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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Remarks:
Method and results sufficient described, similar to OECD-guideline 478

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1976

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)
GLP compliance:
no
Type of assay:
rodent dominant lethal assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Methylmethacrylate (CAS: 80-62-6)
Purity not reported.

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 10-12 w
- Diet: Alderley Park mouse cubes

Administration / exposure

Route of administration:
inhalation
Details on exposure:
During exposure, male CD-1 mice were individually housed in chambers made of stainless steel and glass with an internal capacity of three liters. Seven groups of mice, previously shown to be fertile, were treated according to the scheme presented below.
Fertility testing: Prior to the five-day inhalation exposures, male mice were each mated with two virgin adult female mice for five days. After a five-day mating period, the females were transferred to other cages. The females were sacrificed 15 days following the first day of placement with the males and examined for pregnancy. Only males successful in mating were used on the test.
Experimental mating and necropsy: After treatment, male mice were individually housed. Two virgin female mice were placed in each cage. After a five-day mating period, the females were removed and pair-housed. After a two-day rest period, two new virgin female mice were housed with each male for a five-day mating period. This process was repeated until the male mice had been mated for eight weeks. The male mice were then sacrificed and discarded without necropsy. It was assumed the females were fertilized within two to three days after mating pairs were set up. Thirteen days after the fertilization date, each female was sacrificed and examined for pregnancy, living fetuses and early and late fetal development. 
Duration of treatment / exposure:
5 days, 6 hours/day
Frequency of treatment:
Daily
Doses / concentrationsopen allclose all
Dose / conc.:
0.405 mg/L air
Remarks:
corresponding to 100 ppm

Dose / conc.:
4.05 mg/L air
Remarks:
corresponding to 1000 ppm
Dose / conc.:
36.45 mg/L air
Remarks:
corresponding to 9000 ppm
No. of animals per sex per dose:
total number of animals: control: 35; test groups: 20; positive controls: 13, 5 and 12
Control animals:
yes, concurrent no treatment
Positive control(s):
200 mg cyclophosphamide in water/kg bw once by i.p. injection on day 5; 150 mg ethylmethane sulphonate in water/kg bw orally once a day for 5 days ; 2.5 mg meclorethamine in saline once 

Examinations

Tissues and cell types examined:
1) total implants/pregnancy; early deaths/pregnancy; and early deaths/total implants/pregnancy. 
Statistics:
A simple 2X2 Chi-square was used to analyze the data. Also, a week-by-week hierarchical analysis of variance was applied. The following three responses on each female were analyzed: 1) total  implants/pregnancy; early deaths/pregnancy; and early deaths/total  implants/pregnancy. For response 2, the Freeman-Tukey Poisson variance stabilizing transformation was used. Non-pregnant females were taken as missing data. Dunnett's t-test was used for multiple comparisons.

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Mortality was observed in the three dose groups exposed to the test substance. One animal died in the 100-ppm group the week following exposure, one animal died (95% survival) in the 1000-ppm group and six animals died (70% survival rate) in the 9000-ppm group during exposure. Five animals from the cyclophosphamide positive control group died within eight weeks after dosing.  
Fertility Successful mating: No effects observed in the MMA-exposed groups. Positive controls showed appropriate reduction in fertility.
Pregnancy frequency: Reduction in the 1000-ppm group in week 6 only was not considered related to MMA toxicity. Positive controls showed a  decrease in frequency.
Total implantations: No effects observed in the MMA-exposed groups. Positive controls showed appropriate reduction in implant numbers.
Early deaths: Percentages of early deaths were not affected in the MMA-exposed groups. Positive controls showed an appropriate increase in the number of early deaths.
Mean number of early deaths: No effects observed in the MMA-exposed  groups. Positive controls showed an appropriate increase in the number of early deaths.
Percentage of total implantations per pregnancy that were early deaths: No effects observed in the MMA-exposed groups.  
Late deaths: No effects were observed in this study.

Applicant's summary and conclusion