Waging War on the Insects
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
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.
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
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.
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