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Toxicological information

Genetic toxicity: in vitro

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Administrative data

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:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions

Data source

Reference
Reference Type:
publication
Title:
Salmonella mutagenicity tests: III. Results from the testing of 255 chemicals
Author:
Zeiger E, Anderson B, Haworth S, Lawlor T, Mortelmans K and Speck W
Year:
1987
Bibliographic source:
Environ Mutagen, 9(suppl.9), 1-109

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
not specified
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test compound: sodium thioglycolate
CAS no.: 367-51-1
Source: Matheson Coleman. Bell
Batch: no data
Purity: no data

Method

Target gene:
Histidine reversion
Species / strain
Species / strain:
other: Strains: TA98, TA100, TA1535 and TA1537
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:
no data
Controls
Negative controls:
no
Solvent 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 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

Results and discussion

Test results
Key result
Species / strain:
other: Strains: TA98, TA100, TA1535 and TA1537
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity:
yes
Remarks:
> 1000 µg/plate
Vehicle controls valid:
yes
Negative controls valid:
not examined
Positive controls valid:
yes
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Chemical Name:

Sodium thioglycolate

CAS Number:

367-51-1

Study Type:

Salmonella

Study ID:

471613

Study Result:

Negative

Year Completed:

1979

Vehicle Control:

Water

Protocol:

Preincubation

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

10% HLI

10% RLI

(Negative)

(Negative)

(Negative)

(Negative)

(Negative)

ug/Plate

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

0     

7

0.7

7

0.6

6

0.9

7

2.6

7

0.7

10     

6

1

6

0.9

5

0.9

6

2

8

1.2

33     

5

1.5

6

0.9

7

1.5

9

1.2

6

1.3

100     

8

3.5

9

1.3

7

0.6

9

0.7

6

0.9

333     

6

0.6

6

0.9

5

1.2

7

1.5

8

1.2

1000     

5

1.2

8

2

5

0.3

8

1.2

8

0.9

Positive Control

288

32.3

251

40.8

106

16

43

4.1

135

9.7

Strain: TA100

Dose

No Activation

No Activation

10% HLI

10% HLI

10% RLI

10% RLI

(Negative)

(Negative)

(Negative)

(Equivocal)

(Negative)

(Negative)

ug/Plate

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

Mean

± SEM

0     

100

5

110

5.8

185

26.5

179

11.7

175

27.8

189

8.7

10     

95

5

126

11.4

160

18

164

6.2

140

30.4

204

37.7

33     

105

31.2

129

7.5

195

30

174

7.6

170

40.9

189

3.5

100     

115

10

121

3.8

220

18

221

4.2

145

18

175

9

333     

125

13.2

122

8.5

160

5

173

10.1

135

8.7

221

8.1

1000     

120

30

124

8.8

215

13.2

202

4.3

155

35

181

18.1

Positive Control

430

27.8

599

36.4

558

5.9

836

172.5

300

11.1

430

70.3

Applicant's summary and conclusion

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.