Particles of sprayed pesticides can float into the air. When it rains, other particles can wash off plants to the ground and from there into ground water. Farm workers who use pesticides run the highest risk. If the pesticide touches their skin, or if they breathe fumes from pesticide spray, they can be poisoned. Some researches think that hundreds of thousands of farm workers in the U.S. suffer from pesticide poisoning every year.
Some pesticides can cause cancer and birth defects in people.
Even wild animals can die if they eat crops or smaller animals that have come into contact with pesticides. Even so, insects cause more crop damage now than they did then. Sometimes an insect does more than develop resistance to a pesticide. It grows to depend on the pesticide. Normally, a deadly dose of DDT for bees is 6 parts per million.