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REACH

Octanoic acid, 6,8-dimercapto-

EC number: 610-288-5 | CAS number: 462-20-4

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 mutagenic potential of Dihydrolipoic Acid was assessed according to OECD 471 ("Bacterial Reverse Mutation Test").

Link to relevant study records

Reference

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31.08.2000 - 10.10.2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Target gene:

Gene involved in histidine synthesis.

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Details on mammalian cell type (if applicable):

n. a.

Additional strain / cell type characteristics:

not specified

Species / strain / cell type:

E. coli WP2 uvr A

Details on mammalian cell type (if applicable):

n. a.

Additional strain / cell type characteristics:

not specified

Metabolic activation:

with and without

Metabolic activation system:

Mammalian Microsomal Fraction S9 Mix

Test concentrations with justification for top dose:

Experiments I and II: 50; 150; 500; 1500; 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle:The test item was dissolved in DMSO and diluted prior to treatment. The solvent was compatible with the survival of the bacteria and the S9 activity.

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

True negative controls:

Positive controls:

yes

Positive control substance:

4-nitroquinoline-N-oxide

9-aminoacridine

N-ethyl-N-nitro-N-nitrosoguanidine

benzo(a)pyrene

other: 2-aminoantracene

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 48 hours

DETERMINATION OF CYTOTOXICITY
- Method: cloning efficiency

Evaluation criteria:

The test material may be considered positive in this test system if the following creiteria are met: The test material should have induced a reproducible, dose-related and statistically (see below) significant increase in the revertant count in at least one strain of bacteria.

Statistics:

The data were evaluated according to Dunnett's method of linear regression (Kirkland D J (Ed) (1989) Statistical Evaluation of Mutagenicity Test Data. UKEMS Subcommitee on Guidelines for Mutagenicity Testing, Report - Part III, Cambridge University Press.)

Key result

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

True negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

not determinable

Table 1: Test Results of Experiment 1 (without and with metabolic activation).

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

WP2uvrA-

TA98

TA1537

134

158

121

(138)

18.8#

(22)

1.0

(29)

7.1

(24)

8.3

(18)

1.5

116

132

134

(127)

9.9

(25)

6.5

(27)

5.6

(23)

3.1

(21)

6.1

150

118

132

109

(120)

11.6

(19)

2.6

(23)

3.1

(31)

14.0

(24)

1.5

500

119

132

131

(127)

7.2

(16)

7.0

(33)

7.2

(35)

3.8

(23)

6.2

1500

103

134

121

(119)

15.6

(21)

7.5

(19)

1.5

(23)

3.2

(20)

4.0

5000

110

128

(106)

24.2

(20)

6.6

(22)

5.5

18S

12S

(16)

3.5

(12)

0.6

Positive controls

Name

Concentration (µg/plate)

ENNG

4NQO

9AA

0.2

S9-Mix

No. colonies per plate

430

483

390

(434)

46.7

261

163

181

(202)

52.2

541

580

488

(536)

46.2

145

177

(138)

42.4

1408

1119

1083

(1203)

178.2

135

130

131

(132)

2.6#

(16)

4.0

(34)

6.5

(38)

7.1

(21)

0.6

129

145

162

(145)

16.5

(17)

4.9

(28)

4.5

(42)

5.5

(19)

4.2

150

134

144

(141)

5.8

(21)

1.7

(27)

6.2

(37)

5.2

(20)

2.3

500

126

141

149

(139)

11.7

(22)

1.5

(23)

2.1

(41)

15.4

(19)

3.8

1500

119

157

116

(131)

22.9

(12)

1.5

(29)

1.5

(39)

0.6

(19)

5.6

5000

102

106

(96)

13.4

11S

(7)

3.8

(19)

3.0

(25)

3.6

(18)

5.0

Positive controls

Name

Concentration (µg/plate)

2AA

S9-Mix

No. colonies per plate

1983

1902

1988

(1958)

48.3

325

246

265

(279)

41.2

957

740

942

(880)

121.2

177

173

166

(172)

5.6

482

414

473

(456)

36.9

ENNG: N-ethyl-N'-nitro-N-nitrosoguanidine

4NQO: 4 -Nitroquinoline-1-oxide

9AA: 9-Aminoacridine

2AA: 2-Aminoanthracene

BP: Benzo(a)pyrene

S: Sparse bacterial background lawn

#: Standard deviation

Table 2: Test Result of Experiment 2 (without and with metabolic activation).

