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#751 - The Latest Hormone Science -- Part 2, 04-Sep-2002

In this series we are exploring whether mainstream scientists
take seriously the idea that some industrial chemicals can
interfere with hormones (the "endocrine system") in living
things and thus cause health problems. The NEW YORK TIMES says
they don't. See RACHEL'S #750.

Hormones are naturally-occurring chemicals that circulate at
very low levels in the blood stream of all vertebrate animals
including reptiles, amphibians, fish, birds and mammals.[1]
(Vertebrates are animals with a backbone.) In all vertebrate
species, hormones act as chemical messengers and as switches,
turning on and off bodily systems that control growth,
development, learning and behavior. Hormones start affecting
every animal shortly after it begins life as a fertilized egg.
Hormones control growth and development prior to birth or
hatching, and they continue to influence behavior throughout
life. Hormones determine when bears will hibernate, when salmon
will return to their spawning grounds, and when women will
menstruate. Hormones profoundly affect the nervous system, the
reproductive system, and the immune system. Naturally-occurring
hormones are also implicated in some forms of cancer, such as
female breast cancer which is widely believed to be linked to a
woman's lifetime exposure to estradiol (estrogen), the main
female sex hormone.

The question is, do some hormonally-active industrial chemicals
interfere with naturally-occurring hormones and give rise to
disease (certain cancers or autoimmune disorders such as
diabetes, for example), or hinder growth, development,
behavior, intelligence, learning, or immunity? Three years ago,
in 1999, the National Academy of Sciences studied this question
and concluded that the answer is a qualified Yes:

Here are some quotations from the Academy's 1999 report:

"Adverse reproductive and developmental effects have been
observed in human populations, wildlife, and laboratory animals
as a consequence of exposure to HAAs [hormonally active

"Studies with laboratory animals have shown that prenatal
exposure to some HAAs, such as methoxychlor [a pesticide], TCDD
[dioxin], and octylphenol and bisphenol A can reduce sperm

"Taken together, the results of animal and human studies
indicate that prenatal exposure to PCBs can affect neurologic
development."[2,pg.175] [PCBs are highly-toxic, persistent
industrial chemicals released into the environment for 40 years
by Monsanto and now found in food, water and soil world-wide.]

"In the Michigan/Maternal Infant Cohort Study, Fein et al.
(1984) evaluated the birth size and gestational age of 242
infants and found that maternal consumption of fish and
concentrations of PCBs in cord serum [in blood in the umbilical
cord] were correlated with lowered birth weight, shortened
gestation [time in the womb], and smaller head circumference.
Lower weight was also observed in children from this cohort at
4 yr [years] in a dose-dependent fashion (Jacobson et al.
1990). Children with cord serum PCB levels of 5.0 ng/mL
[nanograms per milliliter] or more weighed 1.8 kg [4 pounds]
less on average than the lowest exposed children. Prenatal
exposure was also associated with deficits in neurologic
development in followup studies of these children at up to 11
yr [years]."[2,pg.125]

"It has been well documented that HAHs [halogenated aromatic
hydrocarbons] such as TCDD [dioxin], polychlorinated
dibenzofurans (PCDFs), and PCBs, affect immune response, and
they appear to affect all functional arms of the immune system
(innate immunity and host resistance, cell-mediated immunity,
and humoral immunity)."[2,pg.178]

"There have only been a few studies of the effects of HAAs
[hormonally active agents] in humans, but the results of
laboratory and wildlife studies suggest that HAAs have the
potential to affect human immune functions."[2,pg.194]

With this background, let's review the last two years' worth of
peer-reviewed journal published by the federal National
Institutes of Health. This will tell us whether scientists have
recently rejected or abandoned the idea that industrial
chemicals can interfere with hormones.

