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#514 - Chemicals Linked to Declining Male Reproductive Health, 02-Oct-1996

A lengthy new report from the National Institute of Environmental
Health Sciences [NIEHS], a federal agency, describes serious
deterioration of the male reproductive system in many regions of the
world and suggests it may be caused by environmental chemicals that
interfere with hormones.[1] The report begins by describing negative
trends in men's reproductive health, then describes similar findings
among wildlife, and finally reviews evidence that certain chemicals
could cause the observed problems. The report ends by describing a
research agenda that would help scientists understand these problems
better and would provide additional support for public health officials
taking action to protect future generations. Here is part of the
summary provided by the authors of the new study:

"Male reproductive health has deteriorated in many countries during the
last few decades. In the 1990s, declining semen quality has been
reported from Belgium, Denmark, France, and Great Britain. The
incidence of testicular cancer has increased during the same time.
Incidences of hypospadias [a birth defect of the penis] and
cryptorchidism [undescended testicles] also appear to be increasing.
Similar reproductive problems occur in many wildlife species. There are
marked geographic differences in the prevalence of male reproductive
disorders. While the reasons for these differences are currently
unknown, both clinical and laboratory research suggest that the adverse
changes may be inter-related and have a common origin in fetal life or
childhood." The authors say they strongly suspect that the common
origin is exposure to environmental chemicals (pesticides, plastics,
detergents, and others) that interfere with hormones.

The authors emphasize that chemicals that interfere with hormones may
not be the ONLY cause of the recent decline in male reproductive
health. Other chemicals may poison men by a mechanism that does not
involve hormones: "For example," they say, "some chemicals that are now
known as occupational toxicants were shown to affect the semen quality
of the workers through a toxic action on the gonads, without any
apparent estrogenic effects." Estrogen is the main female sex hormone.
[For a superb, clear, down-to-earth discussion of both male and female
Physicians for Social Responsibility, which we will review in the next
few weeks. Anyone concerned about these problems should own a copy of

Sperm Quality

The authors review recent studies showing declining sperm quantity and
quality among men in many countries, and a few studies that show no
such declines. In general, they see declines in urban areas and no
declines in rural areas. Rural France and Finland, in particular, seem
not to be experiencing a sperm decline. Still, the authors summarize
the situation as "decreasing sperm quality worldwide" (pg. 743) and
they see an urgent need for understanding the causes: "Follow-up of
semen quality is very important, since the sperm concentration has
decreased drastically during the last two generations and the declining
trend appears to be continuing." (pg. 760)

Testicular Cancer

Here, too, there are geographical differences. Increases in testicular
cancer are apparent in the U.S., England and Wales, Scotland, the
Nordic and Baltic countries, Australia, and New Zealand. Finland seems
to be an exception. The authors suggest that good, steady sperm quality
and the low testicular cancer rate in Finland, a mostly rural country,
may be somehow linked. Within countries there are differences: whites
in the U.S. are three times as susceptible to testicular cancer as are
African Americans.

Conclusion: "...it is obvious that there is a worldwide trend toward an
increased incidence of testicular cancer...," the authors of the report
conclude. (pg. 743)

Conclusion: "Other disorders of the male reproductive tract may also be
increasing in incidence, with several European countries reporting a
progressive rise in hypospadias [a birth defect of the penis]... and an
apparently emerging trend toward an increasing incidence of testicular
maldescent [undescended testicles]." (pg. 768)

Similarly, male reproductive problems can be observed among wildlife.
Gastropods (periwinkles and whelks), best known for the sea shells they
live inside, worldwide have shown sex reversal because of exposure to a
compound of the metal tin. Tributyltin, widely used in paint to keep
seaweed and barnacles from growing on the bottoms of boats and ships,
is now known to change male gastropods into female gastropods. (pg.

Alligators and turtles have had their sex lives disrupted by exposure
to pesticides in Florida and in laboratory experiments. The sex of
turtles is normally determined by the temperature at which their eggs
incubate. Eggs incubated at 26 degrees Celsius (78.8 Fahrenheit) turn
out 100% male. However, eggs incubated at male-producing temperatures
but painted with PCBs produce female turtles instead. (pg. 749) PCBs
are industrial chemicals, banned in this country in 1976, but still
found everywhere in the environment. The same PCB-induced sex reversal
can be seen in alligator eggs. Furthermore, alligators in pesticide-
contaminated lakes in Florida have such small penises that they are
sexually incompetent --a result of exposure to hormone-disrupting
pesticides. (pg. 749)

Male fish exposed to hormone-disrupting chemicals discharged by sewage
treatment plants begin to produce a protein called vitellogenin, which
is normally only produced by female fish as a step toward making eggs.
Male fish normally produce no vitellogenin but in England and Wales
male fish produce vitellogenin when they are caged in river waters
below sewage treatment plants. (pg. 750) The river water has become

Florida panthers, which get a large dose of hormone-disrupting
chemicals by eating raccoons (who get these chemicals from the fish
they eat), have undescended testicles, poor sperm production, and other
reproductive problems. (pg. 751)

