animals was considered to be unaffected by treatment. There was no effect of treatment on group mean male body weight gain during the premating phase and only a marginal reduction in body weight gain was observed at 15 and 60 mg/kg bw/day (p<0.05) during the mating period. There were no changes in hematological parameters that could be considered toxicologically relevant.

For blood biochemistry investigation, one female dosed with 60 mg/kg bw/day had increased total bilirubin concentration and another one had increased biliary acid concentration, these changes were correlated with histopathological findings in the liver. There were no effects of treatment on pH, specific gravity or volume of urine produced by the males in any group. The necropsy of the adult males and females revealed the presence of yellowish areas in the liver of 2/5 females in the 60 mg/kg bw/day dose group. At histopathology, several foci of degenerated/necrotic hepatocytes, together with slight periportal fibrosis, slight biliary proliferation, and greenish-pigment-laden macrophages, were noted in 3/5 females given 60 mg/kg bw/day. There were no other treatment-related histopathological changes for either sex at any dose.

Conclusion

The test item, Allyl Methacrylate (AMA; CAS RN 96-05-9), was administered to male and female Sprague-Dawley rats by oral route (gavage), under the above detailed experimental

conditions, at the dose-levels of 3, 15 or 60 mg/kg/day.

The following observations were made in the dose groups:

60 mg/kg/day group:

Hypersalivation (although not considered to be related to AMA toxicity) was recorded in all the males and females and hypotonia and half-closed eyes were observed in one female. A marginally lower body weight gain was recorded in males during the mating period. Females gained less weight during the premating phase, which coincided with reduced food consumption during this period and lactation. Male and female pups gained less weight than controls, and the number of pups cold to the touch was higher than in the control litters. At clinical pathology, a higher plasma concentration of total bilirubin (1/5) and biliary acids (1/5) in females given 60 mg/kg/day were recorded and correlated with histopathological findings in the liver. At necropsy, 2/5 females had yellowish areas in the liver. Histopathology revealed the presence of foci of degenerated/necrotic hepatocytes (associated with periportal fibrosis, biliary proliferation and greenish-pigment-laden macrophages) in 3/5 females.

15 mg/kg/day group:

The majority of males and females had hypersalivation throughout the study. A slight reduction in body weight gain was recorded for males during the mating period. Females gained less weight than the controls during the premating phase associated with a slight reduction in food consumption. During lactation, food consumption was marginally reduced.

Male and female pups gained less weight than controls. None of these changes was considered to be related to AMA toxicity.

3 mg/kg/day:

Body weight gain and food consumption of females were lower than controls during the

premating phase. Food consumption was marginally reduced during the lactation period. None of these changes was considered to be related to AMA toxicity.

There were no substance-induced effects on the male and female reproductive performance, or on the progeny of the parental rats at any dose-level.

Based on the results of this study, the dose-level of 15 mg/kg/day was considered to be the No Observed Adverse Effect Level (NOAEL) for parental toxicity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

15 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

One OECD guideline and GLP study sufficient for DNEL derivation available. Key information is provided by read-across to the structural analogues Allyl acetate and Methyl methacrylate.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Public available literature with good documentation, equivalent or similar to OECD guideline.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)

Deviations:

not specified

Principles of method if other than guideline:

Groups of 6 male and 6 female rabbits were dermally dosed with the neat test compound for 6 hr/day, 5 days/week, for 4 weeks. The dosing site was occluded with an impervious material for the 6-hr exposure period. A satellite high dose group (6 males and 6 females) was held after the termination of the main study for 3 additional weeks to determine the reversibility of toxic effects.

GLP compliance:

not specified

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Langshaw Farms, Augusta, Michigan
- Age at study initiation: approximately 11 weeks old
- Housing: single
- Diet: PURINA Rabbit Chow, ad libitum
- Water: fresh water, ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 48 - 55

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on exposure:

TEST SITE
- Type of wrap if used: The entire back was wrapped by an impervious sleeve of plastic material which was held in place with cloth bandage taped to the hair.
- Time intervals for shavings or clippings: The backs of the test animals were clipped free with electric clippers at least 24 hours before initial application of the test compound. Subsequent periodic clipping was performed according to the rate of hair growth.

