2,4-dithiapentane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 October 2016 - 22 November 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

1997

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

JAPAN: Guidelines for Screening Mutagenicity Testing Of Chemicals

Version / remarks:

1993

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

2,4-dithiapentane

EC Number:

216-577-9

EC Name:

2,4-dithiapentane

Cas Number:

1618-26-4

Molecular formula:

C3H8S2

IUPAC Name:

bis(methylsulfanyl)methane

Test material form:

liquid

Method

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9 induced by ß-Naphthoflavone/phenobarbital

Test concentrations with justification for top dose:

1st series: 5, 18, 50, 158, 500, 1580, 5000 µg/plate (with and without S9 mix)
2nd series: 50, 158, 500, 1580, 5000 µg/plate (with and without S9 mix)
top dose: maximum recommended concentration (according to OECD 471)

Vehicle / solvent:

- Solvent used: DMSO
- Justification for choice of solvent: solubitlity properties of the test item, non toxicity to bacteria

Controls

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

sodium azide

other: 2-aminoanthracene 2-10 µg/plate, daunomycin 1 µg/plate

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration: 2-3 days

NUMBER OF REPLICATIONS: 3 replicates for test item concentrations and positive controls, 6 replicates for solvent controls

DETERMINATION OF CYTOTOXICITY
- Method: counting numbers of revertants

OTHER:
-S9 concentration: 1st series 10%, 2nd series 30%

Evaluation criteria:

A test material was to be defined as negative or non-mutagenic in this assay if
• the assay was to be considered valid, and
• "no" or "weak increases" occurred in the test series performed ("weak increases" randomly occur due to experimental variation)
For valid data, the test material was considered to be positive or mutagenic if:
• a dose dependent (over at least two test material concentrations) increase in the number of revertants was induced, the maximal effect was a "clear increase", and the effects were reproduced at similar concentration levels in the same test system, or
• "clear increases" occurred at least at one test material concentration, higher concentrations showed strong precipitation or cytotoxicity, and the effects were reproduced at the same concentration level in the same test system.

Statistics:

Not performed as not mandatory for this test system.

Results and discussion

Test results

Test results 1

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

Test results 2

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

Test results 3

Key result

Species / strain:

S. typhimurium TA 98

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

Test results 4

Key result

Species / strain:

S. typhimurium TA 100

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

Test results 5

Key result

Species / strain:

E. coli WP2 uvr A

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:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: No precipitation occurred.

Any other information on results incl. tables

Table 2: Summary of Experiment 1

Metabolic Activation	Test material	Concentr. (µg/plate)	Revertant Colony Counts (Mean ± SD)
			TA 98	TA 100	TA 1535	TA 1537	WP2 uvrA
Without Activation	DMSO		32 ± 4	124 ± 17	29 ± 4	27 ± 7	39 ± 7
	Test item	5	25± 3	112±19	29±6	22±6	34±6
		15.8	29±6	122±16	28±7	30±10	32±3
		50	29±8	122±14	20±0	28±7	29±2
		158	27±7	124±4	27±5	31±1	26±6
		500	30±7	112±15	28±1	26±2	32±3
		1580	26±11	122±16	32±8	24±3	30±1
		5000	21±1	120±8	30±5	29±5	33±5
	DAUN	1	393±50
	NaN3	2		1597±59	914±82
	9-AA	50				1812±272
	NQO	2					2128± 269
With Activation	DMSO		34±3	144±20	26±6	27±2	36±7
	Test item	5	32± 13	140±2	26±1	33±3	38±1
		15.8	35±9	144±17	29±4	26±3	39±7
		50	26±5	143±2	21±6	23±6	31±1
		158	34±3	153±27	22±6	28±3	41±6
		500	33±11	131±17	30±2	27±4	33±4
		1580	28±10	142±25	26±3	29±5	37±7
		5000	25±2	140±22	23±1	23±3	30±2
	2-AA	2	426± 24	1286±371
	2-AA	5			265±33	412±48
	2-AA	10					445±161

 

Table 3: Summary of Experiment 2

Metabolic Activation	Test material	Concentr. (µg/plate)	Revertants per plate (Mean ± SD)
			TA 98	TA 100	TA 1535	TA 1537	WP2 uvrA
Without Activation	DMSO		36 ± 8	123 ± 8	31 ± 2	26 ± 7	26 ± 6
	Test item	50	37± 10	115± 8	25±6	29± 2	29± 9
		158	42± 8	119± 6	31± 1	28± 8	21± 4
		500	37± 4	107± 19	27± 3	23± 6	26± 2
		1580	39± 5	115± 7	22± 9	25±8	28± 4
		5000	33± 5	111± 9	22± 8	27± 5	28± 6
	DAUN	1	196± 41
	NaN3	2		911± 25	678± 25
	9-AA	50				539± 139
	NQO	2					1173± 58
With Activation	DMSO		47± 9	118± 9	28± 3	31± 1	30± 3
	Test item	50	42± 7	117± 14	28± 4	29± 6	29±1
		158	41±5	124± 16	24± 10	31± 6	35± 4
		500	38±7	119± 10	31± 6	30± 5	32± 6
		1580	48± 3	134± 15	29± 4	30± 6	32± 3
		5000	35± 5	117± 14	31± 4	38±4	37± 7
	2-AA	2	226± 4
	2-AA	5		1073± 42
	2-AA	10			390± 36	523± 81	122±1

 

Key to Positive Controls

NaN₃                Sodium azide

2-AA                2-Aminoanthracene

9-AA                9-Aminoacridine

DAUN              Daunomycin

NQO                4-Nitroquinoline-N-oxide

Applicant's summary and conclusion

Conclusions:

The test item is considered non-mutagenic under the test conditions described.

Executive summary:

The test item was examined for its mutagenic activity in two series of in vitro microbial assays employing Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537, and Escherichia coli WP2 uvrA as indicator organisms. The plate incorporation test with and without addition of liver S9 mix from Aroclor 1254-pre-treated rats was used. In this study, two experimental series was performed. In the experiments with S9 mix, 10 and 30% S9 were used in the 1st and 2nd series, respectively. Treatments of all tester strains were performed using test item formulations prepared in anhydrous analytical grade dimethyl sulfoxide (DMSO) in the absence and in the presence of S9 mix, using final concentrations between 5 and 5000 µg/plate, plus vehicle and positive controls. The strain specific positive control test materials, namely daunomycin, sodium azide, 4-nitroquin-olin-N-oxide, and 9-aminoacridine in the absence of S9 mix, yielded the expected mutant frequencies that were greatly in excess of the negative controls. The genotype of the tester strains used was thus confirmed. 2-Aminoanthracene which requires metabolic activation was strongly mutagenic. This indicates that the exogenous metabolizing system used in the present investigation (S9 mix) was functioning. Thus, the acceptance criteria have been met in total and the study is considered valid. Following test item treatments, precipitation of the test material on the agar plates was not occurred. There was no toxicity to the bacteria observed. Under the conditions described, there were no relevant increases in revertant numbers after test item exposure observed in both, the absence and presence of S9 mix. According to the criteria for negative and positive results, the test item was not mutagenic under the described experimental conditions (UN GHS: no category).