Dimethylbis[(1-oxoneodecyl)oxy]stannane

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Key Study OECD 471 (1998) with Dimethyltin bis(neodecanoate):

Under the conditions of the study Fomrez UL-28 was considered to be negative in the bacterial reverse mutation assay with independent repeat assay

Read-across to structurally similar substance dimethyltin dichloride (DMTC) (CAS Number 753-73-1): Genetic toxicity in vitro (Ames): Holmes 1990a & 1990b

The test material was not mutagenic when tested according to the procedures used in this assay.

Read-across to structurally similar substance DMTE (Dimethyltin bis (2-ethylhexyl thioglycolate) CAS 57583 -35 -4)

In vitro Gene mutation (Reverse mutation assay/Ames): S. typhimurium and E. coli- negative in all strains with and without metabolic activation.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

11 April 1990 to 19 July 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

other: read-across target

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

Histidine

Species / strain / cell type:

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

Species / strain / cell type:

S. typhimurium TA 1538

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254-induced rat liver S-9

Test concentrations with justification for top dose:

Range finding assay: 10, 50, 100, 500, 1000, and 5000 µg/plate
First mutagenicity assay: 10, 50, 100, 500, 1000, and 5000 µg/plate
Second mutagenicity assay: 5, 10, 50, 100, 500, and 1000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: Deionised water for the test material; DMSO for the positive control substances.

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-Anthramine: 2 µg/plate for strains TA1538, TA98, and TA100 and at 4 µg/plate for strains TA1535 and TA1537 in the presence of metabolic activation.

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Preincubation period: The cultures were allowed to sit unshaken for 2 to 4 hours, they were then gently shaken (100 rpm) for 11 to 14 hours at 37 °C.
- Exposure duration: After the top agar had set, the plates were incubated at 37°C for about 48 hours.
- Expression time (cells in growth medium): the plates were incubated at 37°C for about 48 hours. The histidine-independent revertant colonies were counted following the incubation period; however, if the plates could not be immediately evaluated, they were refrigerated at 4°C until they could be counted.

NUMBER OF REPLICATIONS: three plates per dose level, both with and without a mammalian liver metabolic activation.

NUMBER OF CELLS EVALUATED: 10^8

DETERMINATION OF CYTOTOXICITY
Toxicity is evidenced by several phenomena: a substantial decrease in the number of revertant colonies on the test plates compared with the controls, the clearing or absence of the background lawn growth, or the formation of pinpoint nonrevertant colonies.

Evaluation criteria:

The histidine-independent revertant colonies were counted using an automated colony counter. When accurate counts could not be obtained (e.g., because of precipitation on the plates), the colonies were counted manually using an electric probe colony counter.

CRITERIA FOR INTERPRETATION
Positive - A test material is considered a mutagen when it induces a reproducible, dose-related increase in the number of revertants in one or more strains. This increase should occur for at least three consecutive dose levels.

Negative - A test material is considered a non-mutagen when no dose-related increase in the number of revertants is observed in at least two independent experiments.

Inconclusive - When a test material cannot be identified clearly as a mutagen or non-mutagen, the results are classified as inconclusive.

Statistics:

Mean and standard deviation values were determined for the number of revertants at each dose level.

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

≥ 1000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

The Ames Salmonella/microsome assay was used to evaluate the ability of the test material to induce genetic damage in S. typhimurium strains TA1535, TA1537, TA1538, TA98, and TA100. The assays were performed using the standard plate incorporation procedure, in both the presence and absence of a rat liver metabolic activation system. The presence of the appropriate genetic characteristics was verified for the strains used in this study. The results of the controls were acceptable for all assays.

The preliminary assay was conducted with tester strain TA100 in the presence and absence of metabolic activation containing 4% S-9. The doses used were 10, 50, 100, 500, 1000, and 5000 µg/plate. Toxicity was indicated with revertant counts below the spontaneous background level at the 1000 µg dose and thinning of the background lawn at 5000 µg, both in the presence and absence of metabolic activation. Based on these results, the first assay was conducted at the same dose levels, with all five tester strains, in the presence and absence of 4% S-9.
There was no evidence of a dose-related increase in the number of histidine revertants with any tester strain. Toxicity was noted with all tester strains at 5000 µg as background lawn thinning or complete absence of bacterial growth. Some toxicity was also noted at 1000 µg. The second assay was conducted at dose levels of 5, 10, 50, 100, 500, and 1000 µg/plate, and the percent of S-9 in the metabolic activation mixture was increased to 10% due to the lack of response in the first assay. Again, there was no dose-related increase in the number of histidine revertants with any tester strain. Toxicity was observed at the 1000 µg dose with some strains, indicated by a decrease in the number of revertant colonies below background levels.

Conclusions:

The test material was not mutagenic when tested according to the procedures used in this assay.

