the metabolism and blood sugar levels. The female ovaries, male testes, and pituitary, thyroid, and adrenal glands are major constituents of the endocrine system.
The Endocrine Disruptor Screening Program (EDSP) focuses on the estrogen,
androgen, and thyroid hormones. Estrogens are the group of hormones responsible
for female sexual development. They are produced primarily by the ovaries and in
small amounts by the adrenal glands. Androgens are responsible for male sex
characteristics. Testosterone, the sex hormone produced by the testicles, is an
androgen. The thyroid gland secretes two main hormones, thyroxine and triiodothyronine, into the bloodstream. These thyroid hormones stimulate all the cells in the
body and control biological processes such as growth, reproduction, development,
and metabolism.
It is thought that EDCs may be responsible for some reproductive problems in
both women and men as well as for the increases in the frequency of certain types of
cancer. EDCs have also been linked to developmental deficiencies and learning
disabilities in children. Because hormone receptor systems are similar in humans and
animals, effects observed in wildlife species raise concerns of potential human health
effects. During fetal development and early childhood, low-dose exposure to EDCs
may have profound effects not observed in adults such as reduced mental capacity
and genital malformations. Evaluating potential low-dose effects of environmental
estrogenic compounds has been identified as a major research priority.
There is growing evidence that artificial chemicals in the environment can disrupt
hormones by sending erroneous signals or blocking legitimate signals. Since the
hormones are part of the endocrine system, the hormone disrupters are also called
endocrine disrupters. And since the concern originated with estrogen, the “female”
hormone, they are sometimes called estrogen mimics.
The strongest evidence that endocrine disrupters are damaging human or animal
health comes from the animal kingdom. In the 1980s and 1990s, fish and beluga
whales with horrible malformations showed up in the Great Lakes region, with
cancers, ulcers, and other deformations. In the 1990s, an epidemic of misshapen
reproductive organs in Florida alligators was blamed on a pesticide spill into the
lake. Other reproductive abnormalities in gulls, mink, eagles, and other animals have
been blamed on chemicals that mimic hormones. Furthermore, in the laboratory, tiny
concentrations of hormone mimics lock onto cell receptors, causing the cells to
reproduce in a phenomenon suspiciously like cancer.
The controversy about endocrine disrupters began with concern about chemicals
that disrupt estrogen, but now it has expanded to cover chemicals that interfere with
androgens male hormones. Keeping in mind that males have female hormones, and
vice versa, it is immediately realized that the endocrine story is a lot more complicated than once thought.
Several studies have found a worldwide lowering of sperm counts and blamed it
on the rising concentrations of estrogen mimics in the environment. Some scientists
say estrogen mimics could also explain the growing incidence of breast cancer and
perhaps prostate cancer as well [4–6].
The putative endocrine disrupters have structures akin to real hormones and seem
to include breakdown products of several pesticides that are now banned, such as
(a) DDT; (b) PCBs, a persistent group of chemicals still found in electrical
172
N. K. Shammas et al.
The Endocrine Disruptor Screening Program (EDSP) focuses on the estrogen,
androgen, and thyroid hormones. Estrogens are the group of hormones responsible
for female sexual development. They are produced primarily by the ovaries and in
small amounts by the adrenal glands. Androgens are responsible for male sex
characteristics. Testosterone, the sex hormone produced by the testicles, is an
androgen. The thyroid gland secretes two main hormones, thyroxine and triiodothyronine, into the bloodstream. These thyroid hormones stimulate all the cells in the
body and control biological processes such as growth, reproduction, development,
and metabolism.
It is thought that EDCs may be responsible for some reproductive problems in
both women and men as well as for the increases in the frequency of certain types of
cancer. EDCs have also been linked to developmental deficiencies and learning
disabilities in children. Because hormone receptor systems are similar in humans and
animals, effects observed in wildlife species raise concerns of potential human health
effects. During fetal development and early childhood, low-dose exposure to EDCs
may have profound effects not observed in adults such as reduced mental capacity
and genital malformations. Evaluating potential low-dose effects of environmental
estrogenic compounds has been identified as a major research priority.
There is growing evidence that artificial chemicals in the environment can disrupt
hormones by sending erroneous signals or blocking legitimate signals. Since the
hormones are part of the endocrine system, the hormone disrupters are also called
endocrine disrupters. And since the concern originated with estrogen, the “female”
hormone, they are sometimes called estrogen mimics.
The strongest evidence that endocrine disrupters are damaging human or animal
health comes from the animal kingdom. In the 1980s and 1990s, fish and beluga
whales with horrible malformations showed up in the Great Lakes region, with
cancers, ulcers, and other deformations. In the 1990s, an epidemic of misshapen
reproductive organs in Florida alligators was blamed on a pesticide spill into the
lake. Other reproductive abnormalities in gulls, mink, eagles, and other animals have
been blamed on chemicals that mimic hormones. Furthermore, in the laboratory, tiny
concentrations of hormone mimics lock onto cell receptors, causing the cells to
reproduce in a phenomenon suspiciously like cancer.
The controversy about endocrine disrupters began with concern about chemicals
that disrupt estrogen, but now it has expanded to cover chemicals that interfere with
androgens male hormones. Keeping in mind that males have female hormones, and
vice versa, it is immediately realized that the endocrine story is a lot more complicated than once thought.
Several studies have found a worldwide lowering of sperm counts and blamed it
on the rising concentrations of estrogen mimics in the environment. Some scientists
say estrogen mimics could also explain the growing incidence of breast cancer and
perhaps prostate cancer as well [4–6].
The putative endocrine disrupters have structures akin to real hormones and seem
to include breakdown products of several pesticides that are now banned, such as
(a) DDT; (b) PCBs, a persistent group of chemicals still found in electrical
172
N. K. Shammas et al.