On Tue, 19 Feb 2002, lorna bloom wrote:
> I have been in correspondence with someone living in Africa, who says people
> over reacted to this pesticide and that it's a crime it has been banned. He
> reckons it should be reintroduced to third world countries.
>
> Here are some of his arguments:
>
> Introduced in 1945, DDT's instant success led to a Nobel Prize for the
> scientist who discovered the pesticide's effectiveness. DDT is estimated by
> the World Health Organisation to have saved some 50 million lives. The
> pesticide essentially wiped out malaria in America and Europe.
>
> The benefit to poor nations was also enormous. For instance, after the
> introduction of DDT, malaria diminished dramatically in India, Sri Lanka and
> Bangladesh
>
> Unfortunately, the pesticide was also used indiscriminately for agriculture.
> Although there is no persuasive scientific evidence that DDT harms humans,
> it did reduce the population of raptors and songbirds. Rachel Carson's
> Silent Spring helped generate pressure on the Environmental Protection
> Agency to ban DDT in the United States in 1972, despite the lack of evidence
> that it harms humans.
Your friend has the history a little muddled. DDT has never been
globally banned. The UNEP POP treaty would have seen DDT essentially
globally banned from 2007, but anti-malarial (and similar) use was
exempted when the treaty was signed in December 2000.
DDT was a key part of WHO's post-WWII anti-malarial campaign. Sadly its
not a magic bullet. Vector control is only one part of fighting malaria
and its effectiveness against vector populations varies. Sri Lanka is
a good example. Use of DDT allowed malaria to be almost eliminated in
the early 1960s. A few public health mistakes saw DDT resurge to former
levels in the late 1960s and vector resistance to DDT saw it abandoned
for more expensive alternatives in the 1970s.
Historically, I believe malaria was pretty much controlled in the USA
before DDT saw widespread use. DDT was certainly important in post-WWII
mediterranean Europe. Its still useful (and used) in India and a number
of other countries.
Theoretically we don't need DDT to eliminate malaria but its cheap and
easy to deploy and the countries using are very poor. Anti-malarial use
typically involves spraying of house walls and much smaller quantities
than the broadscale agricultural applications that devastated raptors
and other wildlife.
Presumably your correspondant is not referring to consuming DDT directly
- he or she will certainly find doing that harmful. I find convincing
Bruce Ames' arguments that the effects of trace levels of pesticides in
the human diet are greatly overrated. However the tendancy of DDT to
bioaccumulate in humans just as it does in raptors makes it stand out
from the crowd and is alarming.
I highly recommend Derek ratcliffe's "The Peregrine Falcon" for a first
account of the discovery of DDT impacts on Peregrines.
Andrew Taylor
Birding-Aus is on the Web at
www.shc.melb.catholic.edu.au/home/birding/index.html
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