Dimethyl sulphate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data available

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Reasonably well described study. Purity of test substance not stated. Number of cells analysed in 12h-24h groups too small.

Data source

Reference

Reference Type:

publication

Title:

Transplacental Genetic and Cytogenetic Effects of Alkylating Agents in the Mouse. II Induction of Chromosomal Aberration.

Author:

Braun, R. et al.

Year:

1986

Bibliographic source:

Teratogenesis, Carcinogenesis, and Mutagenesis 6: 69-80

Materials and methods

Test guideline

Qualifier:

no guideline followed

GLP compliance:

no

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl sulphate

EC Number:

201-058-1

EC Name:

Dimethyl sulphate

Cas Number:

77-78-1

Molecular formula:

C2H6O4S

IUPAC Name:

dimethyl sulfate

Details on test material:

- Name of test material (as cited in study report): Dimethyl sulphate
No further details are given.

Test animals

Species:

mouse

Strain:

NMRI

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 10-16 weeks old
- Housing: The animals were maintained under barrier conditions.
- Diet: ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 1
- Humidity (%): 65 +/- 5
- Photoperiod (hrs dark / hrs light): 12/12

No further details are given.

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

mutagen dissolved in 0.5 ml solvent (no further specified)

Details on exposure:

Three females were mated with one male and vaginal plug were checked within a 4-day mating interval in the morning of each day. Females having a vaginal plug were seperated. In the morning of day 10, the animals were injected intraperitoneally with DMS.

Duration of treatment / exposure:

single intraperitoneal administration

Frequency of treatment:

6 hours between the intervals

Post exposure period:

up to 24 hours

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0 mg/kg
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
12.5 mg/kg
Basis:
nominal conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
25 mg/kg
Basis:
nominal conc.

Doses / concentrations 4

Remarks:

Doses / Concentrations:
50 mg/kg
Basis:
nominal conc.

Doses / concentrations 5

Remarks:

Doses / Concentrations:
100 mg/kg
Basis:
nominal conc.

No. of animals per sex per dose:

between 2 and 4 female mice and 6 to 12 embryos
see table below

Control animals:

yes

Positive control(s):

no data

Examinations

Tissues and cell types examined:

embryonic cells

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: no data

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): Two pregnant females per dose per group were killed 6, 12, 18 and 24 hours after DMS injection. Three embryos from each killed female were separately dissected in a watch glass containing 2.5 ml Dulbecco's minimal essential medium supplemented with 0.15 µg/ml colcemid. A cell suspension was obtained by aspirating the embryos into a 2-ml syringe using an 18-gauge needle. The cells were incubated for 90 minutes at 37°C in a 5% CO2 atmosphere. Incubation was followed by hypotonic treatmentand fixation and preparing slides.

DETAILS OF SLIDE PREPARATION: A few microdrops of the final cell suspension were placed onto the surface of an ice-cold wet slide. The slides were air dried and stained with 2% aceto-orcein.

METHOD OF ANALYSIS:Microscopic analysis was performed under 1000 -1400 x magnification in the light microscope. The following events were scored on coded slides: gaps, chromatid breaks and fragments, and chromatid exchanges. Chromosome-type aberration occurred only rarely and in most cases during late preparation times.

OTHER: The mitotic index was calculated from a sample size of 2000 cells per embryo. Calculation of the aberration frequency was based on 50 metaphases examined per embryo.

Evaluation criteria:

no data

Statistics:

The statistical analysis was performed by the Mann-Whitney test comparing the aberration frequencies in mutagen-treated embryos with the frequencies found in the control group. A P-value of < 0.05 was taken as indication for a statistically significant difference between the groups. A linear regression analysis was performed in order to characterise the dose dependence of the aberration frequencies.

Results and discussion

Test results

Sex:

not specified

Genotoxicity:

positive

Toxicity:

yes

Vehicle controls validity:

not specified

Negative controls validity:

not examined

Positive controls validity:

not specified

Additional information on results:

highest chromosome aberration frequency 6 hours after treatment:
0 mg/kg 0% aberrant cells (1200 scored)
12.5 mg/kg 0.8% aberrant cells (500 scored)
25 mg/kg 5.71% aberrant cells (1050 scored)
50 mg/kg 9.58% aberrant cells (1200 scored)
75 mg/kg 11.69% aberrant cells (700 scored)
100 mg/kg 5.7% aberrant cells (550 scored)
excluding gaps
in groups examined after 12, 18 and 24 hours only 300 cells scored

Any other information on results incl. tables

Table 1: Dimethyl sulphate-induced chromatid aberrations in mouse embryos treated on the 10th day embryonic development

Dose (mg/kg)	Interval (hours)	No. of females	No. of embryos	No. of cells scored	Cells with aberrations (%)^a	Events per cell
						Gaps	Breaks	Exchanges	Mitotic index (%)
0	6	4	12	1200	0.00	0.007	0.000	0.000	4.3
12.5		4	10	500	0.80	0.040	0.008	0.000	7.0
25		4	12	1050	5.71^b	0.081	0.059^b	0.008	3.3
50		4	12	1200	9.58^b	0.103	0.091^b	0.018^b	5.0
75		4	10	700	11.69^b	0.171	0.116^b	0.040^b	1.2
100		4	10	550	5.70^b	0.096	0.069^b	0.009	0.4
0	12	2	6	300	0.00	0.017	0.000	0.000	4.3
25		2	6	300	0.00	0.013	0.000	0.000	4.9
50		2	6	300	1.00	0.013	0.010	0.000	4.1
0	18	2	6	300	0.00	0.000	0.000	0.000	5.4
25		2	6	300	0.00	0.027	0.000	0.000	6.0
50		2	6	300	1.00	0.023	0.007	0.004	6.6
0	24	2	6	300	0.00	0.003	0.000	0.000	4.3
25		2	6	300	2.33^b	0.040	0.023^b	0.003	6.4
50		2	6	300	0.67	0.023	0.020	0.000	6.0

a: excluding cells with only gaps; b: significantly different from the control

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): positive
DMS showing clastogenic effect 6 hours after treatment in embryonic cells.