Sodium 2-[methyl(1-oxododecyl)amino]ethanesulphonate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

There are several read-across studies covering bacterial point mutation testing as well as chromosome mutations in mammalian cell systems. Three studies were performed on the closely related read-across analogue SMCT (which contains SMLT as a major component) and one study was performed on the read-across analogue SMOT.

The read-across substance SMCT was not mutagenic in a guideline conform Salmonella typhimurium reverse mutation assay (Ames test) with and without metabolic activation (S9-mix from induced rat liver). Likewise, the reac-across substance SMCT did not induce chromosome aberrations or clastogenic effects in a guideline conform micronucleus test in vitro with and without metabolic activation.

SMOT does not induce gene mutation in Chinese hamster V79 cells after in vitro treatment in the absence or presence of S9 metabolic activation, under the reported experimental conditions. Based on read-across, the same conclusion is therefore drawn for the registration (target) substance SMLT.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Read-across study

Justification for type of information:

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Refer to section 13 for read-across justification.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

S9-mix from Aroclor 1254 pretreated rats

Test concentrations with justification for top dose:

4 up to 5000 microgram / plate

Vehicle / solvent:

Aqua bidest

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Evaluation criteria:

2-fold increase in mean number of revertants per plate
Dose-related increase in mean number of revertants per plate

Key result

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

Interpretation of results:
negative with metabolic activation
negative without metabolic activation

Based on the study results of this bacterial mutagenicity assay (Ames test), sodium methyl cocoyl taurate (SMCT) is not mutagenic with or without metabolic activation.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Hence, the registration/target substance SMLT is not expected to be mutagenic with or without metabolic activation. Refer to section 13 for read-across justification.

Executive summary:

The read-across source substance sodium methyl cocoyl taurate (SMCT) was tested for mutagenicity with the strains TA 100, Ta 1535, TA 1537, and TA 98 of Salmonella typhimurium. The mutagenicity studies were conducted in the absence and in the presence of a metabolizing system derived from rat liver homogenate. The test substance was dissolved in Aqua bidest and a dose range of 6 different doses from 4 microgram/plate to 5000 microgram/plate was used. Control plates without mutagen showed that the number of spontaneous revertant colonies was similar to that described in the literaure. All the positve control compounds gave the expected increase in the number of revertant colonies. In the cytotoxicity tests, the test item proved to be toxic to most of the bacterial strains at doses of 2500 microgram/plate and above. In the mutagenicity study, 5000 microgram/plate was chosen as top dose level which did not result in any relevant (dose-dependent) increase in the number of revertants in any of the bacterial strains tested, neither in the preence nor in the absence of metabolic activation. On the basis of the results of this study, it can be stated that SMCT is not mutagenic in these bacterial test systems neither with nor without exogenous metabolic activation at the dose levels investigated.

This study for the source substance SMCT is used as read-across to the registration/target substance SMLT. Hence, SMLT is not expected to be mutagenic in bacterial test systems with or without metabolic activation. Refer to section 13 for read-across justification.

Reference 2

Endpoint:

in vitro cytogenicity / micronucleus study

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1994-95

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Read-across study

Justification for type of information:

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Refer to section 13 for read-across justification.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 487 (In vitro Mammalian Cell Micronucleus Test)

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian cell micronucleus test

Target gene:

Not applicable.

Species / strain / cell type:

lymphocytes:

Details on mammalian cell type (if applicable):

human lymphocyte cultures

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Aroclor 1254 induced rat liver post-mitochondrial fraction (S9)

Test concentrations with justification for top dose:

Experiment 1: 437, 218 and 109 ug/ml (+S9) and 250, 125 and 62.5 (-S9)
Experiment 2: 300, 250 and 125 ug/ml (+S9) and 125, 62.5 and 31.3 ug/ml (-S9)

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: distilled water
- Justification for choice of solvent/vehicle: test item was soluble in distilled water allowing a top concentration of 350mg/ml to be prepared for addition to the test cultures. It was insoluble at higher concentrations in distilled water, dime thy lsulphoxide, acetone and 95 % ethanol.

Untreated negative controls:

no

Remarks:

Not applicable for this assay.

Negative solvent / vehicle controls:

yes

Remarks:

distilled water

True negative controls:

no

Remarks:

Not applicable for this assay.

