Mortality study of fertiliser manufacturers in Iceland

A retrospective cohort study was carried out on workers in a fertiliser plant to assess the risk of stomach and lung cancer. The cohort comprised 603 subjects and their death rates were compared with those of the general male population in Iceland. The study period was 1954 to 1985. The results do not provide evidence of an excess of deaths from stomach or lung cancer. Total mortality was lower than expected and even lower when the analysis was restricted to those who had worked at the plant for more than one year. Shiftwork operators had the highest SMRs for all cancers, however, with a reverse dose response according to duration of employment, indicating that this might be due to factors unrelated to manufacture of fertilisers. As examples of these factors life style and social class may be implicated, as well as possible selection of weaker subjects to do this assumed easy work.