Is cadmium a human carcinogen?

Continuing observations on cadmium-exposed workers have failed to yield evidence of an increased mortality from prostatic cancer, as initially suspected. There is, however, evidence of an increased mortality from lung cancer and, in at least two of the studies, of a dose-response relationship, but interpretation of these studies with regard to the role of cadmium is complicated by concurrent exposure to other known or suspected carcinogens, including arsenic, nickel, beryllium, chromium and heated mineral oils. An update of a long-term cohort mortality study from 17 plants in England employing a wide range of cadmium processes, while confirming an increased lung cancer risk related to intensity of cadmium exposure, shows some evidence of this risk also being associated with exposure to arsenic. It is thus not possible at present to attribute the excess mortality from lung cancer to cadmium owing to the presence of multiple confounding factors in the populations studied. Their role in the 17-plant study is currently being further investigated.