Lung cancer and mesothelioma risk assessment for a population environmentally exposed to asbestos (original) (raw)
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Annals of Occupational Hygiene, 2002
Introduction. The risk of asbestos diseases cannot be measured directly in populations with low level chrysotile asbestos exposure. Risk assessments must be used to extrapolate risks from past heavy industrial asbestos exposures to today's low chrysotile exposures. We tested the US Environmental Protection Agency (EPA) mesothelioma risk model in a population having experienced relatively high and mostly non-occupational chrysotile exposures. Methods. Female mesotheliomas first diagnosed from 1970 to 1989 in chrysotile asbestos mining districts (Asbestos and Thetford) were identified from the Quebec Tumour Registry and hospital records gathered throughout the province. Diagnoses were reviewed by three pathologists. An international expert panel estimated historical ambient exposure levels in these districts. A 'time-area-job-family exposure' matrix was derived from these estimates, occupational and cohabitation exposure estimates and a survey of 817 female residents. We applied the EPA mesothelioma incidence model to the population time-area-job-family exposure matrix and compared this predicted incidence with that actually observed. Results. Ambient airborne asbestos exposures were between 0.1 and 3 fibres/ml before 1970. The EPA asbestos risk model predicted 150 (range 30-750) female mesotheliomas in Asbestos, while only one case (peritoneal) was observed; 500 cases (range 100-2500) were predicted in Thetford Mines, while 10 cases (pleural) were observed. These large discrepancies cannot be explained by random or systematic errors.
Modeling Mesothelioma Risk Associated with Environmental Asbestos Exposure
Environmental Health Perspectives, 2007
BACKGROUND: Environmental asbestos pollution can cause malignant mesothelioma, but few studies have involved dose-response analyses with detailed information on occupational, domestic, and environmental exposures. OBJECTIVES: In the present study, we examined the spatial variation of mesothelioma risk in an area with high levels of asbestos pollution from an industrial plant, adjusting for occupational and domestic exposures. METHODS: This population-based case-control study included 103 incident cases of mesothelioma and 272 controls in 1987-1993 in the area around Casale Monferrato, Italy, where an important asbestos cement plant had been active for decades. Information collected included lifelong occupational and residential histories. Mesothelioma risk was estimated through logistic regression and a mixed additive-multiplicative model in which an additive scale was assumed for the risk associated with both residential distance from the plant and occupational exposures. The adjusted excess risk gradient by residential distance was modeled as an exponential decay with a threshold. RESULTS: Residents at the location of the asbestos cement factory had a relative risk for mesothelioma of 10.5 [95% confidence interval (CI), 3.8-50.1), adjusted for occupational and domestic exposures. Risk decreased rapidly with increasing distance from the factory, but at 10-km the risk was still 60% of its value at the source. The relative risk for occupational exposure was 6.0 (95% CI, 2.9-13.0), but this increased to 27.5 (95% CI, 7.8-153.4) when adjusted for residential distance. CONCLUSIONS: This study provides strong evidence that asbestos pollution from an industrial source greatly increases mesothelioma risk. Furthermore, relative risks from occupational exposure were underestimated and were markedly increased when adjusted for residential distance.
Prediction of mesothelioma and lung cancer in a cohort of asbestos exposed workers
European Journal of Epidemiology, 2008
Background Several papers have reported statewide projections of mesothelioma deaths, but few have computed these predictions in selected exposed groups. Objective To predict the future deaths attributable to asbestos in a cohort of railway rolling stock workers. Methods The future mortality of the 1,146 living workers has been computed in term of individual probability of dying for three different risks: baseline mortality, lung cancer excess, mesothelioma mortality. Lung cancer mortality attributable to asbestos was calculated assuming the excess risk as stable or with a decrease after a period of time since first exposure. Mesothelioma mortality was based on cumulative exposure and time since first exposure, with the inclusion of a term for clearance of asbestos fibres from the lung. Results The most likely range of the number of deaths attributable to asbestos in the period 2005-2050 was 15-30 for excess of lung cancer, and 23-35 for mesothelioma. Conclusion This study provides predictions of asbestos-related mortality even in a selected cohort of exposed subjects, using previous knowledge about exposure-response relationship. The inclusion of individual information in the projection model helps reduce misclassification and improves the results. The method could be extended in other selected cohorts.
