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PESTICIDES

Pesticides are a broad class of chemicals and biological agents that
are specifically designed and applied to kill a pest. Specific types
of pesticides target specific types of pests: insecticides kill
insects, fungicides kill fungi and bacteria, herbicides kill weeds and
other unwanted plant vegetation, molluscacides kill mollusks,
acaricides kill spiders, and so on. Pesticide use dates back to
ancient times.

Pesticides are regulated in the United States at both the federal and
state level. The primary legislation, one of the oldest environmental
laws, is the Federal Insecticide, Fungicide, and Rodenticide Act
(FIFRA, 1972), which is administered by the Environmental Protection
Agency (EPA). Each state also has an agency responsible for carrying
out FIFRA mandates. These agencies may be environmental or
agricultural in nature, depending on the state. State laws can be more
restrictive than the federal laws.

Pesticides are sometimes called "economic poisons." They are developed
to kill something, and they are, therefore, inherently toxic.
Pesticides that are less toxic are classified as "general use
pesticides." These can be purchased by the average homeowner and
applied without any special license or permits. More toxic compounds
are called "restricted use pesticides" and their use requires a
license. In some cases the restricted use materials have the same
active ingredients as the general use materials, but at a higher
concentration.

Anything that claims that it has pesticidal activity is, by law, a
pesticide, and is subject to registration by the EPA and local state
agencies. Household cleaners and bleach are legally pesticides—the
pesticide registration number can be found on the product container.

Within the broad classes of products that have similar types of action
(e.g., weed killers, insect killers) there are further distinctions
regarding the type of chemistry. For example, among insect killers,
there are synthetic pyrethroids, organophosphates, and
organochlorines. The most well known are the organochlorines, such as
chlordane and DDT, which became popular after World War II, and were
used in agriculture, and for home and commercial use, for decades.
These compounds have low acute toxicity, but are persistent in the
environment and have caused a series of long-term environmental health
problems. They remain in soil and tissue for a very long time, and
they have been shown to have a harmful impact on animal endocrine
systems. Most organochlorines were phased out of use in the 1980s.
They were replaced by organophosphate materials that are less
persistent, but more acutely toxic. In the beginning of the 1990s
these compounds, too, were beginning to be phased out through
government actions, and voluntarily by the manufacturers.

Pesticides have entered the food system in many parts of the world.
Though credited with an enormous increase in food and fiber
production, indiscriminate use of these products has led to acute and
long-term health problems for humans and animals. There are risks
associated with the application of a pesticide into a system, while at
the same time there are benefits for using these materials to reduce
disease, increased food production, and lessen the risk of starvation.

Pesticides have been applied in many part of the world to control
vector-borne diseases such as malaria, yellow fever, dengue, and
others. The most prudent way to balance the benefits with the risks is
an integrated approach to pesticide use, combining all control
methods—physical, biological, cultural, and chemical.

MARK G. ROBSON

(SEE ALSO: Environmental Movement; Environmental Protection Agency;
Fungicides; Toxicology)

BIBLIOGRAPHY

Hayes, W., and Laws, E. (1991). Handbook of Pesticide Toxicology, Vol.
1. San Diego, CA: Academic Press.

Wallace, R., ed. (1998). Maxcy-Rosenau-Last Public Health and
Preventive Medicine. Stamford, CT: Appleton and Lange.


OR:

http://dictionary.reference.com/browse/pesticide