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Toxicological information

Genetic toxicity: in vitro

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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: Main parameters measured are comparable to guideline study, GLP status unknown, limitations in design and reporting but otherwise acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Tests with a preincubation modification of the Salmonella/microsome assay
Author:
Zeiger E and Haworth S.
Year:
1985
Bibliographic source:
Progress in Mutation Research, 5: 187-199

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
no TA102 used
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): benzene
- Analytical purity: not stated
- no further details

Method

Species / strain
Species / strain / cell type:
other: Salmonella typhimurium strains TA97, TA98, TA100 and TA1535
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254 induced S9 from male Sprague-Dawley rats and Syrian hamsters
Test concentrations with justification for top dose:
0, 0.01, 0.033, 0.1, 0.333, 1.0 mg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 9-aminoacridine 4 µg/plate and 2-aminoanthracene 0.75, 1.5 and 2 µg/plate
Remarks:
TA97 with and without S9
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylene-diamine 12 µg/plate and 2-aminoanthracene 0.75, 1.5 and 2 µg/plate
Remarks:
TA98 with and without S9
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
other: sodium azide 2.5 µg/plate and 2-aminoanthracene 0.75, 1.5 and 2 µg/plate
Remarks:
TA100 and TA1535 with and without S9
Details on test system and experimental conditions:
METHOD OF APPLICATION:
- Preincubation method used (20 min), then plated onto agar
- In the first experiment, the concentration of S9 in the S9 mix was 10%. If all tests (nonactivation, rat S9 and hamster S9) were negative, they were repeated, with the S9 concentrations at 30% instead of the original 10%. If the repeat tests were also negative, the chemical was declared nonmutagenic
-Chemicals in this study were tested at a minimum of five doses up to a toxic dose or the limit of solubility, to a maximum dose of 10 mg/plate. Benzene was tested to a maximum dose of 1 mg/plate.

NUMBER OF REPLICATIONS: 3
Evaluation criteria:
A positive response was defined as a dose-related increase over the control, regardless of its magnitude; an equivocal response was a non dose-related increase over the control or an elevated response at only a single dose. A chemical was declared mutagenic if it gave a reproducible, dose-related increase in any strain-activation combination.

Results and discussion

Test results
Species / strain:
other: Salmonella strains TA97, TA98, TA100 and TA1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Positive controls validity:
valid

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative with metabolic activation
negative without metabolic activation

Benzene was not mutagenic under the conditions of the assay.
Executive summary:

Genotoxicity of benzene was assessed in vitro in a pre-incubation modification of the Salmonella microsome assay. Testing was performed with and without metabolic activation by Arochlor-1254 induced rat and hamster S9. Salmonella typhimurium strains TA97, TA98, TA100 and TA1535 were used.

Benzene was not mutagenic under the conditions of the assay.