REMOVAL OF TEST SUBSTANCE
- Washing: with lukewarm water and dried with a soft cloth
- Time after start of exposure: 6 h (at the end of each daily treatment period)

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

no data

Duration of treatment / exposure:

6 h/day

Frequency of treatment:

5 days/week for 4 weeks

Remarks:

Doses / Concentrations:
0, 25, 50 and 100 mg/kg/d
Basis:
no data

No. of animals per sex per dose:

6

Control animals:

yes, concurrent no treatment

Details on study design:

- Post-exposure recovery period in satellite groups: yes, a satellite high dose group (6 males and 6 females) was held after the termination of the main study for 3 additional weeks to determine the reversibility of toxic effects;

Positive control:

not required

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least twice daily

DERMAL IRRITATION (if dermal study): Yes
- Time schedule for examinations: at least twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: at the initiation of the study and after every fourth day (days 4, 8, 12, 16, 20, 24, and 28)

FOOD CONSUMPTION: Yes
- Time schedule for examinations: at the initiation of the study and after every fourth day (days 4, 8, 12, 16, 20, 24, and 28)

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the termination of the study
- Anaesthetic used for blood collection: Yes (methoxyflurane)
- How many animals: all animals

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the termination of the study
- How many animals: all animals

URINALYSIS: Yes
- Time schedule for collection of urine: A sixteen hour of urine sample was also collected from five male and five female rabbits of control, low and higher dose levels just before the sacrifice.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes (all major tissues, organs, all orifices, cranial, thoracic, abdominal and pelvic cavities and their viscera)
HISTOPATHOLOGY: Yes

Other examinations:

none

Statistics:

Statistical comparisons between control and test groups were carried out where applicable. The data were analyzed by employing Dunnett's test. Where appropriate, a non-parametric analysis of variance by ranks was used to evaluate these parameters. The 95% (p<0.05) confidence level was chosen as the criteria of significance.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

No abnormal behavior was seen among the rabbits during the treatment period. The only significant observations were increased respiration, hypoactivity and mild lacrimation in some of the treated animals.

Dermal irritation:

effects observed, treatment-related

Description (incidence and severity):

The treated skin appeared hard, dry, brittle and cracked at several places.

Mortality:

mortality observed, treatment-related

Description (incidence):

Two female rabbits died during the treatment period at the highest dose level (100 mg/kg/day) and two female rabbits receiving 50 mg/kg/day. Allyl Methacrylate developed diarrhea and died during the second and fourth weeks of the study. No deaths were observed in the lower dose level and control animals.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There were no significant differences in body weight gains between control and treated female rabbits throughout the study. Among male rabbits, there was a dose related reduction in the total average weight gains (-10 to -49%). Significant reduction in the male body weight gains was observed at the highest dose level. This reduction in weight gain was generally accompanied by a dose related reduction in food consumption.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

Although the average food intake over the entire period was lower in both sexes of the rabbits at the high dose levels as compared to controls, the significant differences in the reduction of food consumption were obtained with the male rabbits only. However, not all of these differences were statistically significant and no clear trend existed between the test and control animals.

Haematological findings:

no effects observed

Description (incidence and severity):

Allyl methacrylate had no apparent effects on hematological parameters in both male and female rabbits. A comparison between the test and control animals demonstrated a significant decrease in the hematocrit value for females receiving 100 mg/kg/day Allyl Methacrylate. This finding, however, was judged to be of no biological significance and was within limits of the normal range.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

Significant differences between treated and control animals were obtained in some of the serum parameters. Total protein and creatinine values were significantly lower in female rabbits at two higher dose levels. These values, however, were within the limits of the normal range and considered incidental rather than a direct or indirect consequence of Allyl Methacrylate application.

Urinalysis findings:

no effects observed

Description (incidence and severity):

No treatment-related effects were observed.

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

Although the male absolute adrenal weights showed a significant decrease in animals treated with either 50 or 100 mg/kg/day Allyl Methacrylate, the relative weights were comparable with the control values. Also, this decrease in male absolute adrenal weights has no significance, as no histological abnormalities were observed in this organ. The mean absolute or relative weights of other organs of both male and female rabbits were not affected by the treatment and they were comparable to the control values.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

No effects in survivors at necropsy, except slight hemorrhage in the fascia of the skin at the treatment site in the high dose group animals were seen. Other gross lesions in rabbits sacrificed at termination were of parasitic etiology or mild hemorrhagic or inflammatory lesions of no significance. The cause of death in the mid and high dose group females could not be determined but gross observations for one animal from each group suggested enteritis as the cause of death. One rabbit from the 100 mg/kg/day group which died had an unusual response in that there was complete necrosis of the epidermis and superficial dermis.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Microscopic effects were limited to hyperplastic thickening of the epidermis with hyperkeratosis of the treatment-site skin, primarily in the high dose group. Following the recovery period, the animals from the high dose group appeared normal.

Description (incidence and severity):

The animals in the satellite group treated with 100 mg/kg for determination of recovery showed no treatment related effects following a recovery period of 20 days. These animals appeared fully recovered following the 28-day exposure to 100 mg/kg/day Allyl Methacrylate and their food consumption and body weight gain were comparable to that of the control rabbits.

