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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
Study period:
not reported.
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference
Reference Type:
publication
Title:
Further mutagenicity studies on pesticides in bacterial reversion assay systems.
Author:
Moriya, M., Ohta, T., Watanabe, K., Miyazawa, T., Kato, K. & Shirasu, Y.
Year:
1983
Bibliographic source:
Mutation Reseach., 1983, Vol. 116, p.185-216, ©Elsevier Biomedical Press.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
not specified
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Most of the pesticide samples were obtained from the Agricultural Chemicals Inspection Station of the Ministry of Agriculture, Forestry and Fisheries (Kodaira). They were standard materials obtainable in Japan. Pesticides soluble in water were dissolved in sterile distilled water, and all the other pesticides were dissolved in dimethyl sulfoxide (DMSO).

Method

Target gene:
Salmonella typhimurium: Histidine locus.
Escherichia coli: Tryptophan locus
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain / cell type characteristics:
other: TA1537 & TA98 frameshift mutation,
Species / strain / cell type:
S. typhimurium TA 1538
Additional strain / cell type characteristics:
other: frameshift
Species / strain / cell type:
E. coli WP2
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
S9
Test concentrations with justification for top dose:
Pesticides were tested up to a dose of 5000 µg/plate, unless the compounds showed toxicity to bacteria at the dose. When a pesticide showed mutagenicity only at higher doses such as 1000-5000 µg/plate, the compound was tested at doses of more than 5000 µg/plate to obtain a dose-response relationship.
Vehicle / solvent:
Pesticides soluble in water were dissolved in sterile distilled water, and all the other pesticides were dissolved in dimethyl sulfoxide (DMSO).
Controls
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
not specified
True negative controls:
not specified
Positive controls:
not specified
Positive control substance:
not specified
Details on test system and experimental conditions:
Most procedures were performed according to the methods described by Ames et al. (1975). When the E. coil strain was used, histidine and biotin in top agar were replaced by tryptophan at the same concentration. To 2 ml of the top agar were added 0.1 ml of one of bacterial suspensions in phosphate buffer (1/15 M), 0.1 ml of a solution of a pesticide and, when required, 0.5 ml of the S9 mix (0.3 ml of S9 fraction/ml S9 mix). The contents were poured onto the surface of a minimal agar plate with modified Vogel-Bonnet E medium (Moriya et al., 1978). Plates were incubated at 37°C for 2 days, after which the number of revertant colonies on each plate was counted.
For the gaseous pesticide, methyl bromide, a plate overlaid with the top agar containing one of the strains with or without the S9 mix was placed upside down without a lid in a glass container. Gaseous methyl bromide was injected into the container from a syringe. The container was incubated at 37°C for 2 days with stirring of the inside air by a small electric fan.
Pesticides were tested up to a dose of 5000 /µg/plate, unless the compounds showed toxicity to bacteria at the dose. When a pesticide showed mutagenicity only at higher doses such as 1000-5000/µg/plate, the compound was tested at doses of more than 5000 µg/plate to obtain a dose-response relationship.

Ames, B.N., McCann, J. & Yamasaki, E. (1975) Methods for detecting carcinogens and mutagens with the Salmonella/mammalian-microsome mutagenicity test, Mutation Res., Vol. 31, pp. 347-364.

Moriya, M., Kato, K. & Shirasu, Y. (1978) Effects of cysteine and a liver metabolic activation system on the activities of mutagenic pesticides, Mutation Res., Vol. 57, pp. 259-263.
Evaluation criteria:
not reported.
Statistics:
not reported.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium, other: TA1535, TA100, TA98
Metabolic activation:
without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
S. typhimurium, other: TA1537, TA1538
Metabolic activation:
without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Species / strain:
E. coli WP2
Metabolic activation:
without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Untreated negative controls validity:
not specified
Positive controls validity:
not specified
Additional information on results:
The mutagenic action of EDB was not greatly affected by the addition of S9 mix.
Remarks on result:
other: strain/cell type:
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
positive

The test material was found to be mutagenic to S. typhimurium and E. coli both with and without metabolic activation under the conditions of the test.