[Cancer among captains and mates on Norwegian tankers]

1,687 registered captains and mates from a Norwegian census in 1970 were monitored up to 1987. By matching the data from the census with data from the Norwegian Cancer Registry we discovered 104 cases of cancer. A control group of 376 was chosen among those without cancer. A nested case-control study design was used. The material was analysed using multivariate logistic regression. Increased risk of developing cancer was found in the group of seamen who had been working on tankers, especially among seamen who had been working as mate on these tankers. Exposure to chemicals is the major factor distinguishing tankers from other ships. Mates are exposed to chemicals while captains are not. The study indicates the presence of carcinogenic agents on these tankers.