Farmers have long struggled to defend their crops from harmful insects, weeds and diseases. Early in the 20th century, scientific innovation led to the development of pesticides--products that are used to combat impediments to food production.
Traces of the chemicals used to manufacture pesticides have been found not just on farms, but also in food, in the atmosphere and in water. Some studies have shown that these chemical residues may cause or contribute to problems such as animal extinction, cancer, birth defects and global warming.
Do pesticides pose a dangerous threat to the world's environment, or are they harmless tools that help farmers more efficiently feed the global population?
In order to combat pests, many farmers use pesticides, which are also grouped into three categories. Insecticides are used to fight off harmful insects; herbicides are used to control weeds; and fungicides are used to protect plants from fungi.
Some pesticides are derived from bacteria or chemicals found in the natural world. An example is nicotine, a chemical in tobacco that is also used to kill insects. Other pesticides are synthetic, or manufactured from chemical substances designed specifically for crop protection.
Pesticide residues, which can travel far from their sources, are believed to cause many negative side effects. Some studies have shown that water contaminants from pesticides may accumulate in the tissues of fish, ultimately killing the fish or poisoning the predators that eat them.
According to some biologists, residues disproportionately affect children, who are smaller and have a lower tolerance for chemicals. Farm workers, who are exposed to high concentrations of pesticides, are also believed to face an increased chance of developing illnesses.
Farmers are also attempting to reduce the use of pesticides by growing genetically engineered (GE) crops. Such crops, which are biologically engineered to be more resistant to the threat of insects and weeds, may help reduce the need for chemicals.
Yet some observers worry about the environmental consequences of GE crops. Critics contend that the crops may disrupt the balance of ecosystems by spreading the natural toxins that GE crops are made to produce.
Block, Betsy. "What You Need to Know About Organic Food." Boston Globe (March 29, 2000): E1.
Claiborne, William. "7 Groups Quit Food Panel; EPA Termed Soft On Pesticide Risks." Washington Post (April 28, 1999): A23.
Ehler, Lester E. "The Illusion of Integrated Pest Management." Issues in Science and Technology (Spring 2000): 61.
Carson, Rachel. Silent Spring. Boston, Mass.: Houghton Mifflin, 1962.
Hough, Peter. The Global Politics of Pesticides: Forging Consensus From Conflicting Interests. London: Earthscan, 1998.
Uri, Noel D. Agriculture and the Environment. Comack, N.Y.: Nova Science Publishers, 1999.