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

WP2uvrA-

TA98

TA1537

(98)

1.4#

(23)

1.2

(28)

3.6

(24)

7.6

(22)

4.0

102

(97)

4.2

(19)

1.7

(25)

3.2

(21)

0.6

(14)

1.5

150

112

(97)

12.9

(13)

4.7

(17)

2.0

(22)

2.5

(23)

4.2

500

106

(97)

9.0

(21)

1.0

(23)

1.5

(25)

3.8

(22)

2.6

1500

(76)

5.0

(15)

3.8

(28)

7.4

(24)

6.7

(19)

2.0

5000

(60)

11.1

(18)

3.2

(23)

6.2

(24)

4.9

(10)

2.0

Positive controls

Name

Concentration (µg/plate)

ENNG

4NQO

9AA

0.2

S9-Mix

No. colonies per plate

430

440

413

(428)

13.7

128

101

156

(128)

27.5

623

637

579

(613)

30.3

103

(93)

12.7

1018

912

1008

(979)

58.5

119

102

107

(109)

8.7#

(18)

1.2

(32)

4.2

(40)

4.0

(22)

3.1

118

104

108

(110)

7.2

(22)

2.5

(31)

7.5

(35)

3.1

(21)

4.0

150

126

103

113

(114)

11.5

(13)

3.2

(24)

4.0

(36)

5.1

(20)

6.5

500

144

102

(114)

26.2

(10)

2.3

(24)

7.1

(35)

2.5

(21)

3.8

1500

104

107

101

(104)

3.0

(21)

6.7

(31)

8.0

(31)

2.1

(18)

4.6

5000

103

(92)

12.7

(9)

3.1

(27)

8.6

(27)

4.9

(14)

4.4

Positive controls

Name

Concentration (µg/plate)

2AA

S9-Mix

No. colonies per plate

1026

850

1018

(965)

99.4

201

158

192

(184)

22.7

479

493

434

(469)

30.8

395

413

331

(380)

43.1

392

433

492

(439)

50.3

ENNG: N-ethyl-N'-nitro-N-nitrosoguanidine

4 NQO: 4-Nitroquinoline-1-oxide

9AA: 9-Aminoacridine

2AA: 2 -Aminoanthracene

BP: Benzo(a)pyrene

C: Contaminated

#: Standard deviation

Executive summary:

In a study according to OECD 471 and EU Method B.14 the Salmonella typhimurium strains TA1535, TA1537, TA98, TA100 and the Escherichia coli strain WP2uvrA- were treated with suspensions of Dihydrolipoic Acid using the Ames plate incorporation method at five dose levels, in triplicate, both with and without the addition of a rat liver homogenate metabolising system (10 % liver S9 in standard co-factors). The dose range was determined in a preliminary toxicity assay and was 50 to 5000 µg/plate in the first experiment. The experiment was repeated using the same dose range as Experiment 1, fresh cultures of the bacterial strains and fresh test material formulations.

The vehicle (dimethyl sulphoxide) control plates gave counts of revertant colonies within the normal range. All of the positive control chemicals used in the test induced marked increases in the frequency of revertant colonies, both with and without metabolic activation. Thus, the sensitivity of the assay of the S9-mix were validated.

The test material caused eighter an intermittet but visible reduction in the growth of the bacterial backround lawn and/or a significant decrease in the frequency of revertant colonies in the majority of the tester strains, both with and without metabolic activation at 5000 µg/plate. The test material was, therefore, tested up to the maximum recommended dose level of 5000 µg/plate. No test material precipitate was observed on the plates at any of the doses tested in eighter the presence or absence of S9-mix.

No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test material, eighter with or without metabolic activation. The test material was considered to be non-mutagenic under the conditions of this test.

Endpoint conclusion

Endpoint conclusion:: no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vitro:

Dihydrolipoic Acid was tested for genotoxic effects in a GLP guideline study according to OECD 471 ("Bacterial Reverse Mutation Test"). Concentrations up to 5000 µg/plate were tested. No significant increases in the frequency of revertant colonies were recorded for any of the bacterial strains, with any dose of the test material, eighter with or without metabolic activation. The test material was considered to be non-mutagenic under the conditions of the test.

Justification for classification or non-classification

The mutagenic potential of Dihydrolipoic Acid was assessed according to OECD 471 ("Bacterial Reverse Mutation Test"). The test material was considered to be non-mutagenic under the conditions of the test. Therefore the Dihydrolipoic Acid does not need to be classified as mutagenic.

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