Restoring children's birthrights
THEO COLBORN
describes worldwide effects of endocrine-disrupting
chemicals and calls for a new global research
effort to tackle them
Everyone reading this article is carrying at least 500 measurable chemicals in his or her body that
were never in anyone's body before
the 1920s. There is undeniable
evidence that females share some of these man-made chemicals with their babies in their wombs and during
breastfeeding. These chemicals are capable of interfering with natural chemical messengers that tell babies how to
develop.
We have dusted the globe with man-made chemicals that can undermine the development of the brain and behaviour, and
the endocrine, immune and reproductive systems - vital systems that assure perpetuity. We are just beginning to
understand how these chemicals can affect our children's ability to learn, to integrate socially, to fend off disease
and to reproduce.
This message comes from physicians, researchers studying human health, laboratory scientists and wildlife biologists.
The story has evolved, article by article, in the world's most reputable, well-respected, scientific and medical
journals, such as Science, Nature, The New England Journal of Medicine, British Medical
Journal, and The Lancet, to mention only a few.
Everyone is exposed - not to one chemical at a time - but to complex mixtures that change day by day, hour by hour,
depending on the environment. One cannot escape from exposure in homes, work and meeting places, automobiles or
outdoors.
Many of these chemicals build up in body tissue and remain there for years. Others do not, but are constantly present
in our daily lives; they are in the common everyday products on which we have become dependent. Others are industrial
chemicals and pesticides to which we are exposed in a variety of ways.
Consider the following: mothers who ate moderate amounts of fish from Lake Michigan shared the chemicals in the fish
with their babies - some of whom had measurable neurobehavioural decrements at birth, short-term memory problems at
age four, and a 6.2 IQ deficit at age 11. The most highly exposed children are now more than one year behind their
schoolmates. The severity of the effects reflects the amount of a group of persistent chemicals the mother and infant
shared.
In a more recent study, mothers who ate fish from Lake Ontario shared the chemicals in the fish with their babies.
Those whose mothers ate the largest amount of fish also had neurobehavioural decrements at birth similar to those in
the Lake Michigan children. With an additional new battery of tests they were also found to be hyper-reactive to
unpleasant events, just like rat pups whose mothers were fed fish from the same lake.
Mothers from The Netherlands also shared the chemicals in their bodies with their babies. This study looked at a
cross-section of the population, not necessarily fish eaters. Shortly after birth, measurable neuromotor decrements,
changes in their immune competency and reduced levels of thyroid hormone were discovered in the more highly exposed
children. (Thyroid hormones guide brain development and the growth of children.) The chemicals associated with the
effects are similar to those in the mothers from the Great Lakes. As in the Great Lakes studies, the concentrations of
these chemicals in the mothers were well within the normal range of the average population in the developed world,
suggesting
that a sizeable segment of newborns is being affected.
This problem is not restricted to Europe and the United States. As researchers tracked the polar migration of
persistent chemicals toward the North Pole they found that Native American mothers in eastern Arctic Canada share
seven times more contamination with their babies than the mothers in the Great Lakes and The Netherlands. The native
youngsters have 20 times more middle ear infections than children in the lower North American continent. Native
mothers in Western Greenland share twice as much again with their babies as their Canadian counterparts.
Even female albatrosses, feeding only on the surface of the North Pacific Ocean, transfer the same suite of chemicals
to their eggs, and at concentrations that initiate a measurable toxic response similar to that found in troubled bird
populations in the contaminated areas of the Great Lakes. The Pacific birds also hold unexpected levels of newly
produced DDT in their bodies.
Chemical legacy
This evidence demonstrates that
these chemicals are found around the world. They are the legacy of the industrial chemistry of the past 70 years; the
burgeoning development of new generations of pesticides, plastics, construction materials and other common products,
from canned foods to dental sealants.
In the United States alone, it is estimated that over 72,000 different chemicals are used regularly; some 2,500 new
chemicals are introduced annually and, of these, only 15 are partially tested for their safety. Not one of the
chemicals in use today has been adequately tested for these intergenerational effects initiated in the womb.
Although effects have been reported in adults who were directly exposed to some of the chemicals, the most insidious
and irreversible effects are expressed in their offspring. Everyone is at risk, including those who have not yet been
born. When tested in laboratory settings on a chemical-by-chemical basis these substances are associated with a litany
of adverse health effects, for example, weakened immune systems, reproductive problems, metabolic problems, impacts on
the thyroid and other organs. Perhaps of greatest concern are the functional deficits - such as reduced intelligence,
reduced sexual function, behavioural changes - which add up to a reduction in potential of all those affected.
We do not fully understand the magnitude of the risks, nor do we fully understand the biological mechanisms through
which these problems occur.
We do not know how adequately to test for these effects, nor do we understand fully the consequences of these effects,
much less their true costs to society. There are no institutions to deal with the problem at the state, national or
global level.
What should be done? For a start, we need an international research effort better to understand the problem. The
man-made chemicals with which we must deal are not limited to one nation or group of nations, nor to one geographic
region. They have become an integral part of the economies of the industrialized world and are central to the
aspirations of the developing world. They flow in international commerce, as well as in air and water. As a result,
any strategy to address the problem must be transboundary and global in scope.
With hindsight, we know we must address the fact that these chemicals are moving poleward on oceanic and atmospheric
currents, accumulating in wildlife and human tissue in the far northern hemisphere, and taking their toll on those who
never produced the chemicals or benefited from their use.
And with foresight we must consider those nations that are suffering from economic hardship and overpopulation, and
are in dire need of clean water and sufficient food. It is imperative that we seek answers through our research
efforts to how these countries can meet their need for food, water and insect vector control. We must not let them
perpetuate our mistakes.
International cooperation
We must establish an international entity to oversee the funding, design and implementation of a global research
strategy to address the threats posed by these chemicals. A research agenda such as this will require cooperation
among industry, governments, national agencies, acadaemia and non-governmental organizations. In light of the weight
of evidence concerning the ultimate threat to human health and survival, and to biodiversity, it is imperative to
establish this international entity as soon as possible. If the hypothesis associating contaminants with damage holds,
the research costs will seem infinitesimally small compared with what the costs might be if society does not heed the
message from the scientific community.
Some factors are in our favour. First and most important, the effects caused by these man-made chemicals are not
mutations. If we reverse exposure, future generations can develop once again according to the genetic blueprint they
inherit from their ancestors.
Second, over the past five years, scientists from around the world have directed their research toward the problem.
Our learning curve has literally shot straight up. The United States National Academy of Sciences and sister
institutions in other nations are assessing the issue. Paradigms on how chemicals should be tested for their safety
and on how we measure risk are being challenged. Industrialists are rethinking how products should be designed.
More than 100 nations have called for negotiation of an international convention to reduce or eliminate persistent
organic pollutants (POPs), among which are endocrine-disrupting chemicals. The United States Congress, in its last
session, enacted several federal laws acknowledging the problem.
We must capitalize on this momentum and turn our attention to those in the womb and protect our most precious
resource. The longer we ignore the issue, the greater our potential peril. Let us restore our children's and
grandchildren's birthright to reach their fullest potential.
Dr. Theo Colborn is Director of the Wildlife and Contaminants Program of the World Wildlife Fund, United States of
America, and principal author of Our Stolen Future.