Positive controls:

yes

Remarks:

Ethyl methanesulphonate (EMS) and Cyclophosphamide

Remarks:

EMS at 500 ug/ml and CP at 12.5 ug/ml

Details on test system and experimental conditions:

First cytogenetics assay:

The tests performed in the presence and absence of S9 mix were performed on separate occasions. Duplicate cultures were used for each treatment and positive control. Quadruplicate negative control cultures were prepared.

All lymphocyte cultures were incubated for approximately 48 hours, following stimulation with PHA, before addition of the test substance and, where appropriate, S9 mix. Serial two-fold dilutions were made for both sets of cultures. The highest concentration was achieved by dosing with Adinol CT95 in distilled water at 350 ug/ml giving a final concentration of 3500 ug/ml.

Cultures treated in the absence of S9 mix were incubated for approximately 20 hours after addition of test compound before harvesting, corresponding to approximately 1.5 cell cycles (the cell cycle time for human lymphocytes in the testing laboratory is approximately 13-15 hours). Cultures treated with S9 mix were exposed to the test material in the presence of S9 mix for 3 hours after which time the cells were spun down, the test solutions removed and fresh medium added for the remainder of the culture period. Colchicine was added to all cultures approximately 2.5 hours before harvesting to give a final concentration of 0.5 ug/ml.

Second cytogenetics assay:

The second assay was performed using the methods described for the first assay. Cultures treated at the top concentration and solvent controls were also harvested at an extended harvest time about 24hr after the first harvest. Such cultures without S9 therefore received about 44 hours treatment with the test substance while those with S9 were treated for 3 hours as with the earlier harvest time.

Harvesting:

Following the treatment with colchicine the cells were spun down at 1000rpm for 5 minutes in a Centaur centrifuge. After discarding the supernatant the pellet was resuspended in PBS and the washing repeated. The cells were then treated twice with a hypotonic solution (5ml of 0.56%(w/v) KCI) and following further centrifugation they were fixed with freshly prepared 3: 1 methanol: glacial acetic acid. The cells were washed with fixative until the supernatant appeared clear. The fixed cell suspension was left to stand for at least 30 minutes before slide preparation.

Key result

Species / strain:

lymphocytes: human lymphocyte cultures

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

at concentrations equal to or greater than 125 µg/mL in the absence of S9, and 300 µg/mL in the presence of S9

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Conclusions:

Interpretation of results: negative with and without metabolic activation

It is concluded that the test item SMCT produced no increase in the number of chromosome aberrations in human lymphocytes either in the presence or absence of rat liver S9 microsome mix when tested up to the limit of toxicity. The positive control mutagens induced cytogenetic damage as expected.

Under the conditions of this study, SMCT showed no evidence of clastogenicity in human lymphocytes.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Hence, SMLT is not expected to be mutagenic in bacterial test systems with or without metabolic activation.

Executive summary:

The read-across source substance SMCT was tested for the potential to induce micronuclei in human lymphocytesin vitroin the absence and presence of metabolic activation (S9-mix) in a GLP study conducted in accordance with OECD test guideline 487. SMCT produced no increase in the number of chromosome aberrations in human lymphocytes either in the presence or absence of rat liver S9 microsome mix when tested up to the limit of toxicity (125 µg/mL without S9 and 300 µg/mL with S9). Therefore, it is concluded that SMCT shows no evidence of clastogenicity in human lymphocytesin vitro.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Hence, SMLT is not expected to be exhibit clastogenic effects with or without metabolism in vitro,

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: compliance to GLP and test guideline; coherence between data, results and conclusion

Justification for type of information:

This study for the source substance SMOT is used as read-across to the registered (target) substance SMLT. Refer to section 13 for read-across justification.

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian cell gene mutation assay

Target gene:

hypoxanthine-guaninphosphoribosyl-transferase (HPRT)

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Details on mammalian cell type (if applicable):

- Type and identity of media:

EMEM Minimal Medium
EMEM Complete Medium (10% Fetal Bovine Serum)

DMEM Minimal Medium
DMEM Complete Medium (10% Fetal Bovine Serum)

- Properly maintained: yes

- Periodically checked for Mycoplasma contamination: yes

- Periodically "cleansed" against high spontaneous background: yes

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

Liver S9 fraction from rats induced with phenobarbitone and beta-naphthoflavone (Mixed Induction).

