A pesticide is a chemical used to prevent, destroy, or repel pests. Pests can be insects, mice and other animals, weeds, fungi, or microorganisms such as bacteria and viruses. Some examples of pests are termites causing damage to our homes, dandelions in the lawn, and fleas on our dogs and cats. Pesticides also are used to kill organisms that can cause diseases.
Most pesticides contain chemicals that can be harmful to people, animals, or the environment. For this reason the Office of Pesticide Programs of the Environmental Protection Agency regulates pesticides in the United States to protect public health and the environment.