Pleural Mesothelioma: Dose-Response Relation at Low Levels of Asbestos Exposure in a French Population-based Case-Control Study

Abstract

A hospital-based case-control study of the association between past occupational exposure to asbestos and pleural mesothelioma was carried out in five regions of France. Between 1987 and 1993, 405 cases and 387 controls were interviewed. The job histories of these subjects were evaluated by a group of experts for exposure to asbestos fibers according to probability, intensity, and frequency. A cumulative exposure index was calculated as the product of these three parameters and the duration of the exposed job, summed over the entire working life. Among men, the odds ratio increased with the probability of exposure and was 1.2 (95% confidence interval (CI) 0.8-1.9) for possible exposure and 3.6 (95% CI 2.4-5.3) for definite exposure. A dose-response relation was observed with the cumulative exposure index: The odds ratio increased from 1.2 (95% CI 0.8-1.8) for the lowest exposure category to 8.7 (95% CI 4.1-18.5) for the highest. Among women, the odds ratio for possible or definite exposure was 18.8 (95% CI 4.1-86.2). We found a clear dose-response relation between cumulative asbestos exposure and pleural mesothelioma in a population-based case-control study with retrospective assessment of exposure. A significant excess of mesothelioma was observed for levels of cumulative exposure that were probably far below the limits adopted in most industrial countries during the 1980s.

Attributable risk in men in two French case-control studies on mesothelioma and asbestos

“…Studies A [3] and B [4] were multicenter case-control studies. Study A was a hospital-based casecontrol study where cases were selected in five French administrative regions.…”

“…Experts in industrial hygiene, five in study A and two in study B, assessed occupational asbestos exposure by consensus [7]. Expertise methods were different: in study A, experts assessed the subjects" jobs sorted by industry, blinded to the full carrier of subjects [3], and in study B, experts assessed consecutively all the jobs of each subject [4]. The socioeconomic category of the subject was determined by the last occupation and work sector before the interview and was coded using the major groups of the International Standard Classification of Occupations (ISCO edition 1968) [8] and the International Standard Industrial Classification of All Economics Activities (ISIC revision 2) [9], respectively.…”

“…We also characterized each subject"s history by: the highest probability of any job period during lifetime work history; total duration of exposure (years); time since first exposure (latency period); age at first exposure (year); Cumulative Exposure Index (CEI) expressed in "fibers/ml-years" (f/ml-years) and defined as the sum of the products of probability, frequency, intensity, and duration for each job period. To calculate the CEI, we attributed weighting factors used in a previous study [3] to each exposure category of these three parameters. Then, we categorized CEI as continuous variable in four CEI levels.…”

“…To study the relationship between pleural mesothelioma and occupational asbestos exposure in France, two large case-control studies have been conducted. A first hospital-based case-control study was conducted between 1987-1993 (hereafter called "study A") [3], and a second population-based study nested in the French National Mesothelioma Surveillance Program (PNSM) was performed between 1998-2002 (hereafter called "study B) [4]. A substantial difference in the attributable risk in the male population (AR p ) was observed: 44.5% (95% CI: [32.6-56.4]) in study A and 83.2% (95% CI: [76.…”

Occupational, domestic and environmental mesothelioma risks in the British population: a case–control study

“…Earlier case -control studies have used hospital-based controls or relied on next-of-kin interviews and most involved small numbers of cases (Muscat and Wynder, 1991;Howel et al, 1997;Teschke et al, 1997;Iwatsubo et al, 1998;Agudo et al, 2000;Rodelsperger et al, 2001). We carried out the first populationbased study in Britain of the relationship between mesothelioma risk and lifetime occupational and residential history of asbestos exposure obtained at interview, and the largest worldwide.…”