Occupational Medicine 1977;27:97-101
© 1977 Society of Occupational Medicine
research-article |
Biochemistry of Occupational Cancer
Visiting Professor of Environmental Toxicology, TUC Centenary Centre of Occupational Health, London School of Hygiene and Tropical Medicine
Most human cancer is due to environmental factors, which are mainly chemical. A few causes of cancer have been found by epidemiological investigations but some have been first found by animal tests. Such tests show that there are great differences in the potency of different carcinogens. Many carcinogens including hydrocarbons and aromatic amines are only active after being metabolized by tissue enzymes which generally inactivate toxic compounds. These biochemical potentialities may not have been removed by evolutionary processes because cancer occurs after reproduction in the female is over and because a factor which reduces the proportion of senile individuals in a group would give such a group advantages for survival. Some carcinogens, such as mustard gas and other alkylating agents, are themselves chemically reactive and do not need metabolic activation. Benzopyrene and other polycyclic hydrocarbons are activated by oxidation to epoxides or arene oxides which like other alkylating agents react with nucleic acid. This reaction causes genotoxic effects which may be mutagenic, teratogenic or carcinogenic. Vinyl chloride, which induces tumours in man and animals, is also metabolized to an epoxide, which reacts in a similar manner to the oxides of carcinogenic hydrocarbons. Chemical and biochemical studies can therefore give indications of possible carcinogenic activity.
Requests for reprints should be addressed to: Professor E. Boyland, Visiting Professor of Environmental Toxicology, TUC Centenary Institute of Occupational Health, London School of Hygiene and Tropical Medicine, Keppel Street (Gower Street), London WC1E 7HT.