2-ethylhexyl 10-ethyl-4,4-dimethyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Preferred study for this SIDS endpoint; EPA/OECD GLP compliance was noted. Composition/purity of the test substance not reported.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: OECD, USEPA and USFDA and proposed revisions to OECD (1994). Specific guidelines not provided.

Deviations:

yes

Remarks:

, analyses were not performed to verify the homogeneity, stability or accuracy of preparation of the test and control article dosing solutions.

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl 10-ethyl-4,4-dimethyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate

EC Number:

260-829-0

EC Name:

2-ethylhexyl 10-ethyl-4,4-dimethyl-7-oxo-8-oxa-3,5-dithia-4-stannatetradecanoate

Cas Number:

57583-35-4

Molecular formula:

C22H44O4S2Sn

IUPAC Name:

2-ethylhexyl 2-{[({2-[(2-ethylhexyl)oxy]-2-oxoethyl}sulfanyl)dimethylstannyl]sulfanyl}acetate

Constituent 2

Reference substance name:

8-Oxa-3,5-dithia-4-stannatetradecanoic acid, 10-ethyl-4,4-dimethyl-7-oxo-, 2-ethylhexyl ester

IUPAC Name:

8-Oxa-3,5-dithia-4-stannatetradecanoic acid, 10-ethyl-4,4-dimethyl-7-oxo-, 2-ethylhexyl ester

Details on test material:

- Name of test material (as cited in study report): Dimethyltin bis (2-ethylhexylthioglycolate)
- Physical state: liquid
- Lot/batch No.: 1706-152
- Stability under test conditions: stable
- Storage condition of test material: room temperature

Method

Target gene:

Strains TA1535 and TA100 detect base pair substitution mutations affecting the hisG46 allele.
Strain TA98 detects frameshift mutations affecting the hisD3052.
Strain TA1537 detects frameshift mutations affecting the hisC3076 allele.
Strain TA102 can detect a variety of genetic damage affecting AT base pairs in the hisG428 allele.
Strain WP2 uvrA detects AT base pair mutations at the trp locus.

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:

S. typhimurium TA 102

Species / strain 3

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced male Sprague-Dawley rat liver homogenate

Test concentrations with justification for top dose:

16.7, 50, 167, 500, 1670, and 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: the test substance demonstrated solubility in the solvent.

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

no

Positive controls:

yes

Positive control substance:

other: Evaluated in the absence of S9: sodium azide; 9-aminoacridine; 2-nitrofluorene; mitomycin C; ENNG. In the presence of S9: 2-Aminofluorene and 2-anthramine

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium; in agar (plate incorporation) and preincubation.
Evaluated in both toxicity prescreen and mutation assays using both the liquid pre-incubation and plate incorporation treatment.


DURATION
- Preincubation period: 30 minutes (liquid pre-incubation method)
- Exposure duration: 48-hours
- Expression time (cells in growth medium): 48 hours
- Selection time (if incubation with a selection agent): 30 minutes
- Fixation time (start of exposure up to fixation or harvest of cells): 48 hours


SELECTION AGENT (mutation assays): Na2HPO4

NUMBER OF REPLICATIONS: triplicate

Evaluation criteria:

A positive result is defined as a statistically significant, dose-dependent increase in the number of histidine- or tryptophan-independent revertants with at least one dose level inducing a revertant frequency that is two-fold the solvent control value. If the test article does not induce a statistically significant, dose-dependent increase in revertant frequency, but does induce a revertant frequency at one dose level that is two-fold the spontaneous control value, the result is considered equivocal. A negative result is defined as the absence of a statistically significant or dose-dependent increase in the number of histidine or tryptophan-independent revertants.

Statistics:

Statistical analyses were conducted using the program developed by Snee and Irr (1981), with significance established at the 95% confidence limit. A positive result was defined as a statistically significant, dose-dependent increase in the number of histidine- or tryptophan-independent revertants, with at least one dose level inducing a revertant frequency that was two-fold the solvent control value. An equivocal result was declared if the test substance did not induce a statistically significant, dose-dependent increase in revertant frequency, but did induce a revertant frequency at one dose level that was two-fold the spontaneous control value. A negative result was defined as the absence of a statistically significant or dose-dependent increase in the number of histidine- or tryptophan-independent revertants. Statistical analyses were only conducted when a 50% increase in revertant frequency (relative to the concurrent negative controls) was observed.

