Mortality and cancer morbidity in workers from an aluminium smelter with prebaked carbon anodes--Part III: Mortality from circulatory and respiratory diseases.

OBJECTIVE: To investigate associations between exposure to pot emissions (fluorides, sulphur dioxide) and mortality from chronic obstructive lung disease, coal tar pitch volatiles and mortality from diseases related to atherosclerosis, and carbon monoxide and mortality from ischaemic heart disease.
METHODS: Mortality between 1962 to 1991 was investigated in a cohort of 1085 men hired by a Norwegian aluminium smelter between 1922 and 1975. Associations between cumulative exposure and mortality were investigated through SMR analysis based on national mortality rates; temporal relations were explored by considering exposures only within specific time windows. Circulatory mortality was also investigated by Poisson regression analysis.
RESULTS: There were 501 deaths v 471.3 expected in the cohort. The excess was confined to short term workers and did not seem to be associated with exposures in the smelter. Analysis of mortality among the 661 men with at least three years employment showed associations between cumulative exposure to tar 40 years before observation and atherosclerotic mortality (P = 0.03), and between exposure to pot emissions 20-39 years before observation and mortality from chronic obstructive lung disease (P = 0.06). No association was found between exposure to carbon monoxide and mortality from ischaemic heart disease, but cerebrovascular mortality was associated with exposure to pot emissions (P = 0.02). Results for atherosclerotic and cerebrovascular diseases were confirmed through Poisson regression analysis.
CONCLUSIONS: The data support previous findings of increased mortality from ischaemic heart disease in workers exposed to tar, and some support is also provided for earlier reports of increased respiratory mortality in potroom workers.