Test concentrations with justification for top dose:

Experiments without S9 mix:
32.3, 23.1, 16.5, 11.8, 8.40 and 6.00 ug/mL for the first experiment
28.2, 21.7, 16.7, 12.8 and 9.87 ug/mL for the second experiment

Experiments with S9 mix:
600, 462, 355, 273, 210 and 162 ug/mL for the first experiment
500, 458, 382, 318 and 265 ug/mL for the second experiment

Vehicle / solvent:

Minimal Culture Medium.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9,10-dimethylbenzanthracene

Remarks:

with S9 mix

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

ethylmethanesulphonate

Remarks:

without S9 mix

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium;

DURATION
- Exposure duration: 3 hours in the absence and presence of S9 metabolism
- Expression time (cells in growth medium): day 6 and day 9
- Selection time (if incubation with a selection agent): 10-15 days

SELECTION AGENT (mutation assays): 6 -thioguanine
STAIN: Giemsa

NUMBER OF REPLICATIONS: Two replicate cultures for each experimental point; two indipendent mutation experiments

NUMBER OF CELLS EVALUATED: 1x10^5 cells/ 100 mm tissue culture petri dishes (five plates, a total of 5 x10^5 cells)

DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency; relative cloning efficiency;

DETERMINATION OF MUTATION
- Method: Induced mutant frequency

Evaluation criteria:

For a test item to be considered mutagenic in this assay, it is required that:

(i) There is a five-fold (or more) increase in mutation frequency compared with the solvent controls, over two consecutive doses of the test item. If only the highest practicable dose level (or the highest dose level not to cause unacceptable toxicity) gives such an increase, then a single treatment-level will suffice.

(ii) There must be evidence for a dose-relation (i.e. statistically significant effect in the ANOVA analysis).

The “five-fold increase” in mutant frequency above the concurrent negative control is used as arbitrary criteria for positive response and it was established in our laboratory based on analysis of variation of negative control data.
If spontaneous mutation frequency is in the upper part of the historical range, significance of mutation increase is evaluated case by case.
Historical control data are used to demonstrate biological relevance of the results obtained.

Statistics:

ANOVA analysis for effect of replicate culture, expression time and dose level

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not specified

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
No precipitation of the test item was noted upon addition of the test item to the culture in all treatment series and by the end of treatment incubation period.
The addition of the test item solution did not have any obvious effect on the osmolality or pH of the treatment medium.

RANGE-FINDING/SCREENING STUDIES:
Two preliminary cytotoxicity assays were performed.
In the first experiment the test item was assayed at a maximum dose level of 5000 g/mL and at a wide range of lower dose levels: 2500, 1250, 625, 313, 156, 78.1, 39.1 and 19.5 µg/mL. In the absence of S9 metabolism, no cell survived after treatment at the seventh highest dose levels, while marked toxicity was noted at 39.1 µg/mL reducing survival to 16% of the negative control value. In the presence of S9 metabolism, no cell survived at the three highest dose levels. Marked toxicity was observed at the next lower dose level (625 µg/mL) reducing survival to 10% of the concurrent negative control value, while no toxicity was observed over the remaining dose levels.
Since the plating efficiency obtained in this experiment did not meet the acceptability criteria, a second preliminary cytotoxicity assay was performed. Taking into account the results obtained in the first experiment, the following dose levels were selected:
without S9 mix: 62.5, 31.3, 15.6, 7.81, 3.91, 1.95, 0.977, 0.488 and 0.244 µg/mL
with S9 mix: 1000, 500, 250, 125, 62.5, 31.3, 15.6, 7.81 and 3.91 µg/mL
In the absence of S9 metabolism, obvious and dose related toxicity was observed at the three highest dose levels. At 62.5 and 31.3 µg/mL survival was reduced to near the limit of detection, while at 15.6 µg/mL it was reduced to 38% of the concurrent negative control value. In the presence of S9 metabolic activation, survival was reduced to below the limit of detection at the highest dose level, while at the next lower concentration survival was 23% of the concurrent negative control value.

COMPARISON WITH HISTORICAL CONTROL DATA:
Solvent and positive control treatments were included in the mutation experiments in the absence and presence of S9 metabolism. The mutant frequwensy in the solvent control cultures fell within the normal range based on the laboratory historical control data. Marked increases were obtained with the positive control treatments indicating the correct functioning of the assay system.

