Reaction mass of methyl acetate and methanol

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:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

missing positive control

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Evidence that methanol inhalation does not induce chromosome damage in mice.

Author:

Campell, J.A., Howard, D.R., Backer, L.C., Allen, J.W.

Year:

1991

Bibliographic source:

Mutation Research 260 (3), 257-264

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

yes

Remarks:

- primary lung cells in addition to erythrocytes, not included in the guideline; no positive control (only historical)

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Methanol

EC Number:

200-659-6

EC Name:

Methanol

Cas Number:

67-56-1

Molecular formula:

CH4O

IUPAC Name:

Methyl alcohol

Test material form:

liquid

Test animals

Species:

mouse

Strain:

other: C57BL/6J

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: 10 weeks old
- Housing: Mice were housed in an animal facility in laminar-flow rooms
- Diet (e.g. ad libitum): Purina rodent chow
- Water (e.g. ad libitum): tap water


ENVIRONMENTAL CONDITIONS
- Air changes (per hr): 15 cycles/hour of biocleaned air
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: vapour

Vehicle:

none

Details on exposure:

TYPE OF INHALATION EXPOSURE: whole body


GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure: Methanol was vaporised and transported by nitrogen and HEPA-filtered air to stainless steel chambers.
- Air flow rate: 105 L/min
- Air change rate: 15 air changes/hours


TEST ATMOSPHERE
- Brief description of analytical method used:
Chamber methanol concentrations, monitored continuously by a Foxboro Miran 1A Infrared Analyser, indicated that ppm levels did not differ by more than 7% from calculated values.

Duration of treatment / exposure:

5 days

Frequency of treatment:

6 h/day

Post exposure period:

no

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

5.3 mg/L air

Doses / concentrations 2

Dose / conc.:

1.04 mg/L air

No. of animals per sex per dose:

5

Control animals:

yes

Positive control(s):

No positive control group was concomitantly examined. Historical positive controls are available.

Examinations

Tissues and cell types examined:

peripheral blood; primary cultures of lung cells

Details of tissue and slide preparation:

Peripheral blood cell MN analysis:
Immediately following the last exposure, animals were anesthetised and blood smears were made from tail vein blood for erythrocyte MN determination. The cells were fixed in methanol and stained with acridine orange for fluorescence microscopy. All slides were coded prior to scoring of 2000 polychromatic erythrocytes (PCE) and 2000 normochromatic erythrocytes (NCE) per animal.

Lung cell MN analysis:
The same exposure groups of mice used for blood MN analysis were also used for lung cell MN analysis. After blood was removed by perfusion, the lungs were infused with a trypsin, EDTA and collagenase solution; and then removed, minced and incubated in the same enzyme solution. The cells were collected and culture dishes with 160,000 viable cells per animal were established. Lung MN were analysed in 1000 binucleated cells typically examined from each of 5 animals per dose. Percentages of mononucleated, binucleated, trinucleated and quadrinucleatexd cells were also determined.

Statistics:

A 1- way analysis of variance was performed with Statgraphics statistical package. MN data were then analysed by a 1-tailed Dunnett´s test.

Results and discussion

Test results

Key result

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

not applicable

Negative controls validity:

not examined

Positive controls validity:

other: historical positive controls

Additional information on results:

No treatment related effect on micronuclei frequency or cell kinetics and no toxicity were seen at any dose level:

Peripheral blood cell MN analysis:
Mean MN rates were 3.1/1000 and 5.2/1000 in PCE, and 3.4/1000 and 3.6/1000 in NCE at either dose, respectively, vs. 5.0/1000 and 3.7/1000 of respective controls.

Lung cell MN analysis:
Mean MN rates were about 20/1000 to 24/1000 irrespective of a dose or control group. The ratio of bi- to mononucleated cells was not influenced by the treatment, neither was there evidence of a treatment-related increase in the incidence of multi-nucleated cells.

Applicant's summary and conclusion

Conclusions:

Interpretation of results: negative