Registration Dossier

Administrative data

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.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1982

Materials and methods

Test 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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid

Test animals

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

Administration / exposure

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
Doses / concentrations
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

Examinations

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.

Results and discussion

Results of examinations

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.

Effect levels

open allclose all
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

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

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).