Gender differences in the healthy worker effect among synthetic vitreous fiber workers

The aim of this study was to determine whether the healthy worker effect an d its component parts operate similarly for women and men. A cohort of work ers from 14 synthetic vitreous fiber factories in seven countries, employed for at least 1 year between 1933 and 1977 and followed up to the early 199 0s, included 375 deaths and 53,608 person-years among females and 2,568 dea ths and 210,073 person-years among males. Standardized mortality ratios for all-cause and circulatory diseases were adjusted for country, age, calenda r time, and gender. In addition, internal comparisons were adjusted for tim e since hire and employment status. The analyses addressed the following: 1 ) the healthy hire effect, 2) the time since hire effect, and 3) the health y worker survivor effect. In this cohort, an overall healthy worker effect was not present in either gender. The healthy hire effect, based on standar dized mortality ratios for years 1-4 since hire, was observed in males (sta ndardized mortality ratio (SMR) = 0.8; 95% confidence interval (CI): 0.7, 1 .0) but was less in females (SMR = 0.9; 95% CI: 0.5, 1.6). The relative ris ks increased slightly with time since hire in males but not in females. Hig her mortality ratios were seen among those leaving employment than among th ose who remained actively employed; however, this effect was substantially greater for women (relative risk (RR) = 3.4; 95% CI: 1.8, 6.3) than men (RR = 1.8; 95% CI: 1.5, 2.1). The gender difference for active versus inactive status was stronger up to age 60 (men: RR = 1.7; 95% CI: 1.4, 2.0; women: RR = 3.6; 95% CI: 1.8, 7.1) than above that age. In conclusion, it appears that there is a stronger selection of healthy men than women into the workf orce, while health-related selection out of the workforce is stronger for w omen than men.