The Rooted People

Washing produce before eating it is a habit most people have without thinking much about what they’re washing off — or whether washing is enough. The assumption is that a rinse under the tap removes whatever was on the surface. For some things, that’s true. For pesticide residues, the picture is more complicated — and the data on what’s actually present on conventional produce is specific enough to be worth knowing.

What Pesticides Are and Why They’re Used

Pesticides are chemical compounds applied to crops to protect them from damage — a broad category that covers several distinct types. Insecticides target insects that damage or destroy crops. Herbicides target unwanted plants — weeds that compete with crops for nutrients and water. Fungicides target mold and fungal diseases that can devastate yields. Each type addresses a specific agricultural threat, and in conventional farming, they’re applied at multiple points across the growing cycle — sometimes to the seed before planting, sometimes to the soil, sometimes directly to the growing plant, and sometimes post-harvest to extend shelf life during transport and storage.

As Tudi et al. documented in their review of agriculture development and pesticide application, the widespread adoption of synthetic pesticides in the twentieth century significantly increased crop yields and reduced food spoilage — outcomes that shaped the modern food system. The same review documented the environmental and health consequences that have accumulated alongside those productivity gains, including soil contamination, water runoff, and biological accumulation in the food chain.

Pesticides end up on and in produce through direct application and through soil and water uptake. Some residues sit on the surface of the fruit or vegetable and can be partially addressed by washing. Others are systemic — absorbed into the plant tissue through roots or through the surface — and remain present in the flesh of the produce regardless of how thoroughly the outside is cleaned.

How Residue Gets Tested — and Who Does It

The most comprehensive domestic source of data on pesticide residues in the U.S. food supply is the USDA’s Pesticide Data Program — commonly referred to as the PDP. Established in 1991, the PDP tests fresh and processed food samples collected from retail locations across the country and analyzes them for hundreds of individual pesticide compounds. The program publishes its findings annually, making it one of the more transparent sources of real-world residue data available to consumers and researchers.

The EPA sets maximum residue limits — called tolerances — for pesticides on food. These tolerances represent the maximum amount of a given pesticide that can legally be present on a food item at the point of sale. They’re set based on risk assessments that consider the toxicity of the compound, how much of the food a person is assumed to consume, and what exposure level the EPA has determined is acceptable. Detecting a residue below the tolerance level means the product is legally compliant — it doesn’t mean the residue is absent or that the compound has no health implications at that level.

The distinction between “within legal limits” and “safe” is worth holding onto as you read the data. Legal tolerances reflect regulatory decisions made within a specific framework — one that has historically been slower to account for cumulative exposure from multiple compounds simultaneously, endocrine disruption at low doses, and the particular vulnerability of children and pregnant people to certain compounds.

What the Data Actually Shows

The USDA PDP findings are consistent enough across years to establish clear patterns. A significant majority of conventional produce samples test positive for at least one pesticide residue. Multiple residues on a single sample — sometimes ten or more individual compounds — are common rather than exceptional for certain produce items.

The most recent PDP data shows that strawberries, spinach, kale, peaches, pears, nectarines, apples, grapes, bell peppers, cherries, blueberries, and green beans consistently carry among the highest residue loads of any produce tested. Some of these items show residues from dozens of individual pesticide compounds in a single sample — not because any one residue is necessarily above its legal tolerance, but because the cumulative presence of multiple compounds is a different question from any single compound’s individual tolerance.

Kaur et al.’s 2024 comprehensive review of pesticides and their health and environmental effects documented the breadth of compounds detected in food globally and their associations with human health — spanning endocrine disruption, neurological effects, immune system impacts, and chronic disease associations. Mostafalou and Abdollahi’s review of pesticides and human chronic diseases documented specific mechanisms through which pesticide exposure contributes to conditions including diabetes, cardiovascular disease, and certain cancers — with evidence spanning both high-dose occupational exposure and lower-level chronic dietary exposure. The Council on Scientific Affairs’ review of cancer risk in agricultural workers — a population with higher pesticide exposure than the general public — established associations between pesticide exposure and elevated cancer risk that have informed subsequent research on dietary exposure at lower levels.

Keifer and Firestone’s review of pesticide neurotoxicity documented that several classes of pesticides — including organophosphates and carbamates, which are among the most widely used in conventional agriculture — have demonstrated neurotoxic effects. Organophosphates work by disrupting the nervous system of the insects they target — a mechanism that has implications for human neurological health at sustained low-level exposure, particularly during developmental windows in children and during pregnancy.

