Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.

REACH

Ammonium mercaptoacetate

EC number: 226-540-9 | CAS number: 5421-46-5

Life Cycle description
Uses advised against

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 ammonium thioglycolate is not genotoxic.

Link to relevant study records

Reference 1

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:: 1 (reliable without restriction)
Rationale for reliability incl. deficiencies:: guideline study
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 reversion
Species / strain / cell type:: S. typhimurium, other: Strains: TA1535, TA1537, TA98, TA100 and TA102
Metabolic activation:: with and without
Metabolic activation system:: S9-mix (from livers of male Sprague-Dawley rats treated by Aroclor 1254)
Test concentrations with justification for top dose:: 15, 50, 150, 500, 1500 and 5000 µg a.i./plate.
Two distinct experiments were performed using these doses.
Vehicle / solvent:: sterile distilled water
Untreated negative controls:: no
Negative solvent / vehicle controls:: yes
True negative controls:: no
Positive controls:: yes
Positive control substance:: 4-nitroquinoline-N-oxide; 9-aminoacridine; N-ethyl-N-nitro-N-nitrosoguanidine; benzo(a)pyrene; mitomycin C; other:
Details on test system and experimental conditions:: METHOD DETAILS:
- Test concentrations:
. Preliminary study (on TA100): 0, 0.15, 0.5, 1.5, 5, 15, 50, 150, 500, 1500 and 5000 µg/plate
. Main study: see the "Test concentration" field
- Number of replicates: 3
- Positive controls:
without S9-mix
. for TA1535 and TA100: N-ethyl-N'-nitro-N-nitrosoguanidine (5 and 2 µg/plate respectively)
. for TA1537: 9-aminoacridine (80 µg/plate)
. for TA98: 4-Nitroquinoline-1-oxide (0.2 µg/plate)
. for TA102: mitomycin C (0.5 µg/plate)
with S9-mix
. for TA1535, TA1357 and TA100: 2-aminoanthracene (2; 2 and 1µg/plate respectively)
. for TA98: benzo(a)pyrene (5 µg/plate)
. for TA102: 1,8-Dihydroxyanthraquinone (10 µg/plate)
- Pre-incubation time: no
- Pre-incubation temperature: no
- Incubation time: 48h
- Incubation temperature: 37°C

EXAMINATION:
- Bacterial toxicity: determined by examination of background lawn growth
- Number of revertants / plate

ANALYTICAL DEVICE: Colonies were counted electronically using a Domino Colony Counter.
Evaluation criteria:: The reverse mutation assay may be considered valid if the following criteria are met: All tester strain cultures exhibit a characteristic number of spontaneous revertants per plate in the vehicle and untreated controls. Acceptable ranges are presented below with historical control ranges for 2001 and 2002 presented in Table 1.

Spontaneous Mutation Ranges:
TA1535 7 to 40
TA100 60 to 200
TA1537 2 to 30
TA98 8 to 60
TA102 180 to 400

The test material may be considered positive in this test system if the following criteria are met: The test material should have induced a reproducible, dose-related and statistically significant increase in the revertant count in at least one strain of bacteria.
Statistics:: Dunnett's method of linear regression
: Key result
Species / strain:: S. typhimurium, other: Strains: TA1535, TA1537, TA98, TA100 and TA102
Metabolic activation:: with and without
Genotoxicity:: negative
Remarks:: all strains/cell types tested
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:: CYTOTOXICITY:
The test substance was toxic at 5000 µg/plate in the TA100 strain (without S9 mix: very weak bacterial background lawn, with S9 mix: sparse bacterial background lawn).

GENOTOXICITY:
No significant increases in the number of revertants were observed at any dose level, with or without metabolic activation.
Conclusions:: Interpretation of results (migrated information):
negative

Ammonium thioglycolate was considered to be non-mutagenic under the conditions of this test.
Executive summary:: Ammonium thioglycolate was tested in a bacterial gene mutations assay performed following a protocol compliant with the OECD guideline # 471. The direct plate incorporation procedure was performed with Salmonella typhimurium TA 98, TA 100, TA 102, TA 1535 and TA 1537 at concentrations up to 5,000 µg/plate. Cytotoxic effects were observed in the absence and in the presence of a metabolic activator (Aroclor 1254-induced rat liver S9) at the concentration of 5,000 µg/plate. Ammonium thioglycolate did not induce mutations in the bacterial mutation test in either the absence or presence of metabolic activator in any strain tested. The positive and negative controls included in the experiment showed the expected results.

