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EC number: 200-677-4 | CAS number: 68-11-1
Endpoint summary
Administrative data
Key value for chemical safety assessment
Genetic toxicity in vitro
Description of key information
In reverse gene mutations assays with multiple strains of Salmonella typhimurium performed with methods compliant or comparable to the OECD guideline # 471, mercaptoacetic acid and its ammonium and sodium salts were not mutagenic in the presence and absence of metabolic activation. In a gene TK+/- mutation assay in mouse lymphoma L5178Y cells, performed following the OECD guideline # 476, ammonium mercaptoacetate was also not mutagenic in the presence and absence of metabolic activation. As well, mercaptoacetic acid was not clastogenic, with or without metabolic activation, in an in vitro chromosomal aberration assay in human lymphocytes performed following the OECD guideline # 473.
Gene Mutations Assays
Several bacterial and mammalian mutation assays have been conducted and demonstrated no mutagenic activity.
The most recent bacterial gene mutations assay was conducted with ammonium mercaptoacetate 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 mercaptoacetate 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 former studies performed according to the US NTP protocol, four S. typhimurium strains were exposed to mercaptoacetic acid (TA97, TA 98, TA 100 and TA 1535) or sodium mercaptoacetate (TA 98, TA 100, TA 1535 and TA 1537) in a preincubation assay. Based on a preliminary toxicity assay, concentrations up to 3,333 (TGA) or 1000 (NaTG) µg/plate were used with or without metabolic activation (rat and hamster S9) in all four strains. Mercaptoacetic acid and its sodium salt did not induce mutations in these studies. Positive and solvent controls gave the expected results (Zeiger et al., 1987).
Ammonium mercaptoacetate 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 mercaptoacetate 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).
Chromosomal aberrations Assays
Mercaptoacetic acid was tested at concentrations of 0, 30, 100 and 300 µg/ml, without metabolic activation and 0, 100, 300 and 1000 µg/ml with metabolic activation (rat S9), in an in vitro chromosome aberration test in human lymphocytes performed according to the OECD guideline # 473. Exposures were for 24 and 48 hours in absence of S9 and 2 hours in presence of S9. Two hundreds cells per dose level were evaluated for chromosomal aberrations. Cytotoxicity was observed at concentration of 300 µg/plate without S9 and>1000 µg/ml with S9. The positive controls (mitomycin-C, without activation and cyclophosphamide with activation) gave the expected values. Mercaptoacetic acid did not induce structural chromosome aberrations in this test (Molinier, 1994).
Link to relevant study records
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP 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: 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: 2-aminoanthracene, 1,8-Dihydroxyanthraquinone
- 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 TA 1535
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- 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:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 98
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- no cytotoxicity, but tested up to precipitating concentrations
- 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:
- = 5000 µg/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:
- no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
- 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.
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- Deviations:
- not specified
- GLP compliance:
- not specified
- Type of assay:
- bacterial reverse mutation assay
- Target gene:
- Histidine reversion
- Species / strain / cell type:
- S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
- Metabolic activation:
- with and without
- Metabolic activation system:
- Rat and hamster liver S9 induced with aroclor 1254
- Test concentrations with justification for top dose:
- 0, 10, 33, 100, 333 and 1000 µg/plate
- Vehicle / solvent:
- no data
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: Without activation : sodium azide (TA1535 and TA 100), 9-aminoacridine (TA 97), 4-nitro-o-phenylenediamine (TA98). With activation : 2-aminoanthracene (all strains).
- Details on test system and experimental conditions:
- In the Salmonella assay, a test tube containing a suspension of one strain of Salmonella typhimurium plus S9 mix or plain buffer without S9, is incubated for 20 minutes at 37º C with the test chemical. Control cultures, with all the same ingredients except the test chemical, are also incubated. In addition, positive control cultures are also prepared; these contain the particular bacterial tester strain under investigation, the various culture ingredients, and a known potent mutagen. After 20 minutes, agar is added to the cultures and the contents of the tubes are thoroughly mixed and poured onto the surface of Petri dishes containing standard bacterial culture medium. The plates are incubated for 48 hours and then counted. The substance was tested initially in a toxicity assay to determine the appropriate dose range.
The toxicity assay was performed by using TA 100. Toxic concentrations were those at which a decrease in the number of his+ colonies was seen or at which there was a clearing in the density of the background lawn.
- Test Design . Number of replicates : 3
- Description of follow up repeat study : same conditions than the initial experiment performed 1 week later - Evaluation criteria:
- The positive control plates are counted, and the number of mutant colonies appearing on them must be significantly increased over the spontaneous control number for the test to be considered valid. If no increase in mutant colonies is seen after testing several strains under several different culture conditions, the test chemical is considered to be non mutagenic in the Salmonella test.
- Statistics:
- None
- Key result
- Species / strain:
- S. typhimurium TA 98
- 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 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 1535
- 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 1537
- 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
- Conclusions:
- Under these experimental conditions, sodium thioglycolate is considered as non-genotoxic
- Executive summary:
In a study performed according to the US NTP protocol, four S. typhimurium strains (TA 98, TA 100, TA 1535 and TA 1537) were exposed to sodium thioglycolate in a preincubation assay. Based on a preliminary toxicity assay, concentrations up to 1000 µg/plate were used with or without metabolic activation (rat and hamster S9) in all four strains. Sodium thioglycolate did not induce mutations in these studies. Positive and solvent controls gave the expected results.
- Endpoint:
- in vitro gene mutation study in bacteria
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- study well documented, meets generally accepted scientific principles, acceptable for assessment
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 471 (Bacterial Reverse Mutation Assay)
- GLP compliance:
- not specified
- Type of assay:
- bacterial reverse mutation assay
- Target gene:
- Histidine reversion
- Species / strain / cell type:
- S. typhimurium, other: Strains: TA97, TA98, TA100 & TA1535
- Metabolic activation:
- with and without
- Metabolic activation system:
- 10% and 30 of Rat and Hamster liver S9 induced with Aroclor 1234
- Test concentrations with justification for top dose:
- 0, 33, 100, 333, 1000, 2000, 3333 µg/plate
- Vehicle / solvent:
- water
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: Without activation : sodium azide (TA1535 and TA 100), 9-aminoacridine (TA 97), 4-nitro-o-phenylenediamine (TA98). With activation : 2-aminoanthracene (all strains).
- Details on test system and experimental conditions:
- In the Salmonella assay, a test tube containing a suspension of one strain of Salmonella typhimurium plus S9 mix or plain buffer without S9, is incubated for 20 minutes at 37º C with the test chemical. Control cultures, with all the same ingredients except the test chemical, are also incubated. In addition, positive control cultures are also prepared; these contain the particular bacterial tester strain under investigation, the various culture ingredients, and a known potent mutagen. After 20 minutes, agar is added to the cultures and the contents of the tubes are thoroughly mixed and poured onto the surface of Petri dishes containing standard bacterial culture medium. The plates are incubated for 48 hours and then counted. The substance was tested initially in a toxicity assay to determine the appropriate dose range. The toxicity assay was performed by using TA 100. Toxic concentrations were those at which a decrease in the number of his+ colonies was seen or at which there was a clearing in the density of the background lawn.
- Description of follow up repeat study : same conditions than the initial experiment performed 1 week later - Evaluation criteria:
- The positive control plates are counted, and the number of mutant colonies appearing on them must be significantly increased over the spontaneous control number for the test to be considered valid.
If no increase in mutant colonies is seen after testing several strains under several different culture conditions, the test chemical is considered to be non-mutagenic in the Salmonella test. - Statistics:
- None
- Key result
- Species / strain:
- S. typhimurium TA 97
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- With S9: >= 2000 µg/plate. Without S9: >= 1000 µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Key result
- Species / strain:
- S. typhimurium TA 98
- Metabolic activation:
- with and without
- Genotoxicity:
- negative
- Cytotoxicity / choice of top concentrations:
- cytotoxicity
- Remarks:
- With S9: >= 2000 µg/plate. Without S9: >= 1000 µg/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:
- With S9: >= 2000 µg/plate. Without S9: >= 1000 µg/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:
- With S9: >= 2000 µg/plate. Without S9: >= 1000 µg/plate
- Vehicle controls validity:
- valid
- Untreated negative controls validity:
- not examined
- Positive controls validity:
- valid
- Endpoint:
- in vitro gene mutation study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP 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:
- no
- Positive controls:
- yes
- Positive control substance:
- other: methyl methanesulfonate (13 µg/mL) without activation; cyclophosphamide with activation (3 µg/mL)
- 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.