Details on results:

CLINICAL SIGNS AND MORTALITY: No abnormal behavior was seen among the rabbits during the treatment period. The only significant observations were increased respiration, hypoactivity and mild lacrimation in some of the treated animals. The treated skin appeared hard, dry, brittle and cracked at several places. Two female rabbits died during the treatment period at the highest dose level (100 mg/kg/day) and two female rabbits receiving 50 mg/kg/day Allyl Methacrylate developed diarrhea and died during the second and fourth weeks of the study. No deaths were observed in the lower dose level and control animals.

BODY WEIGHT AND BODY WEIGHT GAIN: There were no significant differences in body weight gains between control and treated female rabbits throughout the study. Among male rabbits, there was a dose related reduction in the total average weight gains (-10 to -49%). Significant reduction in the male body weight gains was observed at the highest dose level. This reduction in weight gain was generally accompanied by a dose related reduction in food consumption.

FOOD CONSUMPTION: Although the average food intake over the entire period was lower in both sexes of the rabbits at the high dose levels as compared to controls, the significant differences in the reduction of food consumption were obtained with the male rabbits only. However, not all of these differences were statistically significant and no clear trend existed between the test and control animals.

HAEMATOLOGY: Allyl methacrylate had no apparent effects on hematological parameters in both male and female rabbits. A comparison between the test and control animals demonstrated a significant decrease in the hematocrit value for females receiving 100 mg/kg/day Allyl Methacrylate. This finding, however, was judged to be of no biological significance and was within limits of the normal range.

CLINICAL CHEMISTRY: Significant differences between treated and control animals were obtained in some of the serum parameters. Total protein and creatinine values were significantly lower in female rabbits at two higher dose levels. These values, however, were within the limits of the normal range and considered incidental rather than a direct or indirect consequence of Allyl Methacrylate application.

URINALYSIS: No treatment-related effects were observed.

ORGAN WEIGHTS: Although the male absolute adrenal weights showed a significant decrease in animals treated with either 50 or 100 mg/kg/day Allyl Methacrylate, the relative weights were comparable with the control values. Also, this decrease in male absolute adrenal weights has no significance, as no histological abnormalities were observed in this organ. The mean absolute or relative weights of other organs of both male and female rabbits were not affected by the treatment and they were comparable to the control values.

GROSS PATHOLOGY: No effects in survivors at necropsy, except slight hemorrhage in the fascia of the skin at the treatment site in the high dose group animals were seen. Other gross lesions in rabbits sacrificed at termination were of parasitic etiology or mild hemorrhagic or inflammatory lesions of no significance. The cause of death in the mid and high dose group females could not be determined but gross observations for one animal from each group suggested enteritis as the cause of death. One rabbit from the 100 mg/kg/day group which died had an unusual response in that there was complete necrosis of the epidermis and superficial dermis.

HISTOPATHOLOGY: Microscopic effects were limited to hyperplastic thickening of the epidermis with hyperkeratosis of the treatment-site skin, primarily in the high dose group. Following the recovery period, the animals from the high dose group appeared normal.

The animals in the satellite group showed no treatment related effects following a recovery period of 20 days. These animals appeared fully recovered following the 28-day exposure to 100 mg/kg/day Allyl Methacrylate and their food consumption and body weight gain were comparable to that of the control rabbits.

Dose descriptor:

NOAEL

Effect level:

25 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no effects noted at this dose

Dose descriptor:

LOAEL

Effect level:

50 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: death of animals, effects on body weight

Critical effects observed:

not specified

Conclusions:

In this study, the NOAEL was found to be 25 mg/kg/day and the LOAEL 50 mg/kg/day in male and female rabbits based on mortality and effects on body weight.

Executive summary:

A 28-day subacute dermal toxicity of Allyl methacrylate (AMA) was conducted in New Zealand white rabbits. Groups of six male and six female rabbits were treated with the test material at dose levels of 0, 25, 50 and 100 mg/kg bw/day for four weeks. One satellite group of male and female rabbits was also treated with 100 mg/kg bw/day of AMA. No overt signs of toxicity or abnormal behavior were seen among the rabbits during the treatment period. Two females from the 50 mg/kg bw/day group and two females at the highest dose level died during the course of the study. No mortalities and no significant adverse effects were observed in the low dose and control rabbits. Males treated with the highest dose level exhibited reduced weight gain and lower food consumption. The test material has no significant adverse effects on serum biochemistry, urine and hematological parameters or absolute and relative organ weights. No chemical related gross pathological alterations were observed in any of the organs or tissues examined at the time of necropsy except slight hemorrhage in the fascia of the skin of rabbits treated with 100 mg/kg bw/day of AMA. There were no significant chemical related microscopic changes found in any of the test rabbits. The animals of the satellite group appeared fully recovered following the 28-day dermal exposure to AMA. In conclusion, the results of the present study failed to demonstrate any significant toxic response or adverse effects in the male and female rabbits at a dose level of 25 mg/kg bw/day of Allyl Methacrylate. The no-effect level established by this study was therefore 25 mg/kg bw/day for 28 days in the rabbit. These results suggest that it is unlikely that AMA will present a significant health hazard from skin contact under normal conditions of industrial handling (Siddiqui, 1982). 

