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#547 - The Weybridge Report, 21-May-1997

During the past six years, evidence has accumulated indicating that
humans and wildlife may be affected by industrial chemicals that
interfere with hormones. (See REHW #263, #264). Hormones are chemical
messengers that travel through the blood stream, turning on and off
bodily processes, thus regulating reproduction, growth, development
(including mental development), and health. The general term for
chemicals that interfere with hormones is "endocrine disrupting
chemicals." About 50 chemicals have so far been identified as endocrine
disruptors, but roughly 70,000 chemicals now in commercial use have not
yet been tested for such effects.

Because we are all now exposed daily to hundreds (if not thousands) of
chemicals in our air, water, and food, it is worrisome (to say the
least) that some of these chemicals might be permanently altering our
development as humans (and the development of our offspring) --not to
mention our health.

Last month, the European Environment Agency published a report[1] on a
major conference on endocrine-disrupting chemicals held December 2-4,
1996, in Weybridge, England. The workshop was organized by the European
Commission; the European Environment Agency; the World Health
Organization's European Centre for Environment and Health; the
Organization for Economic Cooperation and Development [OECD]; national
environmental agencies from England, Germany, Sweden, and the
Netherlands; plus the European Chemical Industry Council [or CEFIC,
which is approximately the European equivalent of the Chemical
Manufacturers Association in the U.S.]; and the European Centre for
Ecotoxicology and Toxicology of Chemicals [approximately the equivalent
of the Chemical Industry Institute of Toxicology in the U.S.].

The new report, which we will refer to as the Weybridge Report,
contains some important conclusions, such as these:

** "It is evident that there are adverse health trends affecting the
reproductive organs of both men and women. Thus, the incidence of
testicular cancer has increased quite dramatically in countries with
cancer registries[,] including Scandinavia, the countries around the
Baltic Sea, Germany, UK [England], USA and New Zealand. Similarly there
has been an increase in the incidence of breast cancer in many
countries and the incidence of prostate cancer also appears to have
risen. While changes in the incidence of prostate cancer may have been
influenced by better reporting and better diagnostics, this can not
explain the bulk of the increase in testis cancer. Similarly, the
reported increase in breast cancer incidence seems real."[1,pg.13]

** The apparent decline in male sperm counts in some countries is
likely to be genuine, and not attributable to confounding factors or
methodological variables;[1,pg.6]

** However, there is "insufficient evidence to definitely establish a
causal link" between the health effects seen in humans and exposure to

** Summarizing: "Although our present knowledge about environmental
[endocrine-disrupting] agents and reproduction is extremely limited, we
know enough about adverse trends in reproductive health to be
concerned," the Weybridge Report concludes.[1,pg.14]

** In wildlife, the following kinds of effects have been noted in
relation to endocrine-disrupting chemicals:

** Female molluscs (e.g., snails, mussels) have turned into males as a
result of exposure to endocrine-disrupting chemicals (a condition
called imposex).[1,pg.14]

** In fish, males have been observed producing vitellogenin (a protein
that gives rise to the yolk of eggs, and which is ordinarily only found
in females). Furthermore, hermaphroditism has been observed in fish (a
single fish having both male and female sex organs).[1,pg.14]

** Some reptiles (turtles and alligators), have reduced fertility due
to undeveloped male sex organs (small penises).

** In birds, abnormal nesting behavior has been observed, namely
female-female pairing.

** In mammals: disturbed fertility has been observed in common seals,
grey seals, and Florida panthers.

In laboratory animals, the following endocrine-disruptor effects have
been observed:

** Rats and hamsters exposed to dioxin prior to birth and shortly after
birth have reduced sperm counts when they become adults. The timing of
the exposure determines the effects that ensue.[1,pg.28] There is also
evidence that permanent exposure to low levels of dioxin can cause
endometriosis in monkeys.[1,pg.28] Endometriosis is a painful disease
of the tissues lining the uterus, which often results in sterility; it
presently afflicts an estimated 5 to 9 million American women.

** Rats exposed to PCBs prior to birth have disturbed thyroid hormones;
as a side-effect, these rats have small testicles and reduced sperm
counts as adults.[1,pg.28]

** Exposure of rodents to endocrine-disrupting chemicals can cause them
to undergo puberty at an early age and can cause persistent estrus
(meaning, being "in heat" for an abnormal, prolonged time).

** Male rodents exposed to chemicals that interfere with androgens
(male sex hormones) can be born with hypospadias (a birth defect of the
penis) and cryptorchidism (undescended testicles).[1,pg.29] The
Weybridge Report notes that, in humans, "there are indications that, in
some countries at least... the incidence of undescended testis and
hypospadias has increased."[1,pg.13] The Weybridge Report specifically
associates these effects (in rodents) with exposure to Vinclozolin, a
powerful anti-androgenic pesticide. (In the U.S. today, Vinclozolin is
legal for use on cucumbers, grapes, lettuce, onions, bell peppers,
raspberries, strawberries, tomatoes, and Belgian endive. U.S.
Environmental Protection Agency (EPA) has no published plans for
banning Vinclozolin.)

** There is evidence from a number of animal species that sex steroids
(for example, estrogen, testosterone) exert long-term effects on the
size of the thymus and "on the immune system in general."[1,pg.29] In
humans, the thymus is an organ, just above the heart, that produces T
cells, which are crucial actors in the immune system.