- 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
- 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:
- 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.
- Endpoint:
- in vitro cytogenicity / chromosome aberration study in mammalian cells
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
- Deviations:
- no
- GLP compliance:
- yes
- Type of assay:
- in vitro mammalian chromosome aberration test
- Species / strain / cell type:
- other: Human lymphocytes
- Metabolic activation:
- with and without
- Metabolic activation system:
- 10% S9 mix, prepared from a liver microsomal fraction (S9) of rats induced with Aroclor 1254.
- Test concentrations with justification for top dose:
- Without S9: 0, 30, 100 and 300 µg/ml
With S9: 0, 100, 300 and 1000 µg/ml - Vehicle / solvent:
- distilled water
- Untreated negative controls:
- no
- Negative solvent / vehicle controls:
- yes
- True negative controls:
- no
- Positive controls:
- yes
- Positive control substance:
- other: mitomycin C 0.2 µG/ml (without S9) and cyclophosphamide 50 µg/ml (with S9)
- Details on test system and experimental conditions:
- For each culture, heparinised whole blood were added to culture medium containing a mitogen (phytohaemogglutinin) and incubated at 37°C. After 48 hours, the conditions of treatment were as follows, using 2 cultures/experimental point: . without S9 mix, the test or control substances remained in the culture medium either for 24 hours or for 48 hours, until harvest, . with S9 mix, the test or control substances remained in the culture medium for 2 hours. The cells were then rinsed and fresh culture medium was added. The cultures were then incubated until the appropriate harvest time, 24 and 48 hours. Each culture was then treated for 2 hours with a colcemid solution to block them at the metaphase-stage of mitosis and harvested. The chromosomal preparations were stained and screened microscopically for mitotic index and for aberrations: 200 well-spread metaphases per dose were read, whenever possible.
- Evaluation criteria:
- A reproducible and statistically significant increase in the aberrant cells frequency for at least one of the doses is considered as a positive response.
- Statistics:
- X² test
- 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
- Executive summary:
The potential of 2-thioglycolic acid to induce structural chromosome aberrations in human lymphocytes was evaluated according to OECD 473 and EC 92/69/EEC B.10 guidelines in compliance with the Principles of Good Laboratory Practice. The 2-thioglycolic acid was tested with or without a metabolic activation system (rat liver S9 mix) (2 cultures/experimental point) at the dose levels of 30, 100 and 300 µg/ml without S9 mix, and 100, 300 and 1000 µg/ml with S9 mix. Without S9 mix: the cultures were incubated with the test or control substances which remained in the culture medium, until the appropriate harvest time : 24 and 48 hours, with S9 mix: the test or control substances remained in a culture medium containing 15% S9 mix (10% S9/S9 mix) for 2 hours. The cells were then centrifuged, the treatment medium removed, the cells resuspended in fresh culture medium. The cultures were then incubated until the appropriate harvest time: 24 and 48 hours. Two hours before harvesting, the cells were treated with a colcemid solution to block them at the metaphase-stage of mitosis. The chromosomal preparations were stained and screened microscopically for mitotic index and for aberrations: 200 well-spread metaphases per dose were read, whenever possible. 2-thioglycolic acid did not induce any noteworthy increase in the number of cells with structural chromosome aberration, both with and without S9 mix, in either harvest time.
Referenceopen allclose all
Table 1:Spontaneous Mutation Rates (Concurrent Negative Controls)
EXPERIMENT 1
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 |
|||||
EXPERIMENT 2
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 |
|||||
Table 2: Test Results: Experiment 1 – Without Metabolic Activation
Test Period |
From : 25 March 2003 |
To : 28 March 2003 |
||||||||||
With or without S9-Mix |
Test substance concentration (µg/plate) |
Number of revertants (mean number of colonies per plate) |
||||||||||
Base-pair substitution type |
Frameshift type |
|||||||||||
TA100 |
TA1535 |
TA102 |
TA98 |
TA1537 |
||||||||
- |
0 |
153 121 131 |
(135) 16.4# |
9 7 8 |
(8) 1.0 |
367 310 385 |
(354) 39.2 |
13 16 24 |
(18) 5.7 |
6 7 11 |
(8) 2.6 |
|
- |
15 |
128 114 130 |
(124) 8.7 |
6 9 5 |
(7) 2.1 |
353 296 434 |
(361) 69.3 |
16 17 17 |
(17) 0.6 |
5 5 3 |
(4) 1.2 |
|
- |
50 |
104 129 118 |
(117) 12.5 |
12 12 5 |
(10) 4.0 |
399 360 399 |
(386) 22.5 |
16 14 12 |
(14) 2.0 |
5 6 4 |
(5) 1.0 |
|
- |
150 |
144 113 118 |
(125) 16.6 |
11 8 8 |
(9) 1.7 |
406 372 360 |
(379) 23.9 |
15 7 16 |
(13) 4.9 |
4 5 6 |
(5) 1.0 |
|
- |
500 |
101 106 118 |
(108) 8.7 |
11 13 11 |
(12) 1.2 |
362 359 393 |
(371) 18.8 |
15 8 12 |
(12) 3.5 |
5 3 3 |
(4) 1.2 |
|
- |
1500 |
116 104 106 |
(109) 6.4 |
5 3 11 |
(6) 4.2 |
382 356 368 |
(369) 13.0 |
17 15 18 |
(17) 1.5 |
7 7 4 |
(6) 1.7 |
|
- |
5000 |
0 V 0 V 0 V |
(0) 0.0 |
3 S 9 S 5 S |
(6) 3.1 |
204 221 153 |
(193) 35.4 |
17 S 14 S 13 S |
(15) 2.1 |
0 S 0 S 4 S |
(1) 2.3 |
|
Positive controls S9-Mix - |
Name Concentration (µg/plate) No. colonies per plate |
ENNG |
ENNG |
MMC |
4NQO |
9AA |
||||||
3 |
5 |
0.5 |
0.2 |
80 |
||||||||
553 474 505 |
(511) 39.8 |
287 284 256 |
(276) 17.1 |
862 859 903 |
(875) 24.6 |
75 81 80 |
(79) 3.2 |
2605 2689 2688 |
(2661) 48.2 |
|||
Table 3: Test Results: Experiment 1 – With Metabolic Activation
Test Period |
From : 25 March 2003 |
