Mortality among seamen with special reference to work on tankers

Several studies demonstrate a high mortality among seamen but this has not been related to different types of work on board. This study examined a possible relationship between work on tankers and mortality. Tankers differ from other ships by carrying different types of oil, oil products and other chemicals.

Mortality was studied in 1687 men who were captains and mates during the period 1970-1987, and were registered by a Norwegian census in 1970. The data were linked to the Norwegian Register of Death Certificates. In all 181 deaths were found. Each case was age-matched at time of death to three individuals from the rest of the population alive at this date. Information about the seamen's work on different ships was obtained for cases and controls. The data were analysed using multivariate conditional logistic regression.

Seamen working on tankers had a higher mortality rate ratio (RR = 2.43, 95% confidence interval [CI]: 1.65-3.60) than seamen who had not been working on tankers. The increased risk was especially related to death from cancer and from accidents, while no significantly increased mortality due to cardiovascular diseases was found. Employment as a mate on tankers showed the highest all-causes risk of death (RR = 3.14, 95% CI: 2.04-4.82) as well as for cancer (RR = 4.24, 95% CI: 2.02-8.88) and accidents (RR = 5.85, 95% CI: 1.66-20.60). Employment as a captain on tankers showed no significantly increased mortality.

Exposure to chemicals on tankers may be related to the increased mortality, as this is the major difference between tankers and other ships and mates are exposed to chemical agents, while captains are not.