Methyl vinyl ether

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to GLP guideline study. Acceptable restriction: OECD TG 474 requires 2000 immature cells to be examined instead of 1000/animal in this study.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

GLP compliance:

yes

Remarks:

(CIVO TNO)

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Methyl vinyl ether

EC Number:

203-475-4

EC Name:

Methyl vinyl ether

Cas Number:

107-25-5

Molecular formula:

C3H6O

IUPAC Name:

methoxyethene

Details on test material:

Methyl vinyl ether (MVE)
obtained from BASF AG; purity 99.7% (analysis available)
reanalysis after termination: no evidence for change of test material

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Five male and 5 female Swiss mice (Charles River CD-1 strain; breeder Charles River France SA, St. Aubin-les Elboeuf, France) were used per group.
Mean body weight: about 30.5 g 22.5 g for males and females, respectively.
Feeding: commercial diet
Drinking water ad libitum
Room temperature: 22 +/- 2 °C Relative humidity: 30 - 70% Ventilation: about 10 air changes per hour Lightening: 12 hours light/12 hours dark
Caging: single Makrolon cages

Administration / exposure

Route of administration:

inhalation: vapour

Vehicle:

air

Details on exposure:

Whole body
Exposure chamber: glass cylinder (length 0.90 m, diameter 15 cm) with sampling ports at the inlets and outlets. Perforated stainless steel plates allowed to house the animals in individual compartments. Atmosphere generation: MVE was added to an air flow (15 l/min) to give concentrations of 0, 5000, and 25 000 ppm. Concentration measurements: 22 measurements/day by infra red-analysis at regular intervals.

Duration of treatment / exposure:

6 hrs/day on 5 consecutive days

Frequency of treatment:

once daily

Post exposure period:

24 h after the last exposure mice were sacrificed

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0; 5000; 25000 ppm (0; 12; 60 mg/L)
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
0, 4898+-200 ppm, 25046+-71 ppm
Basis:
analytical conc.
mean of means on days 1-5 (+/- standard deviation); range of analytical means: 0, 4960-5030, 24970-25110 ppm

No. of animals per sex per dose:

5

Control animals:

yes, sham-exposed

Positive control(s):

Positive control substance: single i.p. dose of Mitomycin C at 1.5 mg/kg bw at 24 hrs before sacrifice.

Examinations

Tissues and cell types examined:

Animals were killed by decapitation the day after the last inhalation exposure (positive control: 24 hrs after i.p. injection). Bone marrow was prepared from femoral bone marrow according to Schmidt, 1976.

Details of tissue and slide preparation:

Slides were stained with acridine orange according to Hayashi et al. (1983) and examined using a fluorescence microscope. Further slides were Giemsa stained and stored because the acridine orange staining is not stable. Counting: The incidence of micronucleated polychromatic erythrocytes (MPE) was determined in a total of 1,000 polychromatic erythrocytes on one slide from each animal. Size distribution: MPEs were categorized according to micronuclear size comparing the diameter of the micronucleus (d) with the diameter of the erythrocyte (D): M (d<0.1D); + 0.1D

Evaluation criteria:

not clearly stated but statistically significant and dose dependent increase assumed

Statistics:

2 linear logistic regression models with factors: sex (male, female) and group and their mutual interactions; levels of the factor group were successivily : 1) negative control, 5000 ppm MVE, 25000 ppm MVE and 2) negative control; Mitomycin C

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Remarks:

(but very high dose levels tested: 60 mg/L)

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Signs of toxicity: In treated animals no apparent signs of intoxication or body weight changes were noted.

Any other information on results incl. tables

Erythrocyte count:
No increased frequency of micronucleated polychromatic
erythrocytes (MPE) containing either small or large
micronuclei was seen in animals receiving MVE. The positive
control substance gave results as expected indicating the
sensitivity of the test system.

Results of repeat study
		Mean number of MPE / 1000 PE
                  Males                 Females
--------------------------------------------------
Control           3.2                      5.2

MVE 5000 ppm      3.0                      4.2
MVE 25000 ppm     2.8                      4.6

Mitomycin C      42.8***                   37.8***
--------------------------------------------------
*** p</= 0.001


There was no inhibition of erythropoiesis since the ratio of
polychromatic to normochromatic erythrocytes was not
significantly affected in the treated animals:

		         Ratio PE:NE
                 Males                 Females
--------------------------------------------------
Control          3.41                    3.62

MVE 5000 ppm     1.03                    2.01
MVE 25000 ppm    1.97                    3.33

Mitomycin C      1.91                    2.22
--------------------------------------------------

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
No signs of toxicity were noted in male and female CD-1 mice repeatedly
exposed to MVE at 5000 or 25000 ppm (n=5 per dose per sex; 6 h/day for 5 days; the high dose level is very close to the lower explosion level; corresponding to 0; 12; 60 mg/L). Examination of erythrocytes from bone marrow (sacrifice 24 h after the last exposure) gave no
indication of an induction of clastogenic/aneugenic effects or
cytotoxicity.
Vehicle control and positive control were valid.
Positive results seen in only one subgroup (high-dose males) in a previous study are outweighed and attributable to some technical flaw in the procedure.