presents a series of historical vignettes, beginning in 1952, that,
viewed now with the benefit of current scientific understanding,
suggest that contaminants might have been interfering with the hormonal
control of development in wildlife and in people. Examples covered
include Bald Eagles in Florida (1952), river otters in England (late
'50s), mink in Michigan (mid-60's), Herring Gulls in Michigan (1970),
Western Gulls in California (early '80s), alligators in Florida
('80s), seals in northern Europe (1988), dolphins in the Mediterranean
(early '90s), and sperm counts of men worldwide (1992).
Poisons describes the scientific odyssey taken by Dr. Theo Colborn
that led to her synthesis of the theory of hormone (endocrine) disruption.
The breakthrough came when, after reviewing hundreds of studies
examining the health consequences of contamination in the Great
Lakes (United States), Colborn realized that a theme running through
many of the impacts observed was that they involved disruption of
the hormonal control of development.
Messengers introduces key work by Dr. Fred vom Saal, University
of Missouri-Columbia, that explores the impact of tiny variations
in hormone exposure on the development of fetal mice, and ultimately
on adult characteristics of those mice when they mature. vom Saal
discovered that natural hormonal gradients around each fetus in
the womb of a mouse alter the development of its neighbors. vom
Saal's discoveries lay the groundwork for understanding how tiny
variations in contaminants that mimic hormones can also alter development.
chapter also builds on vom Saal's work to present an overview of
the control of development by hormones, and particularly the role
of estrogen and testosterone in controlling sexual development.
Havoc examines the tragedy of what can go wrong if the hormonal
control of development is disrupted. It explores the classic case
of diethylstilbestrol, or DES, a synthetic estrogen invented in
1938 and subsequently used by physicians to manage difficult pregnancies.
Research ultimately revealed that not only did DES not help
pregnancies, it did cause severe damage to individuals
exposed to DES when their mother was treated while they were in
the womb. Some of the impacts involved rare cancers, deformed fallopian
tubes, and increased risk of endometriosis. In most cases, the DES
impacts were not detected until after the victim had passed through
puberty, even though exposure took place in the womb.
DES case is particularly instructive because it proved definitively
that the human body could mistake a synthetic compound for a hormone,
with tragic results. It is also important because it reinforced
the value of animal experiments in understanding human vulnerability.
Time and again as scientists explored the impacts of DES on animals
exposed experimentally in the laboratory, the results of these experiments
anticipated human impacts.
Fifty Ways to Lose Your Fertility
Ways to Lose Your Fertility explores key aspects of the ways
that hormones work to control development, particularly the interaction
of a hormone with its receptor. This interaction is crucial to understanding
one of the best understood forms of endocrine disruption, when a
hormone imposter like DES or DDT binds with the estrogen receptor.
It was once thought that hormone-receptor binding was very specific,
like a lock and key. Research has now shown that hormone receptors
not nearly as discriminating as this old perception indicated. Many
synthetic compounds bind with human hormone receptors.
chapter also introduces plant estrogens, or phytoestrogens. These
compounds are made naturally by plants and have the capability of
binding with animal estrogen receptors. At least three hundred plants
from more than sixteen different plant families are known to produce
phytoestrogens. Studies of some of these phytoestrogens have shown
they are capable of interfering with animal fertility.
on this basic information, the chapter then examines what is known
about the impacts of various hormone mimics on reproduction and
fertility. It describes work by Dr. Earl Gray (US EPA) who has studied
how some synthetic chemicals disrupt male development by interacting
with the receptor that normally binds testosterone, the androgen
receptor. An important lesson from Gray's work is that hormone disruption
is not limited to the estrogen system. Virtually every hormone-receptor
interaction is vulnerable. If a disruptor hasn't yet been found
for a particular hormone system among the 70,000-odd chemicals in
modern use, it's probably because no one has looked very thoroughly.
To the Ends of the Earth
the Ends of the Earth follows a polychlorinated biphenyl (PCB)
molecule from its creation in a Monsanto chemical plant near Anniston,
Alabama, to its entry into a polar bear in the Arctic. This hypothetical
journey may differ in detail from the movement of any specific molecule,
but it describes in general the way one type of especially potent
and persistent endocrine disrupting compound, the PCBs, have become
ubiqutious contaminants in virtually every ecosystem on planet Earth.
The global transport of these "persistent organic pollutants"
is especially problematic for people who live in cold regions of the
planet, like the Arctic, and depend upon locally available food.
A Single Hit
much of a synthetic chemical does it take to disrupt hormone levels
and do lifelong harm? This question is at the heart of the debate
over the potential risks inherent in endocrine disruption. Research
on dioxin summarized in this chapter indicates that an exceedingly
tiny amount, so small and so brief that it defies the imagination
to contemplate, is enough to alter the course of development, if
exposure takes place in the womb.
chapter highlights research conducted by Richard Peterson and his
colleagues at the University of Wisconsin. Their work altered the
landscape of what questions needed to be asked about the impact
of contaminants on health. For a host of reasons, laboratory experiments
with animals had focused increasingly on how high doses affected
health outcomes. Peterson looked instead at the impact of low doses
at crucial times during fetal development. They discovered exquisite
Here, There, and Everywhere
risks of hormone disruption are all around us, because of inadvertent
experiments that expose us unintentionally to compounds that no
one thought to question. Here, There and Everywhere delves
into this, beginning with the description of a the discovery by
Dr. Ana Soto and Dr. Carlos Sonnenschein that nonylphenol, a common
additive to certain plastics, binds with the estrogen receptor and
stimulates estrogenic responses in cells and living animals.
and Sonnenschein's discovery is by no means unique even if their
persistence against all odds was extraordinary. The chapter also
describes the discovery that the basic building block of polycarbonate
plastic, a compound called bisphenol A (BPA), also increases breast
cancer cell proliferation rates. BPA, it turns out, was first synthesized
in the great rush toward synthetic estrogens that led to the invention
of diethylstilbestrol (DES). Polycarbonate plastic and hence BPA
is everywhere in modern society. And as a result, so is exposure
to hormone disrupting compounds. But the exposure is not limited
to BPA. It comes from many, often unsuspected sources.
