Abstract
This study was performed with the aim of investigating the temporal patterns and determinants associated with mortality from asbestosis among 21 cohorts of Asbestos-Cement (AC) workers who were heavily exposed to asbestos fibres. Mortality for asbestosis was analysed for a cohort of 13 076 Italian AC workers (18.1% women). Individual cumulative asbestos exposure index was calculated by factory and period of work weighting by the different composition of asbestos used (crocidolite, amosite, and chrysotile). Two different approaches to analysis, based on Standardized Mortality Ratios (SMRs) and Age-Period-Cohort (APC) models were applied. Among the considered AC facilities, asbestos exposure was extremely high until the end of the 1970s and, due to the long latency, a peak of asbestosis mortality was observed after the 1990s. Mortality for asbestosis reached extremely high SMR values [SMR: males 508, 95% confidence interval (CI): 446-563; females 1027, 95% CI: 771-1336]. SMR increased steeply with the increasing values of cumulative asbestos exposure and with Time Since the First Exposure. APC analysis reported a clear age effect with a mortality peak at 75-80 years; the mortality for asbestosis increased in the last three quintiles of the cumulative exposure; calendar period did not have a significant temporal component while the cohort effect disappeared if we included in the model the cumulative exposure to asbestos. Among heaviest exposed workers, mortality risk for asbestosis began to increase before 50 years of age. Mortality for asbestosis was mainly determined by cumulative exposure to asbestos.
Highlights
Asbestosis is an occupational lung disease caused by the inhalation and deposition of asbestos fibres in the lung, thereby leading to diffuse interstitial fibrosis
To account for the commercial type of asbestos used in each factory, we considered in the analysis a fibreweighted Average Exposure Index (AEI) based on the proportion of chrysotile (CHft), amosite (Aft), and crocidolite (CRft) used by each factory and time period
The analysis of 21 cohorts of AC workers in Italy and the occurrence of a large number of deaths from asbestosis allowed to investigate the temporal components of asbestosis mortality, exploring several determinants
Summary
Asbestosis is an occupational lung disease caused by the inhalation and deposition of asbestos fibres in the lung, thereby leading to diffuse interstitial fibrosis. It can be asymptomatic in the early stages but its progression over time entails disability, respiratory insufficiency, and premature death (CDCP, 2004; Lippmann, 2014), causing an average loss of 13.0 potential years of life per decedent (Diandini et al, 2013). The presence of a consistent lung asbestos burden among AC workers provided a further evidence of heavy asbestos exposures (Gylseth et al, 1983; Merler et al, 2017)
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