Hydrocarbons, C4

Endpoint summary

Description of key information

1,3-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. Limited data suggest that 1,3-butadiene has low inhalational acute toxicity in both animals and humans. The acute inhalation LC50 of 1,3-butadiene in mice is 270,000 mg/m3 (122,024 ppm) and humans can tolerate an exposure concentration of 17,702 mg/m3 of (8000 ppm) for 8 hours without adverse symptoms.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

The requirement for data on acute oral toxicity is waived in accordance with REACH Annex XI, as 1,3 -butadiene is a flammable gas at room temperature.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

The quality of data on the acute inhalation toxicity of 1,3 -butadiene is poor. In the rat the LC50 value after a 4h exposure was 285,000 mg/m3(128,803 ppm) and in the mouse was 270,000 mg/m3(122,024 ppm) after 2h exposure. Rapid onset of narcosis was reported in both species (Shugaev, 1969). Similar results from other low quality studies are described in the EU RAR (2002). Volunteer studies have been carried out in humans. Unsteadiness was noted after exposure at 4000 ppm 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). Other human studies described in the EU RAR (2002) are stated to be “unreliable and of doubtful significance” and are not described here.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Quality of whole database:

The requirement for data on acute dermal toxicity is waived in accordance with REACH Annex XI, as 1,3 -butadiene is a flammable gas at room temperature.

Additional information

The requirement for data on acute oral and dermal toxicity is waived in accordance with REACH Annex XI, as 1,3 -butadiene is a flammable gas at room temperature.

The quality of data on the acute inhalation toxicity of 1,3 -butadiene is poor. In the rat the LC50 value after a 4h exposure was 285,000 mg/m³(128,803 ppm) and in the mouse was 270,000 mg/m³(122,024 ppm) after 2h exposure. Rapid onset of narcosis was reported in both species (Shugaev, 1969). Similar results from other low quality studies are described in the EU RAR (2002). Volunteer studies have been carried out in humans. Unsteadiness was noted after exposure at 4000 ppm 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). Other human studies described in the EU RAR (2002) are stated to be “unreliable and of doubtful significance” and are not described here.

 

In conclusion, 1,3 -butadiene has low inhalation acute toxicity in both animals and humans. The lowest LC50 is 270,000 mg/m³(122,024 ppm) for 2h in mice. Limited data suggests that humans can tolerate an exposure concentration of 17,702 mg/m³ (8000 ppm) for 8 hours without adverse symptoms, this was also the conclusion of the EU RAR (2002).

Justification for classification or non-classification

1,3 -Butadiene is a flammable gas at room temperature and therefore inhalation exposure is the only relevant route. 1,3 -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.