To : 28 March 2003 |
||||||||||
With or without S9-Mix |
Test substance concentration (µg/plate) |
Number of revertants (mean number of colonies per plate) |
||||||||||
Base-pair substitution type |
Frameshift type |
|||||||||||
TA100 |
TA1535 |
TA102 |
TA98 |
TA1537 |
||||||||
+ |
0 |
173 145 180 |
(166) 18.5# |
16 11 15 |
(14) 2.6 |
380 373 370 |
(374) 5.1 |
21 26 28 |
(25) 3.6 |
5 6 7 |
(6) 1.0 |
|
+ |
15 |
150 125 163 |
(146) 19.3 |
17 14 12 |
(14) 2.5 |
361 352 376 |
(363) 12.1 |
24 21 25 |
(23) 2.1 |
5 7 12 |
(8) 3.6 |
|
+ |
50 |
156 158 149 |
(154) 4.7 |
9 6 12 |
(9) 3.0 |
332 362 403 |
(366) 35.6 |
22 22 19 |
(21) 1.7 |
5 6 5 |
(5) 0.6 |
|
+ |
150 |
127 140 150 |
(139) 11.5 |
13 19 17 |
(16) 3.1 |
419 369 363 |
(384) 30.7 |
33 20 18 |
(24) 8.1 |
9 3 6 |
(6) 3.0 |
|
+ |
500 |
119 136 164 |
(140) 22.7 |
17 15 18 |
(17) 1.5 |
389 337 345 |
(357) 28.0 |
19 24 20 |
(21) 2.6 |
12 3 6 |
(7) 4.6 |
|
+ |
1500 |
133 130 121 |
(128) 6.2 |
8 6 9 |
(8) 1.5 |
404 412 304 |
(373) 60.2 |
23 25 19 |
(22) 3.1 |
3 14 2 |
(6) 6.7 |
|
+ |
5000 |
98 82 77 |
(86) 11.0 |
6 6 7 |
(6) 0.6 |
75 88 94 |
(86) 9.7 |
7 25 16 |
(16) 9.0 |
0 0 0 |
(0) 0.0 |
|
Positive controls S9-Mix + |
Name Concentration (µg/plate) No. colonies per plate |
2AA |
2AA |
DAN |
BP |
2AA |
||||||
1 |
2 |
10 |
5 |
2 |
||||||||
1982 2219 1854 |
(2018) 185.2 |
378 376 401 |
(385) 13.9 |
789 787 779 |
(785) 5.3 |
220 262 259 |
(247) 23.4 |
284 336 315 |
(312) 26.2 |
|||
Table 4: Test Results: Experiment 2 – Without Metabolic Activation
Test Period |
From : 11 April 2003 |
To : 14 April 2003 |
||||||||||
With or without S9-Mix |
Test substance concentration (µg/plate) |
Number of revertants (mean number of colonies per plate) |
||||||||||
Base-pair substitution type |
Frameshift type |
|||||||||||
TA100 |
TA1535 |
TA102 |
TA98 |
TA1537 |
||||||||
- |
0 |
95 102 128 |
(108) 17.4# |
17 11 16 |
(15) 3.2 |
345 350 358 |
(351) 6.6 |
19 16 14 |
(16) 2.5 |
14 6 C |
(10) 5.7 |
|
- |
15 |
66 50 63 |
(60) 8.5 |
4 19 11 |
(11) 7.5 |
364 322 393 |
(360) 35.7 |
16 C 16 |
(16) 0.0 |
4 7 6 |
(6) 1.5 |
|
- |
50 |
63 66 55 |
(61) 5.7 |
4 11 7 |
(7) 3.5 |
391 383 362 |
(379) 15.0 |
16 18 17 |
(17) 1.0 |
5 9 1 |
(5) 4.0 |
|
- |
150 |
84 82 66 |
(77) 9.9 |
13 8 11 |
(11) 2.5 |
380 345 398 |
(374) 27.0 |
13 14 9 |
(12) 2.6 |
9 7 4 |
(7) 2.5 |
|
- |
500 |
82 92 95 |
(90) 6.8 |
8 17 14 |
(13) 4.6 |
376 326 397 |
(366) 36.5 |
15 12 15 |
(14) 1.7 |
7 6 5 |
(6) 1.0 |
|
- |
1500 |
86 103 85 |
(91) 10.1 |
11 8 6 |
(8) 2.5 |
326 390 329 |
(348) 36.1 |
11 13 22 |
(15) 5.9 |
9 6 3 |
(6) 3.0 |
|
- |
5000 |
0 S 0 S 0 S |
(0) 0.0 |
7 S 3 S 0 S |
(3) 3.5 |
22 23 25 |
(23) 1.5 |
0 S 0 S 0 S |
(0) 0.0 |
0 S 0 S XS |
(0) 0.0 |
|
Positive controls S9-Mix - |
Name Concentration (µg/plate) No. colonies per plate |
ENNG |
ENNG |
MMC |
4NQO |
9AA |
||||||
3 |
5 |
0.5 |
0.2 |
80 |
||||||||
419 381 274 |
(358) 75.2 |
305 227 222 |
(251) 46.5 |
1080 1040 C |
(1060) 28.3 |
160 170 151 |
(160) 9.5 |
1379 1196 1552 |
(1376) 178.0 |
|||
Table 5: Test Results: Experiment 2 – With Metabolic Activation
Test Period |
From : 11 April 2003 |
To : 14 April 2003 |
||||||||||
With or without S9-Mix |
Test substance concentration (µg/plate) |
Number of revertants (mean number of colonies per plate) |
||||||||||
Base-pair substitution type |
Frameshift type |
|||||||||||
TA100 |
TA1535 |
TA102 |
TA98 |
TA1537 |
||||||||
+ |
0 |
94 113 115 |
(107) 11.6# |
11 8 11 |
(10) 1.7 |
397 326 384 |
(369) 37.8 |
22 26 24 |
(24) 2.0 |
5 7 7 |
(6) 1.2 |
|
+ |
15 |
135 92 107 |
(111) 21.8 |
5 11 14 |
(10) 4.6 |
380 399 396 |
(392) 10.2 |
23 23 29 |
(25) 3.5 |
12 7 5 |
(8) 3.6 |
|
+ |
50 |
128 107 129 |
(121) 12.4 |
13 8 14 |
(12) 3.2 |
345 381 394 |
(373) 25.4 |
29 29 28 |
(29) 0.6 |
7 16 7 |
(10) 5.2 |
|
+ |
150 |
110 137 114 |
(120) 14.6 |
8 11 11 |
(10) 1.7 |
422 424 425 |
(424) 1.5 |
21 29 33 |
(28) 6.1 |
6 11 4 |
(7) 3.6 |
|
+ |
500 |
116 119 134 |
(123) 9.6 |
5 12 13 |
(10) 4.4 |
399 405 361 |
(388) 23.9 |
31 C 29 |
(30) 1.4 |
6 3 5 |
(5) 1.5 |
|
+ |
1500 |
76 85 92 |
(84) 8.0 |
11 7 9 |
(9) 2.0 |
434 380 376 |
(397) 32.4 |
36 22 25 |
(28) 7.4 |
7 5 6 |
(6) 1.0 |
|
+ |
5000 |
46 46 37 |
(43) 5.2 |
5 5 7 |
(6) 1.2 |
39 74 44 |
(52) 18.9 |
15 12 21 |
(16) 4.6 |
3 7 1 |
(4) 3.1 |
|
Positive controls S9-Mix + |
Name Concentration (µg/plate) No. colonies per plate |
2AA |
2AA |
DAN |
BP |
2AA |
||||||
1 |
2 |
10 |
5 |
2 |
||||||||
1099 1410 1350 |
(1286) 165.0 |
236 292 243 |
(257) 30.5 |
1135 1103 1090 |
(1109) 23.2 |
383 477 536 |
(465) 77.2 |
876 723 678 |
(759) 103.8 |
|||
S Sparse bacterial background lawn
V Very weak bacterial background lawn
# Standard deviation
C Contaminated
Mutagenicity of Sodium Thioglycolate in Salmonella typhimuriuma
Strain Dose (µg/plate) |
Without S9 |
Without S9 |
With 10% hamster S9 |
With 10% hamster S9 |
With 10% rat S9 |
With 10% rat S9 |
||
TA100 |
||||||||
0 |
100 ± 5 |
110 ± 6 |
185 ± 26 |
179 ± 12 |
175 ± 28 |
189 ± 9 |
||
10 |
95 ± 5 |
126 ± 11 |
160 ± 18 |
164 ± 6 |
140 ± 30 |
204 ± 38 |
||
33 |
105 ± 31 |
129 ± 8 |
195 ± 30 |
174 ± 8 |
170 ± 41 |
189 ± 4 |
||
100 |
115 ± 10 |
121 ± 4 |
220 ± 18 |
221 ± 4 |
145 ± 18 |
175 ± 9 |
||
333 |
125 ± 13 |
122 ± 8 |
160 ± 5 |
173 ± 10 |
135 ± 9 |
221 ± 8 |
||
1,000 |
120 ± 30 |
124 ± 9 |
215 ± 13 |
202 ± 4 |
155 ± 35 |
181 ± 18 |
||
Trial summary |
Negative |
Negative |
Negative |
Equivocal |
Negative |
Negative |
||
Positive controlb |
430 ± 28 |
599 ± 36 |
558 ± 6 |
836 ± 173 |
300 ± 11 |
430 ± 70 |
||
TA1535 |
||||||||
0 |
7 ± 1 |
7 ± 1 |
6 ± 1 |
7 ± 3 |
7 ± 1 |
|||
10 |
6 ± 1 |
6 ± 1 |
5 ± 1 |
6 ± 2 |
8 ± 1 |
|||
33 |
5 ± 1 |
6 ± 1 |
7 ± 2 |
9 ± 1 |
6 ± 1 |
|||
100 |
8 ± 4 |
9 ± 1 |
7 ± 1 |
