1,3-butadiene, or simply butadiene, is a colourless, flammable gas with an odour resembling that of petrol. Butadiene is used as a raw material for the production of synthetic rubber in the car tyre industry and for making such plastics as nylon. Butadiene is released into the atmosphere through industrial processes, during forest fires, and when wood is burned. Once butadiene is released into the atmosphere, it quickly decomposes through exposure to light.

The most important sources that expose people to butadiene are tobacco smoke and exhaust fumes from motor vehicles.

1,3-Butadiene in tobacco smoke

Butadiene is released in tobacco smoke when tobacco is burned. Additives in tobacco, such as cellulose, paraffin, and sugars, cause the smoke to contain more butadiene. Smokers inhale this substance when they take a puff of smoke (first-hand smoke). Butadiene is also inhaled passively by non-smokers (second-hand smoke).

Adverse health effects

Butadiene is a carcinogenic substance. It has been classified by the International Agency for Research on Cancer (IARC) as ‘carcinogenic to humans’ (Group 1). Long-term exposure to butadiene can cause cancer in the lymph nodes, blood, and blood-forming tissue, such as leukaemia and lymphoma. Both smokers and passive smokers have increased chances of contracting these illnesses. In studies on laboratory animals, butadiene has been found to have other adverse health effects in addition to cancer, including anaemia and skeletal abnormalities.