Pollution?

Chemicals we use every day on our crops or in our homes to kill unwanted pests and weeds can also harm or even kill other plant and animals species. Pesticides are often misused, used incorrectly, or used over too large an area. But even if used correctly, many cannot tell the difference between a pest and a friendly species. For example, some pesticides used on crops can harm the bees and other insects needed to pollinate these same crops. In addition, many chemicals have long lives and do not break down easily. They can "bioaccumulate" in food webs—as birds eat bugs, and larger animals eat birds, more and more harmful chemicals accumulate in the tissues of each animal in the food chain. Not only are species harmed themselves, but the foods they eat are also harmed.