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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Peer-reviewed assessment report (attached in section 13)

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
EPA OPPTS 870.5100 - Bacterial Reverse Mutation Test (August 1998)
Deviations:
not applicable
GLP compliance:
yes
Remarks:
self-certified to US EPA regulations [40 CFR Part 160]; and OECD regulations [ENV/MC/CHEM (98) 17]
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Chemical name
IUPAC: 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline
CAS: 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline

Method

Target gene:
histidine locus (Salmonella strains)
tryptophan locus (Escherichia coli tester strain WP2uvrA)
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:
S9 mix that was obtained from Aroclor-induced rat livers.
Test concentrations with justification for top dose:
10.0, 33.3, 100, 333, 1,000, 2,000, and 5,000 µg/plate (±S9, Salmonella strains)
33.3, 100, 333, 1,000, 3,330 and 5,000 µg/plate (±S9, Escherichia coli tester strain WP2uvrA)
Vehicle / solvent:
- Vehicle/solvent used.
Controls
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
not specified
Details on test system and experimental conditions:
The doses tested in the mutagenicity assay were selected based on the results of a dose range finding study using tester strains TA100 and WP2uvrA and ten doses of test article ranging from 6.67 to 5,000 µg/plate one plate per dose, both in the presence and absence of S9 mix that was obtained from Aroclor-induced rat livers.
The tester strains used in the mutagenicity assay were Salmonella typhimurium test strains TA98, TA100, TA1535, and TA1537 and Escherichia coli tester strain WP2uvrA. The assay was conducted in both the presence and absence of S9 mix along with concurrent vehicle and positive controls using three plates per dose. The doses tested in the mutagenicity assay with all Salmonella tester strains in both the presence and absence of S9 mix were 10.0, 33.3, 100, 333, 1,000, 2,000, and 5,000 µg/plate. The doses tested in the mutagenicity assay with tester strain WP2uvrA in both the presence and absence of S9 mix were 33.3, 100, 333, 1,000, 3,330 and 5,000 µg/plate. The results of the initial mutagenicity assay were confirmed in an independent experiment.

Results and discussion

Test resultsopen allclose all
Key result
Species / strain:
S. typhimurium TA 98
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1535
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Positive controls validity:
valid
Key result
Species / strain:
S. typhimurium TA 1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Positive controls validity:
valid
Key result
Species / strain:
E. coli WP2 uvr A
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
not specified
Positive controls validity:
valid

Any other information on results incl. tables

The test article did not cause an increase in the mean number of revertants per plate with any of the tester strains either in the presence or absence of microsomal enzymes (S9). The positive control substances gave the expected increase in mutant frequencies.

Applicant's summary and conclusion

Conclusions:
As information was provided via a peer-reviewed assessment report, it can be considered as sufficiently reliable to assess the potential of ethoxyquin for the induction of gene mutations in bacteria. Under the conditions of this study, ethoxyquin proved negative in a reverse mutation assay (Ames test) in different tester strains of Salmonella typhimurium and Escherichia coli.
Executive summary:

In a reverse gene mutation assay in bacteria (OECD 471), Salmonella typhimuriumtest strains TA98, TA100, TA1535, and TA1537 and Escherichia coli tester strain WP2uvrA  were exposed to ethoxyquin at concentrations of 10.0, 33.3, 100, 333, 1,000, 2,000, and 5,000 µg/plate resp. 33.3, 100, 333, 1,000, 3,330 and 5,000 µg/plate in the presence and absence of mammalian metabolic activation (Aroclor-induced rat liver S9)

Ethoxyquin was tested up to the limit concentration 5000 µg/plate. The positive controls induced the appropriate responses in the corresponding strains.There was no evidence or a concentration related positive response of induced mutant colonies over background.

This study is classified as acceptable. This study satisfies the requirement for OECD 471 for in vitro mutagenicity (bacterial reverse gene mutation) data.