9 ± 1 |
6 ± 1 |
|||
333 |
6 ± 1 |
6 ± 1 |
5 ± 1 |
7 ± 2 |
8 ± 1 |
|||
1,000 |
5 ± 1 |
8 ± 2 |
5 ± 0 |
8 ± 1 |
8 ± 1 |
|||
Trial summary |
Negative |
Negative |
Negative |
Negative |
Negative |
|||
Positive control |
288 ± 32 |
251 ± 41 |
106 ± 16 |
43 ± 4 |
135 ± 10 |
|||
TA1537 |
||||||||
0 |
6 ± 3 |
5 ± 1 |
8 ± 1 |
12 ± 2 |
5 ± 1 |
7 ± 2 |
||
10 |
7 ± 1 |
6 ± 1 |
4 ± 1 |
9 ± 3 |
4 ± 1 |
8 ± 2 |
||
33 |
6 ± 1 |
6 ± 1 |
6 ± 0 |
11 ± 2 |
8 ± 2 |
12 ± 2 |
||
100 |
5 ± 1 |
3 ± 2 |
5 ± 1 |
6 ± 1 |
6 ± 2 |
8 ± 2 |
||
333 |
6 ± 1 |
8 ± 2 |
6 ± 1 |
9 ± 3 |
5 ± 1 |
9 ± 1 |
||
1,000 |
7 ± 2 |
6 ± 0 |
6 ± 0 |
9 ± 0 |
6 ± 1 |
10 ± 2 |
||
Trial summary |
Negative |
Negative |
Negative |
Negative |
Negative |
Negative |
||
Positive control |
133 ± 12 |
248 ± 79 |
92 ± 9 |
48 ± 7 |
48 ± 8 |
60 ± 29 |
||
TA98 |
||||||||
0 |
17 ± 2 |
14 ± 2 |
22 ± 2 |
21 ± 1 |
18 ± 2 |
16 ± 1 |
||
10 |
17 ± 2 |
11 ± 2 |
25 ± 2 |
19 ± 4 |
27 ± 5 |
20 ± 2 |
||
33 |
21 ± 2 |
14 ± 2 |
23 ± 2 |
16 ± 3 |
15 ± 3 |
18 ± 3 |
||
100 |
21 ± 3 |
13 ± 2 |
18 ± 2 |
17 ± 1 |
18 ± 3 |
15 ± 1 |
||
333 |
20 ± 2 |
13 ± 2 |
23 ± 2 |
19 ± 2 |
19 ± 3 |
15 ± 1 |
||
1,000 |
22 ± 3 |
14 ± 3 |
18 ± 3 |
18 ± 1 |
16 ± 1 |
16 ± 3 |
||
Trial summary |
Negative |
Negative |
Negative |
Negative |
Negative |
Negative |
||
Positive control |
246 ± 23 |
256 ± 44 |
468 ± 16 |
444 ± 51 |
142 ± 23 |
134 ± 15 |
||
a Data are presented as revertants/plate (mean ± standard error) from three plates. Study was performed at Case Western Reserve University. The detailed protocol and these data are presented by Zeiger et al. (1987). 0 µg/plate was the solvent control.
b The positive controls in the absence of metabolic activation were sodium azide (TA100 and TA1535), 9-aminoacridine (TA1537), and 4-nitro-o-phenylenediamine (TA98). The positive control for metabolic activation with all strains was 2-aminoanthracene.
Chemical Name: |
Thioglycolic acid |
CAS Number: |
68-11-1 |
Study Type: |
Salmonella |
Study ID: |
301735 |
Study Result: |
Negative |
Year Completed: |
1983 |
Vehicle Control: |
Water |
Protocol: |
Preincubation |
Table Instructions and Notes: You are currently viewing the results for this Salmonella study's detailed data. |
|||||||||||||
Individual strain data is presented as mean ± standard error. |
|||||||||||||
Abbreviations are noted at bottom of page. |
|||||||||||||
Trial summary calls are shown in parentheses. |
|||||||||||||
Strain: TA1535 |
|||||||||||||
Dose |
No Activation |
No Activation |
10% HLI |
30% HLI |
10% RLI |
30% RLI |
|||||||
(Negative) |
(Negative) |
(Negative) |
(Negative) |
(Negative) |
(Negative) |
||||||||
ug/Plate |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
|
0 |
30 |
4.9 |
43 |
3.4 |
11 |
1.2 |
15 |
3.2 |
13 |
1.5 |
17 |
2.6 |
|
33 |
26 |
3.2 |
38 |
7.8 |
7 |
1.5 |
15 |
1.5 |
7 |
0.3 |
14 |
0 |
|
100 |
28 |
4.2 |
41 |
1.2 |
9 |
1.5 |
16 |
1.7 |
11 |
1.5 |
14 |
3.1 |
|
333 |
23 |
1.8 |
41 |
4.3 |
9 |
2.3 |
12 |
2.3 |
9 |
0.3 |
14 |
2.5 |
|
1000 |
9 |
4.9 |
28 |
5 |
7 |
1.2 |
11 |
2 |
9 |
0.9 |
11 |
0.9 |
|
2000 |
|
|
|
|
10 |
1.2 |
10s |
1.2 |
6 |
2 |
10s |
2 |
|
3333 |
1s |
0.3 |
13s |
1.5 |
|
|
|
|
|
|
|
|
|
Positive Control |
1065 |
17.4 |
531 |
10.7 |
122 |
11.5 |
154 |
5.9 |
89 |
2 |
121 |
8.4 |
|
Strain: TA100 |
|||||||||||||
Dose |
No Activation |
No Activation |
10% HLI |
30% HLI |
10% RLI |
30% RLI |
|||||||
(Negative) |
(Negative) |
(Negative) |
(Negative) |
(Negative) |
(Negative) |
||||||||
ug/Plate |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
Mean |
± SEM |
|
0 |
91 |
3.2 |
129 |
5 |
83 |
9 |
109 |
4.7 |
100 |
3.7 |
133 |
8.7 |
|
33 |
91 |
10.1 |
108 |
9.9 |
85 |
1.5 |
111 |
7.9 |
90 |
7.2 |
103 |
2.2 |
|
100 |
92 |
6.7 |
113 |
9.2 |
77 |
2.5 |
100 |
11.9 |
94 |
7.2 |
127 |
6.4 |
|
333 |
81 |
1.3 |
113 |
6.9 |
101 |
3.3 |
89 |
4.4 |
107 |
9.3 |
101 |
8.1 |
|
1000 |
78 |
2.3 |
88 |
4.7 |
87 |
7.5 |
104 |
1.7 |
89 |
3 |
123 |
7.5 |
|
2000 |
|
|
|
|
63 |
9.6 |
88s |
8.3 |
63 |
5.8 |
90s |
3 |
|
3333 |
2s |
0.9 |
39s |
6.3 |
|
|
|
|
|
|
|
|
|
Positive Control |
1407 |
48.6 |
1122 |
27.6 |
1373 |
25.2 |
400 |
39.4 |
1218 |
11.7 |
416 |
10.4 |
|
Frequency of aberrant cells (%)
-S9 |
+S9 |
|||||||
Dose |
24 hours |
48 hours |
24 hours |
48 hours |
||||
(µg/ml) |
+Gap -Gap |
+Gap -Gap |
+Gap -Gap |
+Gap -Gap |
||||
0 |
0 |
0 |
1.5 |
0 |
0 |
0 |
0.5 |
0 |
30 |
0 |
0 |
1.0 |
0.5 |
||||
100 |
0.5 |
0.5 |
0.5 |
0 |
0 |
0 |
0 |
0 |
300 |
2.0 |
0 |
4.5 |
1.5 |
2.0 |
0.5 |
0.5 |
0 |
1000 |
1.0 |
0.5 |
0 |
0 |
||||
+ve control |
23.8 |
21.3 |
13.5 |
13.5 |
||||
Mitotic index (% of control)
Dose |
-S9 |
+ S9 |
||
µg/ml |
24 hours |
48 hours |
24 hours |
48 hours |
30 |
136 |
78 |
82 |
81 |
100 |
100 |
95 |
124 |
81 |
300 |
39 |
89 |
93 |
100 |
1000 |
0 |
0 |
91 |
73 |
3000 |
0 |
0 |
0 |
12 |
5000 |
0 |
|||
+ve control |
67 |
33 |
||
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (negative)
Genetic toxicity in vivo
Description of key information
In a micronucleus assay on the peripheral blood of mice treated dermally for 13 weeks with sodium mercaptoacetate, 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/kg bw/d. The Scientific Committee on Consumer Safety (SCCS/1520/13) agrees with the conclusion that this result is of doubtful significance because mercaptoacetic acid did not induce structural chromosomal aberrations in vitro, and mercaptoacetic 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 the two mouse bone marrow micronucleus assays performed following the OECD guideline 474. In the sex-linked recessive lethal mutations test, sodium mercaptoacetate was not mutagenic. The weight of evidence suggests that mercaptoacetic acid and its salts are not genotoxic.
