Registration Dossier

Administrative data

Description of key information

1,2-Butadiene is a flammable gas at room temperature and therefore the requirement for data on acute oral and dermal toxicity is waived in accordance with REACH Annex XI. The acute inhalation LC50 of 1,2-butadiene in rats is greater than 8000 ppm (17,701 mg/m3) (the explosive limit).

Key value for chemical safety assessment

Additional information

The requirement for data on acute oral and dermal toxicity is waived in accordance with REACH Annex XI, as 1,2 -butadiene is a flammable gas at room temperature. The acute inhalation LC50 of 1,2-butadiene in rats was reported to be greater than 0.8% (v/v) (8000 ppm,17,701 mg/m3). Higher concentrations could not be tested because of the risk of explosion. Exposure to 1,2 -butadiene resulted in narcosis but no mortality or abnormal behaviour occurred in the post-exposure observation period (TNO 1980). There are no acute toxicity data on 1,2 -butadiene in humans but volunteer studies have been carried out on 1,3 -butadiene in humans. Unsteadiness was noted after exposure at 4000 ppm (8851 mg/m3) for 6 h and the odour was described as objectionable, but there was little effect at 8000 ppm (17,701 mg/m3) for 8h (Carpenter et al, 1944). 1,2 -Butadiene is concluded to have low acute toxicity.

Justification for classification or non-classification

1,2 -Butadiene is a flammable gas at room temperature and therefore inhalation exposure is the only relevant route. 1,2 -Butadiene is of low acute toxicity by the inhalation route with LC50 values exceeding the doses which would warrant classification under Dir 67/548/EEC or GHS/CLP.