Silencing Silent Spring

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Rachel Carson's Silent Spring is widely credited with starting the modern environmental movement.  But its publication also marked the beginning of modern anti-environmentalism.  In fact, the attacks on the book began even before it was published (Stauber and Rampton, chapter 9, Lear, chapters 17-19).  What is remarkable is that the criticism continues even today, more than thirty five years after its publication.  The latest assault comes in "100 things you should know about DDT" by J. Gordon Edwards and Steven Milloy.  The authors write that:

Rachel Carson sounded the initial alarm against DDT, but represented the science of DDT erroneously in her 1962 book Silent Spring. Carson wrote "Dr. DeWitt's now classic experiments [on quail and pheasants] have now established the fact that exposure to DDT, even when doing no observable harm to the birds, may seriously affect reproduction. Quail into whose diet DDT was introduced throughout the breeding season survived and even produced normal numbers of fertile eggs. But few of the eggs hatched." DeWitt's 1956 article (in Journal of Agriculture and Food Chemistry) actually yielded a very different conclusion. Quail were fed 200 parts per million of DDT in all of their food throughout the breeding season. DeWitt reports that 80% of their eggs hatched, compared with the "control"" birds which hatched 83.9% of their eggs. Carson also omitted mention of DeWitt's report that "control" pheasants hatched only 57 percent of their eggs, while those that were fed high levels of DDT in all of their food for an entire year hatched more than 80% of their eggs.

But Carson (page 320) cited two papers by DeWitt.  The first, published in 1955 in the same journal, very much supports Carson's statement (page 674):

Hatchability of fertile eggs was appreciably below that of eggs from the control group, and the difference approached significance (P = 0.08).  Many embryos appeared to develop normally during the early stages of incubation, but died during the hatching period.  Mortality among chicks from this group was extremely high, and more than 50% died within the first 5 days after hatching.   

While DeWitt's second study (1956), which used lower amounts of pesticides in the diet, did not produce the same decrease in hatchability but it did find greatly increased mortality among quail chicks even when the chicks themselves received pesticide free diets.  In the control group (table III) 83.3% survived at the end of six weeks.  When the hens were fed 100 ppm of DDT year round only 7.1% were alive after six weeks.  When hens received no DDT in the winter but 200 ppm in their food during the reproductive season only 12.9% were still alive after six weeks.  Among the pheasants, which received lower doses of DDT than the quail, there was no increase in mortality.

Both Carson and DeWitt cite several other studies that support the claim that DDT and other pesticides are harmful to wildlife.  While Carson may have been the first to bring the effects of pesticides to the public's attention, their harmful effects were already known within the scientific community.

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Reated material, EDFs look at Gregg Easterbrook's A Moment on the Earth

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References

Carson, Rachel, Silent Spring, Houghton Mifflin Company, 1962.

DeWitt, James, "Effects of Chlorinated Hydrocarbon Insecticides upon Quail and Pheasants," Journal of Agriculture and Food Chemistry, Vol. 3, 1955, p. 672.

DeWitt, James, "Chronic Toxicity to Quail and Pheasants of Some Chlorinated Insecticides," Journal of Agriculture and Food Chemistry, Vol 4, 1956, p. 863.

Lear, Linda, Rachel Carson:  Witness for Nature, Henry Holt and Company, 1997.

Stauber, John and Sheldon Rampton, Toxic Sludge is Good for You: Lies, Damn Lies and the Public Relations Industry, Common Courage Press, 1995.

Written by Jim Norton

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