Experimental studies in metal cancerigenesis.VIII. On the etiological factor in chromate cancer

s part of a program aimed at the discov-A ery and elucidation, il possible, of the mode of action of environmental agents of present or potential cancerigenic harard to the general population or to special occupational groups, certain metallic elements and their conipounds have been investigated.1621 These investigations are based on reports in the literature on industrial toxicology, suspected or verified clinical hndings related to etiology, and statistically significant abnormal incidence of cancer.Chromium and its compounds, particularly hexavalent compounds, have been singled out for more extensive study because of their long history in industrial toxicology and increasing reports of cancer (probabl) becauqe of better medical observation and diagnosis as well as increased production and usage), particularly cancer of the respiratory system, attending their production and usage.Many other lesions have been described in the literature since 1827.This literatuie was summarked by Gafater.9Because o€ the generally rapid effects produced by hexavalent chromium componnds, their high acute toxicity, and the multiple le-From the National Cancer Institute, of the National Institutes of Health, I'uhlic Health Service, Bethesda, Marvland.Chromite ore used in these studies was supplied by the Mutual Chemical Cornpany of America, Baltimore, Maryland.T h e "Roller" Particle Size Ahalyzer used in the part cle-size fractionations was ohtained from the Amei can lnstrnment Cornpany, Silvcr Spring, Maryland.Electron photomicrographs of the particle-size fraclions were made through tlic courtesy of nr.