Cancer incidence of Nordic asphalt workers

Objectives. The aim of the study was to investigate cancer risk following employment in the asphalt industry. Methods. Cancer incidence was studied among 22 362 male asphalt workers employed for more than one season in jobs entailing exposure to bitumen (mainly road pavers) in Denmark, Finland, Norway, and Sweden. These workers are part of a European cohort of asphalt workers, for which results on mortality have been reported. The follow-up was almost complete, and reference rates were obtained from national cancer registries. Results. The incidence of cancer was reduced in all four countries [overall standardized incidence ratio (SIR) 0.89, 95% confidence interval (95% CI) 0.86-0.94]. Lung cancer incidence was increased in all four countries, yielding an overall SIR of 1.21 (95% CI 1.07-1.36), but no trend was detected according to time since first employment. No overall increased incidence of bladder cancer was observed, but there was a suggestion of a tendency towards higher risk with longer time since first employment, with a relative risk of 1.85 (95% CI 0.90-3.78) for more than 30 years versus 1-14 years (P-value for trend 0.1). The incidence of lip and stomach cancer was non significantly increased, and the excess was present mainly in Denmark. No increased incidence was detected for other neoplasms, notably malignant melanoma, nonmelanoma skin cancer, and kidney cancer. Conclusions. The results of this study confirm the pattern of cancer risk detected in the mortality analysis of the European cohort; in addition, they provide suggestive evidence of an excess risk of bladder cancer among asphalt workers.