Biology Reference
In-Depth Information
pus,andconnectedittoinsecticides.Bythesummerof1958,robinshadbeeneliminated
from campus and parts of the surrounding city.
Wallace'sworkdocumentedthedevastatingeffectthatDDTwashavingonsongbirds.
Meanwhile,PeregrineFalcons,BaldEagles,andOspreyweredecliningdramatically,but
weren't dying outright. However, virtually no juvenile birds were being seen anymore.
In 1968, Daniel Anderson and Joseph Hickey published a paper in
Science
documenting
eggshell thinning in these birds, coinciding with the introduction of pesticides like DDT.
DDT killed insects on food crops and mosquitoes carrying malaria, so many argued
that human beings should take precedence over birds. Although the deaths of songbirds
and eggshell thinning in raptors did figure in Congress's decision to ban DDT in 1972,
another factor was the discovery of DDT and its byproducts in human mother's milk.
The decision to ban DDT proved to have saved human lives. In 2002, scientists ana-
lyzing stored blood samples of pregnant women from the 1960s discovered that DDT
levels in blood serum were highly correlated with low birth rates and premature births.
Those “canaries in the coal mine” were giving us a sound warning. Meanwhile, in every
place where DDT has been applied in the outdoor environment, mosquitoes were grow-
ing ever more resistant to it.
Although DDT is banned in the United States and other developed countries, in areas
of the world where malaria is a problem, the World Health Organization today recom-
mends the use of indoor spraying. DDT is taken up in the feet of mosquitoes, so when
ceilings and bed netting are sprayed, they afford protection while minimizing effects on
our own and natural food chains.
In
Silent Spring,
Rachel Carson wanted us to be mindful of the negative as well as
positiveeffectsofpesticides,toseekoutalternativeswhenfeasible,andwhenapesticide
seems to be the best solution to a serious problem, to use the smallest effective amount
— a common sense approach for protecting humans and our crops as well as the natural
environment.
Q A couple of times this year after my neighbor had her lawn sprayed, I found
robins acting strangely, acting sick and even falling on their sides or on their backs.
They ended up dying. My neighbor says that the pesticides she used are approved
by the EPA and so are guaranteed not to hurt birds. Is that true?
A
The EPA never “approves” pesticides; it registers them. And field-testing to prove a
pesticide is safe for wildlife is no longer a requirement for registration; in order to be
registered, a product must pass a complicated cost/benefit test; no tests on birds are re-
quired. Even a major bird-killing pesticide such as fenthion can remain on the market for
many years, killing millions of birds, before its use is restricted or prohibited.
