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Toxicological information

Genetic toxicity: in vivo

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Administrative data

Endpoint:
in vivo mammalian germ cell study: gene mutation
Remarks:
Type of genotoxicity: genome mutation
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
No data on batch no. Limited reported study, comparable to guideline/standard (guideline was not in place yet). This study was selected as the key study because the information provided for the hazard endpoint is sufficient for the purpose of classification and labelling and/or risk assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1981
Report Date:
1981

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 477 (Genetic Toxicology: Sex-linked Recessive Lethal Test in Drosophila melanogaster)
Principles of method if other than guideline:
OECD Guideline 477 (1984) was not in place yet
GLP compliance:
no
Type of assay:
Drosophila SLRL assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Name of test compound: dimethylether (DME)
Content/purity:
- DME: min. 99.6%
- Saturated C1/C4: max 0.4%
- Water: max 500 ppm
- Sulphur: max 1 ppm
- Methanol: max 10 ppm
- Mineral oil: 30 ppm

Test animals

Species:
Drosophila melanogaster
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: wild-type strain (Berlin-K), no info on supplier
- Age at study initiation: 1 day
- Weight at study initiation: not applicable
- Assigned to test groups randomly:no info
- Fasting period before study: not applicable
- Housing: no info during exposure, after exposure individually with 3 unmated females
- Diet (e.g. ad libitum): no info
- Water (e.g. ad libitum): no info
- Acclimation period: no info


ENVIRONMENTAL CONDITIONS
- Temperature (°C): room T during exposure, matings at 25°C
- Humidity (%): no info
- Air changes (per hr): static test atmosphere, refreshed every 2-3 days (in case of 14 day exposure)
- Photoperiod (hrs dark / hrs light): no info

Administration / exposure

Route of administration:
inhalation: gas
Vehicle:
Air
Details on exposure:
TYPE OF INHALATION EXPOSURE: whole body

Concentrations tested: 0, 16400, 20500, 32800 and 57400 mg/m3
As exposures were conducted at room temperature (assuming 22°C), 1 ppm corresponds to 46.07/24.2 = 1.90 mg/m3,
these levels correspond to: 0, 8632, 10789, 17263, and 30211 ppm (or 0, 0.8, 1.1, 1.7 and 3.0% in air)

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: in vessels filled with test atmosphere
- Method of holding animals in test chamber: no info
- Source and rate of air: static test atmosphere. Exposure duration: 3 or 14 days. With a gastight syringe the test substance was brought into the vessels (after taking out an equivalent volume of air). In the 14-day test, test atmosphere was refreshed every 2-3 days.
The concentrations of the test substance were measured by taking out samples from the vessels and directly injecting these into a GC.
- Method of conditioning air: no info
- System of generating particulates/aerosols: gas was generated
- Temperature, humidity, pressure in air chamber: room T, no info on RH. No info on pressure
- Air flow rate: static test atmosphere.
- Air change rate: not applicable; in the 14-day test, test atmosphere was refreshed every 2-3 days.
- Method of particle size determination: not applicable (gas)
- Treatment of exhaust air: no info

TEST ATMOSPHERE
- Brief description of analytical method used: GC analysis
- Samples taken from breathing zone: taken from glas vessels
Duration of treatment / exposure:
- Exposure duration: 3 or 14 days
- Mating duration: 3-2-2-3-2 days (after 3-day exposure), 3-2-2 days (after 14-day exposure). Each male (wild-type Berlin-K) was mated with 3 females (Basc), and after every 2 or 3 days with new females
- F1 females were individually mated with their brothers; in the F2 generation each culture was scored for the absence of wild-type males
Frequency of treatment:
Continuously for 3 or 14 days
Post exposure period:
Mating period: 12 days (in case of 3-day exposure), 7 days (in case of 14-day exposure). Thereafter, F1 females were mated with their brothers. In the F2-generation absence of wild-type males was scored. Therefore, total duration of post-treatment period not known.
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 16400, 20500, 32800 and 57400 mg/m3
Basis:
analytical conc.
No. of animals per sex per dose:
Starting number not known; finally, ca. 1550 broods were evaluated at each time point in the 3-day test substance exposure group (ca. 380 in controls), and ca. 570 broods in the 14-day test substance exposure group (ca. 560 controls)
Control animals:
yes
Positive control(s):
- Positive control: 1,2-dichloorethaan
- Justification for choice of positive control(s): also gaseous (but positive) test atmosphere
- Route of administration: inhalation exposure
- Doses / concentrations: 150 and 2300 mg/m3 (6-h exposure), 50 and 125 mg/m3 (96-h exposure)

