Objective To conduct an updated literature review and meta-analysis of studies of pleural malignant mesothelioma (PMM) risk among persons exposed to asbestos non-occupationally (household and neighbourhood).
Methods We performed a literature search for articles available in the National Center for Biotechnology Information’s PubMed database published between 1967 and 2016. Meta-analyses were conducted to calculate pooled PMM risk estimates, stratifying for household or neighbourhood exposure to asbestos and/or predominant asbestos fibre type (chrysotile, amphibole or mixed).
Results Eighteen studies in 12 countries comprising 665 cases met the meta-analysis inclusion criteria. We identified 13 estimates of PMM risk from neighbourhood exposures, 10 from household and one from mixed exposure, and combined the estimates using random-effects models. The overall meta-relative risk (meta-RR) was 5.9 (95% CI 4.4 to 8.7). The meta-RRs for household and neighbourhood exposures were 5.4 (95% CI 2.6 to 11.2) and 6.9 (95% CI 4.2 to 11.4), respectively. We observed trends in risk in relation to fibre type for both household and neighbourhood studies. For chrysotile, mixed and amphibole fibres, respectively, meta-RRs for neighbourhood studies were 3.8 (95% CI 0.4 to 38.4), 8.4 (95% CI 4.7 to 14.9) and 21.1 (95% CI 5.3 to 84.5) and meta-RRs for household studies were 4.0 (95% CI 0.8 to 18.8), 5.3 (95% CI 1.9 to 15.0) and 21.1 (95% CI 2.8 to 156.0).
Conclusions PMM risks from non-occupational asbestos exposure are consistent with the fibre-type potency response observed in occupational settings. By relating our findings to knowledge of exposure-response relationships in occupational settings, we can better evaluate PMM risks in communities with ambient asbestos exposures from industrial or other sources.
- pleural mesothelioma
- non-occupational exposures
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Contributors GMM had the idea for the manuscript and was responsible for the overall quality of the work. He also drafted the text and assisted with the biostatistical approach to the analysis. ASR, KAK and SMB reviewed the literature and confirmed the inclusion and exclusion of various studies. KAK and SMB were responsible for drafting the text and creating the figures. ASR was responsible for conducting the analyses and drafting the text.
Funding Schellenberg Wittmer, a Swiss business law firm that provides comprehensive legal services to domestic and international clients.
Competing interests All authors are employed by Cardno ChemRisk, a consulting firm that provides scientific advice to the government, corporations, law firms and various scientific/professional organisations. Cardno ChemRisk has been engaged by Schellenberg Wittmer, a law firm in Switzerland, to provide general consulting and expert advice on scientific matters, as well as litigation support. This paper was prepared and written exclusively by the authors, without review or comment by Schellenberg Wittmer counsel. One of the authors (GMM) has previously testified on behalf of Schellenberg Wittmer in asbestos litigation. The study, the preparation of the paper, including the synthesis of the findings, the conclusions drawn, and recommendations made are the exclusive professional work product of the authors, and may not necessarily be those of their employer.
Provenance and peer review Not commissioned; externally peer reviewed.
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