Asbestos fibre dimensions and lung cancer mortality among workers exposed to chrysotile
OPEN ACCESS- 1School of Community Health Sciences, University of Nevada, Reno, Nevada, USA
- 2Duke University Medical Center, Durham, North Carolina, USA
- 3School of Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
- Correspondence to Professor Dana Loomis, School of Community Health Sciences/MS-274, University of Nevada, Reno, NV 89557, USA; dploomis{at}unr.edu
- Accepted 10 October 2009
- Published Online First 5 November 2009
Abstract
Objectives To estimate exposures to asbestos fibres of specific sizes among asbestos textile manufacturing workers exposed to chrysotile using data from transmission electron microscopy (TEM) and to evaluate the extent to which the risk of lung cancer varies with fibre length and diameter.
Methods 3803 workers employed for at least 1 day between 1 January 1950 and 31 December 1973 in any of three plants in North Carolina, USA that produced asbestos textile products and followed for vital status through 31 December 2003 were included. Historical exposures to asbestos fibres were estimated from work histories and 3578 industrial hygiene measurements taken in 1935–1986. Exposure–response relationships for lung cancer were examined within the cohort using Poisson regression.
Results Indicators of fibre length and diameter obtained by TEM were positively and significantly associated with increasing risk of lung cancer. Exposures to longer and thinner fibres tended to be most strongly associated with lung cancer, and models for these fibres fit the data best. Simultaneously modelling indicators of cumulative mean fibre length and diameter yielded a positive coefficient for fibre length and a negative coefficient for fibre diameter.
Conclusions The results support the hypothesis that the risk of lung cancer among workers exposed to chrysotile asbestos increases with exposure to longer fibres. More research is needed to improve the characterisation of exposures by fibre size and number and to analyse the associated risks in a variety of industries and populations.
Footnotes
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Funding Support for this research was provided by grant R01-OH007803 from the National Institute for Occupational Safety and Health (USA).
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Competing interests Dana Loomis is Editor and David Richardson is Associate Editor of Occupational and Environmental Medicine.
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Ethics approval This study was conducted with the approval of the University of North Carolina, Chapel Hill and the University of Nevada, Reno.
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Provenance and peer review Not commissioned; externally peer reviewed.
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