Chronicle of Loss
impacts of endocrine disruption are not just theoretical. Especially
in the natural world, it is obvious that hormone systems are being
disrupted and that animals are suffering. For better or for worse,
because studies of animals allow experiment and sacrifice, we have
better scientific understanding of what is happening with animals
than with people. This chapter examines a series of examples of
the impacts of hormone disruption on animals, several of which were
highlighted in Omens, the book's first
chapter. Among the examples covered are Beluga whales in the St.
Lawrence River between the US and Canada, Florida panthers, seals
in Europe, alligators in Lake Apopka, Florida, and frogs around
has endocrine disruption meant for people? The answers are not yet
clear. Evidence from wildlife, from studies of laboratory animals,
and from observations of human exposure all indicate we are at risk.
The fact is that basic physiological and developmental processes
that are controlled by hormones have persisted relatively unchanged
through hundreds of millions of years of evolution. Hence it only
to be expected that risks for animals represent risks for people.
As Rachel Carson wrote in Silent Spring, "our fate is connected
with the animals."
Destinies evaluates evidence available to date about what can
be concluded from scientific studies about the impacts of endocrine
disruptors on people. Many plausible impacts can be identified,
including sperm count declines, prostrate problems, reproductive
problems in women (including miscarriages, tubal pregnancies, endometriosis,
and breast cancer), and effects on intelligence, behavior and disease
uncertainty plagues any conclusions, however. Defenders of some
of the compounds that have been implicated may claim that there
is no evidence. That is a distortion of the true circumstance. The
limitations on what can be concluded arise largely because crucial
studies simply haven't been carried out.
there are a few (very few) studies of people who have been exposed
in the womb through industrial accidents, these relatively high-dose
exposures are only marginally relevant to contamination levels experienced
by most people living in the real world. These high-level studies
reveal problems. They don't tell us enough about the possible exposures
taking place at background levels, exposures that in fact are comparable
to those found through careful experiments with animals to have
profound effects. There is too little scientific information available
to state with certainty that concerns raised by animal studies are
not relevant. The few that are available reinforce ideas raised
in Our Stolen Future, that low level contamination by endocrine
disrupting-compounds are causing a variety of health effects in
risks of cancer have dominated fears about the health consequences
of cancer. Those fears are real and warranted, but they have blinded
us to a parallel set of risks whose consequences can be even be
more profound for the human prospect. Cancer kills individuals,
mostly adults. Hormone disruption derails development, putting at
risk the ability of individuals to participate fully in society.
While it has been assumed that protecting people from the contamination
risks of cancer will protect them from other health effects caused
by pollution, it now appears that the opposite may be true. Because
of the extraordinary low levels at which endocrine disruptors derail
development, protecting against their health effects is likely to
provide wide benefit for health, including cancer prevention.
the reality that current regulations do not protect individuals
from endocrine disruption, what should people do? In Defending
Ourselves, we evaluate the choices people have to reduce their
own risks and those of their family members, and also identify a
series of changes in public policy that would be beneficial. While
the facts in hand are cause for deep concern, trends are not destiny.
There are many choices people have to protect themselves, and especially
recommendations include suggestions for avoiding unnecessary uses
of pesticides and reducing intake of contaminated food, both by
choices in diet and changing the way that food is cooked. Don't
microwave in plastic unless you are absolutely certain that the
plastic does not leach endocrine disrupting compounds into the food
We also identify a series of changes in the way that contamination
is regulated. Far from guaranteeing safety, the structure of current
regulations do more to lower legitimate consumer concerns than they
do to protect health.
does the future hold? The science of endocrine disruption is uncertain.
Animal studies identify many plausible risks. Some data on people
support them. For the most part, however, the crucial human studies
have not been carried out. To do so carefully and definitely will
take decades. We must ask, nonetheless, whether a series of disturbing
social and behavioral problems have their roots in the impacts of
contamination on human development. Are falling SAT scores linked
to intrauterine exposure? What about global declines in sperm count?
Or increases in societal levels of aggression. All these endpoints--cognitive,
behavioral, reproductive--are shown vulnerable in animal studies
to exposure to endocrine disruption. What can we conclude for people?
Flying Blind we step back from the details of endocrine disruption
to ask why are we in this predicament and what must be
done to get out of it? These questions are provoked unavoidably
by what we have learned about endocrine disruption, but they arise
from a larger consideration. Growth in human population and technological
prowess over the past century has placed all of humanity, indeed
all of the planet, in a series of unplanned, poorly monitored indeed
often unwitting experiments. There is no uncontaminated place or
people, no unsoiled valley anywhere. The scale of the human enterprise,
our capacity to invent new substances and bring them to market far
more quickly than science can hope to understand their unintended
consequences, and the huge gaps in our knowledge of how the world
works, together make us vulnerable to some of the very advances
on which modern society is built.
we work to create a future where children can be born free of chemical
contamination, our scientific knowledge and technological expertise
will be crucial. Nothing, however, will be more important to human
well-being and survival than the wisdom to appreciate that however
great our knowledge, our ignorance is also vast. In this ignorance
we have taken huge risks and inadvertently gambled with survival."