Executive summary:

The test material was examined for mutagenic activity in the Salmonella/microsome assay using the standard plate incorporation procedure with Salmonella typhimurium strains TA1535, TA1537, TA1538, TA98 and TA100, in both the presence and absence of an Aroclor 1254-induced rat-liver metabolic activation system.

No reproducible, dose-related increase in the number of histidine revertant colonies was observed with any tester strain. Therefore, the test material was found not mutagenic when tested according to the procedures used in this assay.

Reference 2

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted on read-across material

Justification for type of information:

Read-across to structurally similar substance dimethyltin dichloride (DMTC) (EC Number 212-039-2, CAS Number 753-73-1), see attached justification.

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

≥ 1000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

1000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

12 June 1990 to 25 July 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

other: read-across target

Qualifier:

according to guideline

Guideline:

OECD Guideline 472 (Genetic Toxicology: Escherichia coli, Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

Tryptophan

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

S-9 liver fraction from male Sprague-Dawley rats given a single 500-mg/kg intraperitoneal injection of Aroclor 1254

Test concentrations with justification for top dose:

10, 50, 100, 500, 1000, and 5000 µg/plate.

Vehicle / solvent:

For test article: Water, deionised
For positive control substances: Dimethylsulfoxide (DMSO)

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

N-ethyl-N-nitro-N-nitrosoguanidine

other: 2-Anthramine - at 20 µg/plate in the presence of metabolic activation

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Preincubation period: The culture was allowed to sit unshaken for 2 to 4 hours, then gently shaken (100 rpm) for 11 to 14 hours at 37°C.
- Exposure duration: After the top agar had set, the plates were incubated at 37 °C for about 48 hours.
- Expression time (cells in growth medium): The tryptophan-independent revertant colonies were counted following the incubation period; however, if the plates could not be immediately evaluated, they were refrigerated at 4°C until they could be counted.

NUMBER OF REPLICATIONS: The test material was assayed twice, with three plates per dose level, both with and without a mammalian liver metabolic activation mixture.

NUMBER OF CELLS EVALUATED: 10^8

DETERMINATION OF CYTOTOXICITY
Toxicity is evidenced by several phenomena: a substantial decrease in the number of revertant colonies on the test plates compared with the controls, the clearing or absence of the background lawn growth, or the formation of pinpoint non-revertant colonies.

Evaluation criteria:

The tryptophan-independent revertant colonies were counted using an automated colony counter. When accurate counts could not be obtained (e.g., because of precipitation on the plates), the colonies were counted manually using an electric probe colony counter.

CRITERIA FOR INTERPRETATION
Positive - A test material is considered a mutagen when it induces a reproducible, dose-related increase in the number of revertants. This increase should occur for at least three consecutive dose levels.

Negative - A test material is considered a non-mutagen when no dose-related increase in the number of revertants is observed in at least two independent experiments.

Inconclusive - When a test material cannot be identified clearly as a mutagen or nonmutagen, the results are classified as inconclusive.

Statistics:

Mean and standard deviation values were determined for the number of revertants at each dose level.

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

The E. coil WP2 (uvrA)/microsome assay was used to evaluate the ability of the test material to induce genetic damage in E. coli strain WP2 (uvrA). The assays were performed using the standard plate incorporation procedure, in both the presence and absence of a rat-liver metabolic activation system. The presence of the appropriate genetic characteristics was verified for the strain used in this study. The results of the controls were acceptable for all assays.

The first assay was conducted in the presence and absence of metabolic activation containing 4% S-9. The doses used were 10, 50, 100, 500, 1000, and 5000 µg/plate. There was no evidence of a dose-related increase in the number of tryptophan revertants. Slightly low revertant counts at the 5000 µg dose may indicate toxicity. Based on these results, the second assay was conducted at the same dose levels, but the percent of S-9 in the metabolic activation mixture was increased to 10% due to the lack of response in the first assay. Note that the portion of the second assay with 10% S-9 was repeated on a separate day due to unacceptable 2-anthramine control values. There was no dose-related increase in the number of tryptophan revertants, and low revertant counts were observed at the 5000 µg dose level, confirming toxicity at this dose.

Conclusions:

In conclusion, the test material was found to be non-mutagenic when tested according to these procedures.

Executive summary:

The test material was examined for mutagenic activity in the the Escherichia coli WP2 (uvrA)/microsome plate incorporation assay performed using the standard plate incorporation procedure with Escherichia coli strain WP2 uvrA, in both the presence and absence of an Aroclor 1254-induced rat-liver metabolic activation system.

A reproducible, dose-related increase in the number of tryptophan revertant colonies was not observed. Therefore the test material was found to be non-mutagenic when tested according to the procedures used in this assay.

Reference 4

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted on read-across material

Justification for type of information:

Read-across to structurally similar substance dimethyltin dichloride (DMTC) (EC Number 212-039-2, CAS Number 753-73-1), see attached justification.

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

5000 µg/plate

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Reference 5

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

Not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Composition/purity of the test substance not reported.