The clastogenic potential of mercaptoacetic acid and sodium mercaptoacetate was evaluated in 2 micronucleus assays on mouse bone marrow performed according to the OECD guideline # 474 and in a micronucleus assay on mouse peripheral blood performed according to the US NTP protocol.
Mercaptoacetic acid, partially neutralized to pH4, was administered dermally over a 2-day period to three groups of five male and five female Swiss mice at dose-levels of 0, 250, 500 and 1000 mg/kg bw/day for males or 0, 125, 250 and 500 mg/kg/day for females (Haddouk, 2006) and sodium mercaptoacetate was administered by single gavage to three groups of five male and five female NMRI mice at dose-levels of 0, 62.5, 125 and 250 mg/kg bw (Honarvar, 2005). For each study, the positive control was the cyclophosphamide administered orally.
In both studies, the polychromatic erythrocytes/normochromatic erythrocytes ratios (PE/NE) in the treated groups were equivalent to those of the control groups. However, systemic exposure was confirmed by the mortality observed in males given 1000 mg/kg/day mercaptoacetic acid, as well as by the clinical signs observed in males treated with 1000 and 500 mg/kg/day mercaptoacetic acid and in males and females receiving 250 mg/kg bw of sodium mercaptoacetate. No increase of the frequency of the micronucleated polychromatic erythrocytes was observed in the bone marrow harvested 24 hours after the treatment(s). Positive and vehicle controls gave the expected results.
At the end of the 3-month dermal toxicity study with sodium mercaptoacetate (0, 22.5, 45.0, 90.0, 180.0 and 360.0 mg/kg bw /d), peripheral blood samples were obtained from male and female B6C3F1 mice (NTP). Smears were immediately prepared and fixed in absolute methanol. The methanol-fixed slides were stained with acridine orange and coded. Slides were scanned to determine the frequency of micronuclei in 2,000 normochromatic erythrocytes (NCEs) in each of five animals per dose group. In addition, the percentage of polychromatic erythrocytes in a population of 1,000 erythrocytes was determined as a measure of bone marrow toxicity. A slight but statistically significant increase (p = 0.0021) of the frequency of the micronucleated normochromatic erythrocytes was observed in female mice at the top dose level of 360 mg/kg bw/day (4.4‰ vs 2.1‰ in control females). The NIEHS regards this result as negative in males and positive in females.
In a former study, the mutagenic potential of sodium mercaptoacetate was evaluated using the sex-linked recessive lethal mutations test (Gocke et al., 1981). One dose (close to the LD50) of 25 mM sodium mercaptoacetate in 5.0% saccharose was fed to Berlin K (wild type) and Basc strains of Drosophila melanogaster. Approximately 1200 X chromosomes were tested per experiment in each of three successive broods. F2 progeny cultures with two or fewer wild-type males were routinely retested in the F3 generation to confirm X-linked recessive lethal mutations. Sodium mercaptoacetate was not mutagenic.
Link to relevant study records
- Endpoint:
- in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
- Deviations:
- no
- Qualifier:
- according to guideline
- Guideline:
- EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test)
- Deviations:
- no
- GLP compliance:
- yes
- Type of assay:
- micronucleus assay
- Species:
- mouse
- Strain:
- Swiss
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- - Animals
. Preliminary toxicity test: 12 male and 15 female mice were used,
. Main cytogenetic test: 55 mice, 27 males and 28 females were used,
. Blood sampling: six mice, three males and three females were used.
. Strain: Swiss Ico: OF1 (IOPS Caw).
. Breeder: Charles River Laboratories, l'Arbresle, France.
. Age: on the day of treatment, the animals were approximately 6 weeks old.
. Acclimation: at least 5 days before the day of treatment.
- Environmental conditions
· Temperature: 22 ± 2°C,
· Relative humidity: 30 to 70%,
· Light/dark cycle: 12 h/12 h (07:00 - 19:00),
· Ventilation: at least 12 cycles/hour of filtered non-recycled fresh air.
. Housing: individually in polycarbonate cages (24.0 x 13.5 x 13.0 cm) containing autoclaved sawdust (SICSA, Alfortville, France).
- Food and water
. Food: A04 C pelleted maintenance diet (SAFE, Villemoisson-sur-Orge, France), ad libitum.
. Water: drinking water filtered by a FG Millipore membrane (0.22 micron), ad libitum. - Route of administration:
- dermal
- Vehicle:
- - Formulation of the test substance:
. Vehicle:
Purified water (CIT, Millipore) degassed by sonication for at least 15 minutes and saturation with nitrogen gas for at least 15 min .
. Treatment volume:
3 mL/kg.
. Formulation procedure:
All the dose-levels and concentrations were expressed as active item, taking into account the active material content of 80.22% (w/w).
.. For the preliminary tests:
Treatment with neutralized test item: the maximum achieved concentration of the preparation neutralized using NaOH (10 M) was 497 mg/mL (obtained pH ranging from 6.92 to 7.24). Using a treatment volume of 3 mL/kg, the target dose-level was 1491 mg/kg/day.
.. Remaining treatments:
The test item preparations were brought to pH ranging from 3.75 to 4.21, by addition of NaOH (10 M). The preparations were used at the concentrations of 666.6, 500, 333.3, 250 and 166.67 mg/mL, in order to reach the target dose-levels of 2000, 1500, 1000, 750 and 500 mg/kg/day, respectively, using a treatment volume of 3 mL/kg. All the test item dosage forms were prepared extemporaneously. In addition, except for the preparation at 666.6 mg/mL (target dose-level of 2000 mg/kg/day), the preparations were made under nitrogen atmosphere and were stored at room temperature and under nitrogen atmosphere until treatment.
.. For the main cytogenetic test:
The test item dosage forms were prepared extemporaneously under nitrogen atmosphere and were stored at room temperature and under nitrogen atmosphere until treatment. The pH of the preparations was adjusted to a value of approximately 4 (ranging from 4.0 to 4.10) by addition of NaOH (10 M). The preparations were used at the concentrations of 41.67, 83.33, 166.67 and 333.3 mg/mL, in order to reach the target dose-levels of 125, 250, 500 and 1000 mg/kg/day, respectively, using a treatment volume of 3 mL/kg. - Details on exposure:
- - Preparation of the animals:
On the day before the beginning of the treatment period, an area of approximately 1,5 x 2 cm or 2,5 x 2 cm (3 to 5 cm2), estimated to be up to 10% of the total body surface (1) was clipped free from hair, as close to the skin as possible on the dorsum of the animals, with an electric clipper. Before the first dosage form application, the treatment area was examined and any animals showing skin abnormality and/or irritation was replaced from the spare animals ordered. During the treatment period, the animals were clipped whenever necessary, at least 4 hours before dosing.
- Administration
The test item formulated in a vehicle was applied in a film as thin and uniform as possible, to the clipped area of the skin. The dosage forms was applied to the dorsum using a micropipette. No dressing or protective plastic collar was used. Each animal was given the dosage forms once a day, on two consecutive days, at approximately the same time.
