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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
18th August 1992 - 16th October 1992
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. Read across from DBT-2EHMA (CAS: 10584-98-2)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report date:
1992

Materials and methods

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

Test material

Constituent 1
Reference substance name:
TK 11638 (Irgastab T 22 M)
IUPAC Name:
TK 11638 (Irgastab T 22 M)
Details on test material:
- Name of test material (as cited in study report): TK 11638
- Trade Name: Irgastab 22M
- Substance type: Organotin
- Physical state: Liquid
- Identity Main component: Di-n-butyltin bis (2-ethylhexylthioglycolate)
- Purity: 65 %
- Impurities (identity and concentrations): 35 % Mono-n-butyltin tris (2-ethylhexylthioglycolate)
- Reanalysis date: July 1996
- Storage condition of test material: NDA

Method

Target gene:
Salmonella typhimurium: histidine operon
Escherichia coli: tryptophan operon
Species / strainopen allclose all
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Species / strain / cell type:
E. coli WP2 uvr A
Metabolic activation:
with and without
Metabolic activation system:
Arcolor 1254 induced Rat liver S9-mix
Test concentrations with justification for top dose:
Mutagenicity Test, original experiment: 625.0000, 1250.0000, 2500.0000 and 5000.0000 µg/plate
Mutagenicity Test, first confirmatory experiment: 39.0625, 78.1250, 156.2500, 312.5000, 625.0000 µg/plate
Mutagenicity Test, second confirmatory experiment: 4.8828, 9.7656, 19.5313, 39.0625 µg/plate
Vehicle / solvent:
- Vehicle used: acetone
- Justification for choice of vehicle: NDA
Controls
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: See information on methods section.
Details on test system and experimental conditions:
METHOD OF APPLICATION: in medium; in agar (plate incorporation).

DURATION
- Preincubation period: Inoculates from frozen master copies were set up monthly. They were grown in liquid nutrient broth medium (NB-medium) overnight and then plated on NB-agar.
- Exposure duration: 48 h

CONTROL OF THE GENOTYPE OF THE STRAINS
The characteristics of the strains were checked monthly. Histidine-auxotrophy of the Salmonella strains was demonstrated by the requirement for L-histidine. The presence of the rfa character was assayed by the sensitivity for crystal-violet. The deletion of the uvrB gene was demonstrated by the sensitivity for UV-light. The Salmonella strains containing the R-factor (TA 98 and TA 100) were additionally checked for ampicillin resistance. The tryptophan-auxotrophy of E.coli WP2 uvrA was demonstrated by the requirement for tryphophan. The absence of the uvrA gene was demonstrated by the sensitivity of the strain for UV-light. Furthermore, all strains were checked for their characteristic reversion properties with known mutagens (positive controls).

NUMBER OF REPLICATIONS: 2

DETERMINATION OF CYTOTOXICITY
- Method: Number of revertant colonies detrected by an Artek computer
Evaluation criteria:
The test substance is considered to be mutagenic in this test system if:
- A positive effect is observed in one strain and the effect can be reproduced in a confirmatory experiment.
- A positive effect is observed in two or more strains.
A positive effect is defined as an increase of the mean number of revertants per plate for any concentration above that of the negative control by at least a factor of 2.0 with strains TA 98, TA 1535, TA 1537 and WP2 uvrA, or by a factor of at least 1.5 with strain TA 100. Generally a concentration related effect should be demonstrable. If equivocal results are obtained, the final decision has to be based on scientific judgement.
Statistics:
Means and standard deviations for all mutagenicity assays were calculated by a previously validated computer program.

Results and discussion

Test resultsopen allclose all
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
not determined
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
not determined
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
RANGE-FINDING/SCREENING STUDIES:
Six concentrations of TK 11638 ranging from 20.6 to 5000 µg/plate were tested with strains S. typhimurium TA 100 and E. coli WP2 uvrA to determine the highest concentration to be used in the mutagenicity assay. The experiments were performed without and with metabolic activation. Normal background growth was observed with both strains. The numbers of revertant colonies were not reduced. From the results obtained, the highest concentration suitable for the first mutagenicity test was selected to be 5000 µg/plate with and without metabolic activation.
Remarks on result:
other: other: Preliminary cytogenicity test
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative

Based on the results of these experiments and on standard evaluation criteria, it is concluded that TK 11638 (Irgastab T 22 M) and its metabolites did not induce gene mutations in the strains of S. typhimurium and E. coil used.
Executive summary:

The results of the Salmonella - Escherichia coli/Mammalian-Microsome Reverse Mutation Assay with a Confirmatory Assay indicate that under the conditions of this study, in both initial and confirmatory assays, the test article, TK 11638, did not cause a positive increase in the numbers of revertants per plate of any of the tester strains either in the presence or absence of microsomal enzymes prepared from induced rat liver (S9).

Read across from DBT-2EHMA (CAS: 10584-98-2)