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EC number: 252-038-4 | CAS number: 34452-51-2
Endpoint summary
Administrative data
Key value for chemical safety assessment
Genetic toxicity in vitro
Description of key information
The weight of evidence suggests that KTG is not genotoxic.
Link to relevant study records
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Justification for type of information:
- REPORTING FORMAT FOR THE CATEGORY APPROACH
1. HYPOTHESIS FOR THE CATEGORY APPROACH
This scenario covers the category approach for which the hypothesis is based on transformation to a common compound. For the REACH information requirement under consideration, the effects obtained in studies conducted with different source substances are used to predict the effects that would be observed in a study with the target substance if it were to be conducted. The same type of effect is observed for the different source substances; this may include absence of effects for every member of the category. No relevant differences in strengths of effect are observed for several source substances.
There are no relevant variations in properties among source substances and the same potency is predicted for all target substances. This corresponds to Scenario 5 of the RAAF (ECHA, 2017). The substances ATG, MEATG, KTG, CaTG, and NaTG are different inorganic salts of a common acid, thioglycolic acid (TGA; synonym: 2-mercaptoacetic acid). They dissociate rapidly in aqueous media to the common thioglycolate anion and to their different counter ions. The water solubility of all category members is high.
This approach serves to use existing data on aquatic toxicity endpoints for substances in this category.
It can be predicted with high confidence that the target substances will display the same mode of action and lead to the same type and strength of effects as observed with the source substances.
2. CATEGORY APPROACH JUSTIFICATION
For details, refer to Justification for read-across attached to Iuclid section 13 - Reason / purpose for cross-reference:
- read-across: supporting information
- Target gene:
- Histidine reversion
- Key result
- Species / strain:
- S. typhimurium TA 98
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- btw. 1000 - 5000µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 100
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- 1000 - 5000µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 102
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- 1000 - 5000µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 1535
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- 1000 - 5000µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 1537
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- 1000 - 5000 µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Conclusions:
- In analogy to ATG and NaTG, KTG is considered non-mutagenic in bacteria.
- Endpoint:
- in vitro gene mutation study in mammalian cells
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Justification for type of information:
- see attached justification
- Reason / purpose for cross-reference:
- read-across: supporting information
- Key result
- Species / strain:
- mouse lymphoma L5178Y cells
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- other: 4-h experiment (+/-S9): > 1600 µg/ml / 24-h experiment (-S9): >= 800 µg/ml
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Remarks on result:
- other: all strains/cell types tested
- Remarks:
- Migrated from field 'Test system'.
- Conclusions:
- By analogy to ATG, KTG is considered non-mutagenic in mammalian cells.
- Endpoint:
- in vitro cytogenicity / chromosome aberration study in mammalian cells
- Remarks:
- Type of genotoxicity: chromosome aberration
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Justification for type of information:
- see attached justification
- Reason / purpose for cross-reference:
- read-across: supporting information
- Key result
- Species / strain:
- lymphocytes: human
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- other: With S9 : 1000 µg/ml. Without S9 : 300 µg/ml
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Remarks on result:
- other: strain/cell type: Human lymphocytes
- Remarks:
- Migrated from field 'Test system'.
- Conclusions:
- By analogy to TGA, KTG is considered non-clastogenic.
Referenceopen allclose all
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (negative)
Genetic toxicity in vivo
Description of key information
The weight of evidence suggests that KTG is not genotoxic.
Link to relevant study records
- Endpoint:
- in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
- Type of information:
- read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- supporting study
- Justification for type of information:
- see attached justification
- Reason / purpose for cross-reference:
- read-across: supporting information
- Key result
- Sex:
- male/female
- Genotoxicity:
- negative
- Toxicity:
- yes
- Remarks:
- clinical signs
- Vehicle controls validity:
- valid
- Negative controls validity:
- not examined
- Positive controls validity:
- valid
- Conclusions:
- By analogy to NaTG, KTG is considered non-mutagenic in vivo.
Reference
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (negative)
Additional information
Additional information from genetic
toxicity in vivo:
Several in vitro and in vivo genotoxicity studies were performed with thioglycolic acid and its salts. The conducted genotoxicity studies on thioglycolic acid or its salts described in this chapter can be bridged to each other, because in aquous solutions only the organic thioglycolate anion may have the potential to cause genotoxic effects in vitro or in vivo. All genotoxicity studies conducted to date have either negative results or are of douptful significance. Therefore, the weight of evidence suggests that thioglycolic acid and its salts are non-genotoxic.
Justification for classification or non-classification
Conclusive, but not sufficient for classification.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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