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#490 - Our Stolen Future, Part 3: Flying Blind, 18-Apr-1996

OUR STOLEN FUTURE, the new book on hormone-disrupting chemicals,[1]
provides many lessons about our use of chemicals, and about our
reliance on science as a guide for public policy.

Here is a short discussion of the main lessons we find in the book
(numbers inside parentheses are page numbers from the book):

** Genes are not destiny. Many people seem to think that we may be able
to explain everything from cancer to homosexuality by locating the
responsible genes. But in a series of scientific papers starting in
1980, Frederick vom Saal at University of Missouri demonstrated that
there are other powerful forces shaping individuals--both females and
males--before birth. Genes are not the whole story. Before birth,
levels of both male and female sex hormones in the womb can affect the
physical characteristics and the behavior of mice, giving rise to great
variation in offspring that are genetically identical. By examining
human twins, scientists have now revealed similar effects in humans.[2]
Thus we now know that hormones are a way that nature provides variation
within a species. Profound variation among individuals can be caused by
minuscule hormone differences in the womb, differences of a few parts
per trillion. (One part per trillion is a million times lower than one
part per million.) This is a degree of sensitivity to hormones that
approaches the unfathomable, a sensitivity, vom Saal says, "beyond
people's wildest imagination." This exquisite sensitivity provides rich
opportunities for creating varied offspring from the same genetic
stock. However, the dark side is that this same sensitivity also makes
the reproductive system vulnerable to serious disruption if something
interferes with normal hormone levels. (pgs. 39-41)

** The exposure of a million American women to the drug, DES, in the
1960s and 1970s showed that the human body could mistake a synthetic
(human-created) chemical for a natural hormone. (pg. 66)

** Another lesson from the work of vom Saal and others is that hormones
in the womb permanently program (and organize) cells, organs, the
brain, and behavior prior to birth, in many ways determining an
individual's course for life. (pgs. 39-40)

** The dose of hormones that an embryo receives is not the only thing
that matters; the TIMING of the dose --WHEN it occurs during
development in the womb --can be as important as the dose itself. (pgs.

** Birth defects may not be noticeable at birth. Serious effects of
hormones on the unborn and on the newborn may not be recognizable for
decades. (pg. 66)

** In fact, birth defects may never become visible at all, but may
involve cellular damage that undermines an organism's ability to
survive. For example, exposure to the drug DES, a synthetic hormone,
gave rise to a rare form of cancer in female children of DES-exposed
women. (pg. 66)

** Mice and humans share a common fate. To an astonishing degree,
evolution has retained through hundreds of millions of years a basic
strategy for embryonic development in vertebrates [creatures with a
backbone] which depends on hormones. Regardless of whether the
offspring is a human or a mouse, a whale or a bat, a turtle or an
alligator, hormones regulate its development in fundamentally the same
way. In the field of cancer research, scientists argue that data
gathered from experiments on mice may not reveal anything useful about
humans. This uncertainty occurs because the underlying causes of cancer
are poorly understood. On the other hand, the working of hormones is
better understood, and knowledge gained from experiments on non-humans
CAN reveal useful information about humans. "It is important to take
the effects we see in animals seriously," says Dr. Earl Gray, a senior
research biologist with U.S. Environmental Protection Agency [EPA].
(pg. 66)

** Industrial chemicals at exceedingly low levels can combine together
to produce additive effects. Dr. Ana Soto at Tufts University combined
10 hormone disrupters, each at one-tenth of the dose required to
produce a minimal response; she found that the combination produced a
response.[3] Thus combinations of chemicals must be taken into account
when we try to learn how much "effective exposure" we are getting to
hormone-disrupting chemicals.

** Testing hormones at high doses may reveal no effects whereas testing
the same hormones at low doses may reveal dramatic effects. This is
contrary to the traditional assumptions of toxicology [study of
poisons]. The dose-response curve for many hormones is U-shaped: at low
doses, the hormones cause effects but at high doses the system becomes
overwhelmed and shuts down. This has profound implications for testing.
Traditionally, chemicals have been tested on laboratory animals at high
doses; now we know that tests must be conducted at low doses as well.
(pgs. 169-170)

** Up to now our concept of injury from toxic chemicals had focused on
two things: (a) whether a chemical attacks the DNA inside cells,
possibly causing cancer; or, (b) whether a chemical damages and kills
cells, the way poisons do. However, hormone-disrupting chemicals may
not kill or damage cells, and they may not damage DNA. Thus they do not
fit the definition of "poisons" or "carcinogens" yet they may cause
great harm by disrupting normal growth and development of many organs
and tissues, including sex organs, the brain, the nervous system, and
the immune system. The key concept in thinking about this kind of toxic
assault is the disruption of chemical messages. (pgs. 203-204)

** The traditional approach to toxic chemicals is to look for disease
as a result of exposure. However, hormone-disrupting chemicals may not
cause "disease" at all: they may cause diminished function --reduced
IQ, poorer short-term memory, diminished ability to pay attention,
reduced sperm count. These are not signs of "disease" yet they are
toxic effects that can be caused in some species by some hormone-
disrupting chemicals. (pgs. 205-206)

** To screen for chemicals that cause diminished function, it will be
necessary to look for developmental effects across three generations.
The first generation (the generation that gets the initial exposures)
may not be affected at all. The second generation may have diminished
function (for example, diminished ability to reproduce) but the actual
effects may not be apparent until the third generation (the
grandchildren of the exposed generation). (pg. 207)

** We are flying blind. (pgs. 243, 246) We cannot know whether the
ominous shape looming into view is a cloud bank or a mountain. If
anything is certain, it is that we must expect more unpleasant
surprises. We are flying blind; we can never know that new chemicals
are safe (though, if we chose to, we could do a much more thorough job
of testing them than we've done in the past).