- Preliminary toxicity test
In order to determine the highest dose-level, several preliminary tests were performed on groups of six animals (three males and/or three females). Clinical signs, any local reaction at the treatment site (following the below-mentioned scoring scale) and any mortality was recorded over a period of 48 hours. At the end of this period, the animals were killed by CO2 inhalation in excess. - Duration of treatment / exposure:
- 2 administrations at 24-h interval
- Frequency of treatment:
- daily
- Post exposure period:
- none
- Remarks:
- Doses / Concentrations:
Males: 1000, 500 and 250 mg/kg. Females: 500, 250 and 125 mg/kg
Basis: - No. of animals per sex per dose:
- 5 in the control groups and in the low and intermediate dose groups. 7 or 8 in the high dose group
- Control animals:
- yes, concurrent vehicle
- Positive control(s):
- Cyclophosphamide (CPA), batch No. 4A121 (Endoxan, Baxter, Maurepas, France) dissolved in distilled water at a concentration of 5 mg/mL.
. route: oral
. treatment volume: 10 mL/kg
. number of administrations: one - Tissues and cell types examined:
- Bone marrow
- Details of tissue and slide preparation:
- - Preparation of the bone marrow smears:
At the time of sacrifice, all the animals were killed by CO2 inhalation in excess. The femurs of the animals were removed and the bone marrow was flushed out using fetal calf serum. After centrifugation, the supernatant was removed and the cells in the sediment were resuspended by shaking. A drop of this cell suspension was placed and spread on a slide. The slides were air dried and stained with Giemsa. The slides were coded so that the scorer is unaware of the treatment group of the slide under evaluation ("blind" scoring).
- Microscopic examination of the slides:
For each animal, the number of the micronucleated polychromatic erythrocytes (MPE) was counted in 2000 polychromatic erythrocytes; the polychromatic (PE) and normochromatic (NE) erythrocyte ratio was established by scoring a total of 1000 erythrocytes (PE + NE). - Evaluation criteria:
- For a result to be considered positive, a statistically significant increase in the frequency of MPE must be demonstrated when compared to the concurrent vehicle control group. Reference to historical data, or other considerations of biological relevance was also taken into account in the evaluation of data obtained.
- Statistics:
- Normality and homogeneity of variances was tested using a Kolmogorov Smirnov test and a Bartlett test. If normality and homogeneity of variances are demonstrated, the statistical comparisons were performed using a Student t-test (2 groups) or a one-way analysis of variance (>= 3 groups) followed by a Dunnett test (if necessary). If normality or homogeneity of variances are not demonstrated, a Mann/Withney test (2 groups) or a Kruskall Wallis test (>= 3 groups) was performed followed by a Dunn test (if necessary). All these analyses were performed using the software SAS Enterprise Guide V2 (2.0.0.417, SAS Institute Inc), with a level of significance of 0.05 for all tests.
- Sex:
- male/female
- Genotoxicity:
- negative
- Toxicity:
- yes
- Vehicle controls validity:
- valid
- Negative controls validity:
- not examined
- Positive controls validity:
- valid
- Conclusions:
- Interpretation of results (migrated information): negative
THIOGLYCOLIC ACID did not induce any damage to the chromosomes or the mitotic apparatus of mice bone marrow cells after two cutaneous administrations, at a 24 hour interval, at the dose-levels of 250, 500 and 1000 mg/kg/day for males or 125, 250 and 500 mg/kg/day for females. - Executive summary:
The clastogenic potential of thioglycolic acid was evaluated in a micronucleus assay on mouse bone marrow performed according to the OECD guideline # 474. Thioglycolic acid, partially neutralized to pH 4, was administered dermally over a 2-day period to three groups of five male and five female Swiss mice at dose-levels of 0, 250, 500 and 1000 mg/kg bw/day for males or 0, 125, 250 and 500 mg/kg/day for females. The positive control was the cyclophosphamide administered orally. The polychromatic erythrocytes/normochromatic erythrocytes ratios (PE/NE) in the treated groups were equivalent to those of the control groups. However, systemic exposure was confirmed by the mortality observed in males given 1000 mg/kg/day thioglycolic acid, as well as by the clinical signs observed in males treated with 1000 and 500 mg/kg/day thioglycolic acid. No increase of the frequency of the micronucleated polychromatic erythrocytes was observed in the bone marrow harvested 24 hours after the last treatment. Positive and vehicle controls gave the expected results.
- Endpoint:
- in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP guideline study
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
- GLP compliance:
- yes
- Type of assay:
- other: Micronucleus assay on mouse bone marrow
- Species:
- mouse
- Strain:
- NMRI
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- - Animals .
. Source: Harlan Winkelmann GmbH D-33178 Borchen
. Number of Animals: 72 (36 males/36 females), 6 males and 6 females per group
. Initial Age at Start of Acclimatisation: 8-10 weeks
. Acclimatisation: minimum 5 days
. Initial Body Weight at Start of Treatment: males mean value 37.1 g (SD ± 2.9 g) females mean value 31.5 g (SD ± 1.9 g)
- Environmental conditions
. Housing: single Cage Type: Makrolon Type I, with wire mesh top (EHRET GmbH, D-79302 Emmendingen)
. Bedding: granulated soft wood bedding (Harlan Winkelmann GmbH, D-33178 Borchen)
. Temperature 22 ± 3 °C
. Relative humidity 30 - 70 %
. Artificial light 6.00 a.m. - 6.00 p.m.
- Food and water
. Feed: pelleted standard diet, ad libitum (Harlan Winkelmann GmbH, D-33178 Borchen)
. Water: tap water, ad libitum, (Gemeindewerke, D-64380 Roßdorf) - Route of administration:
- oral: gavage
- Vehicle:
- Name: deionised water
Route and Frequency of Administration: orally, once
Volume Administered: 10 mL/kg b.w. - Duration of treatment / exposure:
- single administration
- Frequency of treatment:
- single
- Post exposure period:
- 24 and 48 hours
- Remarks:
- Doses / Concentrations:
0, 62.5, 125 and 250 mg/kg bw
Basis:
actual ingested - No. of animals per sex per dose:
- 5
- Control animals:
- yes, concurrent vehicle
- Positive control(s):
- Name: CPA; Cyclophosphamide
Dissolved in: deionised water
Dosing: 40 mg/kg b.w.
Route and frequency of administration: orally, once
Volume administered: 10 mL/kg b.w. - Tissues and cell types examined:
- Bonne marrow
- Details of tissue and slide preparation:
- - Preparation of the bone marrow smears
Ten animals (5 males, 5 females) per test group (all groups after 24 hours and only the high dose group after 48 hours) were killed by CO2 inhalation, following by bleeding. The femurs of the animals were removed and the bone marrow was flushed out using foetal calf serum. After centrifugation, the supernatant was removed and the cells in the sediment were resuspended by shaking. A drop of this cell suspension was placed and spread on a slide. The slides were air dried and stained with May-Grünwald. The slides were coded so that the scorer is unaware of the treatment group of the slide under evaluation ("blind" scoring).
- Microscopic examination of the slides
For each animal, the number of the micronucleated polychromatic erythrocytes (MPE) was counted in 2000 polychromatic erythrocytes; the polychromatic (PE) and normochromatic (NE) erythrocyte ratio was established by scoring a total of 1000 erythrocytes (PE + NE). - Evaluation criteria:
- The study was considered valid as the following criteria are met:
- the negative controls are in the range of our historical control data.
- the positive controls are in the range of our historical control data.
- at least 4 animals per group and sex can be evaluated
- PCE to erythrocyte ratio should not be less than 20 % of the negative control.
A test item is classified as mutagenic if it induces either a dose-related increase or a clear increase in the number of micronucleated polychromatic erythrocytes in a single dose group. - Statistics:
- Statistical methods (nonparametric Mann-Whitney test (8)) will be used as an aid in evaluating the results. However, the primary point of consideration is the biological relevance of the results. A test item that fails to produce a biological relevant increase in the number of micronucleated polychromatic erythrocytes is considered non-mutagenic in this system.
