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BASF (1975) reported an approximative oral LD50 value of about 900 mg/kg for male and female rats, given the test substance (gavage) as an emulsion in 0.5% aqueous CMC solution. Slight apathy, partially staggering, dyspnoea, diarrheic feces, exsiccosis, abdominal and lateral position were recorded.

DOW (1965) tested 2-ethyloxirane orally (gavage) as a 10% solution in corn oil. Female rats were given doses of 1 or 2 g/kg. No animal died in the low dose group; all animals died in the high dose group. Animals given 1 g/kg appeared normal during and after feeding and during a 2-week observation period. The LD50 was found to be > 1 - < 2 g/kg for female rats.

In an older DOW study (1958) the unchanged test substance was tested. Male rats were dosed with 2-ethyloxirane at levels differing by a factor of 2 in a geometric series. All animals died at 2 ml/kg and one animal died at 1 ml/kg. Clinical signs were not reported. The LD50 was found to be 1.3 ml/kg b.w. for male rats.

2-ethyloxirane given in oral (gavage) doses of 0.63, 1 and 1.58 g/kg (10% in corn oil) resulted in an LD50 value for rats of > 2 and < 1.58 mg/kg bw. No mortalities were seen at 0.63 g/kg; all animals died at 1.58 g/kg; clinical signs were not reported (DOW, 1953).

In an LC50 determination (BASF, 1978), rats inhaled the test material in a concentration of 6.3 mg/l as a vapour for 4 hours. No mortalities and no symptoms were observed. Thus, The LC50 was greater than 6.3 mg/l for 4 hours.

In another BASF study (1975), rats were exposed to an atmosphere saturated with the test substance. Two rats died after 3-min exposure, all rats died at 10-min exposure. Clinical signs were irritation of the mucosa, dyspnoea and narcosis. Necropsy showed acute dilatation of the heart, congestive hyperemia and slight edema of the lung.

DOW (1965) reported, that the test substance has a very high vapour exposure. Rats survived a 6-minute exposure to saturated atmospheres at room temperature but failed to survive a 12-min exposure.

In another DOW study (1958), 8000 or 4000 ppm of the concentrated test substance vapour was tested up to 4 hours. The concentration of 8000 ppm was lethal for 6/6 rats within 4 hours; 1/6 rat died in the 4000 ppm concentration group.

In an older DOW study (1953) it was stated that butylene oxide presents a serious acute vapour inhalation hazard. Vapours in confined spaces may be dangerous even for single short exposure.

An acute dermal LD50 value of 1.77 ml/kg was found for male rabbits. Unchanged 2-ethyloxirane was tested for 24 hours in doses of 1.25 or 2.5 ml/kg under occlusive conditions. The covered applications caused marked erythema of the skin which healed with scab formation. 3 of 4 rabbits died in the 2.5 ml/kg dose group and 1 of 4 rabbits died at the 1.25 ml/kg dose group (DOW, 1958).

The 1% solution of the test substance does not present a problem from skin absorption for rabbits under ordinary handling conditions. Prolonged exposure to relatively large areas of the skin may result in the absorption of toxic amounts. Further details are not given (DOW, 1953).

Smyth et al. (1962) found a dermal LD50 value of > 1500 - < 2950 mg/kg for male rabbits (24-hour occlusive). Further details are not given.

Justification for classification or non-classification

2-ethyloxirane is classified according to Annex I of the Directive 67/548/EEC with Xn; R 20/21/22.