Longer, thinner fibers are associated with increased lung cancer mortality among asbestos textile workers.
Loomis-D; Dement-J; Elliott-L; Richardson-D; Kuempel-E
Proceedings of the 22nd International Conference on Epidemiology in Occupational Health - EPICOH 2011 - September 7-9, 2011 Oxford, England. Oxford: University of Oxford, 2011 Sep; :65
Objectives: Animal and limited human data suggest that the carcinogenicity of asbestos fibers may be a function of their size and shape. We investigated the effects of fiber length and diameter on lung cancer risk in a combined cohort of workers at 4 asbestos textile plants in North Carolina (NC) and South Carolina (SC), USA. Methods: The cohort included men and women who worked =30 days in production departments and were employed between 1.01.1950 and 31.12.1973 in NC or 1.01.1940 and 31.12.1965 in SC and followed through the end of 2003 (2001 for SC). Fiber numbers and dimensions were determined by analysis of 160 historical samples using transmission electron microscopy. Department-specific exposures were estimated using regression models and adjustment factors. Associations of lung cancer with cumulative fiber exposures were estimated by Poisson regression with adjustment for age, sex, race and calendar year. Results: Exposure to fibers throughout the range of length and diameter was significantly associated with increased risk of lung cancer. The best model fits were obtained for fibers >5 Ám long and <0.25 Ám in diameter. The strongest association with lung cancer was seen for fibers 5-10 Ám long and <0.25 Ám in diameter (excess RR 4% per intra-quartile range, p <0.001). When indicators of mean fiber length and diameter were modelled simultaneously, length was positively associated with lung cancer while diameter was negatively associated. Conclusions: Our findings support the hypothesis that long, thin fibers are more carcinogenic than short, wide fibers.
Asbestos-products; Humans; Men; Women; Carcinogens; Exposure-levels; Risk-factors; Lung-cancer; Lung; Pulmonary-disorders; Pulmonary-system; Pulmonary-system-disorders; Respiratory-system-disorders; Textile-workers; Mortality-rates; Morbidity-rates; Fibrous-dusts; Fibrous-bodies; Carcinogens
Proceedings of the 22nd International Conference on Epidemiology in Occupational Health - EPICOH 2011 - September 7-9, 2011
University of Nevada, Reno