Dichlobenil

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 1983

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:

1983

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

GLP compliance:

no

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Dichlobenil

EC Number:

214-787-5

EC Name:

Dichlobenil

Cas Number:

1194-65-6

Molecular formula:

C7H3Cl2N

IUPAC Name:

2,6-dichlorobenzonitrile

Test material form:

solid: particulate/powder

Test animals

Species:

mouse

Strain:

Swiss

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: approximately six weeks old
- Fasting period before study: overnight before first dose administration
- Acclimation period: five days

ENVIRONMENTAL CONDITIONS
- Temperature: 22-24 °C
- Air changes: 16 per hour
- Photoperiod: 12 hours light/12 hours dark

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: 1 % tragacanth suspension

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Dosages were given as two equal administrations separated by a 24 hour interval in a volume of 0.1 mL/10 g body weight prepared in 1 % tragacanth suspension

Duration of treatment / exposure:

Two doses were administered over a 24 hour period

Frequency of treatment:

Two single doses were administered separated by a 24 hour period

Post exposure period:

Six hours after the second dose, the animals were sacrificed.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

300 mg/kg bw (total dose)

Doses / concentrations 2

Dose / conc.:

600 mg/kg bw (total dose)

Doses / concentrations 3

Dose / conc.:

1 200 mg/kg bw (total dose)

No. of animals per sex per dose:

Five per sex per dose

Control animals:

yes, concurrent vehicle

Positive control(s):

- mitomycin C
- Doses / concentrations: 0.4 mg/mL in sterile buffered saline

Examinations

Tissues and cell types examined:

Femur bone marrow

Details of tissue and slide preparation:

Bone marrow was removed by injection of New Born calf serum into the femur. The serum and bone marrow suspension was centrifuged for 5 minutes at 800 rpm. The supernatant was removed and a bone marrow smear made from the pellet.

After air-drying overnight, the smears were fixed in methanol for 5 minutes and then successively placed in 1.25 % May-Grünwald for 15 minutes and in 3 % Giesma for 20 minutes. After rinsing in buffered distilled water, the slides were air-dried and mounted in Depex.

Evaluation criteria:

Smears were examined to determine the incidence of micronucleated cells per 1000 polychromatic erythrocytes per animal and the ratio of normochromatic to polychromatic erythrocytes.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Remarks:

All micronucleated cell counts for the test material were within the concurrent control range. The mean normochromatic/polychromatic ratio was 0.85

Toxicity:

no effects

Remarks:

No mortalities were noted in any of the doses administered

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

No mortalities were observed.

At all dose levels, the mean micronucleated cell counts were in the same range as the counts obtained for the negative control group.

The mean ratios of normochromatic to polychromatic erythrocytes obtained for all dose levels were in the same range as those of the vehicle control group.

Any other information on results incl. tables

Table 1: Group mean results

		Number of micronucleated cells per 1000 erythrocytes		Ratio of normochromatic to polychromatic erythrocytes
Material	Total dose (mg/kg)	Mean	Range	Mean	Range
1% tragacanth	-	0.2	0 - 1	0.85	0.56 - 1.51
Test material	1200	0.2	0 - 1	0.92	0.58 - 1.61
	600	0.8	0 - 3	0.77	0.58 - 1.02
	300	0.5	0 - 1	0.74	0.56 - 1.09
Mitomycin C	*	32.8	12 - 54	1.91	0.90 - 2.90

* 0.16 mg/animal  

Applicant's summary and conclusion

Conclusions:

Under the conditions of the test, the test material did not show any evidence of mutagenic potential for polychromatic erythrocytes of mice.

Executive summary:

In a non-GLP compliant micronucleus test considered to be equivalent or similar to EU Method B.12, the genetic toxicity of the test material was determined.

No mortalities were observed. At all dose levels, the mean micronucleated cell counts were in the same range as the counts obtained for the negative control group. The mean ratios of normochromatic to polychromatic erythrocytes obtained for all dose levels were in the same range as those of the vehicle control group.

Under the conditions of this test, the test material showed no evidence of mutagenic potential for polychromatic erythrocytes of mice.