Pesticides are chemicals designed to kill organisms we consider undesirable. They fall into five major categories including:
  • Insecticides (insect-killers)
  • Herbicides (weed-killers)
  • Fungicides (fungus-killers)
  • Nematocides (roundworm-killers)
  • Rodenticides (rat- and mouse-killers)

Why Pesticide Use Should be Limited
Although pesticides do provide some benefits, at least initially, there are three major reasons why limiting pesticide use is important.

Genetic Resistance & Killing of Natural Pest Enemies
After prolonged exposure to pesticides, many pests develop resistance to the chemicals designed to kill them. This produces a hardier pest that will need a new, stronger dose of chemical to kill it. Pesticides are not usually selective killers; that is they end up killing not only the pest, but also natural enemies of the pest. In other words, you may be killing the aphid but you are also killing the ladybug that may have naturally controlled the aphid population until now. Therefore, you may be killing the pest for now, but you may also be creating a bigger problem in the future.

Mobility & Threats to Wildlife
According to the U.S. Department of Agriculture, no more than 2% of insecticides applied to crops by aerial or ground spraying actually make it to the target pests. The other 98% that miss their target end up in the air, surface water, groundwater, bottom sediments, food, and non-target organisms, including humans. Many pesticides are fat soluble; this means that as an organism eats another organism, pesticides build up in their fatty tissues. With each successive step up the food chain, higher concentrations of pesticides occur because that organism eats more of the smaller organism and therefore biomagnifies the effect.

Threats to Human Health
The National Academy of Sciences concluded in 1993 that the legal limits of pesticides in food may need to be reduced 1000 times to protect children who are more vulnerable to such chemicals than adults because of their lesser body weights. The National Academy of Sciences also estimates that exposure to pesticides through food causes 4000 - 20,000 cases of cancer in the U.S. each year.