1. ^aDepartment of Public Health, Erasmus MC, Rotterdam, CA, The Netherlands
2. ^bDepartment of Research and Registration, Comprehensive Cancer Centre North East, Enschede, The Netherlands
3. ^cSafety Science Group, Delft University of Technology, The Netherlands

Correspondence: Professor Dr Alex Burdorf, Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, The Netherlands. Tel.: +31 10703 8475; Fax: +31 10703 8475; E-mail: a.burdorf@erasmusmc.nl

Received 1 May 2009; Accepted 24 August 2009; Published online 28 October 2009.

Abstract

In a rural area widespread pollution of friable and non-friable waste products was present, used to harden dirt tracks, yards, and driveways during 1935–1974. Exposure to environmental asbestos was assessed by a site approach, based on number of polluted sites within postal code areas, and by a household approach, based on number of households in the close vicinity to polluted sites within postal code areas. Based on asbestos soil investigations, 293 sites were identified with asbestos waste material at the surface, of which 77% contained crocidolite fibres as well as chrysotile fibres. The 293 sites-at-risk varied from 5 m² to 2722 m² and were surrounded by 347 households within 100 m of these sites. Distance to the plant was associated with the number of sites (r=0.36), and with the number of households (r=0.52). However, categorization of postal code areas into low, intermediate or high likelihood of exposure to asbestos showed a modest agreement between the site and household approach. In the site approach a total of 2.3 million person-years at risk were estimated with an average exposure of 1674 fibres/m³ and an expected 1.8 cases of malignant mesothelioma each year. The household approach resulted in estimates of 1.2 million person-years at risk, and 0.9 cases of malignant mesothelioma per year, respectively. This study illustrates that asbestos waste on the surface of roads and yards in an area with over 130,000 inhabitants may result in long-term exposure to asbestos that will cause several cases of malignant mesothelioma each year. Although distance to plant, number of polluted sites and number of exposed household were associated, the modest agreement among these measures of exposure indicate that the exposure assessment strategy chosen in a particular study may result in considerable misclassification. Without detailed information on individual behaviour within the polluted area, it is difficult to show that a more individually oriented approach will perform better than an ecological approach.