Benzene is a colourless liquid with a sweet odour. Benzene evaporates quickly, dissolves poorly in water, and is quite flammable. Benzene is present in the environment: in water, air and the soil. The substance was discovered in the 19th century and is extracted from coal tar. It is currently made primarily from petroleum. It is one of the most commonly produced chemical substances and is used as a raw material for making other chemicals, such as ethylbenzene, from which styrene and eventually plastics are made. Benzene can also be formed by natural processes, such as in volcanoes and forest fires.
Everyone is exposed to small amounts of benzene on a daily basis, both indoors and outdoors. In addition to tobacco smoke, the air around petrol stations and exhaust fumes from motor vehicles and factories are major sources of exposure to benzene. Fumes and gasses released from products such as glue, paint and solvents contain benzene as well. Exposure is highest in factories where benzene is produced or used.
Benzene in tobacco smoke
For smokers, tobacco smoke is the most important source of exposure to benzene. It is released in the smoke when tobacco is burned. Non-smokers are also exposed through tobacco smoke when they inhale smoke passively. A typical smoker inhales an average of ten times more benzene per day than a non-smoker.
Adverse health effects
Benzene 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 benzene can cause acute myeloid leukaemia, which is the most common form of acute leukaemia in adults.