ADDITIONAL INFORMATION ON CYTOTOXICITY AND MUTAGENICITY:
On the basis of the cytotoxicity results, two independent assays for mutation to 6-thioguanine resistance were performed using dose levels described below:
Experiments without S9 mix:
32.3, 23.1, 16.5, 11.8, 8.40 and 6.00 ug/mL for the first mutation assay
28.2, 21.7, 16.7, 12.8 and 9.87 ug/mL for the second mutation assay

Experiments with S9 mix:
600, 462, 355, 273, 210 and 162 ug/mL for the first mutation assay
500, 458, 382, 318 and 265 ug/mL for the second mutation assay

In the first mutation assay, following treatment in the absence of S9 metabolism, a severe toxic effect was observed at the highest dose level (32.3 ug/mL) reducing survival to 6% of the concurrent negative control value. At the next lower concentration, survival was reduced to 30%, while no relevant toxicity was observed at the remaining dose levels. In the presence of S9 metabolic activation, survival was reduced to below the limit of detection at the highest dose level of 600 ug/mL, while the two next lower concentrations (462 and 355 ug/mL) yielded 34% and 58% relative survival, respectively.
In the second mutation assay, in the absence of S9 metabolism, a severe reduction in cell survival was observed at 28.2 ug/mL (9%). At the next lower dose level (21.7 ug/mL) survival was reduced to 38% of the concurrent negative control value, while no relevant toxicity was observed at the remaining dose levels. In the presence of S9 metabolism, marked toxicity was observed at the highest dose level (5% percentage survival) while the next lower concentration (458 ug/mL) yielded 41% relative survival. No relevant toxicity was observed over the remaining dose levels.

No reproducible five-fold increases in mutant numbers or mutant frequency were observed following treatment with the test item at any dose level, in the absence or presence of S9 metabolism.

No reproducible five-fold or greater increase in mutant frequency was observed either in the absence or presence of metabolic activation at any test point. No statistically significant effect of dose level in the ANOVA analysis was observed. It is concluded that HOSTAPON TPHC does not induce gene mutation in Chinese hamster V79 cellsin vitro.

Conclusions:

Interpretation of results:

It is concluded that the read-across (source) substance SMOT does not induce gene mutation in Chinese hamster V79 cells after in vitro treatment in the absence or presence of S9 metabolic activation, under the reported experimental conditions. Based on read-across, the same conclusion is therefore drawn for the registration (target) substance SMLT.

Executive summary:

This report describes experiments performed to assess the mutagenic activity of the test item (SMOT) by assaying for the induction of 6-thioguanine resistant mutants in Chinese hamster V79 cells afterin vitrotreatment (in the absence and presence of S9 metabolic activation).

The Study was performed in compliance with:

-  OECD Guidelines for the testing of chemicals No. 476 (Adopted July 1997).

No reproducible five-fold or greater increase in mutant frequency was observed either in the absence or presence of metabolic activation at any test point. No statistically significant effect of dose level in the ANOVA analysis was observed.

It is concluded that the read-across (source) substance SMOT does not induce gene mutation in Chinese hamster V79 cells after in vitro treatment in the absence or presence of S9 metabolic activation, under the reported experimental conditions. Based on read-across, the same conclusion is therefore drawn for the registration (target) substance SMLT.

Reference 4

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Read-across study. Follows OECD 471 and is GLP but no testing on E.coli strain(s)

Justification for type of information:

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Refer to section 13 for read-across justification.

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Species / strain / cell type:

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

Metabolic activation:

with and without

Metabolic activation system:

S9-mix from Aroclor 1254 pretreated rats

Test concentrations with justification for top dose:

0.5 up to 5000 microgram / plate for toxicity assay
0.5 up to 50 microgram / plate for mutation assay

Vehicle / solvent:

Distilled water

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

other: 2-aminoanthracene

Remarks:

with metabolic activation

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

yes

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

Remarks:

Without metabolic activation

Evaluation criteria:

2-fold increase in mean number of revertants per plate
Dose-related increase in mean number of revertants per plate

Species / strain:

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

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

There was no evidence that the test item SMCT caused an increase in the number of revertants of S.typhimurium under the conditions used. Some high doses indicated a doubling in the numbers of revertant colonies. However the high counts were due to microcolonies induced by the toxicity of the test substance and are not indicative of mutagenic potential. The positive control mutagens were detected in both experiments at S9 levels of 0% and 10% for all strains. At the 30% S9 level the positive control mutagen for TA100 did not induce a doubling over the control value. As the ability to demonstrate a positive response was indicated at the 10% S9-level, and the use of high S9 levels reduces the mutagenic potency of 2AA, this is considered acceptable.

