Registration Dossier

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:
comparable to guideline study with acceptable restrictions
Remarks:
Test carried out with only four strains of Salmonella tyhimurium. A test with Salmonella typhimurium TA102 or Escherichia coli WP2 uvrA was not carried out.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
4 tester strains used
GLP compliance:
no
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): 2,3,6-Trimethylhydrochinon
- Test substance No.: 88/728
- Analytical purity: 99.5%
- Storage condition of test material: room temperature

Method

Target gene:
histidin operon
Species / strain
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain / cell type characteristics:
not applicable
Metabolic activation:
with and without
Metabolic activation system:
Aroclor 1254-induced rat liver S9-mix
Test concentrations with justification for top dose:
1st experiment (standard plate test): TA 100, TA 98: 0, 20, 100, 500, 2500, 5000 µl/plate
2nd experiment (standard plate test): without S9 for all strains: 0, 0.8, 4, 20, 100, 500 µl/plate; with S9 for all strains: 0, 4, 20, 100, 500, 1500 µl/plate
3rd experiment (preincubation test): without S9 for all strains: 0, 0.4, 2, 10, 50, 100 µl/plate; with S9 for all strains: 0, 4, 20, 100, 250, 500 µl/plate
Vehicle / solvent:
Vehicle(s)/solvent(s) used: DMSO
Controlsopen allclose all
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene; 10 µg/plate in DMSO; for TA 100, TA 98, TA 1535, TA 1537
Remarks:
with metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: N-methyl-N'-nitro-N-nitrosoguanidine (MNNG); 5 µg/plate in DMSO; for TA 100, TA 1535
Remarks:
without metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylendiamine; 10 µg/plate in DMSO; for TA 98
Remarks:
without metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
9-aminoacridine
Remarks:
without metabolic activation Migrated to IUCLID6: 100 µg/plate in DMSO; TA 1537
Details on test system and experimental conditions:
METHOD OF APPLICATION: in agar (plate incorporation); preincubation

DURATION
- Preincubation period: 20 min, 37°C
- Exposure duration: 48 h, 37°C

NUMBER OF REPLICATIONS: 3
Evaluation criteria:
In general, a substance to be characterized as positive in the Ames test has to fulfill the following requirements:
- doubling of the spontaneous mutation rate (control)
- dose-response relationship
- reproducibility of the results

Results and discussion

Test results
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:
other: in the standard plate test: > 100µg (without S-9 mix) or > 1500 µg (with S-9 mix); in the preincubation test: > 100 µg (without S-9 mix) or no cytotoxicity (with S-9 mix)
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
Solubility: Complete soluble of the test substance in DMSO.

Applicant's summary and conclusion

Conclusions:
The test substance Trimethylhydroquinone is not mutagenic in the Ames test under the experimental conditions chosen.
Executive summary:

Trimethylhydroquinone was tested for mutagenicity in the Ames test (standard plate test and preincubation test) both in the presence and in the absence of a metabolizing system obtained from rat liver (S-9 mix) using the strains TA 1535, TA 100, TA 1537 and TA 98.

An increase in the number of his+ revertants was not observed both in the standard plate test and in the preincubation test either without S-9 mix or after the addition of a metabolizing system.