To show that we are flying blind, OUR STOLEN FUTURE relies on the
evidence of hormone-disrupting chemicals and of depletion of the
earth's ozone shield by human-created chemicals (see REHW #246, #259,
#285). But there is much additional evidence that could have been cited
as well. For example, during just the past 25 years, we have been
surprised by:

** Global warming brought on by combustion of fossil fuels (REHW #467,

** Mercury build-up to toxic levels in the bodies of fish (chiefly from
burning coal, oil, and municipal solid waste) (REHW #291);

** Increasing birth defects in American children. Of 38 kinds of birth
defects for which the Centers for Disease Control maintains records, 29
have increased during the past 20 years (REHW #410, #411);

** Steadily increasing cancers, particularly of the reproductive system
(prostate; testicles; female breast) and nervous system (brain) (REHW
#412, #447, #462);

** The astonishing toxicity of a family of chemicals called dioxins and
furans (including some PCBs, or polychlorinated biphenyls), which now
contaminate the entire planet from the depths of the oceans to the
polar ice caps (REHW #390, #391, #414);

** The accelerated loss of species, which, according to the fossil
record, is now occurring at rates 10 to 1000 times as fast as natural
background rates that were occurring before humans appeared on the
scene (REHW #441);

** Acid rain damaging lakes, killing trees, stunting forests, and
washing nutrients from soils across much of the northeastern U.S.,
southern Canada, and northern Europe (REHW #476); ** Rapidly increasing
immune system disorders such as asthma (REHW #374) and diabetes (REHW

** Epidemics of disease among marine mammals (seals, dolphins, etc.),
apparently related to chemical contamination and to blooms of toxic
algae caused by excesses of nutrients (chiefly nitrogen and phosphorus)
in near-shore marine ecosystems (REHW #466);

** Diminished IQ and reduced ability to concentrate among 1.7 million
American children and 300 to 400 thousand fetuses (at any given moment
in time), as a result of exposures to the toxic metal, lead (REHW

** Disappearance or decline of some frog and other amphibian
populations worldwide (REHW #380, #441);

** Steep declines or near-total depletion of fish stocks at 13 of the
world's 17 major fisheries (REHW #399).

** Decline of 50% in sperm among men in industrial countries (REHW
#432, #446, #448), and a significant loss of sperm quality during the
same period.

** A 60% increase in the rate of migraine headaches among Americans
during the period 1980 to 1990. Most (71%) of the increase occurred
among people aged less than 45 years.[4]

This does not exhaust the evidence, but represents a fair sample of the
kinds of problems that have suddenly loomed into view since 1970. Have
we encountered the last of such unsuspected and unlooked-for problems?
Certainly not. No, there doesn't seem to be any doubt about it: we are
rushing forward at high speed with no sure way to learn what hazards
lie ahead. We really are flying blind. To us, this seems the most
important lesson of OUR STOLEN FUTURE.

Under such circumstances, can science provide us with adequate
guidance? Next week.

--Peter Montague


[1] See REHW #485 and #486, reviewing Theo Colborn, Dianne Dumanoski
and John Peterson Myers, OUR STOLEN FUTURE (N.Y.: Dutton, 1996).

[2] F. vom Saal and F. Bronson, "Sexual Characteristics of Adult Female
Mice Are Correlated with Their Blood Testosterone Levels During
Prenatal Development," SCIENCE Vol. 208 (1980), pgs. 597-599. And see:
M. Clark and others, "Hormonally Mediated Inheritance of Acquired
Characteristics in Mongolian Gerbils," NATURE Vol. 364 (1993), pg. 712.
Hormones have also been shown to affect humans exposed in the womb: D.
McFadden, "A Masculinizing Effect on the Auditory Systems of Human
SCIENCE Vol. 90 (1993), pgs. 11900-11904.

[3] Reported in Ana M. Soto and others, "The Pesticides Endosulfan,
Toxaphene, and Dieldrin Have Estrogenic Effects on Human Estrogen-
(April 1994), pgs. 380-383.

[4] "Prevalence of chronic migraine headaches -United States, 1980-
1991), pgs. 331-333.

Descriptor terms: endocrine disrupters; hormones; our stolen future;
des; frederick vom saal; ana soto; science; oceans; marine mammals;
global warming; mercury; fish; wildlife; birth defects; cancer; dioxin;
pcdfs; pcbs; species loss; acid rain; lead; migraine headaches; theo
colborn; john peterson myers; dianne dumanoski;