Trace metals and neoplasia.

Numerous trace metals induce cancerous growths in various animal species in vivo and cause mutagenic or chromosomal transformations in cells-cultured cells in vitro. The most potent is probably nickel. The present review indicates that arsenic, cadmium, chromium, nickel and probably beryllium are associated with malignant neoplasms in humans. Inhalation of these metals during processing at refineries has lead to a greater incidence of pulmonary carcinoma as well as other forms of cancer. There is an inverse relationship between the amount of selenium in the environment and the death rate from cancer in humans. Evidence is presented in this review indicating that mutagenic metal ions alter the fidelity of DNA synthesis. This has been demonstrated with purified DNA polymerases using both synthetic and natural DNA templates in vitro, and by mutagenic or carcinogenic effects in vivo. The need for further studies of the molecular effects of metal ions on DNA replication, RNA transcription and translation is indicated by these results.