Reference 2

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

Cited as Directive 2000/32/EC, B.17

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Target gene:

Locus Examined: thymidine kynase, the selection agent used was 5 µg/ml trifluorothymidine

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media: the medium used was RPMI 1640 (complete medium) with 3 or 15 % horse serum.
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically "cleansed" against high spontaneous background: yes

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

S9 derived from male Sprague Dawley (phenobarbital/B-naphtoflavone induced rat liver)

Test concentrations with justification for top dose:

Non-activated conditions: Initial trial: 13, 50, 100, 200, 400, 800 and 1600 µg/mL; Confirmatory trial: 13, 25, 50, 100, 200, 400 and 600 µg/mL
S9-activated conditions: 50, 100, 200, 400, 800 and 1600 µg/mL
Duplicate cultures were processed for all trials.

Vehicle / solvent:

- Solvent used: deionised water

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

True negative controls:

Positive controls:

yes

Positive control substance:

cyclophosphamide

methylmethanesulfonate

Details on test system and experimental conditions:

Experimental Performance:
In the mutation experiment 1x10e7 cells/flask suspended in 10 ml RPMI medium with 3 % horse serum (15 % during 24 h treatment) were exposed to various concentrations of the test item either in the presence or absence of metabolic activation.

After 4 h (after 24 h in the second experiment) the test item was removed by centrifugation and washing twice in "saline G". Subsequently the cells were resuspended in 30 ml complete culture medium and incubated for an expression and growth period of totally 72 h. In the second experiment the expression time without metabolic activation was 48 hours (RPMI medium with 15 % horse serum).

The cell density was determined each day and adjusted to 3x10e5 cells/ml, if necessary. Relative suspension and total growth (RSG and RTG) of the treated tell cultures were calculated after 48 h (72 h following continuous treatment) according to the method of Clive and Spector. One sample of the cells was taken at the end of the treatment (4 h and 24 h, respectively), diluted and seeded into microtiter plates (about 2.5 cells/well), to determine the survival of the cells after treatment (cloning efficiency 1).

After the expression period the tells were seeded into microtiter plates. Cells from each experimental group were seeded into 2 microtiter plates so that each well contained approximately 4x10e3 tells in selective medium with TFT. The viability (cloning efficiency 2) was determined by seeding about 2.5 cells per well into 2 microtiter plates (same medium without TFT). The plates are incubated at 37 °C in 4.5 %C02 and 95.5 % humidified air for 10 - 15 days to determine the cloning efficiency and to evaluate mutagenicity. Then the plates were evaluated manually.

Size Distribution of the Colonies:
The numbers of colonies were counted manually. The colony size distribution was determined in the controls and at all concentrations of the test item

Data Recording:
All plates were evaluated manually.
The mutation frequency was derived from the cloning efficiency under selective conditions compared to the corresponding viability under non-selective conditions

Evaluation criteria:

Acceptability of the Assay:
A mutation assay is considered acceptable if it meets the following criteria:
a) Both plates, from either the survival or the TFT resistance-testing portion of the experiment are analysable.
b) The absolute cloning efficiency 2 of the negative and/or solvent controls is > 0.5 (50 %).
c) The spontaneous mutant frequency in the negative and/or solvent controls are in the range of the historical control data .
d) The positive controls (MMS and CPA) induce significant (at least 2-fold) increases in the mutant frequencies. The values of the cloning efficiencies and the relative total growth are greater than 10 % of the concurrent vehicle control group.

Evolution of results:
A test item is classified as positive if it induces either a reproducible concentration-related increase in the mutant frequency or a reproducible positive response for at least one of the test points

Statistics:

The survival rate and viability was determined based on the Poisson distribution method. The zero term of the Poisson distribution, [P(0)] method, was used.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

all strains/cell types tested

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

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

Additional information on results:

No substantial and reproducible dose dependent increase in mutant colony numbers was observed in both main experiments. No relevant shift of the ratio of small versus large colonies was observed up to the maximal concentration of the test item.
Appropriate reference mutagens were used as positive controls and showed a distinct increase in induced mutant colonies, indicating that the tests were sensitive and valid.