The first thing that struck me as I read through the past 24
monthly issues of EHP is that there is much more human data now
than there was 5 years ago. Most studies still involve
laboratory animals or wildlife, but humans figure prominently
in many recent findings. Here is a sampling:

** Women exposed to dioxin by living near the scene of an
industrial accident in Seveso, Italy in 1976 are now showing an
excess of breast cancer, even though they are still relatively
young (average age 40.8 years). Scientists within U.S.
Environmental protection Agency (EPA) have been referring to
dioxin as an "environmental hormone" since 1992. (See RACHEL'S
#269.) [EHP Vol. 110, No. 7 (July 2002), pgs. 625-628.]

** Forest pesticide applicators who spray the popular herbicide
known as 2,4-D have altered levels of male sex hormone in their
blood. [EHP Vol. 109, No. 5 [May 2001], pgs. 495-500.] Thus
2,4-D joins the growing list of common chemicals known to
disrupt hormones. 2,4-D is the herbicide used more than any
other on lawns to kill dandelions and crab grass. It is sold
under many names, including my personal favorite, Hormotox. It
is also known as Demise, Weed-B-Gone, Weedone, Lawn-Keep, Raid
Weed Killer, Plantgard, and Ded-Weed, among other trademarked
names. Earlier studies showed that pet dogs die of cancer at
twice the normal rate if they live in a family that uses 2,4-D
on its lawn. (See RACHEL'S #250.)

A recent study shows that children's exposure to 2,4-D inside
homes increases 10-fold after lawns are treated with 2,4-D. The
family dog and humans' shoes are the main vehicles transporting
2,4-D into homes, exposing children living there. [EHP Vol.
109, No. 11 (November 2001), pgs. 1185-1191.]

** A study of 100 adolescents who grew up near waste
incinerators or a metal smelter shows developmental delays in
sexual maturity, compared to a control group living in an
uncontaminated rural area. Adolescents in Flanders (Belgium)
living in moderately polluted urban neighborhoods have
"relatively low" levels of PCBs and dioxin-like polychlorinated
aromatic hydrocarbons (PCAHs) in their blood. Even these low
levels correlated with delayed sexual maturation in both girls
and boys, the study concludes. In 1997 the Flemish government
had reported a higher percentage of conceptions requiring
medical assistance near incinerators, compared to the rest of

The authors conclude, "Through endocrine disruption,
environmental exposure to PCAHs may interfere with sexual
maturation and in the long-run adversely affect human
reproduction." [EHP Vol. 110, No. 8 (August 2002), pgs.

** Premature breast development (known as thelarche, pronounced
thee-larkey) is the growth of breasts in girls younger than 8
with no other signs of puberty. Puerto Rico has the highest
incidence of thelarche ever reported. The problem there has
been studied for years, to no avail. Now a study of 41 girls in
Puerto Rico with thelarche and 35 girls without thelarche has
found that 68% of the thelarche girls had high levels of
several phthalates (pronounced tha-lates) in their blood. Only
one of the non-thelarche girls had measureable levels of one
phthalate in her blood. The phthalates found in the thelarche
group are known to have estrogenic and anti-androgenic effects.
(Anti-androgenic means "interferes with male hormone." Humans
of both genders always have a mix of male and female hormones
in their blood stream, the balance between them being
important.) [EHP Vol. 108, No. 9 (September 2000), pgs.

Phthalates are common industrial chemicals used in building
materials, food packaging and food wrap, toys and other
children's products, medical devices, garden hose, shoes, shoe
soles, automobile undercoating, wires and cables, carpet
backing, carpet tile, vinyl tile, pool liners, artificial
leather, canvas tarps, notebook covers, tool handles,
dishwasher baskets, flea collars, insect repellents, skin
emollients, hair sprays, nail polish, and perfumes, among other

In October, 2000, a study reported in EHP measured the
metabolic byproducts of 7 phthalates in the urine of adults and
concluded that exposure to phthalates "is both higher and more
common than previously suspected." The highest levels (1 to 16
parts per million in urine) were phthalates known as MEP, MBP,
and MBzP and they occurred at the highest levels in women of
child-bearing age. MBP and MBzP have previously been shown to
cause reproductive and developmental toxicity in animals. [EHP
Vol, 108, No. 10 (October 2000), pgs. 979-982.]

