Distribution of cadmium, lead and zinc in lung, liver and kidney in long-term exposed smelter workers

Abstract

Increased mortality due to various malignancies is reported from long-term exposed, non-ferrous smelter workers. In the present study the post-mortem distribution of cadmium, lead and zinc in lung, liver and kidney is reported and related to exposure and mortality. The study involved 86 male copper smelter workers who died after April 1975. Lung samples were taken from all workers and liver and kidney samples were taken from about one-quarter of the workers. Two control groups were used. The exposed workers were divided into six groups based upon diagnoses in medical records and autopsy protocols. Lead and zinc were analyzed by atomic absorption spectrophotometry and cadmium by neutron activation analysis. For the skewly distributed tissue levels, non-parametric statistical processing was used. Of the workers, 53% died from cardiovascular diseases and 30% from malignancies (8% from lung cancer). Cardiovascular diseases predominated in the two control groups: about 75 and 100%, respectively. Lung and liver cadmium concentrations were significantly higher in the lung cancer group of smelter workers than in the other groups of smelter workers ( p < 0.05) and rural controls ( p < 0.01). Cadmium in kidney, and lead in lung and liver were significantly higher ( p < 0.03) in the lung cancer group than in rural controls, but did not differ from that of the other workers. Zinc in lung, liver and kidney did not differ between exposed workers and controls. Rather strong Spearman rank-order correlation coefficients were found between the cadmium content of lung, liver and kidney tissue, especially in non-smoking smelter workers and rural controls. Smoking was more common in the lung cancer group than in the total group of smelter workers. Cadmium levels in the lungs of exposed workers were significantly higher ( p < 0.001) in smokers than in both ex-smokers and non-smokers. Earlier studies of the same workers gave significantly lower selenium levels in lung tissue compared with other groups of smelter workers and controls. As other carcinogenic substances are present in the working environment, e.g. arsenic, chromium and benzo[ a]-pyrene, the specific effect of cadmium in the development of lung cancer cannot be evaluated at present.