Scientists expose body toxin
Synthetic chemicals may affect two
generations' ability to have children
By Douglas Fischer, STAFF WRITER
Article Last Updated: 02/04/2007 06:37:49 AM PST
Wendy Botwin suffers
from endometriosis which many medical experts believe is caused by a drug
given to pregnant mothers in the 50-70's. Botwin poses for a photo at
Halcyon Park in Oakland on Friday February 2, 2007. (Sean Connelley - Staff)
SAN FRANCISCO - Your ability to reproduce
- and the health of your child and even your child's children - hinges on an
exquisitely timed series of chemical reactions controlled by infinitesimally
tiny amounts of hormones.
You scramble those reactions at your
peril, in other words, and last week hundreds of researchers gathered at the
University of California, San Francisco, warned society may be doing exactly
that with synthetic chemicals.
The chemicals, known as endocrine disruptors, are found everywhere in our
environment: food, lotions, shampoos, baby bottles, toys, appliances, even
casings for medicines. They mimic hormones at levels scientists only
recently have been able to measure, and some are active at concentrations of
a part-per-trillion or less - a speck of dirt sullying 55 tons of clean
Most worrisome to scientists: In many cases, the effect of such pollution on
our bodies remains as unknown and mysterious as the processes they
"In the absence of concrete data for many of these chemicals, the
precautionary principle should be exercised," said Dr. Linda Guidice,
chairwoman of obstetrics, gynecology and reproductive sciences at UCSF and
the organizer of the reproductive health conference that brought 500
scientists, clinicians and community activists together.
"Just because we measure something
doesn't mean it's harmful," she said. "But there may be harmful things out
there that we don't even know
The list of potential effects,
scientists conclude, cover every aspect of reproductive and sexual
development - from preconception to menopause.
Every key developmental stage is driven by a tightly choreographed
fluctuation in hormones. A flood of endocrine disruptors, scientists fear,
obviates that dance.
"It's a bit like holding the pedal down on your car," said Cheryl Walker, a
Carcinogenesis professor at University of Texas M.D. Anderson Cancer Center.
"All the genes are activated. If you're looking at a window of time when
gene expression is rapidly happening, you might imagine you could wreak
For those suffering from endometriosis, there's no need to imagine.
Wendy Botwin of Oakland was 18 when she felt the first signs: mysterious
sickness, massive abdominal pain, irregular periods, crushing headaches,
painful sex. Two-and-a-half years passed before a doctor diagnosed her with
endometriosis, a debilitating disease where the tissue lining the uterus
appears outside the womb in other parts of the body.
Today, at 37, Botwin has used all types of birth control pills. She says
she's also been advised to get pregnant (she may be infertile) and to have a
hysterectomy. One drug sent her into menopause, at 21.
Nothing has worked and she feels certain something in the environment has
triggered this. Her father died at 62 of stomach cancer. Her younger sister
was diagnosed last year with thyroid cancer. She feels, she said, like a
canary in a coal mine.
"I know we've polluted our bodies and the Earth," she said. "The environment
is really inside of our bodies. It's not just outside."
The science of endocrine disruptors is still controversial. The effects in
humans are uncertain. Government panels assessing the evidence for many
compounds repeatedly have found no need for concern. But scientists say
disturbing gaps remain in our knowledge.
-Several studies have shown pesticides suppress fetal testosterone in
laboratory animals. But scientists can't fully explain the consequence. They
don't know the role testosterone plays in a baby boy's brain development.
-The womb was once thought of as a
gatekeeper, shielding the developing baby from harm. No more. A number of
contaminants readily traverse the placenta, and others - synthetic
fragrances, for one - are thought to hold open the door, so to speak. The
fragrances might be benign, but they let other, more harmful compounds slip
It's akin to having a corrupt bouncer
letting a few thugs inside, scientists say. It ruins the party for everyone.
-Female mice exposed in utero to bisphenol-A, a estrogenic additive used to
line food cans and make plastic shatterproof, among other things, saw a 40
percent increase in chromosomally abnormal eggs, one research team said.
"We've studied these things for years, and we've never seen anything like
this," said Patricia Hunt, a genetics professor at Washington State
University who stumbled upon this by accident when a janitor mistakenly used
a harsher disinfectant on the animals' plastic cages and water bottles.
The result, she said, was a three-generation hit: The mother, her fetus and
the fetus's eggs - the mother's grandchildren.
"We were really mucking up these events."
But this is where the science gets murky. In November a European panel
investigating the effects of bisphenol-A concluded levels found in the
environment pose no threat to our health, despite findings such as Hunt's.
Why? Mice and humans process bisphenol-A differently, the panel said.
Mice recirculate the compound and appear to be sensitive to such weak
estrogens. Humans, in contrast, rapidly transform bisphenol-A in the gut
into a compound devoid of hormonal activity, then pass it via urine.
Such differences, according to the European Food Safety Administration,
"raise considerable doubts about the relevance of any low-dose observations
in rodents for humans."
Steve Hentges, executive director of the polycarbonate business unit for the
American Plastics Council said, "In every case, when that kind of review has
been done, it always comes out the same: They're not too terribly concerned
Another example: DES, or diethylstilbestrol, a drug given in the 1940s to
the 1970s to pregnant women prone to have miscarriages.
The mothers were fine, but DES ravaged the reproductive tracts of their
children. Girls exposed in the womb saw particularly high rates of diseases
such as fibroid tumors and endometriosis, leading causes of infertility and
DES did its damage, scientists now know, because it turned hormones on at a
time during fetal development when they would normally be silent. That,
researchers say, is exactly what bisphenol-A and a soup of other
endocrine-disrupting compounds do.
The dose, they caution, is far less than what DES delivered. But the
mechanism is the same.
Sandra Steingraber, a noted ecologist, author and cancer survivor, echoed
Botwin's thoughts on the environment and endometriosis as she told
scientists of her experience being pregnant with her daughter, Faith.
"We need to start thinking of our reproductive lives as a live musical
performance. Our bodies are the piano, but the hands are the environment,"
"We are nothing less than the receivers of environmental messages. As that
message changes, we are changing ourselves."