The NIEHS report then reviews the experience of male children whose
mothers were exposed to DES (diethylstilbestrol). DES is a synthetic
sex hormone. Between the late 1940s and the early 1970s, DES was given
to 5 million pregnant women to prevent abortion and pregnancy
complications. The sons of these women thus became a "natural
experiment," offering an opportunity to study the effects of human
exposure to hormone-disrupting chemicals while in the womb. Here is the
authors' summary: "Exposure to DES during pregnancy results in
increased risk for several male reproductive disorders, such as
cryptorchidism [undescended testicles], urethral abnormalities
[including hypospadias, pg. 753], epididymal cysts [cysts in the sperm
reservoir of the testicle], and testicular hypoplasia [lack of growth
of the testicles, i.e., small testicles]. In addition, the semen
quality of DES sons is worse than that of controls. Incidence of
testicular cancer is approximately doubled among DES sons compared to
the general population but whether this represents a true increase of
the cancer risk is equivocal [i.e., not certain]." (pg. 754)

In sum, the authors say, "Reproduction is a major concern because
disturbances of this process rapidly threaten populations as a whole.
The male reproductive system is very sensitive to the influence of an
excess of estrogen; therefore, estrogenlike effects in the environment
are a primary suspect for causing the increased reproductive disorders
of men and wildlife animals." (pg. 760)

And: "Male reproductive health has received remarkably little attention
considering that subfertility affects 5% or more of men and that
prostatic hypertrophy [enlargement of the prostate gland] or cancer is
a major problem for older men. It is now evident that several aspects
of male reproductive health have changed dramatically for the worse
over the past 30 to 50 years. The most fundamental change has been the
striking decline in sperm counts in the ejaculate of normal men; recent
evidence from Paris indicates that this decrease amounts to about 2%
per year over the last two decades. The result is that many otherwise
normal men now have sperm counts so low that their fertility is likely
to be impaired....

"These observations suggest that male reproductive health has declined
progressively since the Second World War as a result of changes in
environmental or lifestyle factors. While the etiologies [causes]
underlying these apparent changes are currently unclear, both clinical
[i.e., human] and laboratory [i.e., animal] research suggests that all
of the described changes in male reproductive health appear
interrelated and may have a common origin in fetal life or childhood.
This means that the increase in some of the disorders seen today
originated 20 to 40 years ago, and the prevalence of such defects in
male babies born today will not become manifest for another 20 to 40
years or more.

"Trends in the reproductive health of species other than man also raise
the possibility of environmental factors as partial etiologic [causal]
contributions in a decline noted in male reproductive health of
wildlife." The report then mentions the Florida panther, the male fish
in England and Wales producing vitellogenin, "fish-eating birds in the
United States" whose "male hatchlings were apparently feminized," and
the male turtles turning into female turtles because of PCB exposure of
their eggs in the laboratory. And: "A recent report of lactating male
fruit bats suggested that the males were, in some way, exposed to a
female sex hormone." In sum, "Taken together, this growing body of
evidence suggests that environmental factors that resemble female sex
hormones may be having an adverse effect on the reproductive capacity
and well being of diverse species...."

"The reproductive health trends in men are consistent with this
hypothesis. While exposure levels to estrogenic chemicals are not at
all well known for humans, the large number of chemicals in numerous
environmental categories suggests adequate availability. For example,
environmental chemicals reported to be estrogenic include, but are not
limited to, some ubiquitous [i.e., found everywhere] chlorinated
hydrocarbons, such as PCBs and DDT; some products of detergent and
surfactant manufacture, such as the alkylphenols; and some products
released from plastics such as bisphenol-A and some phthalates. Many
other compounds in our natural and synthetic [human-created]
environment demonstrate estrogenic activities and more are being
discovered as the search continues." (pgs. 768-769)

--Peter Montague (National Writers Union, UAW Local 1981/AFL-CIO)


[1] Jorma Toppari and others, "Male Reproductive Health and
Environmental Xenoestrogens," ENVIRONMENTAL HEALTH PERSPECTIVES Vol.
104 SUPPLEMENT 4 (August 1996), pgs. 741-803. This new report is a
revised and abridged version of a report originally commissioned by the
Danish Environmental Protection Agency in Copenhagen; see REHW #438.

[2] Ted Schettler, Gina Solomon, Paul Burns, and Maria Valenti,
HEALTH IN MASSACHUSETTS (Cambridge, Massachusetts: Greater Boston
Physicians for Social Responsibility [11 Garden Street, Cambridge,
Mass. 02138; telephone (617) 497-7440; fax: (617) 876-4277; E-mail:
psrmabo@igc.apc.org], 1996). Available for $11.50.


In the electronic edition of RACHEL'S #513, we wrote: "One set of
nuclear long johns contained enough plutonium to provide one trillion
(one million million million) 'maximum permissible lung burdens' of
plutonium..." It should have said "...one trillion (one million

Descriptor terms: niehs; male reproductive health; testicular cancer;
hormone disrupters; wildlife; sperm count; sperm quality; hypospadias;
cryptorchidism; undescended testicles; birth defects; teratogens;
pesticides; plastics; detergents; estrogen; france; finland;
gastropods; tributyltin; alligators; turtles; pcbs; penis size;
vitellogenin; florida panthers; des; prostate cancer; children;
alkylphenols; phthalates; bis-phenol-A; DDT; organochlorines;