For education purposes only.
Dursban, the Common Organophosphate
Pesticide,
Deemed "Highly Risky" in New Review
By Cat Lazaroff
WASHINGTON, DC, October 28, 1999 (ENS) - A common,
popular insecticide used on crops, lawns and Christmas trees poses higher
risks to human health and the environment than previously believed, the U.S.
Environmental Protection Agency revealed Wednesday.
An EPA official who asked not to be identified told ENS today that, in light
of the new risk assessment, the EPA will likely seek
to curb the use of the insecticide chlorpyrifos.
Chlorpyrifos, the active ingredient in Dursban* and Lorsban* insecticides,
trademarked names of Dow AgroSciences LLC, is a broad-spectrum, organophosphate
insecticide first registered in the United States in 1965. Registered uses
include a wide variety of food crops, turf and ornamental plants, structural
pest control and residential uses.
Dow AgroSciences markets chlorpyrifos as Dursban Pro and Dursban 50W for
general pest control, and Dursban TC for termite control.
The reassessment of the widely used pesticide chlorpyrifos casts the
agency’s planned reevaluation of thousands of chemicals in a new light,
indicating that new data and improved techniques may reveal toxins in our
own backyards.
Chlorpyrifos and other pesticides are being reviewed under the process developed
by the Tolerance Reassessment Advisory Committee to determine whether their
existing Environmental Protection Agency (EPA) registrations meet stringent,
new safety standards required by the Food Quality Protection Act of 1996.
As part of the retesting, the EPA is using controversial animal tests, as
well as a review of existing data, to determine safe exposure limits for
adults, children, land animals and aquatic animals.
The EPA’s reassessment of chlorpyrifos finds significant risks to humans
and wildlife from outdoor uses of the pesticide. The chemical is so widely
used that "the majority of the U.S. population is exposed to chlorpyrifos,"
the EPA’s preliminary risk report states.
The report notes that previous studies have shown that 82 percent of American
adults and 92 percent of children studied have traces of the chemical in
their urine.
The EPA found that risks from chlorpyrifos use on crops, primarily sweet
corn, are not as high as the agency had feared. But risks from
household uses, including mosquito
fogging, lawn maintenance, and spraying on golf courses and Christmas tree
farms, pose risks that "exceed levels of concern"
for humans, pets and wildlife.
The agency documents numerous cases of fish kills in surface waters near
sprayed areas, including one incident in which 2,000 blue gill sunfish were
killed in a small lake adjacent to a motel, where just two rooms were treated
with chlorpyrifos for termites.
Bird deaths are also seen, though the EPA notes that chlorpyrifos is unlikely
to produce large visible bird kills, as birds have time to fly elsewhere
before showing symptoms.
"Birds have adequate time to feed in chlorpyrifos treated fields, leave the
treated area and disperse to other habitats before they begin to experience
to toxic symptoms, then they seek refuge and hide before dying," the report
states.
The chemical is also highly toxic to honey bees, already in a crisis due
to an epidemic of exotic diseases and parasites.
Another common use of chlorpyrifos is the aerial spraying of Christmas tree
farms, and drenching freshly cut stumps to retard decay after consumers take
the trees home. Previous risk assessments were based on exposure to a single
drop of the 3,595 parts per million spray. But, "few species drink only one
drop when they drink or are thirsty," the report says.
Wild animals are placed at high risk by normal drinking of the spray or bathing
in the runoff. Birds are at risk when preening wet feathers.
The insecticide solution "may pose acute risks to aquatic organisms, if rainfall
washed the spray solution off the tree stumps into adjacent aquatic areas,"
the report notes. And aerially spraying Christmas trees, "exceeds the levels
of concern for most non-target aquatic and terrestrial animals."
Treated lawns and shrubs pose the same threat, as "it is evident that species
.. are capable of drinking more than a single drop off leaves and other
vegetation."
While the EPA cautions against drawing premature conclusions from these
preliminary results, it seems likely that the agency will set lower thresholds
for safe exposure to chlorpyrifos, reducing the possible uses for the chemical.
Dow AgroSciences has already responded to the study, saying that it includes
a "tremendous number of errors and omissions." The company says chlorpyrifos
is quite safe.
"Dow AgroSciences believes the extensive use of chlorpyrifos during the last
three decades is a clear indication of the value of this compound and the
benefits that chlorpyrifos provides to growers and the American public
generally," the company told EPA in an October 19 report.
According to the company’s own risk database, the report says, "realistic
risk concerns are minimal and are clearly outweighed by the significant benefits
provided by chlorpyrifos."
Yet in eight of nine of EPA’s tests on chlorpyrifos, the agency calculated
risk levels well above the EPA cutoff for further action to reduce the
chemical’s health risks.
Without the additional testing required by the Food Quality Protection Act
of 1996, the EPA’s safe exposure levels for organophosphate pesticides
such as chlorpyrifos would remain at their current levels, regardless of
actual risk.
The EPA official said today that testing programs, including the controversial
high production volume chemical testing program, may also lead to a net reduction
in the amount of toxins released to the environment. The HPV program, fast
tracked last fall by Vice President Al Gore, calls for tests on 2,800 widely
produced industrial chemicals.
Last week, People for the Ethical Treatment of Animals (PETA), the Doris
Day Animal League and the Physicians Committee for Responsible Medicine reached
an agreement with the EPA to amend the high production volume program. The
agreement greatly reduces the number of animals that will be used in the
high production volume program. The EPA and other agencies originally estimated
that up to 1.3 million laboratory animals of all kinds would have be sacrificed
to complete the testing. Under the amended plan, as many as 800,000 animals
will be saved.
Under the agreement, the EPA sent a letter to some 900 top chemical companies
with new high production volume testing guidelines. One major change is that
the agency will no longer require companies to perform a checklist of individual
tests for each of the chemicals. If existing data from animal or human testing
provides enough information, chemical companies will not be required to perform
new tests.
EPA officials were unclear today on whether databases such as the internal
resource used by Dow AgroSciences to reach its conclusions about the safety
of chlorpyrifos would be considered sufficient by the EPA.
Copies of the preliminary risk assessment are available on EPA's web site
at:
http://www.epa.gov/pesticides/op/status.htm .
The EPA will accept public comments on the report for 60 days.
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© Environment News Service (ENS) 1999. All Rights Reserved.
Source:
http://ens.lycos.com/ens/oct99/1999L-10-28-06.html
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Environmental News Service site .
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