Results and discussion

Test results

Test results 1

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 2

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 3

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 4

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 5

Species / strain:

S. typhimurium TA 102

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Test results 6

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

Primary test results revealed that in the liquid pre-incubation assay, growth was inhibited in strains TA1535, TA1537, and TA100 at >= 500 ug/plate (in the presence and absence of metabolic activation. Toxicity to strain TA98 was reported at >=1670 ug/plate (without activation) and >=500 ug/plate (with activation). Growth was inhibited in strain TA102 at >= 1670 ug/plate (both with and without activation). A dose level of 5000 ug/plate inhibited growth of strain WP2 uvrA without metabolic activation, and >=1670 ug/plate with metabolic activation. In the plate incorporation assay, both with and without metabolic activation, growth was inhibited in strain TA1537 at >=500 ug/plate and in strain TA1535 at 5000 ug/plate. In the presence of S9, growth in TA100 and TA102 was inhibited at 5000 ug/plate, and without S9 at >=1670 ug/plate. A dose level of >=500 ug/plate inhibited growth in TA98 (without S9) and at >=1670 ug/plate (with S9). No growth inhibition was observed in WP2 uvra. Again, the test substance was reported to be incompletely soluble at levels >= 500 ug/plate.


RANGE-FINDING/SCREENING STUDIES: Preliminary test results revealed that the test substance produced inhibited growth in both Salmonella tester strains (TA1537 and TA100) at doses >= 500 ug/plate, under liquid pre-incubation conditions. Additionally, the test substance was found to be incompletely soluble at levels >= 500 ug/plate.


COMPARISON WITH HISTORICAL CONTROL DATA: all positive and negative control values in both assays were within acceptable historical ranges.

Remarks on result:

other: At dose levels below the solubility of the test substance

Applicant's summary and conclusion

Conclusions:

Interpretation of results: Negative

The results of the tests conducted on the test substance, for both liquid pre-incubation and plate incorporation treatments, in the presence and absence of a metabolic activation system, were negative at dose levels below the solubility of the test substance.

Executive summary:

The test article was evaluated in the Ames/Salmonella-E. coli Reverse Mutation Assay to determine its ability to induce reverse mutations at selected histidine loci in five tester strains of Salmonella typhimurium (TA1535, TA1537, TA100, TA98, TA102) and at the tryptophan locus in one Escherichia coli tester strain (WP2 uvrA), in both the presence and absence of an exogenous metabolic activation system (S9).

Toxicity of the test article was first evaluated in a preliminary toxicity screen using both liquid pre-incubation and plate incorporation treatment conditions. Duplicate cultures were treated at doses of 50.0, 167, 500, 1670 and 5000 ug/plate, and the DMSO solvent control, in the absence of S9. Results of the prescreen indicated that the test substance produced inhibited growth in both Salmonella tester strains at doses >/=500 ug/plate under liquid pre-incubation conditions. In addition, the test article was found to be incompletely soluble at doses >/=500 ug/plate.

The test article next was evaluated for mutagenicity using both treatment conditions. Based upon the results of the prescreen, the test substance was evaluated in triplicate cultures in all six tester strains at doses of 16.7, 50.0, 167, 500, 1670 and 5000 ug/plate with and without S9. Six doses of the test substance were evaluated in the event of unacceptable toxicity and/or insolubility at the highest dose levels evaluated in the mutation assay. The S9 mixture included 6% (v/v) Aroclor 1254 -induced male Sprague-Dawley rat liver homogenate with the appropriate buffer and cofactors. Except for strain WP2 uvrA under plate incorporation conditions, inhibited growth again was observed for all strains/S9/treatment combinations at the highest 1 -3 doses evaluated. In addition, the test article again was found to be incompletely soluble at doses >/= 500 ug/plate. Revertant frequencies for all doses of the test substance in all tester strains with and without S9, under both treatment conditions, approximated or were less than those observed in the concurrent negative control cultures. All positive and negative control values in both assays were within acceptable ranges.

Therefore, the results for the test substance were negative in the Ames/Salmonella-E. coli Reverse Mutation Assay, using liquid pre-incubation and plate incorporation treatments, under the test conditions.