Diethyl sulphide

Endpoint summary

Additional information

No in vitro or in vivo genetic toxicity data are available for diethyl sulphide. Several criteria justify the use of the read across approach to fill data gaps for diethyl sulphide using methyl ethyl sulphide and dimethyl sulphides as analogues. Diethyl sulphide, like methyl ethyl sulphide and dimethyl sulphide, is an odorant and has similar physiochemical properties. Hence, the toxicological properties of these substances are also expected to be similar. Key read across data from methyl ethyl sulphide and dimethyl sulphide was therefore used to evaluate the genetic toxicity potential.

In Vitro Genetic Toxicity

In vitro gene mutation in bacteria

 

In a key read across in vitro reverse gene mutation assay in bacteria (Wagner & Coffman, 1995; Klimisch score = 1), 4 strains of Salmonella typhimurium (TA 98, 100, 1535, and 1537) and 1 strain of Escherichia coli (WP2 uvrA) were exposed to dimethyl sulphide in DMSO via the pre-incubation method at concentrations of 0, 100, 333, 1000, 3333 and 5000 µg/plate in the presence and absence of mammalian metabolic activation (S9 mix). Neither precipitate nor appreciable toxicity was observed. No positive responses were observed in the presence or absence of activation. The positive controls induced the appropriate responses in the corresponding strains. Dimethyl sulphide was concluded to be negative in the Salmonella / Escherichi coli closed-phase pre-incubation mutagenicity assay with an independent repeat assay.

 

In a second key read across in vitro reverse gene mutation assay in bacteria (Haddouk, 1999; Klimisch Score = 1), 5 strains of Salmonella typhimurium (TA98, TA100, TA102, TA1535, and TA1537) were exposed to methyl ethyl sulphide in DMSO with and without metabolic activation (S9 mix) in two separate experiments. The concentrations without activation were 0.312.5, 625, 1250, 2500, and 5000 µg/plate for all tester strains in both experiments except for TA 1537 and TA 98 in the second experiment which were tested at concentrations of 0.156.25, 312.5, 625, 1250, and 2500 µg/plate. Concentrations with activation were 0.312.5, 625, 1250, 2500, and 5000 µg/plate for all strains. Cytotoxicity was observed at concentrations ≥ 2500 µg/plate. Positive controls produced the expected result. Methyl ethylsulphide was not mutagenic under the conditions of the assay.

 

A supporting read across in vitro DNA damage and repair assay (SOS Chromotest) (Nakamura et al., 1990; Klimisch score = 2) with Salmonella typhimurium TA1535/pSK1002 was conducted using dimethyl sulphide at concentrations of 0, 0.2, 0.4 or 0.6%, without metabolic activation. The cytotoxic concentration of 0.8 percent was determined in a preliminary study. No mutagenic activity was observed in this study.

 

In vitro cytogenicity in mammalian cells

 

In a key read across in vitro mammalian cytogenicity test (mammalian chromosome aberration) (Haddouk, 2004; Klimisch Score = 1), human lymphocytes were exposed to methyl ethyl sulphide, both with and without metabolic activation (S9 mix) in two separate experiments. The first experiment tested concentrations at 0.078, 0.156, 0.313, 0.625, 1.25, 2.5, 5 and 10 mM where cultured cells were exposed to the test substance for 3 hours with and without activation and harvested 20 hours after beginning treatment. The second experiment tested concentrations at 0.313, 0.625, 1.25, 2.5, 5 and 10 mM and cultured cells were exposed for 3 hours with metabolic activation followed by 20- or 44-hour culture in treatment-free media prior to cell harvest. The cultures without S9 were exposed for 20 and 44 hours. No cytotoxicity or precipitation occurred at any concentration. Positive controls produced the expected result. Under these experimental conditions, methyl ethyl sulphide did not induce any noteworthy increase in the number of cells with structural chromosome aberration, both with and without S9 mix, in either experiment or at either harvest time. 

 

In vitro gene mutation in mammalian cells

In a key read across in vitro mammalian cell gene mutation (mouse lymphoma forward mutation) assay (Sire, 2010; Klimisch Score = 1), L5178Y TK (+/-) mouse lymphoma cells were exposed to dimethyl sulphide in DMSO at concentrations of 0, 0.313, 0.625, 1.25, 2.5, 5 and 10 mM with and without a metabolic activation system (S9 mix). No noteworthy cytotoxicity was observed at any tested dose-levels, in either experiment, either with or without S9 mix. With and without S9 mix, no noteworthy increase in the mutation frequency was observed at any tested dose‑levels in either experiment. The positive and negative controls produced the desired result in each specific strain. Under the experimental conditions of this study, dimethyl sulphide did not show any mutagenic activity in the mouse lymphoma assay.

 

In Vivo Genetic Toxicity

In a key read across in vivo mouse micronucleus assay (Putman et al., 1995; Klimisch Score = 1), male and female ICR mice (5/sex/dose) were exposed by oral gavage to dimethyl sulphide in corn oil at concentrations of 0, 1250, 2500 and 5000 mg/kg bw.  Bone marrow cells were harvested at 24, 48 and 72 post-treatment. Lethargy was observed during the study, in males and females at all dose levels. Reduction up to 11% in the ratio of polychromatic erythrocytes to total erythrocytes was observed in some of the test article treated groups relative to their respective vehicle control. Dimethyl sulphide was tested at an adequate dose (up to 5000 mg/kg). The positive control induced the appropriate response. There was no significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow after any treatment time.

Short description of key information:
No key genetic toxicity data was identified for diethyl sulphide. Structural analogues dimethyl sulphide and methyl ethyl sulphide were observed to be negative in vitro in reverse mutation assays conducted using bacteria. Methyl ethyl sulphide did not induce an increase in the number of cells with structural chromosome aberrations in an in vitro cytogenicity test with human lymphocytes. Dimethyl sulphide did not show any mutagenic activity in an in vitro mouse lymphoma forward mutation assay. Additionally, no significant increase in the frequency of micronucleated polychromatic erythrocytes in bone marrow cells was observed following treatment with dimethyl sulphide in an in vivo gene mutation assay.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on read across data from structural analogues dimethyl sulphide and methyl ethyl sulphide, diethyl sulphide does not meet the meet the criteria for classification for genetic toxicity under EU Dangerous Substances Directive 67/548/EEC or CLP EU Regulation 1272/2008.