Dimethyl ether

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: gene mutation

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

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

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

Test material information

Constituent 1

Reference substance name:

Dimethyl ether

EC Number:

204-065-8

EC Name:

Dimethyl ether

Cas Number:

115-10-6

Molecular formula:

C2H6O

IUPAC Name:

dimethyl ether

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 or test system 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

Doses / concentrations 1

Dose / conc.:

16 400 mg/m³ air (analytical)

Doses / concentrations 2

Dose / conc.:

20 500 mg/m³ air (analytical)

Doses / concentrations 3

Dose / conc.:

57 400 mg/m³ air (analytical)

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

yes, concurrent vehicle

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/m^3)	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:

Concentrations up to 3% (30000 ppm) did not induce sex-linke recessive lethal mutations in Drosophila melanogaster. The study and the conclusions 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.