Ethoxyquin

Genetic toxicity: in vitro

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 guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

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

Test material information

Constituent 1

Reference substance name:

Ethoxyquin

EC Number:

202-075-7

EC Name:

Ethoxyquin

Cas Number:

91-53-2

Molecular formula:

C14H19NO

IUPAC Name:

ethoxyquin

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 / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

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 results

Test results 1

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

Test results 2

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

Test results 3

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

Test results 4

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

Test results 5

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.