Objectives: to perform a meta-analysis of cohort studies on lung cancer mortality in occupational sectors exposed to asbestos, particularly in the construction sector, and to use data from Italian cohorts exposed to asbestos to estimate the number of lung cancer cases attributable to asbestos in Italy.
Methods: systematic literature review and estimation of lung cancer deaths and cases attributable to asbestos in Italian cohorts and from the Italian National Register of Malignant Mesothelioma (ReNaM).
Setting and participants: the literature search was conducted in Medline and Embase (Ovid), including papers published from 1999 to May 2019. The following sectors were considered most exposed to asbestos: asbestos-cement, rolling-stock, shipyards, dockyards, glass workers, insulators, asphalt roll production workers, industrial ovens, miners. Moreover, the construction sector was included.
Main outcome measures: the standardized mortality ratio (SMR) was estimated from the meta-analysis of the literature review. The ratio lung cancer to mesothelioma attributable cases was estimated by occupational sector from the Italian cohorts. For the construction sector, the ratio lung cancer to mesothelioma cases was estimated within the exposed workers estimated by CAREX (1990-1993). The ratios were applied to the mesothelioma cases registered at the ReNaM for the 2010-2015 period, to obtain a national estimate of lung cancer cases attributable to occupational exposure to asbestos.
Results: the meta-analytical SMR for lung cancer in men varied between 1.05 (asphalt roll) and 2.36 (insulation). The mean risk for all sectors was 1.37 in men and 1.60 in women. It increased in cohorts with latency higher than 20 years. Significant risks were observed in asbestos-cement (both genders), construction, and mining sectors. There was a mean of 1.1, 2.7, and 2.8 lung cancer deaths per mesothelioma death in the cement-asbestos, harbour, and construction sectors, respectively. The impact in terms of lung cancer cases estimated at the national level was equal to 3,814 cases between 2010 and 2015.
Conclusions: to provide an overall assessment of the impact of the occupational asbestos exposure, it is important to consider lung cancer cases, in addition to malignant mesotheliomas. This study was able to estimate the impact of asbestos on lung cancer in Italy 25 years after the ban of this occupational carcinogen, with the largest contribution in terms of attributable cases coming from the construction sector. It is urgent to implement adequate information and prevention strategies, health surveillance of workers, and the appropriate legal framework for insurance purposes.
Keywords: Asbestos; Attributable proportion; Cohorts; Meta-analysis; Occupation.