Conclusions:

Interpretation of results (migrated information):
negative

Ammonium Thioglycolate did not induce mutations in the mouse lymphoma thymidine kinase locus assay using the cell line L5178Y in the absence and presence of metabolic activation.

Executive summary:

Ammonium thioglycolate was tested in an in vitro gene mutation assay using mammalian cells cultures both in the absence and presence of metabolic activation (S9 mix), according to the Directive 2000/32/EC, B17 and in compliance with the Principles of Good Laboratory Practice.

In a mammalian cell gene mutation assay (TK+/-), mouse lymphoma L5178Y cells cultured in vitro were exposed to ammonium thioglycolate (purity 71.1%) in deionised water. Two parallels culture were used. The first main experiment was performed without microsomal activation at concentrations of 0, 13, 50, 100, 200, 400, 800 and 1600 µg/ml, and with activation at concentrations of 0, 50, 100, 200, 400,800 and 1600 µg/ml

with a treatment period of 4 h. The second experiment was solely performed in the absence of metabolic activation at concentrations of 0, 13, 25, 50, 100, 200, 400 and 600 µg/ml, with a treatment period of 24 h. Appropriate positive controls were used and showed a statistical increase in mutant colonies, indicating that the tests were sensitive and valid.

After a 48 rest period, cells were incubated mutagenicity evaluation with trifluorothymidine (TFT).

No substantial and reproductible dose dependant increase in mutant colony numbers was observed in both main experiments. No relevant shift of the ratio of small versus large colonies was observed up to the maximal concentration of the test item.

Under these experimental conditions, ammonium thioglycolate did not induce any increase in mutant colonies and is not considered as mutagenic in this mouse lymphoma mouse.

Reference 3

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:: The read-across is a category approach based on the hypothesis that compounds in this category are transformed to a common compound. This approach serves to use existing data on genotoxicity, repeated-dose toxicity, and reproductive toxicity endpoints for substances in this category.
There are no relevant variations in properties among source substances and the same potency is predicted for all target substances. This is Scenario 5 of the RAAF . 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, e.g., the test organism, to the common thioglycolate anion and to their different counter ions. The water solubility of all category members is high, except for CaTG which is only moderately soluble in water.
In the repeated-dose toxicity studies with NaTG, specific toxicity is exerted via the well-investigated inhibition of mitochondrial fatty acid beta-oxidation by the thioglycolate (2-mercaptoacetate) anion 2,3,4. Inhibition of beta-oxidation leads to increased triglycerides and decreased acetyl-CoA in liver, and subsequently reduced gluconeogenesis. The latter presents as hypoglycaemia in NaTGtreated rats, which is aggravated by fasting (Grosdidier, 2011; Report No. 37043 TSR). This mode of action (MoA) is thought to mediate the acute oral toxicity in fasted rats observed with all category members.
It can be predicted with high confidence that the target substances will display the same MoA and lead to the same effects seen with NaTG.
For more detailed information please refer to section 13.2.
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, ATG is considered to be non-clastogenic in mammalian cells.

Endpoint conclusion

Endpoint conclusion:: no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

By analogy to NaTG, ATG is considered to be non-mutagenic in vivo.

Link to relevant study records

Reference

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:: The read-across is a category approach based on the hypothesis that compounds in this category are transformed to a common compound. This approach serves to use existing data on genotoxicity, repeated-dose toxicity, and reproductive toxicity endpoints for substances in this category.
There are no relevant variations in properties among source substances and the same potency is predicted for all target substances. This is Scenario 5 of the RAAF . 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, e.g., the test organism, to the common thioglycolate anion and to their different counter ions. The water solubility of all category members is high, except for CaTG which is only moderately soluble in water.
In the repeated-dose toxicity studies with NaTG, specific toxicity is exerted via the well-investigated inhibition of mitochondrial fatty acid beta-oxidation by the thioglycolate (2-mercaptoacetate) anion 2,3,4. Inhibition of beta-oxidation leads to increased triglycerides and decreased acetyl-CoA in liver, and subsequently reduced gluconeogenesis. The latter presents as hypoglycaemia in NaTGtreated rats, which is aggravated by fasting (Grosdidier, 2011; Report No. 37043 TSR). This mode of action (MoA) is thought to mediate the acute oral toxicity in fasted rats observed with all category members.
It can be predicted with high confidence that the target substances will display the same MoA and lead to the same effects seen with NaTG.
For more detailed information please refer to section 13.2.
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, ATG is considered to be non-mutagenic in vivo.

