Registration Dossier

Administrative data

Description of key information

Oral (OECD 401): LD50, rat = 3577 mg/kg bw 
Dermal (OECD 402 limit test): LD50, rabbit > 2000 mg/kg bw
Inhalation (OECD 403 limit test): LD50, rat >4.8 mg/L

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
3 577 mg/kg bw

Additional information


One study was available to assess the acute oral toxicity of 2,3 -bis((2-mercaptoethyl)thio)-1 -propanethiol (Mitsui 1993, SNIF#001-4.1.11 -01). The study was performed under GLP according to OECD guideline 401. Five male and female Sprague Dawley CDR rats per group were treated with 1200, 2500 and 5000 mg/kg bw. The observed clinical signs included salivation, hyperactivity, diarrhoea in both groups; convulsions and ataxia in the lowest dose group; and stomach cramps in the highest dose group. Some changes in the gastrointestinal tract were observed, these changes were not described in further detail. The animals that died during the study period partly exhibited gastrointestinal damage indicating a local irritating or corrosive effect of the test substance. It is not clear whether the mortality was caused by local or systemic effects of the substance. However, clinical signs like convulsions and ataxia indicate that the substance is bioavailable and also causes systemic adverse effects. Based on the observed mortality, the oral LD50 was considered to be 3577 mg/kg bw.


The acute inhalation toxicity was evaluated in a GLP-study performed according to OECD guideline 403 (Mitsui 1993, SNIF#001-4.1.20 -01). The study was a limit test, during which five male and 5 female Sprague Dawley CDR rats were treated with the test substance at 4.8 mg/L for 4 hours. The observed clinical signs included difficulty breathing, nasal discharge, tear discharge, salivation and muscle tremor during the exposure. Post-exposure; nasal discharge, difficulty breathing and redness of the skin on the extremities was observed. Since no mortality was observed, the inhalation LD50 was established at > 4.8 mg/L. The test concentration was probably the technical limit concentration, as the limit for classification as acute toxic category 4 is 5 mg/L. However, no additional justification is given for selecting this exposure concentration. Consequently, the LD0 is 4.8 mg/L, as no effect was observed at this exposure level. It was reported in the field 'Remarks' that a follow-up inhalation study with specific neurological assessments and an inhalation study on the metabolism product were performed. As no additional information on these studies was available they can not be assessed.


One acute dermal toxicity study performed under GLP according to OECD guideline 402 was available (Mitsui 1993, SNIF#001 -4.1.30 -01). Five male and 5 female New Zealand White rabbits were exposed to 2,3 -bis((2-mercaptoethyl)thio)-1- propanethiol in a concentration of 2000 mg/kg (limit test) under occlusive conditions for 24 hours. No mortality occured and the only clinical signs were observed in one animal exhibiting red, tearing, glazed eyes during the exposure period. There were no unusual findings at the terminal autopsy. Therefore, the LD50 was considered to be >2000 mg/kg bw.

Justification for classification or non-classification

According to Annex I of DSD (67/548/EC), 2,3 -bis((2-mercaptoethyl)thio)-1 -propanethiol is classified as Xn, R22.

According toAnnex VI of CLP (1272/2008/EC), 2,3 -bis((2 -mercaptoethyl)thio)-1 -propanethiol is classified as Acute tox. 4, H302.

2,3 -bis((2 -mercaptoethyl)thio)-1 -propanethiol should not be classified according to Annex VI of CLP(1272/2008/EC) for acute inhalation toxicity, as the LD0 is very close to the upper classification limit and it is unlikely that the LD50 would >= 5 mg/L. Furthermore, the substance is not classified according to Annex I of DSD (67/548/EC).