Ethyl methacrylate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Method and results sufficiently described, with significant technical problems

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1979

Materials and methods

Test guideline

Qualifier:

equivalent or similar to

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

GLP compliance:

no

Type of assay:

chromosome aberration assay

Test material

Reference

Name:

Unnamed

Type:

Constituent

Details on test material:

Supplied by ICI; contained 11 ppm hydroquinone stabilizer.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Animal Breeding Unit, Alderley Park, Cheshire
- Age at study initiation: 8-10 weeks
- Weight at study initiation: 150-200 g
- Housing: four/cage
- Diet (e.g. ad libitum): Alderley Park rat cubes
- Water (e.g. ad libitum): unspecified


ENVIRONMENTAL CONDITIONS
- Air changes (per hr): minimum 8
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation

Vehicle:

unchanged

Details on exposure:

whole body

Duration of treatment / exposure:

single treatment: 2 hours
repeated treatment: 5 hours

Frequency of treatment:

repeated treatment: daily for 5 days

Post exposure period:

24 h after the last exposure

Doses / concentrations

Remarks:

Doses / Concentrations:
ca. 0.4, 1.6, 2.8 and 4 mg/L (corresponding to 100, 400, 700, 1000 ppm)
Basis:
nominal conc.

No. of animals per sex per dose:

12 animals in the negative control group; 8 animals in each of the treated and positive control groups.

Control animals:

yes, concurrent no treatment

Positive control(s):

Benzene, 7500 ppm

Examinations

Tissues and cell types examined:

Bone marrow

Details of tissue and slide preparation:

Bone marrow was collected 24 hours after the single two hour exposure and processed for scoring (blind). Categories used during evaluation included Chromatid or chromsome gaps, Chromatid breaks, Fragments, Minutes or Any other complex abnormality.

Statistics:

Proportion of cells with any abnormalities or proportion of cells with any abnormalities other than gaps: Analysis of Variance after transformation of the original data using a double arcsine transformation.
Proportion of rats which had any cells with any abnormality other than gaps: One-sided Fischers Exact test.

Results and discussion

Test results

Sex:

male

Genotoxicity:

ambiguous

Toxicity:

no effects

Vehicle controls validity:

not examined

Negative controls validity:

valid

Positive controls validity:

valid

Any other information on results incl. tables

The maximum concentration tested caused significant reductions in mitotic activity in the bone marrow of the
exposed animals. Small and non-dose related increases in 
the percentages of cells with chromosomal aberrations were
observed in the animals exposed to MMA. However, these 
increases were almost exclusively due to gap-type
aberrations and when these were excluded from the data 
small increases were only observed at 400 ppm. Such small 
increases, observed at lower, but not at higher
concentrations tested, are not considered to be 
biologically significant.

For further details, see attached document including 11 tables.