Pesticides 101 - A Primer

What are pesticides?

What is the "Pesticide Treadmill"?

Which rules govern pesticide use?

How much exposure do we face?

What are pesticides?

Insecticides (bug killers), herbicides (weed killers), and fungicides (fungus killers) are all pesticides; so are rodenticides and antimicrobials. Pesticides come in spray cans and crop dusters, in household cleaners, hand soaps and swimming pools.

Insecticides are generally the most acutely (immediately) toxic. Many are designed to attack an insect's brain and nervous system, which can mean they have neurotoxic effects in humans as well. Herbicides are more widely used (RoundUp and atrazine are the two most used pesticides in the world) and present chronic exposure risks, such as cancer and reproductive harm. Fungicides are also used in large amounts; some are more benign, some are not.

Pesticides are also sometimes broken down into chemical classes and modes of action (e.g. fumigants are pesticides applied as gases to "sterilize" soil, and systemics work their way through a plant's tissue after being taken up at the root). Major chemical classes include: carbamates, organochlorines and organophosphates (mostly developed 70 or more years ago for chemical warfare); and newer classes including pyrethroids and neonicitinoids, synthesized to mimic nature's pest protection. For more, see our specific pesticides resource page.

What is the "Pesticide Treadmill"?

Also referred to as the "pesticide trap." Farmers get caught on the treadmill as they are forced to use more and more — and increasingly toxic — chemicals to control insects and weeds that develop resistance to pesticides. As "superbugs" and "superweeds" develop, a farmer will spend more on pesticides each year just to keep crop loss from pests at a standard rate.

Pesticide resistance is increasing. In the 1940s, U.S. farmers lost 7% of their crops to pests. Since the 1980s, loss has increased to 13%, even though more pesticides are being used. Between 500 and 1000 insect and weed species have developed pesticide resistance since 1945. "Pigweed" has developed resistance to RoundUp, for instance, and grows with such uncontrollable vigor in southern cotton fields that farmers report it can "stop a combine in its tracks."

Rachel Carson predicted the phenomenon in her 1962 book Silent Spring.

Which rules govern pesticide use?

Internationally, pesticides are regulated through two treaties that PAN played a formative role in creating. The Stockholm Convention on Persistent Organic Pollutants (POPs treaty) and the Rotterdam Convention on Prior Informed Consent (PIC treaty). The POPs treaty addresses toxins that persist, move around the world on wind and water, and bioaccumulate (DDT, for example), while Rotterdam gives countries the right to refuse the import of highly hazardous toxins. PIC attempts to redress the dumping of obsolete or banned pesticides on the developing world. (While only 25% of global pesticide use takes place in developing countries, 99% of acute pesticide-related fatalities occur there.)

In the U.S., the Environmental Protection Agency (EPA) has primary authority to register and regulate pesticides, authorized by several federal laws including the:

  • Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) — allows EPA to register pesticides using risk/benefit standards (how much risk is balanced by how much benefit?);
  • Federal Food, Drug, and Cosmetic Act (FFDCA)  aims to increase protection for children and infants, setting tolerances (maximum residues on food);
  • Food Quality Protection Act of 1996 (FQPA) — amends the previous laws by establishing a single safety standard for tolerances — not risk/benefit — to increase protection of children from aggregate exposures (dietary, water and residential); adds a 10-fold safety factor and requires ongoing review of registrations; and the
  • Endangered Species Act of 1973 — requires that pesticides that will harm these species will not be registered.

Some states have additional, stricter rules restricting pesticide use.

How much exposure do we face?

It depends on where you live and what you do.

Each year, an estimated 1 billion pounds of pesticides are applied to U.S. farms, forests, lawns and golf courses. More than 17,000 pesticide products are currently on the market.

Pesticide applicators, farmers and farm workers, and communities near farms are often most at risk, but studies by the Centers for Disease Control show that all of us carry pesticides in our bodies. Golf courses use pesticides heavily, so do some schools and parks. Consumers also face pesticide exposure through food and water residues. For instance, atrazine is found in 94% of U.S. drinking water tested by the USDA.

There is another way. Agroecology is the science behind sustainable farming. This powerful approach combines scientific inquiry with place-based knowledge and experimentation, emphasizing approaches that are knowledge-intensive, low cost, ecologically sound and practical.

Home use of pesticides — which on a per acre basis outpaces use on farms by a ratio of 10 to 1 — puts families across the North America at unnecessary risk. Alternatives are available to manage home, lawn and garden pests without toxic pesticides.