RETROSPECTIVE COHORT STUDY OF WORKERS OF A SYNTHETIC TEXTILES PLANT IN QUEBEC .2. COLORECTAL-CANCER MORTALITY AND INCIDENCE

This paper describes standard mortality and nested case-control analys es of colorectal cancer for a cohort of synthetic textiles workers in which a cluster of five cases was observed previously. The cohort cons isted of 7,487 men and 2,724 women who had more than 1 year's experien ce at the plant and who were either working in 1947 or were newly empl oyed between 1947 and 1977. The Standardized Mortality Ratio (SMR) for colorectal cancer for men was 0.69 (95% confidence interval (Cl): 0.5 2-0.92; 50 deaths) and for women it was 1.02 (95% CI: 0.57-1.69; 15 de aths). Among men only there was a suggestion that risks increased acco rding to the length of service at the plant. In the nested case-contro l study, incident cases as well as deceased cases were included. A var iety of analyses were carried out according to duration of employment in the processing units. For men the risk of colon cancer increased wi th duration of employment in the polypropylene and cellulose triacetat e extrusion unit (unadjusted odds ratio (OR) for greater-than-or-equal -to 5 years duration = 5.52; 95% CI: 1.12-27.26; 4 exposed cases). It was not possible, however, to provide an independent confirmation of t his putative association because the case series included three of the original five cases. There was some evidence of increased risks in th e cellulose acetate fiber manufacturing unit and in the dyeing and fin ishing unit, but the data were compatible with the null hypothesis of no effect. No associations were observed for employment in any of the other processing units. (C) 1994 Wiley-Liss, Inc.