Occupational cancer

Occupational cancers are those that are due to exposure to chemical or physical carcinogens in the workplace. Clinically, cancer due to occupation is at present undistinguishable from cancer due to other causes. The occupational origin is essentially considered as proven when there is an unequivocally identified exposure causally associated with an increased occurrence of a cancer.

Adequately documented cases of occupational cancer represent only a fraction of 1% of cancer in Western countries although occasionally it can represent a very large percentage of cancer in a single manufacturing plant. For the latter reason, occupational cancer has frequently been detected through the clustering of otherwise frequently occurring cancers (mainly of the skin, lung or bladder) or through the occurrence of otherwise extremely rare cancers (angiosarcoma of the liver after exposure to vinylchloride monomer, to arsenic or to thorotrast). The real incidence of occupational cancer must inevitably be higher than the adequately documented cases. Initiation and interpretation of epidemiologic investigations may be difficult because frequently only small numbers of workers are involved, because of multiple exposures in the working environment, because of the movement of workers from one job to another or from one country to another, and, above all, because of the lack of detailed cancer registries in many industrialized countries.