6,6'-di-tert-butyl-4,4'-thiodi-m-cresol

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

Study period:

1994-1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is performed according to OECD guidelines 471 and 472 under GLP conditions, although the exact study period is not mentioned.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): TBBC
-Substance type: white crystalline powder
- Physical state: solid
- Analytical purity: > 98%
- Impurities (identity and concentrations): not mentioned
- Purity test date: not mentioned
- Lot/batch No.:not mentioned
- Expiration date of the lot/batch: not mentioned
- Stability under test conditions: stable during test period according to authors of report; data not shown
- Storage condition of test material: not mentioned

Method

Target gene:

Histidine gene in S. Typhimurium
Tryptophan gene in E. Coli

Species / strain

Species / strain 1

Species / strain / cell type:

E. coli WP2 uvr A

Species / strain 2

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

Rat S9

Test concentrations with justification for top dose:

Dose-range finding: 0, 50, 150, 500, 1500, 5000 µg/plate.
Main test - S9: 0, 0.781, 1.56, 3.13, 6.25, 12.5, 25, 50, 100, 200 µg/plate.
Main test + S9: 0, 12.5, 25, 50, 100, 200, 400, 800 µg/plate.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO

Controls

Untreated negative controls:

yes

Remarks:

DMSO

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

9-aminoacridine

Remarks:

Migrated to IUCLID6: 2-aminoanthracene, AF-2, sodium azide

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hours

No details mentioned in report

Evaluation criteria:

It was assessed that the test substance was mutagenic (positive) in this test system if the mean numbers of mutant colonies on the plates containing the test substance increase by at least double compared to those of the vehicle control under conditions with or without the S9 mix in 1 or more of the 5 test strains used and if reproducibility or dose dependence is observed in this increase.

Statistics:

No statistical methods were used in the evaluation.

Results and discussion

Test results

Test results 1

Key result

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

Test results 2

Key result

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:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
-Precipitation: observed at all test conditions with E. Coli, except vehicle.

RANGE-FINDING/SCREENING STUDIES:
Range-finding: when tests were performed with TBBC within the range of 50-5000 μg/plate at a geometric ratio of approximately 3, antibacterial activity was observed in tests without the S9 mix at all of the doses for TA100, TA1535, and TA1537 and at doses of 150 μg/plate or higher for TA98, but no antibacterial activity was observed with WP2 uvrA. In tests with the S9 mix, antibacterial activity was observed at doses of 500 μg/plate or higher for all four S. typhimurium strains, but no antibacterial activity was observed with WP2 uvrA. Therefore, the maximum doses in the main study were set to 50 μg/plate for tests without the S9 mix (200 μg/plate for TA98 and 5000 μg/plate for WP2 uvrA) and 800 μg/plate for tests with the S9 mix (5000 μg/plate for WP2 uvrA).

Main study:
Tests without the S9 mix were performed at TBBC doses within the range of 0.781-50 μg/plate for TA100, TA1535, and TA1537, 3.13-200 μg/plate for TA98, and 313-5000 μg/plate for WP2 uvrA with a geometric ratio of 2, and tests with the S9 mix were performed at TBBC doses within the range of 12.5-800 μg/plate for the four S. typhimurium strains and 313-5000 μg/plate for WP2 uvrA with a geometric ratio of 2. The results showed no increases in the numbers of mutant colonies exceeding double the vehicle control values in the tests on the 5 test strains used, with or without S9, in either of the two studies.
In all of the tests performed with TBBC, increases in the numbers of mutant colonies were observed with all of the test strains in the positive control groups, and, as in the vehicle control group, the numbers of mutant colonies measured were within the ranges of historical control values, so the effectiveness of this test system was confirmed.

Any other information on results incl. tables

none

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

The gene reverse mutation test was performed using Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2 uvrA. The results showed no increases in the numbers of reverse mutation colonies exceeding twice the vehicle control values in either of the two studies at any of the doses of the five types of test bacteria used, so it was assessed that 4,4'-thiobis(6-tert-butyl-m-cresol) did not express mutagenicity potential in the test system used.