INCIDENCE OF CANCER AND MORTALITY AMONG WORKERS EXPOSED TO MERCURY-VAPOR IN THE NORWEGIAN CHLORALKALI INDUSTRY

Incidence of cancer and mortality were studied among 674 men exposed t o mercury vapour for more than one year at two chloralkali plants. Mer cury excretion in urine had been monitored among the workers at the tw o plants since 1948 and 1949. An individual cumulative urinary mercury dose was calculated, based on about 20 000 urinary mercury measuremen ts. The incidence of cancer and the mortality were followed up from 19 53 to 1989 and 1953 to 1988 respectively. The general Norwegian male p opulation served as a reference population. There was a lung cancer ex cess of borderline significance (standardised incidence ratio = 1.66, 95% confidence interval = 1.00-2.59). The introduction of a 10 year la tent period before developing lung cancer did not increase the inciden ce ratio. The excess may be partly explained by the smoking habits in the cohort or possibly by exposure to asbestos. No excess of cancer wa s found in the target organs for mercury toxicity-namely, the kidney a nd the nervous system. No significant excess mortality was found for n ephritis and nephrosis or nonmalignant diseases of the nervous system.