Registration Dossier

Administrative data

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
May 16 1986 to June 6 1986
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to a protocol that was similar to an appropriate OECD test guideline, with acceptable restrictions. The restrictions were that the range of strains does not comply with the current guideline. Read across to the registered substance is considered scientifically justified.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1986
Report Date:
1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Method

Target gene:
Histidine operon
Species / strain
Species / strain / cell type:
S. typhimurium, other: TA 98, 100, 1535, 1537, 1538
Metabolic activation:
with and without
Metabolic activation system:
Aroclor induced rat liver S9
Test concentrations with justification for top dose:
0.050 - 10.000 µl/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: based on solubility of test substance
Controlsopen allclose all
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
sodium azide
Remarks:
TA 100 and TA 1535 without metabolic activation

Migrated to IUCLID6: 10 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
2-nitrofluorene
Remarks:
TA 98 and YA 1538 without metabolic activation

Migrated to IUCLID6: 10 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: quinacrine mustard 5 µg/plate
Untreated negative controls:
no
Negative solvent / vehicle controls:
yes
True negative controls:
no
Positive controls:
yes
Positive control substance:
other: 2-anthramine 2.5 µg/plate
Remarks:
all strains with metabolic activation
Details on test system and experimental conditions:
Activation: S9 mix contained 10% S9 and cofactors glucose-6-phosphate and NADP; 0.5 ml were added to agar, test substance and indicator organisms to a total volume of 2.75 ml.

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Preincubation period: none
- Exposure duration: 2 days
- Expression time (cells in growth medium): 2 days
- Fixation time (start of exposure up to fixation or harvest of cells): 2 days

SELECTION AGENT (mutation assays): histidine deficient medium

NUMBER OF REPLICATIONS: triplicate plates

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index; cloning efficiency; relative total growth; other: condition of background lawn

Evaluation criteria:
A positive result is a reproducible dose-related increase in the mean number of revertants relative to solvent control.
Statistics:
No statistical methods employed.

Results and discussion

Test results
Species / strain:
S. typhimurium, other: TA 98, 100, 1535, 1537, 1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
cytotoxicity
Remarks:
5 µl/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
not applicable
Positive controls validity:
valid
Additional information on results:
TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: no information
- Effects of osmolality: no information
- Evaporation from medium: no information
- Water solubility: no information
- Precipitation: no information
- Other confounding effects: none

RANGE-FINDING/SCREENING STUDIES: test concentrations were based on the preliminary range-finding study

COMPARISON WITH HISTORICAL CONTROL DATA: The solvent controls were within the range of the historical controls

ADDITIONAL INFORMATION ON CYTOTOXICITY: test material was toxic at 4.69 µl/plate and above in the preliminary toxicity test, as evidenced by the reduced number of revertants and the clearing of the background lawn on the minimal media plates.
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Any other information on results incl. tables

Table 1 Revertants per plate (mean of 3 plates)

Concentration µl/plate

TA 1535

TA 1537

TA 1538

TA 98

TA 100

- MA

+ MA

- MA

+ MA

- MA

+ MA

- MA

+ MA

- MA

+ MA

0*

29.0

15.0

9.0

10.0

13.0

17.3

26.3

29.3

171.3

138.7

0.050

27.3

14.7

10.3

11.7

11.3

20.7

25.3

37.3

175.3

150.3

0.100

22.7

13.0

6.7

7.0

9.3

17.7

21.3

28.7

169.3

167.3

0.250

21.0

12.7

8.0

8.3

10.3

15.7

20.3

31.0

179.3

157.0

0.500

23.0

14.7

7.3

11.0

9.3

14.0

23.3

33.7

182.7

152.3

1.000

19.3

14.7

7.0

11.0

10.3

16.7

19.0

32.0

166.7

155.0

2.500

16.0

13.3

8.3

4.3

7.0

9.3

18.7

30.0

190.3

152.3

5.000

9.0

6.3

6.3

4.3

1.7

1.0

12.7

13.0

126.7

91.7

10.000

0.0

0.0

3.0

0.0

0.0

0.0

0.0

.0.

37

0.0

Positive control

1459.3

154.7

1431.3

159.0

1330.3

136.3

986.3

1535.0

1542.0

1456.0

*Solvent control with DMSO

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information):
negative with and without metabolic activation

2,2'-dithiobisethanol has been tested according to a protocol that is similar to OECD 471 and under GLP. The test substance did not induce an increase in the number revertants in any of strains tested, either with or without activation. It is concluded that 2,2'-dithiobisethanol is negative for induction of mutations in bacteria under the conditions of the test.