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EC number: 204-815-4 | CAS number: 126-97-6
Toxicological information
Endpoint summary
Administrative data
Key value for chemical safety assessment
Genetic toxicity in vitro
Description of key information
The weight of evidence suggests that MeaTG is not genotoxic.
Link to relevant study records
- 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:
- HYPOTHESIS FOR THE CATEGORY APPROACH
The substances of this category have similar toxicological properties because:
- all substances are small organic molecules;
- they share structural similarities with common functional groups: one or more thiol and/or thioether group(s) and carboxylic acid (as free acid, salt or ester);
- the metabolism (i.e. ester hydrolysis) leads to comparable products (sulfur-containing core structure in its acid form and alcohols of differing chains lengths)
The substances were assigned to subgroups according to their main structural features (see Table 1); further justification for subgrouping based on toxicological properties is given below:
- TGA family: Thioglycolic acid, its salts and esters
- 3-MPA family: 3-Mercaptopropionic acid, its salts and esters
- TLA family: Thiolactic acid and its salts
- Intramolecular-S family: Thiodiglycolic acid or Dithiodiglycolic acid and its esters, Thiodipropionic acid or Dithiodipropionic acid and its esters, Methylene bis(butyl thioglycolate)
- Mercaptanes: Thioglycerol, Bis(2-mercaptoethyl) sulfide, 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol
The acids and salts will dissociate to the respective Thioglycolate or 3-Mercaptopropionate or Thiolactate and the corresponding cation. In case of the esters, the metabolism expected to occur is ester hydrolysis resulting in the corresponding acid and alcohol.
It was demonstrated, that PETMP and 3-MPA strongly bind to plasma proteins (e.g. via S-S bond to cysteine) in vitro, which is well known for substances containing free SH-groups (Bruno Bock, 2014). Strong protein binding is also expected to occur with the other substances assessed within this paper. The members of the intramolecular-S family are an exception, as they do not contain free SH-groups – protein binding may be less relevant for this family.
This read-across hypothesis corresponds to scenario 4 of the Read-Across Assessment Framework (RAAF), ECHA, March 2017 - different compounds have qualitatively similar properties - of the read-across assessment framework i.e. variations in the properties are observed among the source substances; the prediction is based on a worst-case approach.
Overall, based on close structural similarities, a read-across from the existing repeated dose and reproduction toxicity studies is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.
A detailed justification for this category approach is attached to Iuclid section 13. - Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across: supporting information
- Reason / purpose for cross-reference:
- read-across source
- 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'.
- Endpoint:
- in vitro gene mutation study in bacteria
- Remarks:
- Type of genotoxicity: gene mutation
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Justification for type of information:
- HYPOTHESIS FOR THE CATEGORY APPROACH
The substances of this category have similar toxicological properties because:
- all substances are small organic molecules;
- they share structural similarities with common functional groups: one or more thiol and/or thioether group(s) and carboxylic acid (as free acid, salt or ester);
- the metabolism (i.e. ester hydrolysis) leads to comparable products (sulfur-containing core structure in its acid form and alcohols of differing chains lengths)
The substances were assigned to subgroups according to their main structural features (see Table 1); further justification for subgrouping based on toxicological properties is given below:
- TGA family: Thioglycolic acid, its salts and esters
- 3-MPA family: 3-Mercaptopropionic acid, its salts and esters
- TLA family: Thiolactic acid and its salts
- Intramolecular-S family: Thiodiglycolic acid or Dithiodiglycolic acid and its esters, Thiodipropionic acid or Dithiodipropionic acid and its esters, Methylene bis(butyl thioglycolate)
- Mercaptanes: Thioglycerol, Bis(2-mercaptoethyl) sulfide, 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol
The acids and salts will dissociate to the respective Thioglycolate or 3-Mercaptopropionate or Thiolactate and the corresponding cation. In case of the esters, the metabolism expected to occur is ester hydrolysis resulting in the corresponding acid and alcohol.
It was demonstrated, that PETMP and 3-MPA strongly bind to plasma proteins (e.g. via S-S bond to cysteine) in vitro, which is well known for substances containing free SH-groups (Bruno Bock, 2014). Strong protein binding is also expected to occur with the other substances assessed within this paper. The members of the intramolecular-S family are an exception, as they do not contain free SH-groups – protein binding may be less relevant for this family.
This read-across hypothesis corresponds to scenario 4 of the Read-Across Assessment Framework (RAAF), ECHA, March 2017 - different compounds have qualitatively similar properties - of the read-across assessment framework i.e. variations in the properties are observed among the source substances; the prediction is based on a worst-case approach.
Overall, based on close structural similarities, a read-across from the existing repeated dose and reproduction toxicity studies is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.
A detailed justification for this category approach is attached to Iuclid section 13. - Reason / purpose for cross-reference:
- read-across: supporting information
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Statistics:
- None
- Key result
- Species / strain:
- S. typhimurium, other: Strains: TA98, TA100, TA1535 and TA1537
- 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
- Remarks on result:
- other: all strains/cell types tested
- Remarks:
- Migrated from field 'Test system'.
