Cancer incidence in Thyborøn-Harboøre, Denmark: a cohort study from an industrially contaminated site

In a fishing community Thyborøn-Harboøre on the Danish West coast, a chemical factory polluted air, sea, and ground with > 100 xenobiotic compounds. We investigated cancer incidence in the community. A historical cohort was identified from the Central Population Register and followed for cancer incidence in the Danish Cancer Register including inhabitants from 1968-1970 at height of pollution, and newcomers in 1990-2006 after pollution control. Two fishing communities without pollution, Holmsland and Hanstholm, were referent cohorts. We calculated rate ratios (RR) and 95% confidence intervals (CI). In 1968-1970, 4914 persons lived in Thyborøn-Harboøre, and 9537 persons in Holmsland-Hanstholm. Thyborøn-Harboøre had a statistically significant excess cancer incidence compared with Holmsland-Hanstholm; RR 1.20 (95% CI 1.11-1.29) deriving from kidney and bladder cancer; stomach and lung cancer in men, and colorectal cancer in women. In 1990-2006, 2933 persons came to live in Thyborøn-Harboøre. Their cancer incidence was the same as for newcomers to Holmsland-Hanstholm; RR 1.07 (95% CI 0.88-1.30). Persons in Thyborøn-Harboøre at height of chemical pollution had a cancer risk 20% above persons living in non-polluted fishing communities with a pattern unlikely to be attributable to life style. The study suggested that chemical pollution may have affected cancer risk.