Methyl methacrylate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / 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,pre guideline study 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

Guideline:

OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)

Version / remarks:

pre guideline study. OECD 478 was first adopted 1984

Deviations:

no

GLP compliance:

no

Type of assay:

rodent dominant lethal assay

Test material

Test material information

Constituent 1

Reference substance name:

Methyl methacrylate

EC Number:

201-297-1

EC Name:

Methyl methacrylate

Cas Number:

80-62-6

Molecular formula:

C5H8O2

IUPAC Name:

methyl 2-methylprop-2-enoate

Test material form:

liquid

Specific details on test material used for the study:

Methylmethacrylate (CAS: 80-62-6)
Purity: not reported

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 10-12 w
- Diet: Alderley Park mouse cubes

Administration / exposure

Route of administration:

inhalation

Vehicle:

dry clean air

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 / concentrations

Doses / concentrations 1

Dose / conc.:

0.405 mg/L air

Remarks:

corresponding to 100 ppm

Doses / concentrations 2

Dose / conc.:

4.05 mg/L air

Remarks:

corresponding to 1000 ppm

Doses / concentrations 3

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 (CTX in water), 5 (EMS in water) and (12 HN2 in saline)

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 frequency: 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.

Any other information on results incl. tables

Mean early death per pregnancy

		Treatment Group
		Methyl methacrylate [ppm]
Period Week	Negative control	100	100	9000	CTX	E.M.S	HN2
Before treatment	0.66	0.39	0.46	0.54	0.71	0.40	0.6
1	0.75	0.72	0.52	0.72	5.53***	5.29***	1.2
2	0.67	0.61	0.61	0.85	3.80***	2.75***	2.2
3	0.78	0.84	1.11	0.87	1.70**	1.00	1.5
4	0.62	0.75	0.61	0.50	0.60	0.86	0.8
5	0.55	0.75	0.40	0.67	0.42	1.11*	0.5
6	0.66	0.65	0.85	0.67	1.00	0.56	0.1
7	0.92	0.74	0.40	0.77	0.83	0.60	0.7
8	0.97	1.00	0.79	0.78	0.93	0.80	0.90

 

Dunnett‘ t-test of transformed values significant at

*           5 %

*           1 %

***       0.1 % level

Percentage of early death / total implants / pregnancy

		Treatment Group
		Methyl methacrylate [ppm]
Period Week	Negative control	100	100	9000	CTX	E.M.S	HN2
Before treatment	5.6	3.7	4.0	4.3	5.8	3.1	9.5
1	6.6	6.0	4.9	9.4	58.3***	61.2***	14.8***
2	5.3	4.8	5.0	8.7	36.5***	21.2***	21.6***
3	7.3	6.7	9.4	7.4	14.8**	13.8	13.1*
4	5.2	6.9	5.3	4.5	4.7	8.5	6.8
5	5.1	6.6	4.0	5.6	3.5	9.5*	4.0
6	5.3	6.4	7.0	6.2	7.7	5.6	0.9
7	7.9	5.9	3.7	8.1	7.9	6.6	6.0
8	7.8	8.8	7.4	6.8	7.4	7.3	6.8

 

Dunnett‘ t-test of transformed values significant at

*           5 %

*           1 %

***       0.1 % level

Applicant's summary and conclusion

Conclusions:

Methyl methacrylate was negative in vaild in vivo germ cell study in mice (rodent dominat lethal test).

Executive summary:

Methyl methacrylate was tested in an in vivo pre guideline dominat lethal test in mice. This test evaluates mutation induction, usually at the chromosome level, in sperm by assessing viability of embryos in subsequent matings. Male CD-1 mice were exposed by inhalation to methyl methacrylate at doses of 100, 1000 and 9000 ppm 6 hours/days for five consecutive days. Specific data on toxicity were not given, however, in the 9000 ppm group 6 out of 20 males died.

After exposure the males were mated to females for 5 days.

Following removal, the females were sacrificed 15 days later and products of conception analyzed. No effects were seen as regards number of early embryo death, mean number of early death per pregnancy or pre-implantation egg loss. This test result was negative indicating no in vivo germ cell mutagenesis. The cyclophosphamid control gave clearly positive results under the conditions of the test.