Respiratory cancer mortality and incidence in an updated cohort of Canadian nickel production workers.

Respiratory cancer mortality and incidence were examined in an updated cohort of >56,000 Canadian nickel mining and refining workers. There was little evidence to suggest increased lung cancer risk in workers who had no experience in high-risk sintering operations that were closed by 1972, apart from that which would be expected from probable increased smoking prevalence relative to the comparison population. There was no substantive evidence of increased laryngeal cancer risk in the cohort, nor was there evidence of increased pharyngeal cancer risk in nonsinter workers. Nasal cancer incidence was elevated in nonsinter workers, but excess risks appeared to be confined to those hired prior to 1960. These findings lead us to tentatively conclude that occupationally-related respiratory risks in workers hired over the past 45 years are either very low or nonexistent.