Reason / purpose for cross-reference:

other: read-across target

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

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 / cell type:

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

Species / strain / cell type:

S. typhimurium TA 102

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 material demonstrated solubility in the solvent.

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 pre-incubation.
Evaluated in both toxicity pre-screen 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 material 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 material 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.

Key result

Species / strain:

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

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

Key result

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

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:

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 µg/plate (in the presence and absence of metabolic activation. Toxicity to strain TA98 was reported at ≥1670 µg/plate (without activation) and ≥ 500 µg/plate (with activation). Growth was inhibited in strain TA102 at ≥ 1670 µg/plate (both with and without activation). A dose level of 5000 µg/plate inhibited growth of strain WP2 uvrA without metabolic activation, and ≥ 1670 µg/plate with metabolic activation. In the plate incorporation assay, both with and without metabolic activation, growth was inhibited in strain TA1537 at ≥ 500 µg/plate and in strain TA1535 at 5000 µg/plate. In the presence of S9, growth in TA100 and TA102 was inhibited at 5000 µg/plate, and without S9 at ≥ 1670 µg/plate. A dose level of ≥ 500 µg/plate inhibited growth in TA98 (without S9) and at ≥ 1670 µg/plate (with S9). No growth inhibition was observed in WP2 uvrA. Again, the test material was reported to be incompletely soluble at levels ≥ 500 µg/plate.

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

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

Conclusions:

The results of the tests conducted on the test material, 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 material.

Executive summary:

The test material 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 material 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 µg/plate, and the DMSO solvent control, in the absence of S9. Results of the pre-screen indicated that the test material produced inhibited growth in both Salmonella tester strains at doses ≥ 500 µg/plate under liquid pre-incubation conditions. In addition, the test material was found to be incompletely soluble at doses ≥ 500 µg/plate.

The test material was also evaluated for mutagenicity using both treatment conditions. Based upon the results of the pre-screen, the test material was evaluated in triplicate cultures in all six tester strains at doses of 16.7, 50.0, 167, 500, 1670 and 5000 µg/plate with and without S9. Six doses of the test material 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 material again was found to be incompletely soluble at doses ≥ 500 µg/plate. Revertant frequencies for all doses of the test material 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 material were negative in the Ames/Salmonella-E. coli Reverse Mutation Assay, using liquid pre-incubation and plate incorporation treatments, under the test conditions.

Reference 6

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted on read-across material

Justification for type of information:

Read-across to structurally similar substance DMTE (Dimethyltin bis (2-ethylhexyl thioglycolate) CAS 57583 -35 -4), see attached justification.

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

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

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

Key result

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

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:

valid

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Read-across to structurally similar substance dimethyltin dichloride (DMTC) (CAS Number 753-73-1): Genetic toxicity in vitro (Ames): Holmes 1990a & 1990b

The test material was examined for mutagenic activity in the Salmonella/microsome assay using the standard plate incorporation procedure with Salmonella typhimurium strains TA1535, TA1537, TA1538, TA98 and TA100, in both the presence and absence of an Aroclor 1254-induced rat-liver metabolic activation system.

No reproducible, dose-related increase in the number of histidine revertant colonies was observed with any tester strain. Therefore, the test material was found not mutagenic when tested according to the procedures used in this assay.

The test material was examined for mutagenic activity in the the Escherichia coli WP2 (uvrA)/microsome plate incorporation assay performed using the standard plate incorporation procedure with Escherichia coli strain WP2 uvrA, in both the presence and absence of an Aroclor 1254-induced rat-liver metabolic activation system.

A reproducible, dose-related increase in the number of tryptophan revertant colonies was not observed. Therefore the test material was found to be non-mutagenic when tested according to the procedures used in this assay.

Read-across to structurally similar substance DMTE (Dimethyltin bis (2-ethylhexyl thioglycolate) CAS 57583 -35 -4)

The test material 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 material 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 µg/plate, and the DMSO solvent control, in the absence of S9. Results of the pre-screen indicated that the test material produced inhibited growth in both Salmonella tester strains at doses ≥ 500 µg/plate under liquid pre-incubation conditions. In addition, the test material was found to be incompletely soluble at doses ≥ 500 µg/plate.

The test material was also evaluated for mutagenicity using both treatment conditions. Based upon the results of the pre-screen, the test material was evaluated in triplicate cultures in all six tester strains at doses of 16.7, 50.0, 167, 500, 1670 and 5000 µg/plate with and without S9. Six doses of the test material 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 material again was found to be incompletely soluble at doses ≥ 500 µg/plate. Revertant frequencies for all doses of the test material 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 material were negative in the Ames/Salmonella-E. coli Reverse Mutation Assay, using liquid pre-incubation and plate incorporation treatments, under the test conditions.

Justification for classification or non-classification

In accordance with the criteria outlined in Regulation (EC) No. 1272/2008 (CLP) and Directive 67/548/EEC (DSD), the substance does not meet the criteria for classification for genotoxicity.