an chronic exposure to relatively low doses of estrogen - as might be
experienced due to environmental contact - at critical times during growth
and development emasculate or reproductively weaken the adult human male?
That is the question posed by Dr. Sam Campbell, chairman of UAH's
Biological Sciences Department, and Marilyn Wyatt, a student from Tugaloo
College in Mississippi.
Scientists are just beginning to recognize the presence of environmental
pollutants which mimic the female sex hormone, estrogen, said Campbell.
"The consequences of such exposure aren't known, but it is possible that
this 'pollution' could lead to increased incidence of breast cancers and
altered reproductive cycles in women and reduced fertility, impotence, or
sterility in men."
In work that began in June 1994 as part of the Alliance for Minority
Participation, Campbell and Wyatt implanted low dose, continuous release
pellets of estradiol (the principal estrogen in the female) in male rats
at developmental periods chosen to be representative of the neonatal,
infant, childhood, and adolescent stages of growth.
Although the research results are preliminary, Campbell said, it appears
that chronic exposure to estrogen during the neonatal and adolescent
stages may contribute to the development of reproductive impairments.
These impairments included reduced testes size, reduced penile shaft
length, low blood testosterone levels, sterility, and infertility.
"It is also necessary to demonstrate that it is, in fact, the
estrogenicity of these compounds which is detrimental ... and not other
unrelated chemical toxicity," he said. "While a great deal of work still
needs to be done, the initial results look interesting and promising."
Estrogen is used therapeutically as a contraceptive, and to treat
menopausal disorders such as "hot flashes" and osteoporosis. It also has
been used to treat prostate cancer in men.
Misuse or chronic, uncontrolled exposure, however, may cause harm.
For instance, mothers with a history of miscarriages who were treated
during their pregnancies with DES, a powerful synthetic estrogen, in an
attempt to prevent spontaneous abortions gave birth to children who later
developed reproductive tissue disorders, such as vaginal or testicular
cancer.
Estrogen mimics are found in polychlorinated biphenyls (PCB's), in the
plastic liners used in some canned foods, and in some commonly used
pesticides.