α,α-dichlorotoluene

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene 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:

Study not sufficiently described and conducted with accepted general scientific principles. GLP status of the study is unknown. However, criteria for interpretation of mutagenicity are sufficiently described.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1978

Report date:

1978

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

only two tested concentrations, two bacterial strains tested, only metabolic activation tested and no positive control

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

α,α-dichlorotoluene

EC Number:

202-709-2

EC Name:

α,α-dichlorotoluene

Cas Number:

98-87-3

Molecular formula:

C7H6Cl2

IUPAC Name:

(dichloromethyl)benzene

Constituent 2

Reference substance name:

Dichloromethylbenzene

EC Number:

249-854-8

EC Name:

Dichloromethylbenzene

Cas Number:

29797-40-8

IUPAC Name:

(dichloromethyl)benzene

Details on test material:

- Name of test material (as cited in study report): BDC, benzal chloride
- Analytical purity: Benzal chloride was purchased from Yoneyama chemicals Ltd. and re-distilled before use.
No further data

Method

Target gene:

No data

Species / strain

Species / strain 1

Species / strain / cell type:

S. typhimurium TA 100

Details on mammalian cell type (if applicable):

Strains TA1535, TA1536, TA1537 and TA1538

Species / strain 2

Species / strain / cell type:

E. coli WP2

Additional strain / cell type characteristics:

other: try hcr

Species / strain 3

Species / strain / cell type:

other: Bacillus subtilis M45 (rec -) and H17 (rec +)

Metabolic activation:

with

Metabolic activation system:

Rat liver microsome fraction S-9 prepared as indicated by Ames et al.

Test concentrations with justification for top dose:

- For the Salmonella and Escherichia strains: 0.6 and 1.2 µmoles/plates
- For the Bacillus strains: 62 and 31 µmoles/disk

Vehicle / solvent:

E. Coli and B. Subtilis: 10 g meat extract, 10g polypeptone and 5g NaCl in 1.000 ML water at pH 7

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

not specified

Positive controls:

not specified

Remarks:

for the reversion assay with E. coli and S. thyphimirum

Controls 2

Untreated negative controls:

no

Negative solvent / vehicle controls:

not specified

True negative controls:

not specified

Positive controls:

not specified

Remarks:

For the recombination assay with B. subtilis

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

not valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 2

Species / strain:

E. coli WP2

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

not valid

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Test results 3

Species / strain:

other: Bacillus subtilis M45 and H17

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

not specified

Remarks on result:

other: strain/cell type:

Remarks:

Migrated from field 'Test system'.

Any other information on results incl. tables

In the following table, detailled results for the reversion assay are presented:

Tested strain	µmoles/plate	Number of revertant colonies
E. coli WP2 hcr	0	16
	0.6	87
	1.2	357
Salmonella TA 100	0	119
	0.6	463
	1.2	706

In the following table, detailled results for the recomination assay are presented:

Recombination assay
µmoles/disk	mm of inhibition for Bacillus subtilis
	H17 Rec +	M45 Rec -
31	0	2.5
62	2.0	5
Conclusion of the assay	+	+

+: positive mutagenicity

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
positive with metabolic activation for the reversion assay
positive without metabolic activation for the recombination assay

In the test conditions, the authors estimated the mutagenicity of benzal chloride to be positive in a reversion assay with metabolic activation to Salmonella TA100 and E. coli WP2 and positive in a recombination assay to Bacillus subtilis M45 and H17 without metabolic activation.

Executive summary:

The authors conducted two different bacterial mutation assay to assess the mutagenicity of benzal chloride (CAS n° 98 -87 -3 ). In one experiment, they conducted a reverse mutation assay similar to the OECD requirement of the guideline 471 with the Salmonella TA100 and the E. coli WP2 strain with a metabolic activation by a S-9 fraction. They tested in this experiment two concentrations (0.6 and 1.2 µmoles/plate diluted in DMSO), besides a solvent control (DMSO). They counted the number of revertant colonies and compared the answers with the solvent controls to establish the mutagenicity of the test material.

Besides, this experiment, the authors conducted a recombination assay with Bacillus subtilis M45 and H17 without metabolic activation to assess an other kind of mutations.They tested again two concentrations (31 and 62 µmoles/disk dissolved in DMSO). They evaluated the mutagenic potential by measuring the inhibition of the growth zone for both strains.

In the test conditions thus, the authors estimated the mutagenicity of benzal chloride to be positive in the reversion assay with metabolic activation to Salmonella TA100 and E. coli WP2 and positive in a recombination assay to Bacillus subtilis M45 and H17 without metabolic activation. Few details are available on the results and explanations on the interpretations of results is not clear.

The study was conducted for one subset of experiment with a methodology similar to the OECD guideline 471. Many deviations are noticed in this study compared with the OECD requirements (only two tested concentrations, two bacterial strains tested, only metabolic activation tested and no positive control). The authors conducted an experiment with an other suitable system but no clear explanation also on the interpretation of the results is given. Therefore the overall study should be considered as not assignable as not sufficiently described.