Respiratory cancer in a cohort of copper smelter workers: Results from more than 50 years of follow-up

Several studies have linked inhalation of airborne arsenic with increased r isk of respiratory cancer, but few have analyzed the shape of the exposure- response curve. In addition, since inhaled airborne arsenic affects systemi c levels of inhaled arsenic, there is concern that inhaled arsenic may be a ssociated with cancers of the skin, bladder, kidney, and liver, which have been linked to ingested arsenic. The authors followed 8,014 white male work ers who were employed for 12 months or more prior to 1957 at a Montana copp er smelter from January 1, 1938 through December 31, 1989. A total of 4,930 (62%) were deceased, including 446 from respiratory cancer. Significantly increased standardized mortality ratios (SMRs) were found for all causes (S MR = 1.14), all cancers (SMR = 1.13), respiratory cancer (SMR = 1.55), dise ases of the nervous system and sense organs (SMR = 1.31), nonmalignant resp iratory diseases (SMR = 1.56), emphysema (SMR = 1.73), ill-defined conditio ns (SMR = 2.26), and external causes (SMR = 1.35). Internal analyses reveal ed a significant, linear increase in the excess relative risk of respirator y cancer with increasing exposure to inhaled airborne arsenic. The estimate of the excess relative risk per mg/m(3)-year was 0.21/(mg/m(3)-year) (95% confidence interval: 0.10, 0.46). No other cause of death was related to in haled arsenic exposure.