Are Food Pesticides Harmful to Humans?

Plenty of people choose organic over conventional produce because they want to ingest fewer pesticides, but it's hard to get away from them entirely. (Photo: Lisovskaya Natalia/Shutterstock)

Farmers use pesticides to keep pests from ruining their fruits and vegetables. The goal is to harm only the targeted pest — including insects, rodents, weeds, bacteria, mold and fungus — but pesticides can also harm the environment and the people who are exposed to them.

In an ideal world, we wouldn't want any pesticides in our bodies, but they are part of our food chain. Here's a look at why how we measure them and what we know about the harm they can cause.

Setting pesticide residue limits

Under the Food Quality Protection Act (FQPA), the U.S. Environmental Protection Agency makes sure that all pesticides used on food meet strict safety standards. The EPA sets limits for the amount of pesticides that can remain on food. The EPA determines those limits by taking into account a number of factors including each pesticide's level of toxicity, how much of it is applied and how often, as well as how much of the food a person is likely to eat.

This maximum legal residue limit is called a "tolerance." In setting a tolerance, the EPA must make a safety finding that the pesticide can be used with "reasonable certainty of no harm." The level applies to food grown in the U.S., as well as imported food.

The U.S. Department of Agriculture maintains a national database that tracks pesticide residue in foods. Of the more than 10,000 pesticide samples in the most recent 2015 Pesticide Data Program (PDP), 85 percent had detectable pesticide residue. Less than 1 percent of samples had residues exceeding the limits set by the EPA.

But according to the EPA's website, "detectable" isn't as bad as it sounds:

It is important to note though, that just because a pesticide residue is detected on a fruit or vegetable, that does not mean it is unsafe. Very small amounts of pesticides that may remain in or on fruits, vegetables, grains, and other foods decrease considerably as crops are harvested, transported, exposed to light, washed, prepared and cooked. The presence of a detectible (sic) pesticide residue does not mean the residue is at an unsafe level. USDA’s Pesticide Data Program (PDP) detects residues at levels far lower than those that are considered health risks.

What is the specific danger?

man spraying pesticides on cantaloupe
Farmers spray pesticides to protect their crops from insects and weeds, bacteria and mold. Alohaflaminggo/Shutterstock

Pesticides are dangerous by design. Their job, after all, is to wipe out living organisms, so it's no surprise that they may cause health risks to people in some cases. Health risks depend not only on the toxicity of a pesticide's ingredients, but also how much you're exposed to them. In addition, some people, like children, pregnant women, sick people and the elderly may be more sensitive to the effects of pesticides than others, points out the National Pesticide Information Center, a project of Oregon State University and the EPA.

Many studies look at people who come in direct contact with pesticides because they apply them as a profession or because they are exposed to them in their homes, work or schools. Ingesting small amounts of pesticides in food may be cause for concern, but often studies do not clearly differentiate between direct contact, limited exposure and ingestion.

However, several studies have examined the link between pesticides and various health issues, including:

Cancer: Numerous studies have investigated links between pesticides and types of cancer. Research has found links between some pesticide exposure and childhood leukemia, brain cancer, and lymphoma, as well as associations with breast cancer. Studies have investigated links between pesticides and prostate, pancreas and liver cancer, as well as increased risk of melanoma.

Neurodevelopmental issues: Pesticide exposure prenatally and in children has been investigated as a source of behavioral problems, neurodevelopmental delays and impaired motor skills.

Hormone disruption: Some chemicals in pesticides can disrupt chemicals such as estrogens, thyroid and androgens, which may impact reproduction and fertility.

Neurological: Farmers exposed to certain pesticides have a 70 percent higher risk of developing Parkinson's disease.

Skin, eye and lung issues: Like other chemicals, pesticides can result in irritation for some people depending on how much they are exposed.

Should you worry?

rinsing strawberries in water in a colander
Strawberries and other berries are superfoods with numerous health benefits. Thomas Klee/

Every year, the Environmental Working Group offers the Dirty Dozen, a list of the conventionally grown fruits and vegetables found to have the highest pesticide residue. Most recently, strawberries topped the list and nearly all samples of strawberries, spinach, peaches, nectarines, cherries and apples tested positive for residue from at least one pesticide.

EWG recommends that shoppers buy organic versions of these foods whenever possible to minimize the amount of pesticides they consume. But going organic doesn't mean going pesticide-free, says 2011 research by two University of California, Davis food scientists. From the study, published in the Journal of Toxicology, "While conventional produce was between 2.9 and 4.8 times more likely to contain detectable pesticide residues than organic produce, samples of organic produce frequently contained residues. The PDP data, in fact, indicated that 23 percent of organic food samples tested positive for pesticide residues."

So, what's the solution? Wash your fruit and veggies under running tap water and use a vegetable brush to help scrub away any residue. However, that may not help with waxy or soft-skinned fruits, according to the National Pesticide Information Center. If produce was treated with wax, residues may be trapped underneath the wax. Fruit and veggie washes haven't been proven to be any more effective than plain water. In fact, detergent residue can stick to your fruit. Peeling your produce helps get rid of pesticides in the skin.