=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #365
—November 25, 1993—
News and resources for environmental justice.
——
Environmental Research Foundation
P.O. Box 5036, Annapolis, MD 21403
Fax (410) 263-8944; Internet: erf@igc.apc.org
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A NEW ERA IN ENVIRONMENTAL TOXICOLOGY
The federal National Institute of Environmental Health Sciences
(NIEHS), in Bethesda, Maryland, has published a new report
describing the “developmental effects” of chemicals on humans and
animals. “Developmental effects” are those that occur during the
earliest time of life when the young are developing in the womb,
or in the egg. [1] With the publication of this report, ideas and
data developed by Dr. Theo Colborn and many of her colleagues [2]
have entered the mainstream of the nation’s scientific and
medical thinking. A new era of environmental toxicology has
begun. We believe that the work of Dr. Colborn and her
colleagues will eventually be seen to be as important as the work
of Rachel Carson, who woke the nation to the dangers of
pesticides and atomic fallout in her book, SILENT SPRING, in 1962.
The Colborn report is peppered with medical language, and is
therefore somewhat difficult for most readers to grasp. However,
the ideas in the report are of such profound importance that
everyone should own a copy, should read it themselves, and should
urge their family doctor to read it. We will mail it free to
anyone who sends a stamped, self-addressed envelope bearing 52
cents postage.
The new report describes a class of chemicals (35 common
pesticides, and 10 common industrial chemicals) [3] and a kind of
health damage from these chemicals that affects the offspring of
exposed adults. The damage to the offspring often remains hidden
until the young grow to maturity and even to middle age. The
damage occurs in three key bodily systems: the reproductive
system, the endocrine system, and the immune system. The report
describes evidence gathered from three sources: wildlife,
laboratory animals, and humans.
The report emphasizes interference with the endocrine system,
which then causes damage to the reproductive and immune systems.
The endocrine system is made up of specialized cells, tissues,
and organs that create and secrete (usually into the blood)
chemicals called hormones, which then regulate other kinds of
cells in the body. Particular hormones only affect particular
cells that contain “receptors” for those hormones. A small
amount of a hormone attaches to a “receptor” (a protein molecule)
and the hormone-receptor pair then initiates a cascade of
chemical changes, often with major and far-reaching consequences
in remote parts of the body. In this way, hormones act as
messengers, sending chemical signals that control the way the
entire body grows, is organized, and behaves.
What Colborn and her colleagues have discovered, examined, and
documented is that many chemicals in common use since World War
II enter the bodies of humans, domestic animals, and wildlife,
chiefly through contaminated food and water, and that these
chemicals mimic hormones. The body mistakes them for natural
hormones and reacts to them in ways that cause deep and permanent
trouble, especially when exposure occurs during the critical
period of development before, and immediately after, birth or
hatching.
Endocrine-disrupting chemicals mimic hormones, but with one key
difference. Natural hormones do their work as messenger (or as
stimulant of a cascade of other effects), and then the body
disassembles them and removes them from the blood stream. In
contrast, when industrial chemicals and pesticides mimic
hormones, they do not disappear quickly. They tend to remain in
the body for very long periods, doing the work of hormones at
times, and in ways, that are inappropriate and destructive.
The Colborn report begins with this summary:
“Large numbers and large quantities of endocrine-disrupting
chemicals have been released into the environment since World War
II. Many of these chemicals can disturb development of the
endocrine system and of the organs that respond to endocrine
signals in organisms indirectly exposed during prenatal and/or
early postnatal life; effects of exposure during development are
permanent and irreversible. The risk to the developing organism
can also stem from direct exposure of the offspring after birth
or hatching. In addition, transgenerational exposure [exposure
of offspring] can result from the exposure of the mother to a
chemical at any time throughout her life before producing
offspring due to persistence of endocrine-disrupting chemicals in
body fat, which is mobilized during egg laying or pregnancy and
lactation [production of milk].”
The report focuses on one group of chemicals, called the STEROID
HORMONES, which are produced by the mother’s ovaries and adrenal
glands, the placenta, and by the fetus’s gonads and adrenal
glands. Steroid hormones have been identified as playing a major
role in regulating developmental processes in many bodily systems
and tissues.
In humans, the development of the body’s organs begins during the
second month in the womb. From then on, the course of
development is regulated by steroid hormones and other parts of
the endocrine system.
Certain organs appear to be particularly vulnerable to
developmental abnormalities when the mother is exposed to
endocrine-disrupting chemicals. In female fetuses, the most
vulnerable organs are: breasts, fallopian tubes, uterus, cervix,
and vagina. In male fetuses, the critical organs are prostate,
seminal vesicles [where sperm originates], epididymides [a
reservoir for sperm], and testicles.
