Some Comments on the History and Experimental Explorations of Metal Carcinogens and Cancers<xref ref-type="fn" rid="FN1">1</xref>

Abstract

The history of metal carcinogens began around 1935, when cancers of the lung were discovered in chromate workers and cancers of the lung and nasal sinuses were found in nickel refiners. Since then other metals and metal compounds have been added to the list of metal carcinogens. The marked diversity of physiologic and toxicologic reactions elicited by metals has thus far prevented development of a unifying hypothesis of the causal carinogenic mechanism. The first cancer in chromate workers was litigated around 1944 and was followed in rapid succession by litigations from this and other chromate plants in the United States. Experiments on several animal species given hexavalent and trivalent chromium compounds have firmly established the carcinogenicity of chromium when it is introduced in a biologically available form. Both sarcomas and carcinomas can thus be induced. Although cancers in nickel workers have not yet been recorded from plants in the United States, they are on record in countries where either the nickel carbonyl Mond process or electrolytic extraction is used. This observation as well as the ease with which experimental animals develop cancers after introduction of nickel compounds and metallic nickel indicates that nickel is the carcinogenic agent. Intrapleural and intrapulmonarymore » administration of powdered iron prepared by the degradation of iron carbonyl did not result in cancers in rats but caused large granulomas. The injection of uranium, a low-level radioactive element, into the marrow cavity of the rat femur induced osteogenic sarcomas. Whether such cancers are induced by radiation or metal or both is uncertain.« less