Environmental Health News

What's Working

  • Garden Mosaics projects promote science education while connecting young and old people as they work together in local gardens.
  • Hope Meadows is a planned inter-generational community containing foster and adoptive parents, children, and senior citizens
  • In August 2002, the Los Angeles Unified School District (LAUSD) Board voted to ban soft drinks from all of the district’s schools

#365 - A New Era In Environmental Toxicology, 24-Nov-1993

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

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: 1) an increase in breast and
prostatic cancer in the United States occurred between 1969 and 1986;
2) a 400% increase in ectopic [tubal] pregnancies occurred in the
United States between 1970 and 1987; 3) a doubling of the incidence of
cryptorchidism [undescended testicles] occurred in the United Kingdom
between 1970 and 1987; and 4) 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


[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.

[2] Theo Colborn and Coralie Clement, editors. CHEMICALLY-INDUCED
CONNECTION. Princeton, N.J.: Princeton Scientific Publishing Co., 1992.

[3] The Colborn report lists the following endocrine-disrupting
chemicals: 2,4,-D; 2,4,5-T; alachlor; amitrole; atrazine; metribuzin;
nitrofen; trifluralin; benomyl; hexachlorobenzene; mancozeb; maneb;
metiram-complex; tributyl tin; zinab; ziram; beta-HCH; carbaryl;
chlordane; dicofol; dieldrin; DDT and metabolites; endosulfan;
heptachlor and heptachlor epoxide; lindane (gamma-HCH); methomyl;
methoxychlor; mirex; oxychlordane; parathion; synthetic pyrethroids;
toxaphene; transnonachlor; aldicarb; DBCP; cadmium; dioxin (2,3,7,8-
TCDD); lead; mercury; PBBs; PCBs; pentachlorophenol (PCP); penta-to
nonylphenols; phthalates; styrenes.

Descriptor terms: niehs; developmental effects; theo colborn; rachel
carson; radiation; nuclear weapons; fallout; pesticides; endocrine
system; immune system; reproductive system; hormones; wildlife;
studies; steroid hormones; estrogen; bald eagle; great lakes; columbia
river; des; breast cancer; prostate cancer; cryptorchidism; undescended
testicles; ectopic pregnancies; reduced sperm count; pcbs; breast milk;
nervous system disorders; dioxin;

Error. Page cannot be displayed. Please contact your service provider for more details. (26)