Internal exposure to pollutants and body size in Flemish adolescents and adults: Associations and dose–response relationships

Abstract

Flanders is densely populated with much industry and intensive farming. Body size of 14- to 15-year old adolescents and of adults aged 50–65 was studied in relation to internal exposure to pollutants. 1679 adolescents (887 boys and 792 girls), 775 men and 808 women were selected as a random sample of the population. Concentrations of pollutants in blood or urine were measured in accordance with quality control/quality assurance procedures. Self-assessment questionnaires provided information on personal and life-style factors. Height and weight of subjects were measured. Confounding factors and significant covariates were taken into account. For boys and girls, height and body mass index (BMI) showed a negative association with urinary concentration of cadmium and BMI also with serum concentration of hexachlorobenzene (HCB) and with the sum of serum concentrations of polychlorinated biphenyls (PCBs) 138, 153, and 180 (marker PCBs), whereas BMI showed a positive association with serum concentration of PCB 118. For boys, height showed a negative association with urinary concentration of 1-hydroxypyrene (1-OHP) and positive associations with serum concentrations of HCB and PCB 118. For adults no significant associations between internal exposure and height were observed. For men, BMI showed negative associations with urinary cadmium concentration and with serum levels of marker PCBs and positive associations with serum levels of HCB, p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE), PCB 118 and the dioxin fraction of dioxin-like activity. For women, BMI showed a negative association with urinary cadmium concentration, with blood lead concentration and with the concentration of marker PCBs in serum, and a positive association with serum concentrations of HCB, p,p′-DDE and PCB 118. 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 body mass index.

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 five-year (2001–2006) biomonitoring program on neonates, adolescents and adults (50–65 years) 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 www.milieu-en-gezondheid.be.

In this study, we report on body size of 50- to 65-year old adults and 14- to 15-year old adolescents in relation to internal exposure to environmental pollutants suspected to affect hormonal equilibrium. PCBs are known to have estrogenic, anti-estrogenic and anti-androgenic activities (Bonefeld-Jorgensen et al., 2001); p,p′-DDE was reported to have anti-androgenic properties (Kelce et al., 1995); HCB was reported to affect oestradiol levels in animals (Alvarez et al., 2000, Foster et al., 1995) and to interact with hormone receptors (Li et al., 2008); cadmium was observed to be able to interact with both estrogen and androgen receptors (Stoica et al., 2000, Martin et al., 2002); lead was reported to have xeno-estrogenic activity (Martin et al., 2003) and to affect pubertal development in girls (Selevan et al., 2003); polycyclic aromatic hydrocarbons were reported to affect development (Choi et al., 2006) and display AhR as well as estrogen receptor-mediated activity (Hilscherova et al., 2000). We wanted to test the hypothesis that low differences in levels of internal exposure (such as these occurring in the general population in Flanders) to endocrine disrupting substances result in differences in body size parameters. In addition, will this effect be larger at the lower end of the range of measured internal exposures than at the higher end of this range? This is what could happen if the above mentioned pollutants interact with receptors, as their dose–response curves might be expected to follow Michaelis–Menten kinetics (Sheehan et al., 1999, Castano & Flores-Saaib, 2008).