The Weybridge Report reaches several other conclusions which hint at
the difficulty of the job that lies ahead as researchers try to pin
down the relationship between endocrine-disrupting chemicals and normal
development in humans and other animals:

** "It is not possible fully to understand the significance of levels
found in tissues or blood until the mechanism and timing of action of
EDS [endocrine disrupting substances] and their metabolites are better
understood."[1,pg.37] In other words, it is not merely endocrine-
disrupting chemicals that must be understood. After they are present in
the body (of animal or human), they are metabolized and they become
different chemicals, which also have effects that must be examined and
understood. Furthermore, the timing of exposure is critical. For
example, exposing a pregnant rat to dioxin on day 15 of pregnancy
causes effects that do not occur if the rat is exposed on day 14 or day
16. This makes laboratory research on endocrine-disruptors a great deal
more complex (and therefore more costly) than typical toxic chemical

And finally, it will be necessary to test at least 2 generations of
animals because effects on offspring are the main concern with
endocrine-disrupting chemicals.[1,pg.43]

** "...it is not anticipated that any useful SAR relationships will
emerge."[1,pg.45] SAR means "structure-activity relationship."
Sometimes the unknown toxicity of a chemical can be estimated by
examining the molecular structure of a chemical with known toxicity. If
this can be done, a structure-activity (really structure-toxicity)
relationship can be observed, and the activity (toxicity) of a chemical
can be estimated from its chemical structure. Observing a SAR can help
scientists decide quickly which chemicals are likely to be bad actors.

Unfortunately, the Weybridge Report concludes, endocrine-disrupting
chemicals do not resemble each other structurally. Their structures
vary all over the map, so no structure-activity relationships are
likely to emerge to help scientists decide which ones are bad actors.
This means all chemicals are candidates for testing --which greatly
complicates (and boosts the price of) testing to find endocrine

** "There was general agreement at the workshop that an endocrine
disrupter could only be adequately defined through the testing of
chemicals in the intact animal."[1,pg.53] This, too, is bad news. It
means that test-tube testing of chemicals will not yield the needed
information --tests must be done on living animals, which is expensive
(and often cruel).

** The potential interactive effects of exposure to several substances
simultaneously needs to be taken into account.[1,pg.41]

In sum, the Weybridge Report says that, to understand the problem of
endocrine-disrupting chemicals, we must study the interactions between
combinations of chemicals; we must study these interactions on at least
two generations of live animals; we must expose these animals at
different moments in their lives (different times prior to birth and
after birth). And of course, the animals must be exposed to various
concentrations of the chemicals to see if a dose-response relationship
becomes evident.

The need to test combinations complicates the picture enormously. For
example, to test just the commonest 1000 toxic chemicals in unique
combinations of 3 would require at least 166 million different
experiments (and this disregards the need to study varying doses given
to animals at varying times during their lives). If we wanted to
conduct the 166 million experiments in just 20 years, we would have to
complete 8.3 million tests each year. The U.S. presently has the
capacity to conduct only a few hundred such tests each year. Just
training sufficient personnel to conduct 8.3 million animal tests each
year is beyond our national capacity.

** Remarkably, the Weybridge Report recommends that, until the
necessary research is completed to give us full scientific knowledge,
consideration should be given to reducing the exposure of wildlife and
humans to endocrine disrupting chemicals, in line with the
Precautionary Principle.[1,pg.52] (As stated in Principle 15 of the
1992 Rio Declaration on Environment and Development, the precautionary
principle says that, "Where there are threats of serious or
irreversible damage, lack of full scientific certainty shall not be
used as a reason for postponing cost-effective measures to prevent
environmental degradation.")[2]

In sum, the Weybridge Report establishes criteria for understanding the
problem of endocrine disrupting chemicals, but it appears that even the
wealthiest nations in the world haven't the capacity to do the
necessary scientific research. This is a problem like no other we have
ever faced. The danger of irreversible damage is real. Therefore,
invoking the Precautionary Principle, to limit our exposure to such
chemicals even before we have full scientific knowledge, would seem to
be the only rational approach to take. In the U.S., this is probably
not possible because of the political muscle of the chemical
corporations. But perhaps other, more rational, democracies can shame
us into precautionary action.

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


PROCEEDINGS [REPORT EUR 17549] (Copenhagen, Denmark: European
Commission DG XII, April 16, 1997). Available from: European
Environment Agency, Kongens Nytorv 6, DK-1050 Copenhagen K, Denmark.
Telephone: (+45) 33 36 71 00; fax: (+45) 33 36 71 99.

[2] Daniel Bodansky, "The Precautionary Principle in US Environmental
Law," in Timothy O'Riordan and James Cameron, editors, INTERPRETING THE
PRECAUTIONARY PRINCIPLE (London: Earthscan Publications [120
Pentonville Road, London N1 9JN], 1994), pgs. 203-228. See also: David
Freestone and Ellen Hey, editors, THE PRECAUTIONARY PRINCIPLE AND
International, 1996).


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Descriptor terms: endocrine disruptors; estrogen; testosterone;
androgens; vinclozolin; structure-activity relationships; SAR; europe;
european environment agency; european commission; world health
organization; who; european centre for environment and health; oecd;
england; sweden; netherlands; germany; cefic; testicular cancer; breast
cancer; hypospadias; cryptorchidism; sperm count; imposex; molluscs;
shell fish; hermaphroditism; intersex; fish; vitellogenin; fertility;
reproductive health; birds; fish; turtles; alligators; dioxin;
endometriosis; pcbs;