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#501 - Chemicals and the Brain, Part 2, 03-Jul-1996

(Continued from RACHEL'S #499.)

Here we continue our presentation of the Erice Statement, a consensus
statement issued May 30, 1996, by an international group of scientists
and physicians, including U.S. government scientists. (The signers were
listed and identified in RACHEL'S #499.) The statement expresses great
concern about the effects of hormone-disrupting chemicals on the brain
and central nervous system. The Erice Statement resulted from a
workshop held November 5-10, 1995 at Erice, Italy.

Hormones are chemical messengers that travel in the blood stream,
turning on and off critical bodily functions to maintain health and
well being. Hormones control growth, development, and behavior in
birds, fish, reptiles, amphibians, and mammals, including humans. In
humans, 100 different hormones have been identified. Taken together,
the tissues and organs that produce, and respond to, hormones are
called the endocrine system. In 1991, an international group of 23
scientists issued a consensus statement, expressing great concern that
many synthetic (human-created) industrial chemicals can interfere with
hormones in wildlife and humans. (See REHW #263, #264). The 1991
statement focused on the ability of industrial chemicals to interfere
with sexual development and behavior in wildlife and humans. The Erice
Statement issued last month focuses attention on industrial chemicals
that can interfere with the development of the brain and other parts of
the central nervous system. The statement is definitely not easy
reading, but it is important, so we present it verbatim, with our
explanations inside square brackets [].

CONSENSUS STATEMENT (continued from Rachel's #499)

2. We estimate with confidence that:

** Every pregnant woman in the world has endocrine disruptors in her
body that are transferred to the fetus. She also has measurable
concentrations of endocrine disruptors in her milk that are transferred
to the infant.

** There may not be definable thresholds for responses to endocrine
disruptors [in other words, any amount may cause some effect]. In
addition, for naturally occurring hormones, too much can be as severe a
problem as too little. Consequently, simple (monotonic) dose-response
curves for toxicity do not necessarily apply to the effects of
endocrine disruptors. [See REHW #490.]

** Because certain PCBs and dioxins are known to impair normal thyroid
function, we suspect that they contribute to learning disabilities,
including attention deficit hyperactivity disorder and perhaps other
neurological abnormalities. In addition, many pesticides affect thyroid
function and, therefore, may have similar consequences.

** Some endocrine disruptors or their breakdown products are nearly
equipotent to [as powerful as] natural hormones. Even weak endocrine
disruptors may exert potent effects because they can bypass the natural
protection of blood binding proteins for endogenous [natural] hormones.
Some disruptors also have a substantially longer biological half-life
than naturally produced hormones because they are not readily
metabolized, and as a result are stored in the body and accumulate to
concentrations of concern. Some man-made chemicals that appear non-
toxic are converted by the liver to more toxic compounds. Also,
compounds that are not toxic in the mother may be toxic to her
developing embryo, fetus or newborn. The exquisite vulnerability of the
fetal brain to methylmercury and lead are prime examples of this
principle.

** Functional deficits are not as easily measured as physical anomalies
or clinical disease, in part because they are typically expressed as
continuous measures, such as IQ, rather than the number of cases in a
population. Consequently, conventional population surveys may overlook
the extent of such deficits. Moreover, because such surveys tend to
express their findings as shifts in mean [average] values even when
they are based on appropriate measures, they tend to obscure influences
on the more susceptible members of the population.

** Large amounts of man-made chemicals capable of disrupting the
endocrine and nervous systems are sold to, or produced and used in,
third world countries that lack the resources or technology to properly
monitor and control exposure levels. Insufficient and improper training
in handling chemicals and ignorance concerning health effects and
monitoring strategies leads to the likelihood of very high levels of
exposure.

3. There are many uncertainties in our understanding because:

** No one is exposure-free, thus confounding [confusing] studies to
determine what is normal. Everyone is exposed at any single time and
throughout life to large numbers of man-made chemicals. Relatively few
of the man-made chemicals found in human tissue have been identified.
Lack of funding has seriously constrained testing these chemicals for
their potential to disrupt natural systems.

