2-(ethylthio)ethanol

Genetic toxicity: in vitro

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

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2,2'-dithiobisethanol

EC Number:

217-576-6

EC Name:

2,2'-dithiobisethanol

Cas Number:

1892-29-1

IUPAC Name:

2,2'-disulfanediyldiethanol

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

Controls

Controls 1

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

Controls 2

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

Controls 3

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

Controls 4

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.