AR-News: Animals' Sexual Changes Linked to Waste, Chemicals

[Masako Miyaji]

http://news.nationalgeographic.com/news/2004/03/0301_040301_genderbender.html

Animals' Sexual Changes Linked to Waste, Chemicals

James Owen
for National Geographic News
March 1, 2004

Animals throughout the world are undergoing unnatural
sexual changes in response to environmental pollution,
according to a group of scientists. The scientists
warn that the gender-bending effects of certain
man-made substances and human sewage seriously
threaten polar bears, alligators, frogs, mollusks, and
other wildlife. 

The group's concerns are set out in a new report
compiled by an international research team for the
Paris-based Scientific Committee on Problems in the
Environment (SCOPE) and the North Carolina-based
International Union of Pure and Applied Chemistry
(IUPAC). The scientists say the report represents the
first major global investigation into body-altering
chemicals known as endocrine active substances, or
EASs. 

"Understanding the scientific issues surrounding
endocrine active substances is an international
priority," the report states. "Endocrine disruptors
affect not only humans, but also other living
organisms. They affect not only our own generation,
but also future generations." 

The report suggests endocrine disruptors are now
widespread in many animals and can seriously harm
populations. The authors call for international
authorities take urgent action to address the threat. 

Endocrine disruptors interfere with animals' endocrine
systems, leading to adverse health effects that can be
passed to offspring. EASs mimic naturally produced
hormones, setting off chemical reactions in the body.
Endocrine disruptors can also block the action of
hormones and alter their concentrations. 

According to the Brussels, Belgium-based European
Commission, endocrine active substances include the
naturally-occurring hormones estrogen and
testosterone. Other EASs are man-made substances like
the synthetic hormones used in oral contraceptives and
hormone-replacement therapies as well as chemicals
used in industry and agriculture (such as pesticides).


Scientists first realized the scale of endocrine
disruptors' gender-bending potential in the 1990s.
According to Joanna Burger, studies have shown over
200 animal species around the world are known or are
suspected to have been affected by EASs. Burger is
co-chair of the SCOPE/IUPAC project and professor of
cell biology and neuroscience at Rutgers University in
New Jersey. 

Sex-Change Pollution 

The masculization of female polar bears in the
Norwegian Arctic was linked to polychlorinated
biphenyls (PCBs), an industrial pollutant that
accumulates along food chains, according to a study
published in 1998 in the Journal of Wildlife Diseases.
The following year, a WWF report associated
spontaneous abortions and declining seal populations
along the Wadden Sea coast of the Neatherlands,
Germany, and Denmark with low female hormone levels
due to PCB contamination. 

Studies undertaken in Lake Apopka, Florida, blame
pesticide pollution for sex-organ abnormalities in
Florida alligators, which researchers say have
resulted in significant population losses. Females
were having difficulty creating viable eggs, while
males experienced premature sperm production and
reductions in penis size, among other effects. 

In Britain studies commissioned by the government's
main environment agency found that sewage effluents
caused egg development in male freshwater fish. 

More recent studies published in the Proceedings of
the National Academy of Sciences and Environmental
Health Perspectives research journals also linked
endocrine disruptors to limb deformities and
feminization in frogs as well as masculization in many
species of marine mollusks. 

The new SCOPE-IUPAC report says endocrine disruption
can be expected in all animalsin which hormones
initiate physical changes, including humans. 

While human effects have not been proven or
quantified, the European Commission has adopted a
precautionary approach based on current knowledge on
the possible effects of endocrine disruption in
humans. Women, they say, may experience a greater risk
for breast and ovarian cancer, and the female
birthrate may decline. Possible male health impacts
include lower sperm counts, smaller penis size, and
increased risk for testicular cancer, according to the
inter-governmental body representing 15 member states.


Peter Matthiessen, head of environmental chemistry and
pollution at the U.K.'s Centre for Ecology and
Hydrology says a major challenge facing scientists who
study the impact of endocrine active substances is
that the larger the animal, the harder it is to prove
the effects of EASs. 

"We've got much better data towards the lower end of
the animal scale than the upper end," he said. "To be
sure you know what's happening, you've really got to
do an experiment in the lab to replicate the effect.
You can do that with a shrimp or a fish, but not with
a whale." 

An added challenge for researchers studying endocrine
disruptors is the likelihood that the substances act
together in complex cocktails. This makes work to
determine precise cause and effect even more
difficult. 

Mattiessen is co-author of a recent U.K. study that
backs the finding of the SCOPE-IUPAC report. The
study, recently published in the scientific journal
Environmental Toxicology and Chemistry, suggests that
the gender-bending impacts of EASs can be reversed. 

Sewage Effluents 

During a five-year study, Matthiessen and his
colleagues conducted a series of annual surveys of
fish along the British coast to gauge trends in levels
of feminization. The study was spurred by previous
observations of feminization in estuarine fish,
particularly the flounder, a common flatfish,
Matthiessen said. 

"We've known for some time that this fish has become
feminized in estuaries where lots of people live and
lots of sewage is going into the water." 

Matthiessen said that the fish's changes were a
reaction to estrogens present in human waste. Such
estrogens derive largely from birth control pills and
hormone-therapy drugs. 

"What's really interesting is that in the Tyne [River]
estuary in northeast England a really strong recovery
kicked in," Matthiessen said, noting the phenomenon
coincided with the upgrading of a major sewage
treatment works. "Until then, most of the fish were
very strongly feminized. For example, yolk was present
in male blood plasma, which is highly abnormal. Then
[after the sewage plant upgrade] there was this sudden
drop in yolk protein concentrations which was
sustained in subsequent years." 

Matthiessen says modern sewage treatments, which are
better at stripping out hormones, can help to tackle
the problem of estrogen pollution. 

Action Requested 

The SCOPE-IUPAC report also calls for more detailed
scientific analysis of endocrine disruptors,
particularly those that may pose a risk even at very
low levels. The report also advocates improved
environmental safeguards, such as routine testing of
chemicals for endocrine-disrupting properties. 

The report also says substantial international
coordination and cooperation on the issue is lacking
at present and that the Intergovernmental Forum on
Chemical Safety (IFCS), based in Geneva, Switzerland,
should initiate global management of endocrine
disruptors. 

The European Union has adopted a community strategy
for addressing the problem, including the development
and validation of test methods and a review of laws
governing chemical use. But this still doesnt go far
enough, environmental groups say. 

Clifton Curtis, of the Washington, D.C.-based WWF,
said: "We know that the global production of chemicals
is increasing, and at the same time we have warning
signals that a variety of troubling threats to
wildlife and human health are becoming more prevalent.
It is reckless to suggest there is no link between the
two, and give chemicals the benefit of the doubt." 



__________________________________
Do you Yahoo!?
Get better spam protection with Yahoo! Mail.
http://antispam.yahoo.com/tools