Estimated Cancer Risk Associated with Occupational Asbestos Exposure
Risk Analysis, 1981
This paper estimates the number of workers in the United States who were occupationally exposed to asbestos during and after World War I1 and assesses the impact of this exposure on overall cancer mortality. The results suggest that over half of the estimated 7-8 million potentially exposed workers employed between 1940 and 1970 may still be alive and at risk of dying from some form of asbestos-related cancer. While the maximum number of excess cancer deaths associated with this occupational exposure is likely to occur sometime in this decade, such deaths will continue to be seen for many years thereafter. At their peak, these deaths may account for an estimated 3% of the annual cancer death toll, with an associated range of 1.4-4.456.
Developments in asbestos cancer risk assessment
American Journal of Industrial Medicine, 2009
Background Efforts have been made for 25 years to develop asbestos risk assessments that provide valid information about workplace and community cancer risks. Mathematical models have been applied to a group of workplace epidemiology studies to describe the relationships between exposure and risk. EPA's most recent proposed method was presented at a public meeting in July 2008. Methods Risk assessments prepared by USEPA, OSHA, and NIOSH since 1972 were reviewed, along with related literature.
BMC Cancer, 2012
Background: Asbestos is classified as a human carcinogen, and studies have consistently demonstrated that workplace exposure to it increases the risk of developing lung cancer. Few studies have evaluated risks in population-based settings where there is a greater variety in the types of occupations, and exposures. Methods: This was a population based case-control study with 1,681 incident cases of lung cancer, and 2,053 controls recruited from 8 Canadian provinces between 1994 and 1997. Self-reported questionnaires were used to elicit a lifetime occupational history, including general tasks, and information for other risk factors. Occupational hygienists, who were blinded to case-control status, assigned asbestos exposures to each job on the basis of (i) concentration (low, medium, high), (ii) frequency (<5%, 5-30%, and >30% of the time in a normal work week), and (iii) reliability (possible, probable, definite). Logistic regression was used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CI). Results: Those occupationally exposed to (i) low, and (ii) medium or high concentrations of asbestos had ORs for lung cancer of 1.17 (95% CI=0.92-1.50) and 2.16 (95% CI=1.21-3.88), respectively, relative to those who were unexposed. Medium or high exposure to asbestos roughly doubled the risk for lung cancer across all three smoking pack-year categories. The joint relationship between smoking and asbestos was consistent with a multiplicative risk model. Conclusions: Our findings provide further evidence that exposure to asbestos has contributed to an increased risk of lung cancer in Canadian workplaces, and suggests that nearly 3% of lung cancers among Canadian men are caused by occupational exposure to asbestos.
Annals of Work Exposures and Health, 2020
Despite numerous studies of asbestos workers in the epidemiologic literature, there are very few cohort studies of chrysotile asbestos miners/millers that include high-quality retrospective exposure assessments. As part of the creation of the Baie Verte Miners’ Registry in 2008, a two-dimensional job exposure matrix (JEM) was developed for estimating asbestos exposures for former chrysotile asbestos miners/millers. Industrial hygiene data collected between 1963 and 1994 were analysed to assess validity for use in a retrospective exposure assessment and epidemiologic study. Registered former employees were divided into 52 exposure groups (EGs) based on job title and department and mean asbestos concentrations were calculated for each EG. The resulting exposure estimates were linked to individual registrants’ work histories allowing for the calculation of cumulative asbestos exposure for each registrant. The distribution of exposure for most EGs (82.6%) could be described as fitting a...