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Date: 7 Aug 2003
Posted by: ERAP <envrisk@cornell.edu>

August 7, 2003
Is There a Place for DDT?
By HENRY I. MILLER

STANFORD, Calif.-The outbreak of West Nile virus in the United States 
is rapidly becoming a significant threat to public health. With the 
peak season just beginning, the mosquito-borne virus has been found 
in animals (primarily birds and horses) in 38 states, and has caused 
103 serious infections and three deaths in humans in 15 states.

Last year, there were more than 4,000 cases and almost 300 deaths. We 
may be on the verge of an epidemic, but there is no treatment and a 
vaccine is at least a decade away.

Public health officials have recognized the seriousness of the 
problem, but too often their response has been tepid and designed to 
avoid controversy. The Centers for Disease Control Web site, for 
example, advises people to avoid mosquito bites by covering up, using 
insect repellent, and staying indoors during peak mosquito hours. 
Missing from its list of suggestions, however, is any mention of 
insecticides or widespread spraying. Anyone curious about the role of 
pesticides in battling mosquitoes and West Nile is directed to a maze 
of other Web sites.

In the absence of a vaccine, elimination of the organism that spreads 
the West Nile virus - in this case, the mosquito - is the key to 
prevention, but fundamental shortcomings in public policy limit the 
tools that are available.

In 1972, on the basis of dubious data about toxicity to fish and 
migrating birds, the Environmental Protection Agency banned virtually 
all uses of the pesticide DDT, an inexpensive and effective pesticide 
once widely deployed to kill disease-carrying insects. Allowing 
political sentiment to trump science, regulators also cited the 
possibility that DDT posed a cancer risk for humans - an assertion 
based on studies showing an increased incidence of the illness in 
mice that were fed extremely high doses of the pesticide.

Not only did government regulators minimize scientific evidence of 
the safety and effectiveness of DDT, they also failed to appreciate 
the distinction between its large-scale use in agriculture and more 
limited application for controlling carriers of human disease. 
Although DDT can be a toxic substance, there is a big difference 
between applying large amounts of it in the environment - as American 
farmers did before it was banned - and applying it carefully and 
sparingly to fight mosquitoes and other disease-carrying insects. A 
basic principle of toxicology is that the dose makes the poison.

The regulators who banned DDT also failed to take into consideration 
the inadequacy of alternatives. Because it persists after spraying, 
DDT works far better than many pesticides now in use, some of which 
are toxic to fish and other aquatic organisms. (While its longevity 
poses risks, they are minimized with targeted use.) Also, the need to 
spray other insecticides repeatedly drives up costs. For example, 
budget problems compelled Maryland this summer to turn down requests 
for spraying from communities badly infested with mosquitoes.

Given the long-term ineffectiveness of other pesticides, DDT remains 
the best alternative to fighting mosquitoes and the West Nile virus. 
It's worth recalling that DDT worked before, eradicating malaria from 
the United States. It's worth recalling, too, that since DDT was 
widely banned, insect-borne diseases like malaria and dengue fever 
have been on the rise worldwide. The World Health Organization 
estimates that malaria kills about one million people annually, and 
that there are 300 million to 500 million new cases each year.

How can we drain the public policy swamp? First, the government 
should undertake a re-evaluation of the voluminous data on DDT that 
has been compiled since the 1970's. It should also make DDT available 
for mosquito control in the United States.

Second, the United States should oppose international strictures on 
DDT. This includes retracting American support for the United Nations 
Persistent Organic Pollutants Convention, which makes it exceedingly 
difficult for developing countries - many of which are plagued by 
malaria - to use DDT.

Finally, federal officials should embark on a campaign to educate 
local authorities and citizens about the safety and potential 
importance of DDT. Right now, most of what people hear is the 
reflexively anti-pesticide drumbeat of the environmental movement.

Because DDT has such a bad rap, it will be politically difficult to 
resurrect its use. But we should begin the process now. In the 
meantime, we'll just slather on the insect repellent, slap, scratch - 
and occasionally become infected with a life-threatening but 
preventable disease.

Henry I. Miller, a doctor, is a fellow at the Hoover Institution. He 
was a Food and Drug Administration official from 1979-1994.

Copyright 2003 The New York Times Company

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