§ Mr. HarveyTo ask the Secretary of State for Health what percentage of known environmental carcinogens she estimates result from vehicle emissions.
§ Mr. SackvilleThe known environmental carcinogens produced by vehicle exhaust emissions are benzene; 1, 3-butadiene; and some polyaromatic hydrocarbons—PAHs—.
The expert panel on air quality standards—EPAQS—which advises my right hon. Friend the Secretary of State for the Environment has reported estimates that 87 per cent. of benzene emissions to the atmosphere are derived from vehicle exhausts. Benzene is classified by the International Agency for Research in Cancer—IARC—as a known human carcinogen. There are other sources of benzene to which people are exposed such as the diet, water and cigarette smoke. The panel has estimated that an urban non-smoker would take in between 61 per cent. and 80 per cent. of daily exposure from inhaled air.
Other than local leaks from industrial plants, vehicle exhaust emissions are the only source of 1, 3-butadiene in the atmosphere. IARC has classified this compound as a probable human carcinogen.
The quality of urban air review group—QUARG—which advises my right hon. Friend the Secretary of State for the Environment has estimated that 14 per cent. of the emissions to the atmosphere of PAHs derive from vehicle exhausts. IARC has classified some PAHs as probable human carcinogens, some as possible human carcinogens, and others, it has not classified.
The classification of carcinogens by IARC is widely accepted and is based on an assessment of the available research findings. Only where this includes human studies are chemicals classified as a known human carcinogen.
The reports of EPAQS and QUARG are available in the Library.