Washington Post (pg. B1)  [Printer-friendly version]
December 4, 2006


[Rachel's introduction: Industrial chemicals are turning male fish
into females. Are humans being affected? Some scientists say Yes.
"This is a transgenerational problem that is undermining the
integrity of humans," says Dr. Theo Colborn.]

By David A. Fahrenthold

Growing evidence that chemicals in the environment can interfere with
animals' hormone systems -- including the discovery that male Potomac
River fish are growing eggs -- has focused the attention of
environmentalists and scientists on a new question: Are humans also at

A decade ago, the very idea that pollutants could interfere with a
body's chemical messages was near the fringes of science. But now, it
is an urgent topic for lawmakers and researchers around the world, and
especially in the Washington area.

In recent years, researchers have linked some common chemicals to
troubling changes in laboratory rodents and wild animals, including
reproductive defects, immune-system alterations and obesity.



In recent years, scientists and lawmakers have become more concerned
about pollutants in the environment that appear to interfere with
natural hormone systems. A few of the most widely known examples:

Bisphenol A -- Description: Building block for plastics. Found in:
Clear plastic bottles such as those used by hikers and infants, as
well as resins used to line food and drink cans. Results of research:
In animals, low doses have been linked to low sperm production,
altered growth and behavioral changes. The chemical industry says
other studies show that the chemical is safe.

Phthalates -- Description: Chemical additives that increase plastic's
flexibility. Found in: Flexible vinyl toys, wallpaper and electronic
devices. Results of research: In animals, these chemicals affect the
functioning of male brains and sex organs. In humans, one recent study
found a correlation between mothers' exposure and subtle developmental
changes in baby boys. The chemical industry says that there is no
proof that human health is at risk.

Treated sewage -- Description: Can include natural hormones excreted
by humans and artifi cial hormones such as those in birth-control
pills. Found in: Rivers and streams where treated sewage is released,
including the Potomac River. Results of research: Blamed for causing
fi sh in several streams to be "intersex," with both male and female


For now, no connections to human ailments have been proved. But some
studies have provided hints that people might be affected by crossed
hormones, and activists wonder if this kind of pollution could
contribute to diabetes, birth defects and infertility.

"There's a lot of concern that a lot of chemicals to which we are
exposed routinely, and without our knowledge, are interfering with the
way hormones work," said R. Thomas Zoeller, a professor of biology at
the University of Massachusetts at Amherst.

The Metropolitan Washington Council of Governments is planning to host
a public forum about hormone-disrupting pollution this spring. U.S.
Reps. James P. Moran Jr. (D-Va.) and Chris Van Hollen (D-Md.) have
said they plan to press the Environmental Protection Agency about its
failure to develop a program to test chemicals for hormonelike
effects, as ordered by Congress in 1996.

The idea that natural hormone messages can be tampered with is not
new; for decades, women using birth-control pills have been counting
on a man-made chemical to do just that.

But the current concern is much wider: Some fear that modern chemistry
might have unwittingly created other compounds with hormonelike
effects and that they might have spread widely around the globe.

In the past few years, scientists working with animals have found
potential problems with several pollutants, among them rocket-fuel
components, pesticides and additives to soap. Among the most heavily

** Phthalates, a family of additives used to make vinyl plastic
flexible and prevent perfume from evaporating, have been linked to
lower sperm counts and other sexual problems in male rats, as well as
to heightened allergic reactions in the animals. Chemical industry
officials have said that these tests used unrealistically high doses
and that the results are not likely to translate to humans.

** Bisphenol A, used as a building block for hard plastic goods like
bottles and as a resin to line food cans, has been connected in some
experiments to abnormal sexual development in male lab rodents, as
well as a predilection for obesity. Officials from the chemical and
pesticide industries have vigorously criticized these results, saying
that other studies have shown the chemical to be harmless.

** Treated sewage, which carries human estrogen and birth-control pill
components excreted in waste, has been linked to "feminized" male fish
in waters around the world. In the St. Lawrence River in Canada, a
recent study found that a third of male minnows had female
characteristics. Another example might be the Potomac, though the
cause of its problems has not been officially pinpointed. The EPA and
sewage-plant officials have said they are working on ways to better
clean the wastewater.

The study of endocrine disruptors began in the late 1980s and early
1990s, with scientists struggling to add up such oddities as male
birds with female organs in the Great Lakes and sexual defects in
Florida alligators.

They eventually found that some chemicals were turning on hormone
switches in the body's endocrine system that trigger biological
processes. Others blocked the switches so natural hormones couldn't
get through.

That revelation meant that a pollutant could be harmful even if it
wasn't poisonous and didn't cause cancer. Even small doses could cause
major damage, if they came at a key time when hormones were guiding
pregnancy or early development.

"We have to ask different questions," said John Peterson Myers, an
activist and former scientist based in Charlottesville. He joined with
scientist Theo Colborn and writer Dianne Dumanoski to write a book
laying out their concerns, 1996's "Our Stolen Future."

Today, despite the wealth of studies in animals, the implications for
human health are unclear. One of the most dramatic studies examined
the sons of mothers whose bodies contained phthalates. It found no
major birth defects but did show that the higher the phthalate level,
the greater chance that the boys' bodies would show subtle signs of
being "undermasculinized," according to researcher Shanna Swan,
director of the Center for Reproductive Epidemiology at the University
of Rochester.

Still, that falls well short of a smoking gun: Humans are not
laboratory rats, so scientists say it is exceedingly hard to craft a
study that shows a particular chemical caused a particular problem,
and not genetics, diet or some other factor.

"They're nowhere near cause-and-effect," L. Earl Gray Jr., a senior
research biologist at the EPA, said of human studies. "We're showing
correlations and associations" between pollutants and human health
effects, he said, but no indisputable sign that one causes the other.

Officials from the chemical and pesticide industries have vigorously
defended their products, saying they see no reason for concern about
products in the environment interfering with human hormones.

Some scientists have also pointed out that human diets have always
included some estrogen-like compounds: They occur naturally in wine
and soy-based products, for example.

Stephen H. Safe, a professor of veterinary physiology and pharmacology
at Texas A&M University, said that overall, despite our poor diets,
"what does the data say about our health in this country? We're living
longer... You know, where are these endocrine threats?"

Still, concerns that human health might be in danger have led to
recent bans on certain phthalates in young children's toys imposed by
the European Union and the City of San Francisco.

Activists in the United States have attacked the EPA for what they
believe is a delayed response to the problem. The agency has defended
itself by saying that it has spent millions on other research programs
looking at ways to identify and limit endocrine disruptors and that it
hopes to begin the long-delayed chemical testing program next year.

Some activists fear that damage is already being done. They caution
avoiding plastic baby bottles, which could contain bisphenol A, and
reducing consumption of animal fat, where some environmental
pollutants can concentrate.

"I feel terrible because we haven't moved on this faster," said
Colborn, the activist who has served as an unofficial leader among
endocrine-disruptor researchers. "This is a transgenerational problem
that is undermining the integrity of humans."

But Paul Foster, an official who evaluates risks to human reproduction
at the National Institute of Environmental Health Sciences, said it
was hard to give useful advice at this point because the chemicals
being investigated are so ubiquitous.

"There's very little that they can do," said Foster, whose agency is
part of the National Institutes of Health. "That's why you can't be
too alarmist about it, because you can't stop people living."

Copyright 2006 The Washington Post Company