Pesticides are chemicals that kill insects, weeds, and other organisms harmful to crops. They are used on farms and in gardens to protect food from being destroyed.
Most pesticides are synthetic chemicals that have been designed to be toxic to pests while not harming plants, humans, or other animals. In many cases, they are able to kill pests by disrupting their nervous system or interfering with their metabolism. Unfortunately, research has discovered these products are incredibly toxic to dogs and humans alike.
The first pesticides were naturally occurring substances such as arsenic and sulfur. These were later replaced by synthetic organic compounds such as DDT (dichloro-diphenyl-trichloroethane), developed in 1874 but banned in many countries after the 1970s because it was found to be harmful to wildlife.