** Sensitive parameters, including neurological abnormalities,
behavioral and neuropsychiatric disorders, and neuroanatomical,
neurochemical, and neurophysiologic endpoints need to be investigated.
Most important, criteria at the population level need to include the
social and economic costs of impairment because the true costs to
society of such problems can be significant, e.g., the costs of a 5
point IQ loss across a population. Investigation of potential toxicity
typically includes laboratory, population and field studies, clinical
reports, and accident reports. However, developmental neurotoxicants
produce a spectrum of effects that are not typically evaluated, such as
the progression and latency of behavioral and neurological changes. In
addition, alteration of other systems can produce subsequent cognitive,
behavioral, and neurological dysfunction; i.e. diseases of other organ
systems that influence the brain; non-CNS [central nervous system]
drugs; other foreign substances such as air pollutants; and immune
system involvements that alter behavior.

** Trade secret laws afford industry confidentiality, depriving the
consumer and public health authorities of the right to know the
components of commercial products so they can be tested.

4. Our judgment is that:

** The benefits of reduced health care costs could be substantial if
exposure to endocrine-disrupting chemicals were reduced.

** A trivial amount of governmental resources is devoted to monitoring
environmental chemicals and health effects. The public is unaware of
this and believes that they are adequately protected. The message that
endocrine disruptors are present in the environment and have the
potential to affect many people over a lifespan has not effectively
reached the general public, the scientific community, regulators, or
policy makers. Although this message is difficult to reduce to simple
statements without over- or under-stating the problem, the potential
risks to human health are so widespread and far-reaching that any
policy based on continued ignorance of the facts would be
unconscionable.

** The outcome of exposure is inadequately addressed when based just on
population averages. Instead, risk should be based on the range of
responses within a population --that is, the total distribution. The
magnitude of the problem can be better determined by knowing the
distribution of responses to endocrine disruptors by individuals within
subsets of the population most at risk, such as pregnant women,
developing embryos, fetuses, and newborns, teens, the aged, the ill or
those with pre-existing endocrine disorders. The magnitude of the risks
also depends upon the endpoint [health effect] under consideration. For
example, a variety of motor, sensory, behavioral, and cognitive
functions, endpoints which are more sensitive than cancer, must be
considered when assessing neurological function. This holds for
wildlife and domestic animals, as well as human populations.

** Wildlife have been effective models for understanding endocrine
disruption at the molecular, cellular, individual, population, and
ecosystem levels. Future research to examine diverse wildlife species
at all levels of biological organization must be broadened and
adequately supported.

** Those responsible for producing man-made chemicals must assure
product safety beyond a reasonable doubt. [See REHW #491.]
Manufacturers should be required to release the names of all chemicals
used in their products with the appropriate evidence that the products
pose no developmental health hazard.

** Current panels of scientists who determine the distribution of
public research funds often have a narrow scope of expertise and are
thus ill-equipped to review the kind of interdisciplinary research that
is necessary in this field. Funding institutions should be encouraged
to increase the scope of representation on review panels and to develop
more appropriate mechanisms for interdisciplinary reviews. Governmental
agencies should also increase funding for multidisciplinary extramural
projects for surveillance of wildlife and human populations where
neurological damage is suspected and follow any leads with laboratory
research. In addition, populations of animals consuming the
contaminated foods also eaten by humans should be studied for
developmental health effects. It is important to observe a variety of
vertebrate species through multigenerational studies.

** Strategies for increasing interdisciplinary communication and
collaborations to optimize resources and future research are needed.
Studies should be designed more economically to include the sharing of
material among many collaborators. Interdisciplinary teams should
explore neurological and other types of damage at all levels of
biological organization from molecular through biochemical,
physiological, and behavioral.

** A concerted effort should be undertaken to deliver this consensus
statement to the public, key decision makers, and the media. In
addition, specially designed messages should be developed for family
physicians and others responsible for public health who are often
unaware of the possible role of occupational and environmental chemical
pollutants as agents underlying or constituting risk factors for
"primary" human diseases. Physicians must be trained in medical school
about often latent effects of pollutants on human development and
health. This training is currently inadequate. A coordinated speakers
bureau and on-line systems such as a site on the World Wide Web for
endocrine-disruptors should be established. [End of consensus
statement.]

The consensus statement developed at Erice has been all but blacked out
by the U.S. media. The LOS ANGELES TIMES and the SACRAMENTO (CAL.) BEE
reported it May 31, but other papers ignored it entirely. Perhaps the
statement challenges too many of our pet assumptions about the safety
of our children in this chemically-altered world.

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

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Descriptor terms: erice statement; hormone disrupters; hormones; brain;
central nervous system; dose-response; pcbs; dioxin; attention deficit
disorder; add; thyroid; development; methylmercury; mercury; lead; iq;
third world; developing countries; trade secrecy; risk assessment;
wildlife; burden of proof; right to know;