Throughout the world, enormous quantities of pesticides are used on crops, forests, nurseries, golf courses, lawns, gardens, and pets, and in public spaces and homes. In the United States about six hundred active ingredients are used in over twenty thousand pesticide products as insecticides, herbicides, rodenticides, and fungicides. Most formulations contain inert ingredients, with their own toxicity and health risks. In 1995, the United States used approximately 1.2 billion pounds of pesticide active ingredients, or about 5 pounds for each person in the country, accounting for 20 percent of world use. 1 Repeated year after year, the environmental and health effects of this volume and mixture of chemicals are extraordinarily important.
Chemical pesticides are designed to kill insects, fungi, plants, or other unwanted organisms, usually by interfering with some essential biochemical process in the target. However, their acute and chronic toxic properties also pose risks to the health of exposed humans, pets, wildlife, and entire ecosystems. In most cases, pesticides are classified according to the mechanism of their toxic action. But even within each class, there is a wide range of chemical structures and potential health effects. Pesticides may cause cancer; adverse reproductive, developmental, neurological, or immune system effects; or other organ damage at varying exposure levels. Each of these outcomes must be considered for each chemical.
Institutional protection from toxic effects depends largely on pesticide registration and regulation (see chapter 8). But there are significant