Comment on ‘Estimating the asbestos-related lung cancer burden from mesothelioma mortality’ – IARC and Chrysotile Risks

Expected number of asbestos-related lung cancers in the Netherlands in the next two decades: a comparison of methods

“…When comparing the exposure–response relationships, the ratio is likely to be affected by follow-up time, (mean) age at time of exposure and exposure intensity 10. Other reasons for the discrepancies may be found in potential confounding, different background of lung cancer rates and smoking levels and misclassification of mesothelioma cases 10 29. The majority of the studies included in the meta-analyses comprised cohorts of highly exposed individuals from which the ratio between mesothelioma and lung cancer was estimated.…”

Reply: Comment on ‘Estimating the asbestos-related lung cancer burden from mesothelioma mortality’

“…Lemen et al (2013) misinterpret our paper suggesting that it ‘minimises the health risks posed by chrysotile'. On the contrary, we concluded the paper by emphasising the cancer risks posed by this asbestos fibre, risks that are often overlooked because they are lung cancers typically occurring in smokers.…”

“…In response to the comments of Lemen et al (2013) on our article (McCormack et al , 2012), we welcome the opportunity to endorse the original article and to demonstrate that none of the concerns raised are substantiated.…”

“…Such ratios are also the most relevant when applied externally to estimate ARLCs from observed mesotheliomas, as the latter usually arise from a combination of different, often unknown, exposure histories. As pointed out by Lemen et al (2013) and in the devoted Discussion section (‘Heterogeneity in ratio estimates within and between cohorts'), variations in the ARLC:mesothelioma ratios between cohorts or between subsets of workers within cohorts may indeed occur due to outcome misclassification, latency, exposure levels, potential confounding. Nevertheless, the best estimates of the average ratios across exposure circumstances are the ones we presented, being based on the most complete evidence-base possible.…”

“…Lemen et al (2013) express concerns pertaining to four issues: (i) studies included and omitted; (ii) a lack of consideration of further factors that affect asbestos-related cancer risks; (iii) discussions of the carcinogenicity of chrysotile; and (iv) risk mitigation. We address each of these in turn.…”