Incidence of lung cancer among shipyard welders investigated for siderosis.

The incidence of lung cancer among 428 shipyard welders exposed for more than ten years to welding fumes was investigated. The welders were examined for siderosis by the Directorate of Labor Inspection in 1975. The present study was a follow-up based on historical information from the Norwegian registry of dust-exposed workers. Twenty-three welders with siderosis, and 156 welders working at the same shipyards as the siderosis cases were studied as sub-cohorts. There was no loss on follow-up. The observation period was 1976 through 1992. There were 32 cases of cancer from all causes vs 41.3 expected. A nonsignificant excess of lung cancer was observed; 10 cases vs 6.5 expected. The incidence of lung cancer was highest for the welders with more than 30 years since first exposure (7 cases vs 4.1 expected). The sub-cohort of welders with siderosis had no case of lung cancer vs 0.5 expected. These welders were assumed to have experienced high exposure levels for welding fumes. The morbidity of cancer from all causes was low for this small group of blue-collar workers, but the incidence of lung cancer was slightly increased. The increase was not attributable to welders with siderosis. Smoking and asbestos exposure are potential confounders.