- Conclusions:
- Read across from sodium thioglycolate, calcium thioglycolate is considered as non-genotoxic
- 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:
- HYPOTHESIS FOR THE CATEGORY APPROACH
The substances of this category have similar toxicological properties because:
- all substances are small organic molecules;
- they share structural similarities with common functional groups: one or more thiol and/or thioether group(s) and carboxylic acid (as free acid, salt or ester);
- the metabolism (i.e. ester hydrolysis) leads to comparable products (sulfur-containing core structure in its acid form and alcohols of differing chains lengths)
The substances were assigned to subgroups according to their main structural features (see Table 1); further justification for subgrouping based on toxicological properties is given below:
- TGA family: Thioglycolic acid, its salts and esters
- 3-MPA family: 3-Mercaptopropionic acid, its salts and esters
- TLA family: Thiolactic acid and its salts
- Intramolecular-S family: Thiodiglycolic acid or Dithiodiglycolic acid and its esters, Thiodipropionic acid or Dithiodipropionic acid and its esters, Methylene bis(butyl thioglycolate)
- Mercaptanes: Thioglycerol, Bis(2-mercaptoethyl) sulfide, 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol
The acids and salts will dissociate to the respective Thioglycolate or 3-Mercaptopropionate or Thiolactate and the corresponding cation. In case of the esters, the metabolism expected to occur is ester hydrolysis resulting in the corresponding acid and alcohol.
It was demonstrated, that PETMP and 3-MPA strongly bind to plasma proteins (e.g. via S-S bond to cysteine) in vitro, which is well known for substances containing free SH-groups (Bruno Bock, 2014). Strong protein binding is also expected to occur with the other substances assessed within this paper. The members of the intramolecular-S family are an exception, as they do not contain free SH-groups – protein binding may be less relevant for this family.
This read-across hypothesis corresponds to scenario 4 of the Read-Across Assessment Framework (RAAF), ECHA, March 2017 - different compounds have qualitatively similar properties - of the read-across assessment framework i.e. variations in the properties are observed among the source substances; the prediction is based on a worst-case approach.
Overall, based on close structural similarities, a read-across from the existing repeated dose and reproduction toxicity studies is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.
A detailed justification for this category approach is attached to Iuclid section 13. - Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across: supporting information
- Reason / purpose for cross-reference:
- read-across source
- 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'.
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 MeaTG is not genotoxic.
Link to relevant study records
- Endpoint:
- in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
- Type of information:
- read-across based on grouping of substances (category approach)
- Adequacy of study:
- key study
- Justification for type of information:
- HYPOTHESIS FOR THE CATEGORY APPROACH
The substances of this category have similar toxicological properties because:
- all substances are small organic molecules;
- they share structural similarities with common functional groups: one or more thiol and/or thioether group(s) and carboxylic acid (as free acid, salt or ester);
- the metabolism (i.e. ester hydrolysis) leads to comparable products (sulfur-containing core structure in its acid form and alcohols of differing chains lengths)
The substances were assigned to subgroups according to their main structural features (see Table 1); further justification for subgrouping based on toxicological properties is given below:
- TGA family: Thioglycolic acid, its salts and esters
- 3-MPA family: 3-Mercaptopropionic acid, its salts and esters
- TLA family: Thiolactic acid and its salts
- Intramolecular-S family: Thiodiglycolic acid or Dithiodiglycolic acid and its esters, Thiodipropionic acid or Dithiodipropionic acid and its esters, Methylene bis(butyl thioglycolate)
- Mercaptanes: Thioglycerol, Bis(2-mercaptoethyl) sulfide, 4-Mercaptomethyl-3,6-dithia-1,8-octanedithiol
The acids and salts will dissociate to the respective Thioglycolate or 3-Mercaptopropionate or Thiolactate and the corresponding cation. In case of the esters, the metabolism expected to occur is ester hydrolysis resulting in the corresponding acid and alcohol.
It was demonstrated, that PETMP and 3-MPA strongly bind to plasma proteins (e.g. via S-S bond to cysteine) in vitro, which is well known for substances containing free SH-groups (Bruno Bock, 2014). Strong protein binding is also expected to occur with the other substances assessed within this paper. The members of the intramolecular-S family are an exception, as they do not contain free SH-groups – protein binding may be less relevant for this family.
This read-across hypothesis corresponds to scenario 4 of the Read-Across Assessment Framework (RAAF), ECHA, March 2017 - different compounds have qualitatively similar properties - of the read-across assessment framework i.e. variations in the properties are observed among the source substances; the prediction is based on a worst-case approach.
Overall, based on close structural similarities, a read-across from the existing repeated dose and reproduction toxicity studies is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.
A detailed justification for this category approach is attached to Iuclid section 13. - Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across source
- Reason / purpose for cross-reference:
- read-across: supporting information
- Reason / purpose for cross-reference:
- read-across source
- 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
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.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