In both sexes, critical organs are the external genitals, the
brain, skeleton, thyroid, liver, kidney and immune system because
they are all targets for steroid hormone action.
Although the report begins by highlighting the role of “steroid
hormones,” much of the discussion centers on the particular
hormone called estrogen because most industrial
endocrine-disruptors mimic estrogen. (See RHWN #334, #343.)
Wildlife Evidence
The Colborn report offers a quick catalog of problems documented
in wildlife: Exposure to endocrine-disrupting chemicals in the
environment has been associated with abnormal thyroid function in
birds and fish; decreased fertility in birds, fish, shellfish,
and mammals; decreased hatching success in fish, birds, and
turtles; demasculinization and feminization of male fish, birds,
and gastropods [the group of animals that includes snails and
slugs]; and, finally, altered immune system function in birds and
mammals.
To illustrate wildlife problems caused by endocrine-disrupting
chemicals, the Colborn report describes the plight of the bald
eagle, also known as the American eagle because it is pictured on
the coat of arms of the U.S. Bald eagles around the Great Lakes
and in the Columbia River basin in Washington state are unable to
reproduce successfully after they have fed on local fish for two
years or longer. Their bodies contain up to 10 times as much DDT,
PCBs and chlordane [all of which have been banned for about 20
years in the U.S.] as would allow them to reproduce successfully.
Most of these chemicals are being transported into the U.S. via
the atmosphere from other countries where their use has not been
banned (and where some U.S.-connected firms continue to produce
them). They are also extremely persistent. “PCBs will be around
over geologic time,” the Colborn report says, meaning thousands
of years.
Human Evidence
The Colborn report spends considerable time discussing DES
(diethylstilbestrol), the synthetic hormone that was given to a
million American women by their physicians between 1960 and 1970
to prevent spontaneous abortions. DES is an endocrine-disrupter.
Daughters of women who took DES suffer reproductive organ
dysfunction, abnormal pregnancies, reduced fertility, immune
system disorders, and periods of depression. As young adults,
these women also suffer elevated rates of a rare vaginal cancer.
The report offers a very long list of problems caused in both
female and male children of DES-exposed mothers. “DES-exposed
humans thus serve as a model for exposure during early life to
any estrogenic chemical, including pollutants in the environment
that are estrogen agonists [mimickers or enhancers].” “It is now
suspected that increases in the incidence of numerous pathologies
[disease conditions] in men and women may be related to exposure
to pesticides and other endocrine-disrupting chemicals that can
mimic DES and are thus estrogen agonists [mimickers or
enhancers]. The clinical and experimental findings with DES show
that consideration must be given to the following facts:
- an increase in breast and prostatic cancer in the United States
occurred between 1969 and 1986; - a 400% increase in ectopic
[tubal] pregnancies occurred in the United States between 1970
and 1987; - a doubling of the incidence of cryptorchidism
[undescended testicles] occurred in the United Kingdom between
1970 and 1987; and - an approximate 50% decrease in sperm count
worldwide over the last 50 years. These trends may be a
reflection of the increase [of] estrogenic pollutants in the
environment. For example, an association between reduced sperm
motility [power of spontaneous movement] and PCBs in men with
fertility problems has been reported….”
“Evidence already exists that a number of organochlorine
chemicals (such as dioxin, PCB, and DDT) has reached
concentrations in aquatic food sources that can lead to
substantial functional deficits in animals that consume this
food,” the report says.
Furthermore, “Based on current breast milk concentrations
nationwide, it is estimated that at least 5% and possibly more of
the babies born in the United States are exposed to quantities of
PCBs sufficient to cause neurological effects.”
–Peter Montague, Ph.D.
=============
[1] Theo Colborn, Frederick S. vom Saal, and Ana M. Soto,
“Developmental Effects of Endocrine-Disrupting Chemicals in
Wildlife and Humans,” ENVIRONMENTAL HEALTH PERSPECTIVES Vol. 101
No. 5 (October, 1993), pgs. 378-384.
Descriptor terms: niehs; national institute of environmental
health sciences; developmental effects; theo colborn; theodora
colborn; rachel carson; radiation; nuclear weapons; fallout;
pesticides; endocrine system; immune system; reproductive
system; hormones; wildlife; reports; studies; steroid hormones;
estrogen; bald eagle; great lakes; columbia river; des;
diethylstilbestrol; breast cancer; prostate cancer;
cryptorchidism; undescended testicles; ectopic pregnancy; reduced
sperm count; pcbs; polychlorinated biphenyls; breast milk;
nervous system disorders; dioxin;