5,7-dichloro-4-(4-fluorophenoxy)quinoline;quinoxyfen (ISO)

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:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OPP 84-2

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 001

Cas Number:

124495-18-7

Test material form:

solid: particulate/powder

Specific details on test material used for the study:

- Substance ID: TSN 100097
- Name of substance: XDE-795
- Lot number: DECO-97-152-1
- Purity: 97.4%

Method

Target gene:

histidine

Species / strain

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

S-9 mix prepared from Aroclor 1254-induced Sprague-Dawley rats

Test concentrations with justification for top dose:

Range finding assay: 5.0, 10, 50, 100, 500, 1000, 5000 µg/plate for both with and without S9 activation
Mutation assay and confirmatory mutation assay: 10, 50, 100, 500, 1000 µg/plate and 50, 100, 500, 1000, 5000 µg/plate with and without S9 activation, respectively

Vehicle / solvent:

Dimethyl sulfoxide

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: 2-Aminoanthracene (TA98, TA100, TA1535, TA1537 with S9)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium; in agar
- Cell density at seeding: 5.0 x 10e7 to 1.0 x 10e8

DURATION
- Incubation temperature: 37 ± 1°C
- Incubation period: 20 minutes before inverting the plates and 68 hours after inverting the plates

NUMBER OF REPLICATIONS: Single

COLONY COUNTING: Hand counting was done for the plates where precipitate was formed. Remaining plates were counted using automatic colony counter.

NUMBER OF CELLS EVALUATED: 0.912 x 10e8

Evaluation criteria:

A response is considered negative if: all of the strains treated with test substance have mean reversion frequencies that are less than three times that of the mean reversion frequencies of the corresponding solvent control plates; and there is no evidence of a dose-dependent response.
A response is considered positive if two or more doses produce a mean reversion frequency that is three times or more greater than the mean reversion frequencies of the corresponding solvent control plates and the response is reproducible.
A response is considered equivocal if it does not fulfill the criteria of either a negative or a positive response and/or the Study Director does not consider the response to be either positive or negative.

Results and discussion

Test results

Key result

Species / strain:

S. typhimurium, other: TA1535, TA1537, TA100, TA98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING STUDIES: In the range finding test the test substance was evaluated at concentrations ranging from 5000 to 5.0 µg/plate in both the absence and presence of exogenous activation. The test substance concentrations of 1000 µg/plate and above produced a significant degree of toxicity in the absence of S-9 activation. The relative cloning efficiency (RCE) was 71% and 0%. The background lawn also was significantly reduced. There were not any revertants observed at the concentration of 5000 µg/plate. A moderate toxicity was observed at concentrations of 1000 µg/plate and above in the presence of S-9 activation. The toxicity was manifested only as a reduction in the number of viable colonies per plate. The relative cloning efficiency was 78% and 72%.
Based on these results, it was decided to perform the mutation assay at test substance concentrations of 1000, 500, 100, 50 and 10 µg/plate and 5000, 1000, 500, 100 and 50 µg/plate in the absence and presence of S-9, respectively.

Any other information on results incl. tables

Table-1: Initial (trial 1) and confirmatory (trial 2) mutation assays results - without metabolic activation

Compound	Conc. mg/plate	TA98		TA100		TA1535		TA1537
		Trial 1	Trial 2	Trial 1	Trial 2	Trial 1	Trial 2	Trial 1	Trial 2
Test substance	1000	22	22	81	87	23	20	11	12
	500	20	19	103	93	19	22	11	10
	100	30	29	100	92	26	26	17	16
	50	24	26	108	93	28	28	17	17
	10	28	27	101	90	28	28	17	19
Solvent control	_	30	31	109	91	30	30	18	19
Positive control	_	903	901	587	618	529	535	209	210

Table-2: Initial (trial 1) and confirmatory (trial 2) mutation assays results - with metabolic activation

Compound	Conc. mg/plate	TA98		TA100		TA1535		TA1537
		Trial 1	Trial 2	Trial 1	Trial 2	Trial 1	Trial 2	Trial 1	Trial 2
Test substance	5000	32	36	142	84	14	15	10	13
	1000	38	34	145	112	17	18	16	16
	500	37	27	129	109	22	24	22	23
	100	41	36	143	106	21	23	21	21
	50	39	41	123	106	23	22	22	22
Solvent control	_	39	41	124	98	25	23	23	23
Positive control	_	1994	1999	1775	1734	156	147	217	221

Applicant's summary and conclusion

Conclusions:

Negative with and without the metabolic activation in S. typhimurium strains

Executive summary:

The test substance was evaluated for its potential to cause mutations at the histidine operon of Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537. The study was conducted following FIFRA guideline 84-2. The test substance was evaluated for toxicity to strain TA100 in the range finding test. Tester strain TA100 was exposed to the test substance in the absence of exogenous activation and in the presence of Aroclor 1254-induced rat liver S-9 plus cofactors. The toxicity was evaluated based on 1) reversion frequency, 2) viability, and 3) integrity of the background lawn. The test substance was evaluated at concentrations ranging from 5000 to 5.0 µg/plate in both the absence and presence of exogenous activation. The results of the range finding test indicated that the test substance produced a significant degree of toxicity at concentrations of 1000 µg/plate and above in the absence of S-9 activation. A moderate toxicity at concentrations of 1000 µg/plate and above was observed in the presence of S-9 activation.

The initial mutation assay was performed using concentrations of 1000, 500, 100, 50 and 10 µg/plate and 5000, 1000, 500, 100, and 50 µg/plate in the absence and presence of S-9, respectively. The same concentrations were used in the confirmatory mutation assay to confirm the results of the initial mutation assay. The results of both mutation assays indicated that the test substance did not induce any positive increase in the number of revertant colonies for any of the tester strains in the absence and presence of Aroclor 1254-induced rat liver S-9.

Under the conditions of this study, the test substance was negative in the Salmonella typhimurium preincubation mutation assay.