Endocrine actions of pesticides in the Flemish Environment and Health studies (FLEHS I & II): dose-effect relationships between biomarker concentrations in urine and serum of Flemish adolescents and hormones and sexual maturation

In 2002, the Centre for Environment and Health in Flanders, Belgium started a human biomonitoring program (FLEHS I). For 1679 adolescents, residing in nine study areas with differing pollution pressure, exposure to the pesticides p,p'-DDE and HCB, hormone levels and the degree of sexual maturation were measured. Possible confounding effects of lifestyle and personal characteristics were taken into account. In 2007, a second cycle of the Flemish human biomonitoring program (FLEHS II) started. The main purpose was generating reference values for several biomarkers, both of exposure and of effect, and establishing dose-effect relationships. In this survey, not only the pesticides p,p'-DDE and HCB were measured, but also metabolites from organophosphate pesticides and para-dichlorophenol (2,5-DCP), a metabolite of para-dichlorobenzene.
Data on internal exposure of the pesticides p,p'-DDE and HCB showed a positive correlation with sexual maturation and the aromatase index for boys and with free T4 (both boys and girls), while a negative association with sexual development in girls was found. For HCB also a positive correlation was found with testosterone (boys) and TSH levels in the blood (boys and girls).
The organophosphate pesticide metabolites were negatively associated with sex hormone levels in the blood of the boys and with sexual maturation (both boys and girls). The pesticide metabolite 2,5-DCP was negatively correlated with free T4, while a positive association with TSH was reported (boys and girls).
These results show that even relatively low concentrations of pesticides can have significant influences on hormone levels and the degree of sexual maturation in 14-15 year-old adolescents.