Cancer incidence within a cohort occupationally exposed to asbestos: A study of dose - Response relationships
Cancers and Populations, ERI3 INSERM, Faculty of Medicine, Caen University Hospital, Caen, France. Occupational and environmental medicine
(Impact Factor: 3.27).
03/2011; 68(11):832-6. DOI: 10.1136/oem.2010.059790
The aim of our study was to analyse the dose-response relationship between occupational asbestos exposure and risk of cancer.
Our study was a retrospective morbidity study based on 2024 subjects occupationally exposed to asbestos, conducted over the period 1 January 1978 to 31 December 2004. Analysis of the dose-response relationship between occupational asbestos exposure, as a time-dependant variable, and risk of cancer was performed using a Cox model. In order to account for the effect of latency, we conducted the analysis with a lag of 10 years.
285 cases of cancers were observed in our cohort. The relative risk of pleuro-peritoneal mesothelioma, lung cancer and colorectal cancer associated with asbestos exposure, adjusted for age as a time-dependant variable and for sex, was correlated with exposure intensity (or average exposure level, AEL). The risk of cancer, whatever the anatomical site, did not increase with the duration of exposure to asbestos.
While confirming the established relationship between asbestos exposure and pleuropulmonary and peritoneal cancers, this study also suggests a causal relationship between asbestos exposure and colorectal cancer.
Available from: Shelley A Harris
- "In contrast, we found that only intensity but not duration of exposure was associated with statistically significant increased risks of lung cancer. This observation is consistent with recently published findings on a cohort of workers employed in an asbestos reprocessing plant in the Calvados region of France
. In this study, Clin and colleagues observed that the average exposure to asbestos expressed in terms of fibers per ml was associated with pleuro-peritoneal mesothelioma, lung cancer, and colorectal cancer (p<0.05), "
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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.
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).
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.
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.
BMC Cancer 12/2012; 12(1):595. DOI:10.1186/1471-2407-12-595 · 3.36 Impact Factor
Available from: Luca Cegolon
Occupational and environmental medicine 08/2011; 69(3):227-8. DOI:10.1136/oemed-2011-100225 · 3.27 Impact Factor
Available from: Luca Cegolon
International Journal of Occupational Medicine and Environmental Health 12/2011; 24(4):418-9; author reply 420-1. DOI:10.2478/s13382-011-0039-6 · 0.70 Impact Factor
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