Authors:
Den Hond, E., Roels, HA., Hoppenbrouwers, K., Nawrot, T., Thijs, L., Vandermeulen, C., Winneke, G., Vanderschueren, D., Staessen, JA.

Title:
Sexual Maturation in Relation to Polychlorinated Aromatic Hydrocarbons: Sharpe and Skakkebaek's Hypothesis Revisited.

Journal:
Environmental Health Perspectives;110: 771-776.2002.

Summary:
Several persistent contaminants are released into the environment through natural and man-made routes. Dioxins are compounds that are released into the environment through incineration and combustion processes while PCBs are a group of man-made chemicals used in transformers, capacitors and other electrical equipment. Some polychlorinated biphenyls (PCBs) and dioxins have the potential to interfere with several biological functions and can exert estrogenic, androgenic or anti-estrogenic effects on the endocrine system. Sharpe and Skakkebaek have hypothesized that increased estrogen exposure in utero may be related to reproductive abnormalities in the male. Furthermore, in utero exposure to PCBs and dioxins has been shown to delay puberty in the offspring of rats.

The objectives of this study were to measure the influence that PCB congeners and dioxin-like compounds have on puberty stages, testicular volume and sexual hormones in adolescents. The authors recruited 100 adolescents living in two polluted suburbs of Antwerp, Belgium (Wilrijk and Hoboken) and 100 adolescents living in a rural community (Peer) served as a reference population. Wilrijk has two waste incinerators, in operation since 1971 and 1980, and a crematory, while Hoboken houses a primary nonferrous smelter. In order to be included into the study, lifelong residence in the area was necessary. Four trained school physicians acquired the medical history and staged sexual maturation according to Marshall and Tanner (1969, 1970) of all the adolescents. Agreement among physician was considered good and beyond chance with Kappa coefficients between 0.61 and 0.80. Questionnaires were administered by a nurse to gather lifestyle and pertinent health information and serum concentration of specific PCB congeners, and dioxin-like compounds were collected.

In general the results showed that adolescents in the polluted suburbs were in earlier stages of development. After controlling for age and lifestyle factors, the results showed that significantly fewer boys were in the later stages of genital development and pubic hair growth in Wilrijk, than in the control town, Peer (p£ 0.01) and Hoboken (p£ 0.01). Testicular volume was also significantly lower in both polluted suburbs than in the control group. Significantly fewer girls were in the later stages of breast development in Wilrijk than in Peer (p£ 0.05). Conversely, pubic hair growth was more developed in girls in Hoboken than in those in Peer (p£ 0.001) or Wilrijk (p£0.001). Serum PCB congeners were significantly higher in boys from Wilrijk than Peer and Hoboken while dioxin-like compounds were significantly higher in girls of both suburbs than in the control area. As well, after controlling for age, body mass index and parental social class, a two fold increase in summated serum markers of PCBs were found to be inversely associated with genital and public hair development in boys (p=0.06). Similarly, for the girls a two fold increase in dioxin-like compounds in serum had a significant inverse relationship with breast development (p=0.02).

An important implication of this study is that it contradicts the findings of other similar studies. Previous studies have suggested that higher serum levels of exogenous chemicals accelerate puberty in girls. However, the findings of this study may be limited due to methodological issues. Nevertheless, the results of this study are consistent with some experimental studies and warrant further investigation into the effects of environmental contaminants on sexual maturation.