Examinations

Tissues and cell types examined:
NUMBER OF CELLS EVALUATED: see table below (at least) ca. 200 per control and ca. 400 per test concentration per time point
Details of tissue and slide preparation:
CRITERIA FOR DOSE SELECTION: tested up to the possibly highest concentration of 3% in air (lower explosion limit)

TREATMENT AND SAMPLING TIMES: 3 days and 14 days (for further details on mating see above)

DETAILS OF SLIDE PREPARATION: not applicable

METHOD OF ANALYSIS: examination of the absence of males with 'round eyes' (for the absence of wild-type males)

DETERMINATION OF CYTOTOXICITY
- Method: observations on activity (narcosis), survival and fertility
Evaluation criteria:
Presence of statistically significant dose-related increase in the percentage of lethal mutations
Statistics:
Done but method not indicated

Results and discussion

Test results
Sex:
male
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
Highest target concentration of about 3% in air (just below explosion limit) did not show toxic effects
Vehicle controls validity:
not examined
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
RANGE-FINDING/SCREENING STUDIES: not done

COMPARISON WITH HISTORICAL CONTROL DATA: yes, spontaneous mutation frequency is 0.15-0.2%

ADDITIONAL INFORMATION ON CYTOTOXICITY: none of the tested concentrations induced an effect on the acitivity of the flies, nor on survival or fertility.

Any other information on results incl. tables

Frequency of sex-linked recessive lethal test mutations (in %)

Study

Exp.

(days)

Conc.

(mg/m3)

Scheme

Brood A

Brood B

Brood C

Brood D

Brood E

Cultures

%

Cultures

%

Cultures

%

Cultures

%

Cultures

%

1

3

0

20500

57400

3-2-2-3-2

196

392

394

1.02

0

0.25

197

385

390

0

0

0

186

396

393

0

0

0.25

195

387

382

0

0

0.26

192

395

377

0

0

0

2

3

0

16400

32800

3-2-2-3-2

191

385

395

0

0

0

190

395

385

0

0

0

196

390

394

0.51

0

0

193

398

383

0.52

0

0

195

386

392

0

0.26

0

Mean 1+2

3

0

DME

3-2-2-3-2

387

1566

0.52

0.06

387

1555

0

0

382

1573

0.26

0.06

388

1550

0.26

0.06

387

1550

0

0.06

3

14

0

57400

3-2-2

568

556

0

0.18

575

559

0

0

590

562

0

0.18

-

-

-

-

-

-

-

-

Note: 3-2-2- means 3 mating periods of 3, 2 and 2 days, respectively

Cultures = number of tested chromosomes;

% = percentage lethal mutations = (number of lethals/number of chromosomes tested) x 100

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
Concentrations up to 3% (30000 ppm) did not induce sex-linke recessive lethal mutations in Drosophila melanogaster.

The study and the conclusions which are drawn from it fulfil the quality criteria (validity, reliability, repeatability).
Executive summary:

In the context of a toxicological evaluation, the test substance was investigated using a battery of short-term tests for genotoxicity, using amongst others, a sex-linked recessive lethal test in Drosophila melanogaster. Drosophila males were exposed for 3 days to 0.8 - 3.0% (or 16.4 - 57.4 g/m3), or for 14 days to 3.0% (57.4 g/m3). These exposures did not affect the viability, fertility or mobility of the flies. Five broods of 2 -3 days duration each were examined after the 3 -day exposure, whereas 3 broods of 2 -3 days each were examined after the 14 -day exposure. Altogether, 9471 treated chromosomes were assayed. No increase of the mutation frequency was observed in the test substance-exposed series when compared to air-exposed controls. 1,2 -Dichloroethane served as a positive control, producing up to 9.8% lethals at 125 mg/m3 for a 4 -day exposure duration.

In conclusion, in the present study the test substance up to a concentration of 3.0% (30000 ppm or 57.4 g/m3) did not induce sex-linked recessive lethal mutations in Drosophila melanogaster.