Health hazards and cancer in relation to occupational exposures among Swedish seafarers

Abstract

This thesis explores health hazards for seafarers in the Swedish merchant fleet, and occupational risks for lung cancer, mesothelioma and hematologic malignancy (HM). A special focus has been exposure to benzene and biomarker levels for work on product or chemical tankers during the mid-1990’ies. In a case report, we describe two cases of mesothelioma and two cases of lung cancer having worked in the engine room. Cumulative exposure to asbestos were up to 5 fibre-years. Other exposures were carcinogenic PAHs and nitroarenes. A web-based survey to active seafarers in the Swedish merchant fleet revealed noise, the risk of accidents, whole-body vibrations and ergonomic strain as main work environment problems. General health, work ability and safety climate were all rated high. Associations were found between lower airway symptoms and soot (PR 2.4, 95% CI 1.1-5.1) and between hearing impairment and noise exposure (PR 1.5; 95% CI 1.3–1.7). Iso-strain was especially common in the service department. Twenty-two percent of men and 45% of women had been subjected to harassments. The tanker study showed a geometric mean for benzene exposure of 0.45 mg/m3 (4hTWA) during a work shift, with a wide range (0.02-143 mg/m3). Correlations were found between exposure and benzene in alveolar air (p<0.0001), unmetabolised benzene in urine (p<0.0001) and ttMA in urine (p=0.0011). All biomarkers increased significantly during work (p<0.002). In a case-referent study with the observation period 1985 to 2014, the OR for HM was 1.32 (95% CI 0.86-2.02) if work on tankers had started before 1985 and with a cumulated tanker service of at least five years. If work on tankers had started after 1985, the OR was 0.85 (95% CI 0.51-1.43). In conclusion, health hazards in today’s seafaring relate to physical, chemical and psychosocial factors. Work on tankers with mixed open and closed cargo systems might have led to important benzene up-take. Possibly, the risk for HM for seafarers on tankers has decreased during the last decades.