In this series we are asking whether mainstream scientists still
believe that industrial chemicals released into the environment
can interfere with hormones in wildlife and humans, causing
widespread harm. The NEW YORK TIMES in August said most
scientists don't. (See RACHEL'S #750, #751.) We have tried to
answer the question by examining the most recent 24 monthly
issues of ENVIRONMENTAL HEALTH PERSPECTIVES (EHP), a
peer-reviewed journal published by the federal National
Institutes of Health.
In RACHEL'S #751 we reported on seven studies linking
hormone-disrupting chemicals to human illnesses. This week, we
continue reporting on human studies, then turn to animal studies
(wildlife and laboratory animals).
** Background (meaning "normal" or everyday) exposure of healthy
Dutch pre-school children to PCBs and dioxins (potent
hormone-disrupting chemicals) via breast feeding is related to a
diminished number of immune system cells and increased middle ear
infections, coughing, and chest congestion, persisting at least
to the age of 42 months. Previously, immune system damage had
been observed in laboratory animals exposed to PCBs and dioxins
in their diet (see RACHEL'S #414).
(Dioxins are extremely toxic chemicals created as by-products of
many industrial processes, such as incinerators, where chlorine
combines with carbon at high temperatures. PCBs are dioxin-like
industrial chemicals manufactured by Monsanto between 1929 and
1976 and now found almost everywhere on the planet. See
An earlier study of Inuit children had found an increase in
otitis media (ear infections) among those exposed to
hormone-disrupting chlorinated chemicals through their mother's
milk. The Inuit live in the extreme northern part of the planet,
about as far away from industrial sources as anyone can get, but
many organochlorine chemicals march steadily northward as time
passes because cool weather "distills" them out of the
atmosphere. (This distillation process was described eloquently
in the book OUR STOLEN FUTURE -- see RACHEL'S #486 and see
The authors of the Dutch study point out that the proper response
to their findings would be to reduce the discharge of
hormone-disrupting chemicals into the environment, not curtail
breast feeding. EHP Vol. 108, No. 12 (December 2000), pgs.
** A pilot study of 29 men in Massachusetts showed an association
between levels of PCBs and DDE in their blood and reduced sperm
count, reduced sperm motility (ability to move), and sperm shape.
(DDE is a breakdown byproduct of the pesticide DDT.) Based on the
findings of the pilot study, a larger study has begun. EHP Vol.
110, No. 3 (March, 2002), pgs. 229-233.
In 1992, an analysis of 62 published studies reported that
American men today produce only half as much sperm as their
grandfather's did. In 1997, a re-analysis of the original 62
studies, using a different statistical technique, confirmed the
finding -- 50% average sperm loss among U.S. and Eur-opean/Australian
men, 1938-1990, though no evident decline among
non-Western males. Within the U.S., regional variations occur,
but the average decline is 50% nationwide.
Now a third analysis has been published, which includes an
additional 47 English-language studies, and extends the
time-period slightly, from 1934 to 1996. The basic finding
remains unchanged: a 50% reduction in sperm count among U.S. and
European/Australian men but not among non-Western men. EHP Vol.
108, No. 10 (October 2000), pgs. 961-966.
** A new study shows that the common plasticizer, DEHP
[Di(2-ethylhexyl) phthalate], blocks the normal action of male
sex hormone (androgen) and disrupts the normal growth of penis,
testicles, prostate, and semen tubes (seminal vesicles) in male
rats. (A plasticizer is a chemical added to hard plastics, such
as vinyl or PVC, to make them soft.) Furthermore, DEHP caused
malformed penises and caused male rats to lose interest in female
rats. The authors report that, at lower doses than were used in
this study, DEHP diminished the size of rats' testicles. The
authors conclude, "These results imply that the acceptable daily
intake for DEHP is only 3 micrograms of DEHP per kilogram of body
weight per day." They report that typical exposure to DEHP in the
U.S. ranges from 4 micrograms to 30 micrograms per kilogram of
body weight per day. Thus typical human exposures in the U.S. far
exceed the level of DEHP thought to be safe. The authors also
point out that DEHP may produce additive effects when combined
with other chemicals that behave in a similar manner. EHP Vol.
109, No. 3 (March 2001), pgs. 229-237.
** Diesel exhaust is a complex mixture of hydrocarbons and
metals. In young rats, exposure to diesel exhaust has been shown
to reduce the levels of certain hormones in the blood and to
diminish the production of sperm. A new study exposed 90 female
rats (72 pregnant, 18 not pregnant) to diesel exhaust for 13 days
(from day 7 to day 20 of pregnancy). In the offspring of the
pregnant rats, the development of testicles, ovaries and the
thymus gland (an important part of the immune system in mammals)
was "delayed and disturbed," the authors say. They go on, "Our
study provides evidence for the first time that inhalation of
diesel exhaust during pregnancy masculinizes fetuses through
accumulation of testosterone in mother rats." The authors wonder
what effects diesel exhaust might have on the immune system in
later life. (EHP Vol. 109, No. 2 [February 2001], pgs. 111-119.)
