UNCORRECTED PROOF Internal exposure to pollutants and sex hormone levels in Flemish male adolescents in a cross-sectional study: associations and dose–response relationships WILLEM DHOOGE a , ELLY DEN HOND b , GUDRUN KOPPEN b , LIESBETH BRUCKERS c , VERA NELEN d , ELS VAN DE MIEROOP d , MAAIKE BILAU e , KIM CROES f , WILLY BAEYENS f , GREET SCHOETERS b,g AND NICOLAS VAN LAREBEKE h a Department of Endocrinology, Ghent University Hospital, Ghent, Belgium b Environmental Toxicology, Flemish Institute of Technological Research, Mol, Belgium c University of Hasselt, Diepenbeek, Belgium d Provincial Institute of Hygiene, Antwerp, Belgium e Department of Public Health, Ghent University, Ghent, Belgium f Analytical and Environmental Chemistry (ANCH), Vrije Universiteit Brussel, Brussels, Belgium g University of Antwerp, Antwerp, Belgium h Study Centre for Carcinogenesis and Primary Prevention of Cancer, Department of Radiotherapy, Nuclear Medicine and Experimental Cancerology, Ghent University, Ghent, Belgium Flanders is densely populated with much industry and intensive farming. Hormonal status of 14- to 15-year-old male adolescents was studied in relation to internal exposure to pollutants. A total of 887 participants were selected as a random sample of the adolescents residing in the study areas. Confounding factors and significant covariates were taken into account. Serum levels of testosterone, free testosterone and estradiol, and the aromatase index showed significant positive associations with serum levels of marker polychlorobiphenyls (sum of PCBs 138, 153, and 180) and of hexachlorobenzene (HCB) and a negative association with urinary cadmium concentration. Serum levels of estradiol also showed a positive association with serum levels of dichlorodiphenyldichloroethylene (DDE). A doubling of serum concentrations of marker PCBs and HCB and of urinary concentration of cadmium were, respectively, associated with an increase of 16.4% (Po0.00001) and 16.6% (Po0.001) and a decrease of 9.6% (Po0.001) in serum testosterone concentration. Similar findings were made after additional adjustment for concurrent exposures. Associations between biological effects and internal exposures were, in terms of the regression coefficient, often stronger at exposures below the median. Environmental exposures to pollutants resulting in ‘‘normal’’ levels of internal exposure were associated with quite substantial differences in hormone concentrations. Journal of Exposure Science and Environmental Epidemiology (2009) 0, 000–000. doi:10.1038/jes.2009.63 Keywords: lead, cadmium, polychlorobiphenyls, hexachlorobenzene, health effects, low dose. Introduction Flanders is one of the most populated areas in Europe, with a dense network of traffic roads, industrial activities, and intensive farming close to habitation. The 5-year (2001– 2006) biomonitoring program on neonates, adolescents, and adults by the Flemish Centre for Environment and Health aimed at measuring internal exposure to pollutants in areas differing in pollution pressure and assessing whether place of residence or observed differences in internal concentrations of pollutants were associated with biological and health effects. All public information on the project can be found on the website http://www.milieu-en-gezondheid.be. In this study, we report on sex hormone levels of 14- to 15-year-old male adolescents in relation to internal exposure to environmental pollutants suspected to affect hormonal equilibrium. Polychlorobiphenyls (PCBs) are known to have estrogenic, anti-estrogenic, and anti-androgenic activities (Bonefeld-Jorgensen et al., 2001); p,p 0 -dichlorodiphenyldi- chloroethylene (p,p 0 -DDE) was reported to have anti- androgenic properties (Kelce et al., 1995); hexachloroben- zene (HCB) was reported to affect estradiol levels in animals (Foster et al., 1995; Alvarez et al., 2000); cadmium was observed to be able to interact with both estrogen and androgen receptors (Stoica et al., 2000; Martin et al., 2002); and lead was reported to have xeno-estrogenic activity (Martin et al., 2003). We wanted to test the hypothesis that Journal: JES  Disk used Despatch Date: 25/11/2009 Article : npg_jes_jes200963 Pages: 8 Op: xxx ED: XXX CE: XXX Graphic: XXX Gml : Ver 6.0 Template: Ver 1.0.1 Received 1 July 2009; accepted 21 October 2009 1. Address all correspondence to: Dr. Nicolas van Larebeke, Department of Radiotherapy, Ghent University, Nuclear Medicine and Experimental Cancerology, Ninoofse steenweg 379, Halle, Belgium B1500. Tel.: þ 320 2380 1410. Fax: þ 320 2381 1645. E-mail: nicolas.vanlarebeke@ugent.be Journal of Exposure Science and Environmental Epidemiology (2009), 1–8 r 2009 Nature Publishing Group All rights reserved 1559-0631/09/$32.00 www.nature.com/jes