2,2-dimethyloxirane

Endpoint summary

Description of key information

The LD50 values derived from the key-studies were: LD50 (oral, rat) 3890 mg/kg bw and LD50 (dermal, rat) >4000 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

3 890 mg/kg bw

Additional information

Acute toxicity: oral
The acute oral toxicity of 2,2-dimethyloxirane in the rat was examined in an in-house study following the principles of OECD TG 401 (BASF AG, 1980). Sprague Dawley rats were given a single oral dose of 2,2-dimethyloxirane (14.7, 21.5, 31.6, 46.4 and 50.0 % emulsion in aqueous 0.5 % carboxymethyl cellulose) at 1470, 2150, 3160, 4640, 6810 mg/kg bw. Animals were then observed for mortality and for clinical symptoms of toxicity for 14 days. All animals were subjected to necropsy. The oral LD50 was estimated as 3890 mg/kg bw. This acute oral study is classified as acceptable.

 

Acute toxicity: inhalation

In an in-house acute inhalation toxicity study (BASF AG, 1980; inhalation risk test), Sprague Dawley rats were exposed to a saturated vapour-air mixture of 2,2-dimethyloxirane at 20° C for 3, 10 or 25 minutes and subsequently observed for mortality and for clinical symptoms of toxicity for 14 days. Due to the high vapour pressure extreme concentrations of approximately 133394, 225072 and 279998 ppm (corresponding to approximately 400, 674 and 839 mg/L) were achieved at 3, 10 and 25 min, respectively. All animals were subjected to necropsy. With reference to the exposure time, after 3 min 1/12, after 10 min 4/6, and after 25 min 4/6 rats died, showing as symptoms escape attempts, eyelid closure, salivation, intermittent respiration, gasping, discharge (eyes, nose), ruffy fur, slight erythema (ears, extremities) and unsteady gait. Gross pathology revealed right-sided acute dilatation of the heart. Surviving animals were without findings in gross necropsy. As the concentrations of the test substance exceeded by far the regulatory threshold concentration for vapours of 20 mg/L/4hr, the study does not allow to conclude on classification and labelling.

 

Acute toxicity: dermal

The acute dermal toxicity of 2,2-dimethyloxirane was examined in an in-house study following the principles of OECD TG 402 (BASF AG, 1980). Sprague Dawley rats were dermally exposed to unaltered 2,2-dimethyloxirane at dosages of 2000 and 4000 mg/kg bw. Animals were then observed for mortality and for clinical symptoms of toxicity for 14 days. All animals were subjected to necropsy. The oral LD50 was estimated > 4000 mg/kg bw. This acute dermal study is classified as acceptable.

Justification for classification or non-classification

Based on the results of the oral and dermal acute toxicity studies, no classification of 2,2-dimethyloxirane is needed according to Regulation 1272/2008/EC.