Immune disorders such as asthma and diabetes are rapidly
increasing in industrialized nations.
** Hypospadias is arrested development of the penis, and it
occurs in about 1 out of every 125 live male births in the U.S.
With hypospadias, the normal opening of the penis occurs not at
the tip but on the underside, sometimes as far back as the
scrotum. In the most extreme cases, hypospadias can make it
difficult to tell whether a newborn is a boy or a girl. The
problem can only be corrected surgically. The cause of
hypospadias is unknown.
The important discovery in 1995, that some environmental
chemicals act as anti-androgens, meaning they disrupt the
normal function of male sex hormones, has led researchers to ask
whether environmental anti-androgens may contribute to the
occurrence of hypospadias.
Four pesticides (or pesticide breakdown byproducts) are now
classified as anti-androgens: DDE (a breakdown byproduct of DDT),
Vinclozolin, Procymidone, and Linuron. In addition, two
phthalates, widely used in plastics and personal care products --DBP
[dibutyl phthalate] and DEHP [Di(2-ethylhexyl) phthalate] --are anti-
androgens. And dioxin and PCBs have anti-androgenic
properties. These eight chemicals have all been shown to cause
hypospadias in laboratory animals.
Hypospadias and other genital abnormalities were recently
reported in mink and river otters on the Columbia River, and
among populations of black bears and polar bears. With the
exception of the black bears, which were not monitored for
chemicals, all the abnormal animals had elevated levels of
organochlorine chemicals in their bodies. EHP Vol. 109, No. 11
(November 2001), pgs. 1175-1183.
** Although chlorinated chemical discharges from pulp (paper)
mills have decreased substantially during the past decade with
the adoption of nonchlorine bleaching systems (especially
outside the U.S.), harmful effects on fish downstream are still
regularly observed, including depression of hormone levels in
blood, delayed maturation, smaller gonad size, and confusion of
sexual characteristics -- for example, females developing an
elongated anal fin that is characteristic of males. This study
took advantage of a "natural experiment
dblquote -- a pulp
mill closed for a period of time, then started up again.
Researchers examined the ratio of male to female eels hatched
in waters below pulp mills that were operating, then when the
mills closed temporarily. While the mill was operating, the sex
ratio was significantly altered (only 42% males instead of the
usual 50%) but returned to normal when the mill temporarily
closed. EHP Vol. 110, No. 8 (August 2002), pgs. 739-742.
** The salmon populations of the northwestern U.S. have been
declining for decades, some to the point where they have already
gone extinct; others are listed as endangered. This study
examined female salmon on the Hanford Reach of the Columbia River
and found that an astonishing 84% of them had a genetic marker
that is normally only found in male salmon. The long-term effect
of this sex reversal would be to reduce the number of females in
each successive generation, eventually driving the species to
extinction. The researchers do not know what has caused the sex
shift in such a large proportion of wild salmon on the Columbia
River. They point out that some pesticides (atrazine, carbofuran,
lindane, methyl parathion, and dieldrin) are known to behave like
estrogen in rainbow trout and are present in the Columbia River,
though at levels considered too low to create this problem. Thus
the mystery remains unsolved. EHP Vol. 109, No. 1 (January 2001),
** Among male tadpoles exposed to dibutyl phthalate (DBP) at low
levels, about 7% of the males developed ovaries, thus confirming
previous studies showing that DBP is a hormone disrupter. DBP is
widely used in PVC pipe. The authors conclude that DBP is "an
environmentally dangerous hormone" that disrupts the development
of testicles in male animals. EHP Vol. 108, No. 12 (December
2000), pgs. 1189-1193.
** A survey of bullfrogs and green frogs in New Hampshire found
deformed frogs at 13 of 16 sites that were checked. Examination
of hormone levels in deformed and normal frogs revealed that
normal frogs have 3 times as much male sex hormone (androgen) in
their blood, compared to the deformed frogs. Normal frogs also
had three times as much of a hormone called
gonadotropin-releasing hormone (GnRH) which is produced by the
brain. This study suggests that hormone-disrupting chemicals may
be one of multiple causes that are producing malformed frogs, and
declines in frog populations, at many locations around the world.
EHP Vol. 108, No. 11 (November 2000), pgs. 1085-1090.
>From this brief examination of one peer-reviewed journal over
the past two years, the conclusion seems inescapable that
industrial chemicals in the environment can and do interfere
with the hormones of wildlife and humans, causing widespread
harm. Furthermore, it is clear that large numbers of scientists
agree that this is so because they are spending their lives
researching these problems instead of pursuing more lucrative
opportunities. Unfortunately, the full extent of these problems
remains unknown, and unknowable, for practical reasons that
will become clear in RACHEL'S #753.
[To be continued.] -- Peter Montague
 W.R. Kelce and others, "Persistent DDT metabolite p-p'-DDE
is a potent androgen receptor antagonist," NATURE Vol. 375, No.
6532 (1995), pgs. 581-585.