=======================Electronic Edition========================
RACHEL’S ENVIRONMENT & HEALTH WEEKLY #447
—June 22, 1995—
News and resources for environmental justice.
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THE CHALLENGE OF OUR AGE
In the past 60 days, two important British scientific journals
have published editorials calling for more research into
environmental chemicals that may be harming the reproductive
health and sexual development of men throughout the
industrialized world. NATURE (the equivalent of SCIENCE magazine
in the U.S.) said on June 15th, “The case for research to be
conducted urgently is overwhelming.” [1] The medical journal,
LANCET (approximately equivalent to the NEW ENGLAND JOURNAL OF
MEDICINE in this country) was much more explicit, making the
following points: [2]
** Industrial chemicals that mimic sex hormones (or
xeno-estrogens, as they are sometimes called) “may be responsible
for a massive decrease in male sperm counts and semen quality
since 1940,” LANCET said.
** “Female infertility is the subject of intense research and an
unfailing source of headlines for the popular press. Male
reproductive health has not been studied nearly so thoroughly,
and little attention was paid to a series of observations
indicating that the frequency with which a male factor is
responsible for a couple’s infertility has increased in recent
years from about 10% to 25%,” LANCET said.
** “Numerous compounds in daily industrial, agricultural, or
domestic use have oestrogenic effects [oestrogen is the British
spelling of estrogen], but the endocrine effects of the tens of
thousands of man-made chemicals with which we come into daily
contact have been studied in only a few instances, and then by
accident rather than design…. For most chemical pollutants we
do not know whether they are oestrogenic or not, what their
effects are singly or together, or even the degree of our
exposure…. They will remain in the environment for generations,
and even small amounts of such contaminants can lead to the
accumulation of considerable quantities in animal and human
tissues,” LANCET said.
** “It is the mother’s lifetime exposure [prior to pregnancy]
that determines the fetal dose, not just her exposure during
pregnancy,” LANCET said.
Both these journals called for urgent research to learn more
about the male reproductive system, the chemicals that we
encounter in our daily lives, and the effects those chemicals may
have, singly or in combination, on male reproductive health.
The research task is formidable, to say the least. It is
well-known that sexual differentiation (the point at which males
become males and females become females in the womb) is initiated
by the presence of the Y chromosome, which sets in motion male
development; absence of the Y chromosome sets in motion female
development. After initiation by the Y chromosome (or absence of
it), all further steps are controlled by chemicals called
hormones –estrogens are the “female” hormones and androgens are
the “male” hormones. But the development of gender, with all its
physical and behavioral aspects, depends upon both estrogens and
androgens in both males and females; it is the balance of these
chemicals, in combination, that produces normal differentiation
and development. [3] All females contain some androgens, and all
males contain some estrogens; it is the balance of the two types
of chemicals that is important.
Over the past 30 years, it has been discovered that many
industrial chemicals mimic estrogens. (See RHWN #263, #264, #343,
#365, #372, #377, #446.) An “estrogen hypothesis” has been
proposed to explain why each year more men in the industrialized
world are getting cancer of the testicles, birth defects
affecting the penis, lowered sperm count, lowered sperm quality,
and undescended testicles. The estrogen hypothesis suggests that
all of these effects can be traced to one cause: industrial
chemicals mimicking hormones, affecting male children while they
are still in the womb. [4]
However, in the last two years, a different set of concerns has
been raised: some chemicals that don’t mimic estrogens can still
interfere with sexual differentiation and development in
laboratory animals; they do it by interfering with the action of
androgens (male hormones). Since it is the BALANCE of estrogens
and androgens that creates one gender or another, anti-androgens
can interfere with male development as effectively as excessive
estrogens can. In NATURE June 15, William Kelce, a researcher at
U.S. Environmental Protection Agency (EPA) reported that a
breakdown byproduct (“metabolite”) of the pesticide DDT (called
p,p’-DDE, and pronounced “p, p-prime D D E”) is a powerful
anti-androgen. [5] Anti-androgen drugs (developed as therapy for
human prostate cancer), when given to animals before and shortly
after birth, can cause reproductive tract disorders, including
small penis, hypospadias, [6]and undescended testicles. Thus it
is important to learn that a DDT metabolite is a powerful
anti-androgen. DDT has been banned in this country, but many
countries still allow its use, including its use on food products
that are imported into the U.S. [7]Furthermore, despite the ban,
many ecosystems in the U.S. remain heavily contaminated from past
DDT use.
Therefore, the research task requires us to know not only which