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

25 mg/kg bw/day

Study duration:

subacute

Species:

rabbit

Quality of whole database:

Only one public available literture with good documentation, equivalent or similar to OECD guideline.

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral:

In an OECD 422 study, three groups of 10 male and 10 female Sprague-Dawley rats received the test item, Allyl methacylate (AMA), by daily oral (gavage) administration for 15 days before mating, through mating, gestation and the beginning of the lactation period (until day 5 post-partum (p.p.)). The dose-levels were 3, 15 and 60 mg/kg bw/day.Based on findings related to liver damage, the dose-level of 15 mg/kg bw/day was considered to be the NOAEL for parental toxicity.

As a general principle, the first step in Methacrylic acid ester metabolism is cleavage to methacrylic acid and the regarding alcohol. Consequently, toxicity of Allyl methacrylate can be approximately described by the toxicity of the cleavage products Allyl alcohol and Methacrylic acid and / or structural analogue Methacrylate esters.

The requirements of REACH Annex IX, 90 d repeated dose toxicity study, aare fullfilled by read across with Allyl acetate (Allyl alcohol miety) and Methyl methacrylate (Methacrylic acid) by oral admisnistration)

An existing subchronic oral study on Allyl acetate is considered as appropriate to address the toxicity of the Allyl alcohol moiety of Allyl methacrylate. In this study, the substance was administered to 10 male and female rats (Wistar) per group by oral gavage for 14 weeks. The dose levels were 0, 6, 12, 25, 50, and 100 mg/kg body weight. Liver damage as the main finding is in principle in accordance with observations on the metabolites Allyl alcohol and Acrolein which were tested in parallel in the same study. The LOAEL for Allyl acetate in this study was 25 mg/kg, based on liver lesions.  The NOAEL was determined to 12 mg/kg b.w./day.

To address the repeated-dose toxicity of the Methacrylic acid moiety of Allyl methacrylate, data were adopted by read- across to a chronic toxicity study in rats with the structural analogue Methyl methacrylate (MMA).In this study with 25 male and 25 female rats administered with 6, 60 and 2000 ppm MMA via drinking water, no adverse effects other than elevated kidney weights were reported. However, the effect was without corresponding histopathology in female rats at 2000 ppm (Borzelleca et al., 1964). Therefore, the NOAEL was reported as 2000 ppm (corresponding to 193.8 mg/kg bw/d) in male and female rats.

In addition, three subacute studies with Methyl methacrylate are reported as supporting studies.

Inhalation:

Inhalation studies with Allyl methacrylate are not required as subacute studies are available by oral and dermal exposure. The requirements according Annex IX are fullfilled by read across with Allyl acetate and Methylmethacrylate by oral exposure.

Dermal:

A 28-day subacute dermal toxicity of Allyl methacrylate (AMA) was conducted in New Zealand white rabbits. The NOAEL established by this study was 25 mg/kg bw/day based on mortalities and body weight changes in the higher dose groups.These results suggest that it is unlikely that AMA will present a significant health hazard from skin contact under normal conditions of industrial handling. 

 

Conclusion for hazard assessment:

The NOAEL of a subacute study (OECD 422) with Allyl methacrylate in rats was found to be 15 mg/kg bw/day.

This result is in good accordance with the NOAEL for subchronic toxicity of the structurally closely related Allyl acetate in rats which is 12 mg/kg bw/day. Due to the structural similarities of both methacrylates, a similar mode of action, especially ester cleavage catalyzed by unspecific esterases as the first metabolic step, can be assumed. Moreover, potential toxicity of the Methacrylic moiety is addressed by the chronic oral study provided on Methyl methacrylate. In the view of the overall database, no further subchronic testing with Allyl methacrylate is needed. In accordance with animal welfare legislation, further testing must not be performed.

Justification for classification or non-classification

Based on the results obtained for the oral route, allyl methacrylate is classified with STOT RE 2, H373: May cause damage to organs (liver) through prolonged or repeated exposure (oral) according to Regulation (EC) No 1272/2008 (CLP).