4 November 2002
boyhood curiosity to scientific discovery
Biologist links pesticides to amphibian deformities
about Hayes's research
T. Hall, Chronicle Science Writer
Hayes may not fit the stereotype of the big-time scientist. But
he figures it doesn't hurt that he sometimes stands out in a crowd
of his peers.
give a talk at a meeting, and everybody remembers the black guy
in the braids," he said. "They may not remember what I
said, but they tend to remember me."
it's not his braids but his work that is starting to draw most of
35, an African American biology professor at UC Berkeley, has produced
a series of high-profile studies challenging the ecological safety
of atrazine, the most widely used pesticide in the United States.
latest research suggests that the weed-killer may be short-circuiting
the reproductive machinery of amphibians exposed to farm chemicals
in spring runoff. A summary of the latest findings appears in the
Oct. 31 issue of the journal Nature.
mysterious ill health of amphibians native to North America is one
of the more alarming environmental stories of recent years, and
Hayes is the first to find a link to pesticides, both the laboratory
and in field studies.
and his colleagues have found large numbers of "feminized"
male frogs in water containing traces of atrazine. The results are
being challenged and have not been replicated, but Hayes is not
one to back down easily.
our study, the only fair conclusion you can make is that if there
are abnormalities, there's atrazine," he said. "We wanted
to find out if atrazine has an effect or not. The answer is that
OF THE LEADERS IN THIS FIELD'
Now, Hayes and a large coterie of students are busily working on
at least seven related papers, including gene studies and more ambitious
field investigations. He also has had to spend time rebutting charges
from other scientists that his approach is all wrong and his data
are riddled with major inconsistencies.
not to suggest Hayes lacks supporters defending his work.
an outstanding scientist, one of the leaders in this field,"
said Andrew Blaustein, an ecologist and amphibian specialist at
Oregon State University. "Everybody better start waking up.
We have all these chemicals out there permeating the environment,
and when anyone says something may be wrong, people start jumping
on the person making the statement."
week's paper in Nature -- and a story about the controversy and
research appearing a day later in the competing journal Science
-- mark the high point in a remarkable scientific odyssey that began
in the muck of the great Congaree Swamp in South Carolina.
grew up near Columbia, and one of his favorite boyhood pastimes
was messing with the turtles, snakes, toads and many other slithery
creatures native to the region.
was not expected to become an eminent scientist. His father, Romeo
Hayes, never graduated from high school, and he worked as a carpet
installer. His mother, Susie, tended to the family at home.
the eldest son, landed a scholarship to attend Harvard University
in 1985. His flight to Massachusetts as an incoming freshman was
his first time on an airplane. When he graduated, he became the
first in his family to earn a college degree. He earned his doctorate
in animal endocrinology at Berkeley.
and former students describe him as a careful, hardworking researcher
and an impassioned teacher. His large laboratory is a magnet for
a diverse group of students and researchers who approach their work
as a calling.
gets very excited about the work that he's doing, and he's very
charismatic, so he's able to project his interest and get other
people interested," said Dan Buchholz, a former doctoral student
in Hayes' lab now working at the National Institutes of Health.
ON AGRIBUSINESS GIANTS
In his zeal, however, Hayes can demand little short of total commitment
from those around him.
one time he got everybody in the lab, even if they had other projects
going on, to devote a couple of months to weighing tadpoles on one
of his big projects, because there was a big wave of work that had
to be done," Buchholz said.
took a fair amount of mostly good-natured arm-twisting. Now, the
challenges have escalated far beyond the lab, as Hayes takes on
some of the biggest powers in agribusiness -- most notably atrazine's
manufacturer, Syngenta, the agribusiness giant based in Switzerland
that reported $6.3 billion in sales last year in 20 countries.
aligned with Syngenta argue that Hayes is the only one coming up
with results casting aspersions on one of the world's most widely
used weed- killers.
took potshots at Tyrone, including me," said Richard Wenning,
a senior manager at Environ, an Emeryville consulting firm that
has had Syngenta as a client, work that included a critical evaluation
of Hayes' frog research.
has reported laboratory work and field studies suggesting that even
low-dose exposure to atrazine might pose a hazard to amphibians.
He makes a case that atrazine functions as an "endocrine disrupter"
in wild amphibians -- a chemical that plays havoc with their natural
herbicide is said to promote activity of an enzyme called aromatase,
which converts the male hormone testosterone into estradiol, a form
of estrogen, the female hormone.
that happens at the wrong time in a young frog's development, the
result can be a high incidence of males with feminized gonads, as
well as smaller- than-normal voice boxes, Hayes said. The effects
do not appear to be limited to any particular species but are masked
by the fact that affected frogs show no obvious, outward signs of
gene studies are under way that might help explain the basic physiological
processes at work when a frog is exposed to pesticides. Hayes said
at least one more "major impact" paper is imminent, while
other research is showing odd effects in amphibians exposed to cocktails
of atrazine and other pollutants.
are now approaching everything I have been dreaming about since
becoming a scientist," Hayes said. "We're trying to put
it all together."
THE EPA'S ATTENTION
Hayes' first bombshell came in April with a paper in the Proceedings
of the National Academy of Sciences, focusing on a species of African
clawed frog widely used in laboratory studies of amphibians. The
Environmental Protection Agency was nearing the critical stage of
a years-long re-review of atrazine, part of a broader look the agency
is taking at all pesticides.
it was, the 11th hour of the EPA review, and then Tyrone comes out
with this study, and says, 'Hey, this is a huge endocrine disrupter,
and maybe that's why the amphibian populations are declining in
the Midwestern United States.' Man, did that get their attention,"
has escalated with the latest high-profile studies. They showed
essentially the same hermaphroditic effects in the common American
leopard frog, Rana pipiens.
time, however, Hayes sampled watersheds in the field, where he found
the same mutations he had observed in his laboratory studies. The
finding attracted a steady stream of reporters and camera crews
to his fifth-floor offices and basement specimen housing on the
appeared to tolerate the media interest in good humor, inviting
one reporter to sit in on some of his lectures. He also issued his
own detailed rebuttal when asked what he thought of his critics'
appraisal of his work.
goals seem to be getting ever more ambitious the more controversy
he generates. Now, he is laying plans to sample the vast Missouri
River drainage from its relatively pristine source all the way down
to its terminus on the Mississippi, to see how changing pesticide
levels might affect amphibian health all the way down the river.
sees his work coming back around to his boyhood, an extension of
his exploration of the swamps of South Carolina. Now it's just being
done with greater sophistication. While others have found no evidence
of damage from atrazine runoff, Hayes said that's because "nobody's
he said, "you have to know what you're looking for."