Still no evidence that coal tar exposure confounded the association between bitumen/asphalt fume and lung cancer in the cohort of European asphalt workers.

摘要

We read with great interest the report by Fayerweather(1) on adjustment of the results of studies carried out in the asphalt industry for co-exposure to coal tar. The validity of Fayerweather's approach to adjustment for confounding depends of course on the choice of model of confounding (borrowed from previous investigators and well accepted as a crude, yet sometimes useful methodology),(2,3) but principally on the validity of three assumptions about intensity and duration of exposure to polycyclic aromatic hydrocarbons (with benzo(a)pyrene as their proxy) due to coal tar use and prevalence of coal tar use in the study population. We will demonstrate that when peer reviewed published data is used to make assumptions about exposure to benzo(a)pyrene due to coal tar in asphalt mixes, especially those that are derived for the purpose of the study of the European asphalt workers coordinated by the International Agency for Research on Cancer (IARC), Fayerweather's calculations fail to support his conclusions.Appropriate estimates of exposure intensity could have been easily derived by Fayerweather as illustrated below. Burstyn et al.,(4) in developing a job-exposure matrix for the study of European asphalt workers, calculated average exposure to benzo(a)pyrene in countries and time periods where coal tar use was prevalent in the industry to be on the order of 400 ng/m3.