Dioxins, Male Pubertal Development and Testis Function

Description

Objectives/Hypothesis:

The objectives of this project are to investigate the relationships between dioxins and male reproductive tract malformations, male pubertal development and alterations in testis function. We hypothesize that dioxins, measured in adolescence prior to the onset of puberty, are associated with disturbances in physical growth, sexual maturation (age of onset and tempo), and testis function as an adult, specifically alterations in reproductive hormones and semen quality. We also hypothesize that in utero levels of dioxins are associated with alterations in physical growth and sexual maturation in boys. In utero dioxin levels will be estimated using the childs' current serum dioxin level, as well as historical reproductive (e.g., breast feeding) and residential information. In addition, the study will investigate whether in utero levels of dioxins are associated with reproductive tract abnormalities, specifically hypospadias and cryptorchidism.

Approach:

We propose to study a population with high environmental exposures. Individuals in Chapaevsk, Russia are exposed to high levels of dioxins as a result of environmental contamination from a large complex of chemical plants in the city. This project will assemble a cohort of pre-pubertal male children for prospective follow-up. These children will undergo a physical examination, complete a questionnaire along with their mother on birth history, medical history and lifestyle factors, and provide a blood sample for measurement of dioxins. Each year thereafter they will undergo a brief examination consisting of height and weight. Every three years they will undergo a complete physical examination and provide a blood sample.

Expected Results:

The results of this epidemiological study will further our understanding of the relationship between childhood exposure to dioxins and physical growth and sexual maturation. We will explore whether dioxins alter the age of onset or tempo of puberty. In addition, when the boys are of reproductive age we will investigate whether childhood exposure to dioxins altered testicular function, impairing semen quality. These results will form part of the scientific knowledge that will be used to inform national policy on endocrine disrupters and their effects on the male population. The dioxin exposure levels in the proposed study are higher than those in other areas of Russia, the United States or other countries. Therefore, this maximizes the power of the study to detect an association between dioxins and altered male sexual development, if one exists.

Supplemental Key Words: dioxin, puberty, cohort, reproduction, testis, adolescence, Chapaevsk Russia, hypospadias, cryptochidism

Relevant Web Sites:

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