A case-control study of lung cancer in a cohort of workers potentially exposed to slag wool fibres.

A cohort of 4841 men were identified as having worked for more than a year at nine slag wool plants. Some of these men were potentially exposed to man made vitreous fibres (MMVF). The vital status of the entire cohort was ascertained to the end of 1989. Of the 504 deaths that occurred between 1970 and 1989, 61 were attributed to lung cancer (cases). Individually matched controls were randomly selected from the remaining deaths. Attempts were made to locate and interview the surviving families of the cases and controls. The families of three lung cancer cases could not be located and no matched controls were found for another three cases. Included in the final analysis were 55 cases and 98 controls. Estimates of individual exposure to MMVF were based on employment records and industrial hygiene surveys. Data on smoking and histories of employment outside the MMVF industry were obtained from telephone interviews and employment records. Relative risks were calculated for cigarette smoking and exposure to MMVF. No increased risk of lung cancer was found associated with exposure to MMVF, and analysis by cumulative fibre exposure did not indicate any trend. As expected, cigarette smoking was found to be responsible for the observed increase in mortality from lung cancer in this group of MMVF workers, and the risk increased with increasing pack-years of cigarette smoking.