Mortality and cancer incidence in chloralkali workers exposed to inorganic mercury

Mortality and cancer incidence were studied in men exposed to inorganic mercury at eight Swedish chloralkali plants where individual biological monitoring data were available. Urinary mercury excretion has declined from about 200 micrograms/l during the 1950s to less than 50 micrograms/l today. These workers had also been exposed to chlorine and static magnetic fields. At some of the plants there had been a low degree of exposure to asbestos. In total, 1190 men had been monitored for at least one year between 1946 and 1984. Their mortality and cancer incidence were compared with those of the general male population. Mortality from all causes was not significantly increased (rate ratio = 1.1). Cardiovascular mortality was slightly increased (rate ratio = 1.3; 95% CI 1.0-1.5) for no known reason. An excess of lung tumours was seen (rate ratio = 2.0; 95% CI 1.0-3.8), possibly caused by previous exposure to asbestos. Mortality from non-malignant diseases of the brain and the kidneys, the main target organs in mercury poisoning, was not increased, nor was the incidence of brain tumours (3 observed v 1.1 expected) or kidney tumours (3 observed v 1.9 expected).