Conclusions:

Interpretation of results:
negative with metabolic activation
negative without metabolic activation

Based on the study results of this bacterial mutagenicity assay (Ames test), sodium methyl cocoyl taurate (SMCT) is not muatgenic neither in the presence or absence of metabolic activation.

Executive summary:

The read-across analogue substance sodium methyl cocoyl taurate (SMCT) was tested for mutagenicity with the strains TA100, TA1535, TA1537, and TA98 of Salmonella typhimurium. The mutagenicity studies were conducted in the absence and in the presence of a metabolizing system derived from rat liver homogenate S9. The test substance was dissolved in distilled water and a range of 5 different doses from 0.5 to 5000 microgram/plate and 0.5 microgram/plate to 50 microgram/plate was used for the toxicity and mutagenicity assays, respectively.

No increase in the number of revertant colonies occurred with any of the four strains of bacterium at the concentrations tested either in the presence or the absence of metabolic activation. The ability of the test system to detect known mutagens was demonstrated.

On the basis of the results of this study, it can be stated that sodium methyl cocoyl taurate (SMCT) is not mutagenic in these bacterial test systems neither with nor without exogenous metabolic activation at the dose levels investigated.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. Hence, SMLT is not expected to be mutagenic in bacterial test systems with or without metabolic activation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The read-across source substance SMCT substance was tested for potential point mutation in two guideline bacterial reverse mutation assay (Ames test) studies conducted according to OECD TG 471 with and without metabolic activation. The only deviation from current OECD 471 guidelines is that E.Coli strains were not included in the studies. Independent experiments using several test concentrations up to the limit dose of 5000 µg/plate in the key study and up to 50 µg/plate in the second supporting study did not cause gene mutations by base pair changes or frameshifts in the genome of any of the tester strains used. Therefore, based on read-across of this result for SMCT, the registration/target substance SMLT is considered to be non-mutagenic in the bacterial reverse mutation assay.

The read-across source substance SMCT was tested for the potential to induce micronuclei in human lymphocytesin vitro in the absence and presence of metabolic activation (S9-mix) in a GLP study conducted in accordance with OECD test guideline 487. SMCT produced no increase in the number of chromosome aberrations in human lymphocytes either in the presence or absence of rat liver S9 microsome mix when tested up to the limit of toxicity (125 µg/mL without S9 and 300 µg/mL with S9). Therefore, it is concluded that SMCT shows no evidence of clastogenicity in human lymphocytesin vitro. Based on read-across of this result for SMCT, the registration/target substance SMLT is expected to exhibit the same properties i.e. no clastogenicity in human lymphocytesin vitro

The read-across (source) substance SMOT was subjected to experimental testing to assess its mutagenic activity by assaying for the induction of 6-thioguanine resistant mutants in Chinese hamster V79 cells afterin vitrotreatment (in the absence and presence of S9 metabolic activation). The Study was performed in compliance with OECD Guidelines for the testing of chemicals No. 476 (Adopted July 1997). No reproducible five-fold or greater increase in mutant frequency was observed either in the absence or presence of metabolic activation at any test point. No statistically significant effect of dose level in the ANOVA analysis was observed. Hence it is concluded that the read-across (source) substance SMOT does not induce gene mutation in Chinese hamster V79 cells after in vitro treatment in the absence or presence of S9 metabolic activation, under the reported experimental conditions. Based on read-across, the same conclusion is therefore drawn for the registration (target) substance SMLT.

In conclusion, the registration substance is expected to be not genotoxic/mutagenic in various test systems.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data from 3 in vitro mutagenicity assays from the structurally analogous compound SMCT and 1 in vitro mutagenicity assay from the structurally analagous compound SMOT, respective mutagenic potential of the registration/target substance SMLT can be excluded with a high degree of confidence. Thus, the registration substance SMLT does not have to be classified for mutagenicity in accordance with the criteria laid down in the in the EU Classification, Labellling and Packaging Regulation (1272/2008/EC).