Lincoln Lab Is Only One in U.S. to Test Pesticides on Humans
BY JAKE THOMPSON
COPYRIGHT 1999 OMAHA WORLD-HERALD CO.
Washington - In the only known testing of its kind under way in
the United States, MDS Harris Laboratory in Lincoln has been
conducting pesticide research on humans.
Researchers this year asked volunteers in Nebraska to swallow
small doses of a pesticide to examine its potential harmful
effects on people.
The study was one of 14 submitted to the Environmental
Protection Agency that involve people ingesting 10 different
pesticides. The 13 other studies were on volunteers in the
Together, the studies are at the heart of a debate among
scientists, ethicists and pesticide makers about the scientific
value, the standards for and the moral justification of testing
pesticides on humans.
While some at the EPA, which regulates pesticides, see clear
value in these human studies, which are legal, many do not, said
John Carley, special assistant in the EPA's Office of Pesticide
"There are many people at the agency who are troubled by the
fact this testing has ever gone on and is going on, or might
ever go on in the future," Carley said.
The EPA recently established a panel to review human testing.
For the MDS Harris research, some of the 60 volunteers swallowed
a capsule containing chlorpyrifos, a pesticide widely used on
crops as well as in schools, hospitals and 20 million homes to
kill such pests as termites, ticks, cockroaches and fire ants.
The pesticide is commonly marketed as Lorsban or Dursban.
Some of the 60 volunteers were part of a control group and were
given a placebo. The volunteers earned $460 for their
participation. Carley said participants in Great Britain are
paid twice as much.
Earlier this year, the EPA concluded that chlorpyrifos poses
high risks to millions of Americans because it can disrupt the
Supporters of the research said it is hoped that the tests will
show how much of the pesticides can be ingested without any
noticeable harm to people. Those supporters note that doses
given to the volunteers fell well under a toxic dose.
According to results from the MDS Harris study, volunteers who
swallowed the pesticide capsules reported developing one
incident each of nausea, vomiting, abdominal pain, shortness of
breath, impairment of sensation and chest pain. Those symptoms
were possibly or probably related to ingesting the pesticide,
according to the study.
MDS Harris declined to discuss the study, referring questions to
its client, Dow Chemical, the principal maker of chlorpyrifos.
But Dr. Jim McClurg, MDS Harris' president of life sciences,
said all of its studies follow international rules protecting
participants and are reviewed by independent experts before and
after the work. McClurg said the Lincoln-based company, founded
in 1933, has clinics in a handful of cities worldwide and does a
large amount of research on the clinical development of drugs.
Garry Hamlin, a spokesman for Dow AgroSciences, said Dow sought
the human research to add to the 3,600 previous research studies
and reports on the pesticide. They involved lab studies, animal
research and studies of people who apply the pesticide or
routinely work in areas in which it is applied.
Direct testing on human volunteers can help clear up uncertainty
that exists between animal studies and the eventual impact on
people, he said.
The previous research guided the dosage levels in MDS Harris'
study so that it "would not cause any harm to the volunteers,"
Ken Cook, president of the Environmental Working Group, an
activist organization in Washington that has tracked the human
research trend, called the testing questionable. "Would you want
your kid to participate in a study like this?"
The American Crop Protection Association says that human tests
are safe and that the compounds studied are widely found in
small concentrations in the environment and the nation's food
For years, the EPA has neither required nor encouraged human
tests. And while such tests flourished in the 1960s and 1970s,
according to Carley, concerns about the ethics and safety led
most companies to discontinue such tests.
Then, in 1996, Congress passed the Food Quality Protection Act,
which required stricter protections for children from
Attempting to show that their products are safe, large pesticide
makers resumed testing their pesticides on people to aid in the
government's risk assessment. The argument is this: Human
studies are more accurate than animal studies and might
establish a higher safe dose.
In May 1998, the EPA published a federal notice that human tests
might be helpful in assessing safety risks.
When criticism of the notice surfaced, the EPA set up a special
advisory panel to recommend a refined policy that considers the
safety, ethics and conditions for human tests.
The advisory panel held its second meeting Nov. 30. An EPA
background paper for the meeting noted that the agency accepts
other human tests, such as those studying people who apply
pesticides on fields and for businesses.
But the agency said that the 1996 law "may have unintentionally
created an incentive" to test pesticides in human volunteers.
"These studies raise difficult scientific and ethical questions
we are not yet able to answer, and we are deeply concerned about
them," the background paper states.
The pesticide makers compare the pesticide studies to what are
called Phase 1 clinical drug tests commonly submitted to the
U.S. Food and Drug Administration. In those tests, the objective
is to determine adverse reaction levels to a drug.
Jeffrey Kahn, a bioethicist at the University of Minnesota and
an EPA advisory panel member, said the pesticide tests are
The ultimate goal in drug tests is to make people healthy, he
said, but the pesticide tests help determine at what levels of
exposure people become sick.
Further, the drug tests usually involve people who already are
ill, while the pesticide tests seek healthy subjects.
"I think there's a question of how much risk healthy individuals
should bear when there's not a clear benefit to the person,"
Kahn said. "All of the risk is to the individual subjects, and
all the benefits are to society or the companies producing these
Another issue before the advisory panel is whether human
pesticide studies are statistically valid.
Dr. Herbert Needleman of the University of Pittsburgh, who is a
member of the advisory panel, said the sample size in the 14
studies sent to the EPA was too small. One examined seven
subjects and another examined 50, he said.
That cannot help establish what is called a no-effect level, a
government standard below which there is no noticeable reaction.
A study would need from 1,000 to 5,000 human participants to be
statistically correct, Needleman said.
Ray McAllister, senior director of scientific and regulatory
policy for the Washington-based crop association, disagreed. He
said that the studies are valid because they examine enzyme
function, which varies in humans anyway. So finding a response
in a small number of human pesticide testers could be translated
to the population at large, he said.
It's also important, McAllister said, that the testing subjects
volunteer and are informed of the substance they are taking, the
dosage and its risks.
A copy of the informed-consent form was included in the study
sent to the EPA. The seven-page form explains that the test
involves chlorpyrifos, sketches its effects on the nervous
system, outlines how the study will be conducted and warns that
there are 15 potential adverse reactions, including headache,
dizziness, abdominal cramps, tremors and tightness in the chest.
It also has a pregnancy-related warning: "Although animal
studies indicate little or no risk in humans, the possible side
effects to a fetus or embryo are unknown."
Of the volunteers in the MDS Harris study, 30 were men and 30
were women. Slightly more than one-third were 18 to 25 years
old, the rest in their late 20s to early 50s. Most were
The volunteers were enlisted through ads in newspapers and on
MDS Harris' Internet site, such as one ad that says, "EARN EXTRA
MONEY. Make a Difference by Assisting in Medical Research. "
Participants were given health screenings and drug and alcohol
tests to determine medical history and fitness. They were told
that the test material was a registered insecticide, according
to the study.
The volunteers were given capsules with either chlorpyrifos or
the placebo. They were given pills three or four times a day.
Their vital signs were tracked and urine and blood samples were
collected by MDS Harris staff.
The study used two phases and several groups to examine the
effects of a rising dose of chlorpyrifos, documents show.
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