chemicals mimic estrogens, but also which chemicals interfere
with androgens. For example, a common pesticide, Vinclozolin,
was recently discovered to be a powerful anti-androgen. [8]
Dosing a pregnant female rat with Vinclozolin at a level that
caused no toxicity in the mother, gave rise to baby male rats
which all appeared to be female at birth. The newborn male rats
developed nipples (which, in rats, only females normally have),
and they all had the hypospadias birth defect, [6]and undescended
testicles. Furthermore, they were all sterile, unable to
produce enough sperm to inseminate a female. In the U.S. today,
Vinclozolin is legal for use on cucumbers, grapes, lettuce,
onions, bell peppers, raspberries, strawberries, tomatoes, and
Belgian endive. [9] It is sold under the following trade names:
Ronilan, Ornalin, Curalan, and Vorlan. It is also one of the
ingredients in the following mixtures: Hitrun, Konker, Ronilan M,
Ronilan T combi, Silbos, and Fungo-50. EPA has no published
plans for banning Vinclozolin.
Note that in the cases of both DDT and Vinclozolin, the chemical
itself has certain gender-bending properties, but the breakdown
byproducts (metabolites) have even more powerful anti-androgenic
properties. For example, the M1 metabolite of Vinclozolin is 100
times more powerful than Vinclozolin itself. Therefore,
researchers will need to study not only the main chemicals but
all of their important metabolites. In the case of Vinclozolin,
there are at least 2 important metabolites. Obviously, the need
to, first, identify and, second, test, metabolites greatly
increases the size and scope of the research task.
The problem of chemical combinations is even more difficult.
Several prominent researchers calling for urgent work on
gender-benders have suggested that combinations of chemicals
might be important. For example, we quoted the editorial from
LANCET April 15: “For most chemical pollutants we do not know
whether they are oestrogenic or not, what their effects are
singly OR TOGETHER, or even the degree of our exposure….”
Suppose we wanted to study only the possible 2-chemical
combinations among the commonest 500 industrial chemicals. To do
this, we would have to run 124,749 different experiments (let’s
call it 125,000). [10] To study all the different 3-chemical
combinations among the 500 would require 20.7 million
experiments–an impossible task. Even testing all 3-chemical
combinations among only 100 chemicals would require 161,700
experiments. Testing combinations is a burden.
If we were worried about 500 chemicals, each with one metabolite,
for a total of 1000 chemicals, and we wanted to study all
possible 2-chemical combinations, we’d have to run 499,500 (just
shy of half a million) experiments; to learn about all the
different 3-chemical combinations of these 1000, we’d have to run
166 million experiments–simply out of the question.
Running even 125,000 experiments (all 2-chemical combinations of
the top 500 chemicals) would require quite a different attitude
than public health officials presently exhibit toward these
problems. Many dozens of competent laboratories would have to
get involved. Hundreds of researchers and technicians would have
to be trained (or re-trained). Much current research would have
to be abandoned. If each experiment cost only $100,000, then
125,000 experiments would cost $12.5 billion and 499,500
experiments would cost $50 billion.
Finally, recent research on dioxin reveals that, at dose levels
not toxic to the mother, both male and female offspring of
dioxin-exposed pregnant rats and hamsters have their sexual
development stunted. [11]In females, the external genitalia were
malformed; in males, testicles were reduced in weight, and sperm
count was reduced by more than 50%. These effects were not caused
by estrogen-mimicking, nor by an anti-androgen mechanism. Some
entirely different mechanism, not understood, allows dioxin to
interfere with sexual development of mammals at extremely low
levels of exposure. Are there other chemicals like dioxin in
this regard? It seems a fair question.
For scientists all these research questions may seem interesting,
if not actually doable. But for the public, a different question
seems paramount: how can we avoid exposure to dioxin and to all
the other gender-benders found in pesticides, detergents, paints,
plastics, and so on? After they are made and released into the
environment, there is no avoiding them. Therefore, we must
prevent their manufacture in the first place. This is the
life-and-death challenge of our age.
                
                
                
                
    
–Peter Montague
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[1] Anonymous, “Masculinity at risk [editorial]”, NATURE Vol.
375 (June 15, 1995), pg. 522.
[7] Richard M. Sharpe, “Another DDT connection,” NATURE Vol. 375
(June 15, 1995), pgs. 538-539.
[9] See 40 CFR [Code of Federal Regulations] Chapter 1 (7-1-94
edition), section 180.380.
Descriptor terms: nature; lancet; endocrine disruptors;
endocrine system; xenoestrogens; estrogen; hormones; androgens;
infertility; fertility; reproductive health; testicular cancer;
sperm count; sperm density; sperm quality; hypospadias;
cryptorchidism; undescended testicles; birth defects; epa;
william kelce; metabolites; ddt; dde; p,p’-dde; vinclozolin;
pesticides;