PESTICIDES. A pesticide is any agent used to kill or control a pest. Pests include insects, weeds, and diseases, such as fungi. In addition, mice, rats, birds, and algae may become pests at some time. When pests damage plants or property, people often use pesticides to control them. The term "pesticide" can apply to insecticides, herbicides, fungicides, antimicrobials, growth regulators, defoliants, and desiccants, most of which are applied to food or food plants before or after harvest. Common pesticides are encountered every day—in pet flea collars, kitchen disinfectants, cockroach baits, swimming pool chemicals, and mosquito repellents. Pesticide products contain both active and inert ingredients, and both must be specified on the label.

Pesticide Controversy

Modern farmers use pesticides to help them to grow almost all of the world's food. In general, pesticides have been a quick, effective, and inexpensive method of control for pests that attack most of the world's food crops. Pesticides are credited with helping to save millions of lives by controlling diseases, such as malaria and yellow fever, which are spread by insects. However, most pesticides present some risk of harm to humans, animals, or the environment because they are designed to kill living organisms.

Sulfur, herbal extracts, tobacco, soaps, oil, arsenic, pyrethrum, and lime have been used as pesticides for many centuries, but the widespread use of synthetic pesticides is a relatively recent phenomenon. Dichlorodiphenyltrichloroethane, or DDT, is probably the best known early pesticide. DDT was created in 1873, but it was not until the late 1930s that Swiss researcher Paul Müller discovered that the compound was effective in killing insects. Müller won the Nobel Prize in Physiology and Medicine in 1948 for his work. DDT was an inexpensive and effective solution to many insect problems, and it virtually eliminated malaria from parts of the world. After World War II, DDT became a common agricultural pesticide. In the 1950s, the United States was producing 220 million pounds of DDT per year.

Insect resistance to the substance developed quickly. DDT residues were found in human milk and fatty tissues, and in wildlife food chains. In 1962 writer and ecologist Rachel Carson wrote Silent Spring to warn the public about the long-term effects of misusing pesticides. Carson challenged the practices of agricultural scientists and the government, and called for a change in the way humankind viewed the natural world. Carson testified before Congress in 1963, calling for new policies to protect human health and the environment. While no longer used in the United States, DDT use continues in other parts of the world. Many tropical countries still use DDT to control malaria.

All pesticides (natural and synthetic) have the potential to cause harm during their manufacture or refinement, at the time of application to crops, as residues that persist on food, and in the disruption of the natural balance that exists between pests and their natural enemies. For example, traces of the natural insecticide "rotenone" may be found on vegetables after cooking. Atrazine, a weed-killer commonly used on corn and soybeans, suburban lawns, and utility rights-of-way, has contaminated groundwater where those crops are grown. Insecticides like DDE and dieldrin, which are related to DDT, were banned in the United States in the 1970s, but still show up in the U.S. food supply. Persistent residues of these chemicals travel long distances in global air and water currents. These insecticides are still produced and used in many countries. Recent studies have linked pesticides with acute poisonings, cancer, brain damage, reproductive harm, and many childhood illnesses and learning problems, leading concerned citizens to feel that pesticides should be banned.

Organic Agriculture

Some agricultural experts predict that the quality and quantity of our food supply would be lessened if pesticides were eliminated. However, practitioners of organic agriculture (organic farmers use no synthetic agricultural chemicals and instead rely on management practices such as crop rotation, disease-resistant varieties, and natural enemies to control crop pests) claim that food quality and yield are equally productive under organic management. Fortunately for conventional and organic farmers, the number of safer, reduced-risk options for pest control is increasing. For example, there were approximately seven hundred new, biological pesticide products registered by 1999. Biological pesticides are certain types of pesticides derived from such natural materials as animals, plants, bacteria, and minerals.

Garlic, mint, and baking soda all have pesticide-like properties and are considered biological pesticides. Biological pesticides include the common cabbage worm killer Bacillus thuringiensis, which produces a protein that helps to kill specific worm pests. Some of the new reduced-risk pesticides, while synthesized in a laboratory, are considered safer because they do not kill beneficial insects (such as lady beetles and lacewings), or they break down quickly to inactive products. In 1977 U.S. president Jimmy Carter issued a Presidential Decree that mandated the use of integrated pest management (IPM)—a comprehensive approach to pest control that uses a combination of less toxic means to reduce the status of pests to tolerant levels, while maintaining a quality environment. Together, the new reduced-risk pesticides and IPM practices have helped to lessen the amount of pesticides that are used on food and other crops. Levels of pesticide residues on IPM produce have been reported as higher than those of organically grown food, but lower than those in conventionally grown produce.

Pesticides and Their Regulation

In the United States, pesticides are regulated by the Environmental Protection Agency (EPA). EPA regulates the sale, distribution, and use of pesticides and has the authority to suspend or cancel the registration of a pesticide if information shows that continued use would pose unreasonable risks. In 1996 the Food Quality Protection Act (FQPA) was signed into law, giving EPA more effective power. Among its many benefits, the FQPA established a new health-based safety standard for pesticide residues in food; included special provisions for infants and children; required periodic tolerance reevaluations; incorporated provisions for endocrine testing; and allowed for enhanced enforcement of pesticide residue standards.

Scientists predict that, in the future, pesticides will continue to play a role in pest management of food crops, partly because reduced-risk pesticides have become less harmful to the environment, and less toxic to people and wildlife. Societal concerns, scientific advances, and regulatory pressures continue to drive some of the more hazardous pesticides from the marketplace. In addition, consumer interest in safe and healthy food will create more demand for organically grown products.

See also Herbicides; Organic Agriculture; Organic Farming and Gardening; Food Safety; Toxins, Unnatural, and Food Safety.

Patricia S. Michalak