Occupational mortality and cancer analysis

The 1970-census populations have been followed up for deaths and emigrations in the ten-year period 1970-80 in all the Nordic countries. The data show more than a 2-fold difference in overall mortality between the low-risk group of men with pedagogical work and the high-risk group of deck and engine crew workers. These data files have also been supplemented with cancer register records. In Denmark this combined data set has been used in four different ways. First, in order to check the validity of the register, classic associations known from in-depth epidemiological studies were tabulated. Examples are cancer of the lip in farmers and fishermen, where the standardized incidence ratio (SIR) values were 1.85 and 3.17, respectively, and cancer of the nasal cavities and sinuses in skilled furniture makers, SIR = 12.25. Second, a social cancer map was produced by tabulating the cancer incidence by 20 socioeconomic groups. The social gradient was steepest for certain rare cancers related to specific etiologic factors. The social gradient also varied across cancer sites. Third, the register was used as a library for elucidation of newly reported associations. An association confirmed in the Danish data is an excess risk of bladder cancer in hairdressers, SIR = 2.05. An unconfirmed example is an excess risk of malignant melanoma in the printing industry, where Danish data show an SIR of 0.95. Fourth, a systematic tabulation of each cancer diagnosis across detailed occupational groups may lead to identification of previously unknown associations. This procedure is illustrated using cancer of the larynx as an example. Smiths, mechanics, foremen, and shop owners of engineering works and workshops all have an excess risk of laryngeal cancer, SIR = 1.63.