- Sex:
- male/female
- Genotoxicity:
- negative
- Toxicity:
- yes
- Remarks:
- clinical signs
- Vehicle controls validity:
- valid
- Negative controls validity:
- not examined
- Positive controls validity:
- valid
- Additional information on results:
- As estimated by a pre-experiment 250 mg Sodium Thioglycolate 98%, Pure per kg b.w. was suitable.
The mean number of polychromatic erythrocytes was not decreased after treatment with the test item as compared to the mean value of PCEs of the vehicle control indicating that Sodium Thioglycolate 98%, Pure had no cytotoxic properties in the bone marrow. In comparison to the corresponding vehicle controls there was no statistically significant or biologically relevant enhancement in the frequency of the detected micronuclei at any preparation interval and dose level after administration of the test item.
The mean values of micronuclei observed after treatment with Sodium Thioglycolate 98%, Pure were below or near to the value of the vehicle control group.
40 mg/kg b.w. cyclophosphamide administered orally was used as positive control which showed a statistically significant increase of induced micronucleus frequency. - Conclusions:
- Interpretation of results (migrated information): negative
Sodium Thioglycolate 98%, Pure is considered to be non-mutagenic in this micronucleus assay. - Executive summary:
The clastogenic potential of sodium thioglycolate was evaluated in a micronucleus assay on mouse bone marrow performed according to the OECD guideline # 474.Sodium thioglycolate was administered by single gavage to three groups of five male and five female NMRI mice at dose-levels of 0, 62.5, 125 and 250 mg/kg bw. The positive control was the cyclophosphamide administered orally. The polychromatic erythrocytes/normochromatic erythrocytesratios (PE/NE) in the treated groups were equivalent to those of the control groups. However, systemic exposure was confirmed by the clinical signs observed in males and females receiving 250 mg/kg bw of sodium thioglycolate. No increase of the frequency of the micronucleated polychromatic erythrocytes was observed in the bone marrow harvested 24 or 48 hours after the treatment. Positive and vehicle controls gave the expected results.
- Endpoint:
- in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see 'Remark'
- Remarks:
- For the time being, the draft report (TOX-80) is still undergoing a multi-tiered review that includes NTP staff review and external peer review. The publication of the final TOX-80 is expected in 2009. However, the data available on the NTP website are sufficiently detailed for a preliminary assessment.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
- Qualifier:
- according to guideline
- Guideline:
- other: NTP standard protocol
- GLP compliance:
- not specified
- Type of assay:
- micronucleus assay
- Species:
- mouse
- Strain:
- B6C3F1
- Sex:
- male/female
- Route of administration:
- dermal
- Vehicle:
- water/ethanol
- Details on exposure:
- In a subchronic dermal toxicity study in mice, a blood sample was obtained at the end of the 13-week exposure period from male and female mice in each dose group (5 animals per treatment group per sex).
- Duration of treatment / exposure:
- 14 weeks
- Frequency of treatment:
- 5 days/week
- Post exposure period:
- None
- Dose / conc.:
- 22.5 mg/kg bw/day (actual dose received)
- Dose / conc.:
- 45 mg/kg bw/day (actual dose received)
- Dose / conc.:
- 90 mg/kg bw/day (actual dose received)
- Dose / conc.:
- 180 mg/kg bw/day (actual dose received)
- Dose / conc.:
- 360 mg/kg bw/day (actual dose received)
- No. of animals per sex per dose:
- 5
- Control animals:
- yes, concurrent vehicle
- Positive control(s):
- None
- Tissues and cell types examined:
- Peripheral blood
- Details of tissue and slide preparation:
- Slides are prepared, air-dried, fixed, and stained with a fluorescent DNA-specific stain that easily illuminates any micronuclei that may be present. 2,000 mature erythrocytes (normochromatic erythrocytes or NCEs) are scored per animal for presence of micronuclei. These mature erythrocytes represent about 95% or more of the circulating erythrocytes. The percent PCE is determined in the blood as a measure of chemical-induced toxicity to the bone marrow. All data are analyzed separately for male and female mice.
- Evaluation criteria:
- Factors which must be considered in analyzing micronucleus test data include number of animals per dose group (a minimum of 3 is required), dose levels and number of doses administered, route of administration, tissue and cell type analyzed, sample time (interval between last dosing and harvesting of cells for analysis), frequencies of micronucleated cells in the negative and positive controls, and the results of the statistical analyses.
- Statistics:
- A formal statistical analysis of the data is performed, including a trend test, to determine if there is an overall increase across all doses in the frequency of cells containing micronuclei, and a pairwise comparison of each dose group to the corresponding control, to see if any one dose group is statistically different from the control group in frequency of micronucleated cells. Data are typically presented as the mean number of micronucleated cells per 1,000 cells for each treatment group. A positive trend test is one in which the P value is equal to or less than 0.025. For the micronucleus frequency in any dose group to be considered significantly elevated over the control group, the P value must be equal to or less than 0.025 divided by the number of chemical-treatment groups. Thus, if the number of treated groups is 3, then the required pairwise P value is 0.008.
- Sex:
- male/female
- Genotoxicity:
- ambiguous
- Toxicity:
- no effects
- Vehicle controls validity:
- valid
- Negative controls validity:
- valid
- Positive controls validity:
- not examined
- Additional information on results:
- A statistically significant increase (p=0.0021) of the frequency of the micronucleated normochromatic erythrocytes was observed in female mice at the top dose level of 360 mg/kg (4.4 o/oo vs 2.1 o/oo in control females). However, the same values were observed in the treated male mice (4.0 to 4.6 o/oo) but without statistical significance due to a higher control value in male mice (3.4 o/oo).
- Conclusions:
- The Scientific Committee on Consumer Safety (SCCS/1520/13) agrees with the conclusion that this result is of doubtful significance because thioglycolic acid did not induce structural chromosomal aberrations 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 the two mouse bone marrow micronucleus assays performed following the OECD guideline 474.
- Executive summary:
At the end of the 3-month dermal toxicity study with sodium thioglycolate (0, 22.5, 45.0, 90.0, 180.0 and 360.0 mg/kg bw /d), peripheral blood samples were obtained from male and female B6C3F1 mice. Smears were immediately prepared and fixed in absolute methanol. The methanol-fixed slides were stained with acridine orange and coded. Slides were scanned to determine the frequency of micronuclei in 2,000 normochromatic erythrocytes (NCEs) in each of five animals per dose group. In addition, the percentage of polychromatic erythrocytes in a population of 1,000 erythrocytes was determined as a measure of bone marrow toxicity.
A slight but statistically significant increase (p = 0.0021) of the frequency of the micronucleated normochromatic erythrocytes was observed in female mice at the top dose level of 360 mg/kg bw/day (4.4‰ vs 2.1‰ in control females). The NIEHS regards this result as negative in males and positive in females.
- Endpoint:
- in vivo mammalian germ cell study: gene mutation
- Type of information:
- experimental study
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: Test procedure in accordance with national standard methods with acceptable restrictions
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Won (1977) Abstr Ann Meet Am Soc Microbiol, 77, 276.
- GLP compliance:
- not specified
- Type of assay:
- Drosophila SLRL assay
- Species:
- Drosophila melanogaster
- Strain:
- other: Berlin K and Basc
- Sex:
- not specified
- Route of administration:
- oral: feed
- Details on exposure:
- In Drosophila one dose close to the LD50 was applied by the adult feeding method in 5% saccharose. About 1200 X-chromosomes were tested per experiment in each of 3 successive broods (3-3-4 days). In repeat experiments, sometimes only single broods were tested. F2 progeny cultures with 2 or fewer wild-type males were routinely retested in the F3 generation to confirm X-linked recessive lethal mutations (RLs). Mosaics were not counted. "Clusters" of 2 were included because their occurrence was compatible with statistical expectation of independent origin. No additional details available.
