Historical cohort study of US man-made vitreous fiber production workers: V. Tobacco-smoking habits

As part of our ongoing mortality surveillance program for the US man-made v itreous fiber industry, we surveyed a random sample of study members to est imate tobacco-smoking habits for the total cohort. Separate sampling frames were constructed for four study groups: male and female workers within the fiberglass and rock/slag wool subcohorts. The frames included all persons who had worked a year or more between 1945 and 1986 (with some exceptions), and who were alive as adults (18+ years) on January 1, 1980, the year the age distribution of the cohort most resembled the US comparison population. Subjects were randomly selected from the frames, and a structured telephon e interview was administered to the subject or a proxy respondent between J anuary 1995 and December 1997. Using survey data, we estimated the point pr evalence of ever and current cigarette smoking on January 1, 1980, and made comparisons with other occupational groups and general populations. Overal l response rates (interviews/targeted sample) were greater than 78% for eac h of the four study groups. From our estimates, we infer that male workers from both the fiberglass and rock/slag wool cohorts and female rock/slag wo ol workers had higher rates of ever smoking than the corresponding general populations of the United States and most of the states where the study pla nts were located. These findings suggest that at least part of the elevated externally standardized mortality ratios (US and regional rate-based) for respiratory system cancer noted among male subjects and the male-dominated total cohort in our previous cohort analyses were due to uncontrolled posit ive confounding by smoking.