** A study of 63 female Air Force personnel with exposure to
jet fuel (JP-8) and solvents showed that the most exposed women
had the lowest levels of four reproductive hormones in their
urine. The hormones were studied because they indicate
likelihood of success or failure in conception. Thus the
components of jet fuel, and/or solvents, are likely hormone
disruptors in human females. [EHP Vol. 110, No. 8 (August,
2002), pgs. 805-811.]

** Two new studies indicate that Monsanto's herbicide, Roundup,
is a hormone-disruptor and is associated with birth defects in

Farm families that applied pesticides to their crops in
Minnesota were studied to see if their elevated exposure to
pesticides caused birth defects in their children. The study
found that two kinds of pesticides -- fungicides and the
herbicide Roundup -- were linked to statistically significant
increases in birth defects. Roundup was linked to a 3-fold
increase in neurodevelopmental (attention deficit) disorders.
[EHP Supplement 3, Vol. 110 (June 2002), pgs. 441-449.]

A recent test tube study reveals that Roundup can severely
reduce the ability of mouse cells to produce hormones. Roundup
interferes with a fundamental protein called StAR
(steroidogenic acute regulatory protein). The StAR protein is
key to the production of testosterone in men (thus controlling
male characteristics, including sperm production) but also the
production of adrenal hormone (essential for brain
development), carbohydrate metabolism (leading to loss or gain
of weight), and immune system function. The authors point out
that "a disruption of the StAR protein may underlie many of the
toxic effects of environmental pollutants." [EHP Vol. 108, No.
8 (August 2000), pgs. 769-776.]

Monsanto, the St. Louis chemical giant and creator of Roundup
as well as PCBs, is now a leader in genetically engineered
crops. Monsanto sells "Roundup ready" seeds for corn, soybeans,
and cotton; wheat and lawn grasses will be next. These are
seeds engineered to withstand a thorough dousing with Roundup,
which kills weeds without killing the Roundup-ready crops. To
make Monsanto's "Roundup ready" seeds legal, U.S. Environmental
Protection Agency (EPA) had to triple the amount of Roundup
residues that it allows on crops. For years, Roundup has been
Monsanto's most profitable product, and genetic engineering has
now allowed the firm to sell much more of it. See RACHEL'S
#637, #639, #660, #686, #726.

For example, a 1999 study of soybean farming in the U.S.
midwest found that farmers planting Roundup Ready soybeans used
2 to 5 times as many pounds of herbicide per acre as farmers
using conventional systems, and ten times as much herbicide as
farmers using Integrated Weed Management systems, which are
intended to reduce the need for chemical herbicides.[3,pg.2]

More chemical dangers probably lie ahead as new products of
genetic engineering come to market. According to the NEW YORK
TIMES, Scotts Company is collaborating with Monsanto to develop
Roundup Ready grass for lawns.[4] Children and pregnant women,

[To be continued.] --Peter Montague


[1] H. Maurice Goodman, BASIC MEDICAL ENDOCRINOLOGY [Second
Edition] (New York: Raven Press, 1994).

[2] Ernst Knobil and others, HORMONALLY ACTIVE AGENTS IN THE
ENVIRONMENT (Washington, D.C.: National Academy Press, July
1999). ISBN 0-309-06419-8.

[3] Charles Benbrook, "Evidence of the Magnitude and
Consequences of the Roundup Ready Soybean Yield Drag from
University-Based Varietal Trials in 1998," AgBioTech InfoNet
Technical Paper #1, July 13, 1999. Available at

[4] David Barboza, "Suburban Genetics: Scientists Searching for
a Perfect Lawn," NEW YORK TIMES July 9, 2000, pg. A1.