A Hoot for Rachel Carson

The President’s Hoot
by Richard H. Baker, Ph.D.
September 2008

This year marks the 100-year anniversary of the birthday of Rachel Carson, the author of Silent Spring, a book published in 1962 that pointed out the dangers of chemicals impacting the world, especially pesticides and is widely credited with starting the contemporary environmental movement. The recovery of the brown pelican, bald eagle, osprey, and peregrine falcon from near extinction is to a large extent due to the work of Carson and others who realized that the pesticides did harm if not used responsibly.

Rachel Carson (Photo: USFWS)

As a young graduate student studying mosquitoes, I was introduced to Rachel Carson, in Miami, when she gave a keynote speech at the Entomology Society of America meeting in 1962. Needless to say, she was very controversial in that setting. On one side were many toxicologists who were saying DDT was a very safe chemical. In fact, one scientist even suggested that you could drink DDT with no harmful effects, although it is found in our fat tissue even today and in breakdown products in the muck of our lagoon. There is some evidence that these chemicals affect endocrine and reproductive systems.

In public health and in agriculture, DDT was considered a miracle chemical. It killed viruses and insects causing head lice, malaria, and other disease bearing insects as well as agricultural pest insects. But, it was overused especially in agriculture where it ended up in our streams, rivers, and oceans, eventually getting into the food chain of birds, fish, and crabs. Birds were particularly affected by the thinning of their egg shells that broke during incubation.

Vero Beach’s Florida Medical Entomology Lab (FMEL) scientists contributed some of the evidence used by Carson in Silent Spring of the bad effects of pesticides. In 1955 Dr. Robert Harrington, Jr. and Professor William Bidlingmayer observed 2000 acres of saltmarsh treated with dieldrin at 1 lb/acre in an attempt to eliminate sandfly larvae in St. Lucie County. The treatment was not done by the FMEL, but they saw the carnage and decided to document it. By sampling, they estimated that 20-30 tons of fish or 1,175,000 of at least 30 species, including snook, were killed. No live specimens could be found. All crustaceans were virtually exterminated including aquatic and fiddler crabs.

With such wide spread use, most insects became quickly resistant to the chemical. Resistance was first found in malaria carrying mosquitoes in Greece in 1946. While I was doing research in El Salvador, I observed that one cotton crop was being sprayed 14 times to kill the cotton weevil. While the ban on DDT occurred in 1964, the major reason for the ban was that DDT was no longer very effective against insects, not that it was harming our wildlife. Even today some advocate using DDT for malaria, but the resistance genes are still found in nature and will be selected for in a few generations.

On publication of Silent Spring, President Kennedy ordered a special commission to review the use of pestcides and we now have the protection for humans and wildlife that we have today. It stimulated the passing of The Clean Air and Clean Water Acts, and the establishment of the Environmental Protection Agency. Much of our labeling of our chemicals have improved and much of agriculture is using “best management practices.”

While Rachel Carson got the attention of the world, there is still much to be done. Scientists are still trying to determine which pollutants have led towards increased testicular and breast cancer, reduced fertility, and lower sperm counts. And of course, we humans have continued polluting our water and our air with greenhouse gases, rapidly inducing global warming, thus endangering our existence.

Let’s be aware of all unnatural substances we ingest, spray in our homes and spread in our yards…water and air carry them far.

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