Endpoint conclusion

Endpoint conclusion:: no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

Several in vitro and in vivo genotoxicity studies were performed with thioglycolic acid and its sodium and ammonium salts. In aqueous solution – experimental tests and biological systems – the ions of the thioglycolate salts will act separately. Therefore any mutagenicity data on thioglycolic acid or one of its salts can be bridged to thioglycolic acid and the other salts, given that their counter-ions do not contribute any mutagenic properties to the molecule.

The most recent bacterial gene mutations assay was conducted with ammonium thioglycolate following a protocol compliant with the OECD guideline 471. The direct plate incorporation procedure was performed with Salmonella typhimurium TA 98, TA 100, TA 102, TA 1535 and TA 1537 at concentrations up to 5,000 µg/plate. Cytotoxic effects were observed in the absence and in the presence of a metabolic activator (Aroclor 1254-induced rat liver S9) at the concentration of 5,000 µg/plate. Ammonium thioglycolate did not induce mutations in the bacterial mutation test in either the absence or presence of metabolic activator in any strain tested. The positive and negative controls included in the experiment showed the expected results (Thompson, 2003).

In other reverse gene mutations assays with multiple strains of Salmonella typhimurium performed with methods compliant or comparable to the OECD guideline 471, thioglycolic acid and its sodium salt were not mutagenic in the presence and absence of metabolic activation (Zeiger, 1987).

Ammonium thioglycolate was tested in a Mouse Lymphoma Forward Mutation Assay performed according to the OECD guideline 476. At concentrations up to 1,600 µg/ml (10 mM), ammonium thioglycolate did not induce gene mutations in the mouse lymphoma L5178Y heterozygous TK^+/-cells, with or without metabolic activation. The spontaneous mutation frequencies and the levels of activity of the positive controls confirmed the sensitivity of the test system (Wollny, 2004).

In a gene TK^+/-mutation assay in mouse lymphoma L5178Y cells, performed following the OECD guideline 476, ammonium thioglycolate was also not mutagenic in the presence and absence of metabolic activation (Wollny 2004). As well, thioglycolic acid was not clastogenic, with or without metabolic activation, in a n in vitro chromosomal aberration assay in human lymphocytes performed following the OECD guideline 473 (Molinier, 1994).

In a micronucleus assay on the peripheral blood of mice treated dermally for 13 weeks with sodium thioglycolate, a slight but statistically significant increase of the frequency of the micronucleated normochromatic erythrocytes was only observed in female mice at the top dose level of 360 mg/kgbw/d (NTP). This result seems of doubtful significance because thioglycolic acid did not induce structural chromosomal in vitro, and thioglycolic acid and its sodium salt failed to show any evidence of clastogenic potential when administered acutely by the dermal and oral routes up to the maximum tolerated dose in two mouse bone marrow micronucleus assays performed following the OECD guideline 474 (Haddouk 2006, Honarvar 2005). In the sex-linked recessive lethal mutations test, sodium thioglycolate was not mutagenic (Gocke 1981).

Justification for selection of genetic toxicity endpoint
One of several negative test results

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.

Number of revertants (mean number of colonies per plate)
Base-pair substitution type						Frameshift type
TA100		TA1535		TA102		TA98		TA1537
136		9		351		15		5
139	(135)	14	(10)	350	(358)	18	(15)	5	(6)
129		7		373		13		8

Number of revertants (mean number of colonies per plate)
Base-pair substitution type						Frameshift type
TA100		TA1535		TA102		TA98		TA1537
62		18		267		12		6
97	(73)	11	(14)	318	(301)	12	(12)	5	(5)
60		13		318		12		5

Registration Dossier

Registration Dossier

Data platform availability banner - registered substances factsheets

Diss Factsheets

Ammonium mercaptoacetate

Endpoint summary

Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Link to relevant study records

Referenceopen allclose all

Reference 1

Reference 2

Reference 3

Endpoint conclusion

Genetic toxicity in vivo

Description of key information

Link to relevant study records

Reference

Endpoint conclusion

Additional information

Justification for classification or non-classification

Referenceopen all close all