Cancer among captains and mates on Norwegian tankers.

A cohort of 1687 registered captains and mates from a Norwegian census in 1970 was followed until 1987 using a historical prospective design. By matching the data from the census to the Norwegian Cancer Registry, 104 cases of cancer were found. A control group of 376 was chosen among non-cases at baseline (1970). Information about the seamen's work on different ships was obtained from the National Register of Norwegian Seamen. The material was analysed using multivariate logistic regression. An increased risk of developing cancer was found in the group of seamen who had been working on tankers, especially oil tankers (OR = 6.47, 95%CI: 1.14, 7.24). The increased risk was found to be significantly correlated to working as mate on these tankers (OR = 6.95, 95%CI: 3.70, 13.04), whereas working as captain showed a much lower risk (OR = 1.42, 95%CI: 0.64, 3.15). Chemical exposure is the major factor separating tankers from other ships. Mates are exposed to chemicals while captains are not. The study indicates the presence of several carcinogenic agents on these tankers.