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Welcome to PSR's Environmental Health Policy Institute, where we ask questions -- then we ask the experts to answer them. Join us as physicians, health professionals, and environmental health experts share their ideas, inspiration, and analysis about toxic chemicals and environmental health policy.

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Waging War on the Insects

By Steven G. Gilbert, PhD DABT

This essay is in response to: How does our food production system drive our exposure to toxic chemicals?

Human exposure to toxic chemicals and environmental degradation due to our food production system is linked to the ever expanding human population and chemicals developed during the last two world wars, to kill insects as well as humans.

The rapidly expanding human population has driven the need for greater quantities of inexpensive food. This resulted in farmers planting large fields of the same crop, which naturally resulted in greater populations of insects that reduced crop yield. The solution was to wage war on the insects. At the turn of the century lead-arsenic insecticides were used in apple orchards in Eastern Washington. These metal-based insecticides were reasonably effective but left a legacy of contaminated soil. As old orchards become back yards and school playgrounds we must contend with children being exposed to lead which at even very low levels affects the developing nervous system.

DDT
DDT

Lead-arsenic insecticides were used until WWII when the chemical revolution replaced them with more effective but also harmful chemicals such as DDT. DDT (dichlorodiphenyltrichloroethane), an organochlorine, was discovered in 1874 but not recognized as a highly effective insecticide until 1939 by The Swiss chemist Paul Hermann Muller (1899-1965). He received the Nobel Prize in 1948 for the discovery of insecticidal qualities and its subsequent use to control insects that spread diseases such as malaria and yellow fever. DDT was widely used during WWII and following the war its use expanded rapidly. Subsequently we learned that DDT was a highly persistent, bioaccumulative, and toxic chemical. In 1962 the environmental hazards of DDT, exemplified by thinning of bird egg shells, was brilliantly documented by Rachel Carson. It was banned in the US in 1972. However the legacy of DDT lives on. DDT and its metabolites are commonly found in the fat and milk of wildlife as well as in humans.

Organophosphate formula
Organophosphate formula

Another important class of pesticides is the organophosphates. Modern chemical warfare, against bugs or humans, began with the German search for new pesticides in the 1920s and 1930s and was stimulated by the ongoing chemical revolution. With the loss of territory after World War I and Germany's desire to lessen its reliance on food importation, the German leadership emphasized the need for new insecticides to increase food production. Gerhard Schrader (1903–1990), a German chemist, worked to find insecticides to eliminate the threat from the boll weevil. Schrader synthesized a series of “organophosphates” which included Tabun and later the extremely lethal Sarin, which became part of the military arsenal. And thus the race was on to develop and stockpile highly lethal chemical weapons to destroy the ultimate pest. But I digress.

Many types and derivates of organophosphates were developed. They were applied by ever-more-mechanized approaches, such as by air blast spray (see picture). We began to recognize the potential hazards particularly to farm workers and their children. Pesticide application rules, regulation, and training were developed but we still debate the neurological effects of low level exposure particular for children. Numerous studies have documented exposure as well as health hazards of certain pesticides. For example, Europe has greatly restricted the use of the herbicide atrazine based on data that it is an endocrine disruptor, while the US continues basically unrestricted use.

Pesticides and chemical weapons share a common root of development and common mechanism of action. They are two sides of the same sword. From bitter experience we have learned that it is prudent to ban the use of chemical weapons and similarly ban the use of the most hazardous pesticides. We now struggle to adequately regulate the pesticides we need while ensuring that workers and children develop in an environment in which they can reach and maintain their full potential.

Comments

puni said ..

thanks

November 7, 2011
pradip said ..

thank you for the information

November 7, 2011
suzhanna said ..

Thank you for this informative piece. I agree about never understating the link between pesticides and war materials. Frightening.

April 5, 2011
Dave said ..

It's fascinating to think how dangerous the food supply used to be. In the late 1800s, lead arsenic became favored over other arsenicals because it didn't readily wash off the fruit and as a result, killed insects for longer. Of course, this meant human exposure was much much higher. Arsenic was also commonly used in all sorts of products - wall paper, stationary, medicines, etc. (in the good old days). Arsenic poisoning was common. You can still can get traditional Chinese "herbal" medicines that are 70% arsenic trioxide (that is, if you want to experience arsenic poisoning). "The good old days, they were terrible."

March 31, 2011
Sharon said ..

As long as we think that we need pesticides, we will have no choice but to keep looking for new ones and realizing their effects long after the damage.It is possible to farm without pesticides.

March 28, 2011
Richard Weiskopf said ..

It's important to know this history and particularly about the bioaccumulation of many of these pesticides (persistent organic pollutants). Studies have shown that exposure to low levels can do harm.

March 4, 2011
Northwest Center for Alternatives to Pesticides said ..

Excellent points. It's important to recall the link between pesticides and war chemicals. They are certainly one and the same.

February 28, 2011
sean said ..

If a chemical kills bugs it ain't gonna be great for humans to ingest or breathe either - i don't care if the amount is small - i don't want myself or my child to be exposed to it at all.

February 27, 2011

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