- Duration of treatment / exposure:
- 3 broods
- Dose / conc.:
- 25 other: mM
- Control animals:
- yes, historical
- Positive control(s):
- Positive control: treminon
- Sex:
- not specified
- Genotoxicity:
- negative
- Toxicity:
- not specified
- Vehicle controls validity:
- valid
- Negative controls validity:
- not examined
- Positive controls validity:
- valid
- Conclusions:
- Negative
- Executive summary:
The mutagenic potential of sodium thioglycolate was evaluated using the sex-linked recessive lethal mutations test. One dose (close to the LD50) of 25 mM sodium thioglycolate in 5.0% saccharose was fed to Berlin K (wild type) and Basc strains of Drosophila melanogaster. Approximately 1200 X chromosomes were tested per experiment in each of three successive broods. F2 progeny cultures with two or fewer wild-type males were routinely retested in the F3 generation to confirm X-linked recessive lethal mutations. Sodium thioglycolate was not mutagenic.
Referenceopen allclose all
- PRELIMINARY TOXICITY TEST
. Treatment with neutralized test item (target pH of 7):
At 1491 mg/kg/day, no mortality and no clinical signs were noted in the three males and three females treated with the test item. In one male (1/3), a very slight erythema was noted since 24h after the first treatment until sacrifice.
. Treatment with partially neutralized test item (target pH of 4):
For all dose-levels tested no cutaneous reactions were noted in any of the treated animals.
At 2000 mg/kg/day, 2/3 males and 2/3 females were found dead 16 hours following the first treatment. The two surviving animals (one male and one female) were sacrificed and no second treatment was performed.
At 1500 mg/kg/day (males only), 2/3 males were found dead 17 hours following the first treatment. The surviving animal was sacrificed and no second treatment was performed.
At 1000 mg/kg/day, no deaths occurred in males, either hypoactivity, half-closed eyes and piloerection or only piloerection were observed following the second treatment. In females, one animal (1/3) was found dead more than 16 hours following the second treatment. The two surviving females showed hypoactivity, lateral recumbency, tremors, piloerection and/or half-closed eyes.
At 750 mg/kg/day (females only), one animal (1/3) was found dead 21 hours following the first treatment. The two surviving females showed poor clinical conditions and were therefore sacrificed immediately.
At 500 mg/kg/day (females only), no deaths occurred. Dyspnea and piloerection were noted in 3/3 females following the second treatment.
- CYTOGENETIC TEST
In males treated at 1000 mg/kg/day, mortality was observed (3/7). Piloerection was noted in the surviving animals.
In males treated at 500 mg/kg/day, piloerection was noted (3/5).
No clinical signs and deaths were observed in males treated at 250 mg/kg/day as well as in females during the study.
For all dose-levels tested no cutaneous reactions were noted in any of the treated animals.
For both males and females, the mean values of MPE as well as the PE/NE ratio in the groups treated with the test item, were equivalent to those of the vehicle group.
Cyclophosphamide induced a significant increase in the frequency of MPE, indicating the sensitivity of the test system under our experimental conditions. The study was therefore considered valid.
Results of the cytogenetic test: data summary
Group |
Doses(1) (mg/kg/day) |
MPE/1000PE |
PE/NE ratio |
Time of sacrifice after the last administration |
||
mean |
(sd) |
mean |
(sd) |
|||
Males |
||||||
Vehicle |
- |
2.1 |
(0.5) |
0.5 |
(0.2) |
24 h |
Test item |
250 |
2.3 |
(1.7) |
0.6 |
(0.1) |
|
500 |
1.6 |
(1.1) |
0.6 |
(0.1) |
||
1000 |
1.1 |
(0.5) |
0.6 |
(0.2) |
||
Cyclophosphamide |
50 |
19.6 |
(4.2)* |
0.5 |
(0.0) |
|
Females |
||||||
Vehicle |
- |
0.9 |
(0.5) |
0.6 |
(0.1) |
24 h |
Test item |
125 |
1.7 |
(0.8) |
0.8 |
(0.2) |
|
250 |
0.9 |
(0.7) |
0.9 |
(0.4) |
||
500 |
1.5 |
(0.7) |
0.8 |
(0.3) |
||
Cyclophosphamide |
50 |
15.1 |
(6.2)** |
0.7 |
(0.1) |
|
(1)expressed as active item
Five animals per group (except for the high-dose treated group of males: four animals)
MPE: Micronucleated Polychromatic Erythrocytes
PE: Polychromatic Erythrocytes
NE: Normochromatic Erythrocytes
sd: standard deviation
Statistical significance:* p < 0.05 ** p < 0.01
Summary of Micronucleus Test Results
test group |
dose (mg/kg b.w) |
sampling time (h) |
PCEs with micronuclei (%) |
range |
PCE per 2000 erythocytes |
vehicle |
0 |
24 |
0.050 |
0 - 2 |
1098 |
test item |
62.5 |
24 |
0.060 |
0 - 2 |
1124 |
test item |
125 |
24 |
0.025 |
0 - 1 |
1123 |
test item |
250 |
24 |
0.055 |
0 - 3 |
1100 |
Positive control |
40 |
24 |
1.500 |
10 -43 |
1099 |
test item |
250 |
48 |
0.095 |
0 - 6 |
1123 |
Historical Controls (1999 – 2004)
Vehicle Controls |
Positive Controls (CPA) |
|||||
Males |
Females |
Total |
Males |
Females |
Total |
|
Mean*±SD |
0.078±0.04 |
0.058±0.033 |
0.069±0.028 |
1.867±0.57 |
1.368±0.497 |
1.632±0.468 |
Range** |
0.01 - 0.23 |
0.0 - 0.19 |
0.01 - 0.15 |
0.70 -3.46 |
0.49 -3.55 |
0.77 - 3.48 |
No. of Experiments |
229 |
217 |
230 |
228 |
217 |
229 |
*: mean value (percent micronucleated cells)
**: range of the mean group values (percent micronucleated cells)
Frequency of Micronuclei in Peripheral Blood Erythrocytes of Mice Following Dermal Application of Sodium Thioglycolate for 3 Monthsa
Dose (mg/kg) |
Number of Mice with Erythrocytes Scored |
Micronucleated NCEs/1,000 NCEsb |
P Valuec |
PCEsb (%) |
||
Male |
||||||
95% Ethanol:deionized waterd |
5 |
3.4 ± 0.29 |
3.20 ± 0.18 |
|||
Sodium thioglycolate |
22.5 |
5 |
4.1 ± 0.51 |
0.2090 |
3.28 ± 0.11 |
|
|
45 |
5 |
4.6 ± 0.73 |
0.0894 |
4.08 ± 0.23 |
|
|
90 |
5 |
4.3 ± 0.56 |
0.1521 |
4.04 ± 0.35 |
|
|
180 |
5 |
4.0 ± 0.16 |
0.2423 |
3.80 ± 0.43 |
|
|
360 |
5 |
4.4 ± 0.37 |
0.1283 |
3.58 ± 0.29 |
|
P=0.290e |
||||||
Female |
||||||
95% Ethanol:deionized water |
5 |
2.1 ± 0.10 |
3.88 ± 0.17 |
|||
Sodium thioglycolate |
22.5 |
5 |
3.0 ± 0.32 |
0.1035 |
3.22 ± 0.26 |
|
|
45 |
5 |
2.6 ± 0.24 |
0.2326 |
3.48 ± 0.44 |
|
|
90 |
5 |
3.1 ± 0.48 |
0.0825 |
2.68 ± 0.15 |
|
|
180 |
5 |
3.3 ± 0.20 |
0.0510 |
3.30 ± 0.44 |
|
|
360 |
5 |
4.4 ± 0.29 |
0.0021 |
3.32 ± 0.18 |
|
P=0.002 |
||||||
a Study was performed at ILS, Inc. The detailed protocol is presented by MacGregor et al. (1990). NCE=normochromatic erythrocyte; PCE=polychromatic erythrocyte
b Mean ± standard error
c Pairwise comparison with the vehicle control group; dosed group values are significant at P=0.005
d Vehicle control at a 1:1 ratio
e Significance of micronucleated NCEs/1,000 NCEs tested by the one-tailed trend test; significant at P=0.025
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed (negative)
Additional information
Justification for classification or non-classification
According to REGULATION (EC) No 1272/2008 of 16 December 2008 and the available genotoxicity data, no classification is warranted for mercaptoacetic acid.
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