| Abstrakt | | Background Information on cancer causation has come from investigation of the patterns of cancer in human populations and the induction of tumours in experimental animals following treatment with cancer-causing agents. It has been proven that genetic susceptibility may significantly alter the risk from environmental exposures. The most important human carcinogens include tobacco, asbestos, aflatoxins and ultraviolet light. Almost 20% of cancers are associated with chronic infections, the most significant ones being hepatitis viruses (HBV, HCV), papillomaviruses (HPV) and Helicobacter pylori. Pollution of air, water and soil is estimated to account for 4‐7% of all cancers in developed world. A small proportion of lung cancer (< 5%) is attributable to outdoor air pollution by industrial effluent, engine exhaust products and other toxins. Chlorofluorocarbons cause destruction of the ozone layer and enhance the risk of skin cancer through increased ultraviolet radiation. Contamination of drinking water is not a general carcinogenic hazard, but high levels of arsenic and chlorination by-products in some communities carry a risk. Food may be contaminated by natural or man-made toxins, including substances shown to be carcinogenic in experimental animals and, in some cases, in humans. Naturally-occurring carcinogens include mycotoxins, particularly aflatoxins, which contribute to causation of liver cancer. Food can be contaminated by residual pesticides. Conclusions Means to reduce and, in some cases, eliminate risk of cancer include elimination of carcinogenic factor (asbestos) enforced by regulation and reduction of exposure or use of preventive and prophylactic measures (Hepatitis B, HPV vaccination, avoiding of sun).
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