The Dirty Dozen and Clean Fifteen

The Environmental Working Group publishes two lists annually based on USDA PDP data — the Dirty Dozen and the Clean Fifteen — that translate the testing data into practical purchasing guidance.

The Dirty Dozen identifies the twelve produce items with the highest pesticide residue loads in that year’s testing — the items where the case for choosing organic is strongest based on the data. The list is updated each year as new PDP data becomes available, though the same items tend to appear consistently. Strawberries have topped the list for several consecutive years.

The Clean Fifteen identifies the fifteen produce items with the lowest residue loads — items where the practical need to choose organic is lower based on testing data, and where conventional options present less concern.

A few things worth understanding about how to use these lists. They reflect averages across many samples — individual items will vary. They rank produce relative to each other rather than against an absolute safety threshold. And they’re based on residues detected after standard USDA washing — which means the data reflects what remains after washing rather than what was applied before it.

The lists are a practical tool for prioritizing organic purchases when budget is a consideration — not a binary determination of safe versus unsafe. A dedicated article on the Dirty Dozen and Clean Fifteen goes into more detail on how the lists are compiled and what the annual data shows.

Does Washing Remove Residue?

Washing produce removes some surface residues — but the effectiveness depends significantly on the washing method and on whether the residues are surface deposits or systemic compounds absorbed into the plant tissue.

Water alone removes a portion of surface pesticide residues — particularly water-soluble compounds on smooth-skinned produce. Research has consistently shown that water washing is more effective than no washing but leaves meaningful residues on most produce items. For produce with textured surfaces — leafy greens, berries, broccoli — residues can be trapped in crevices where water doesn’t reach effectively.

Baking soda — sodium bicarbonate — dissolved in water has been shown in research to be more effective than plain water at removing surface pesticide residues, particularly for certain compound classes. Soaking produce in a baking soda solution for ten to fifteen minutes before rinsing is a practical and low-cost method that meaningfully improves on plain water washing. Strong white vinegar — used as a diluted solution — works through a similar principle, using acidity to break down certain pesticide residues on the surface. Both are accessible alternatives to plain water washing that don’t require any specialized equipment.

Studziński, Narloch, and Dąbrowski’s 2024 research on electrolyzed water for pesticide removal from produce found that electrolyzed water — water treated with a mild electrical current to produce oxidizing compounds — performed significantly better than plain water at reducing surface pesticide residues on lemons and vegetables. Electrolyzed water kitchen devices are available as consumer products and represent an emerging option for produce washing that goes beyond what plain water, baking soda, or vinegar achieves.

What none of these methods can address is systemic residues — compounds that have been absorbed into the flesh of the produce through roots or surface uptake. For produce items with high systemic pesticide absorption — strawberries and leafy greens are among those most documented — washing reduces surface residues but doesn’t change what’s inside the fruit or vegetable. For these items, choosing organic is the more direct response to the residue concern that washing can’t solve.

What Organic Certification Addresses

USDA Organic certification prohibits the use of synthetic pesticides in certified organic production — which is the most direct regulatory response to conventional pesticide residue concerns available in the U.S. market. An organic certification on produce means the crop was grown without the synthetic pesticides that generate the residues documented in PDP testing.

What organic doesn’t guarantee is zero residue. Schleiffer and Speiser’s review of pesticide presence in organic food found that organic produce can carry trace residues — from pesticide drift from neighboring conventional fields, from pesticides that persist in soil from previous conventional use of the land, and in some cases from approved organic pesticides. The residue levels in certified organic produce are generally significantly lower than in conventional produce, and the compounds detected are typically different — but the expectation of zero residue in organic food isn’t supported by the testing data.

Approved organic pesticides — compounds that are permitted under organic certification because they’re derived from natural sources — are not automatically without health implications. Some naturally derived pesticides have documented toxicity profiles. Organic certification speaks to the source of the pesticide rather than its toxicity, which is a distinction worth knowing.

The practical value of organic for produce is real and data-supported — residue loads are meaningfully lower, synthetic compounds are absent, and for the items on the Dirty Dozen where systemic absorption is documented, organic is the most effective available response. It’s a strong signal, not an absolute guarantee.

Practical Steps

The most useful framework for navigating produce purchasing is prioritization rather than all-or-nothing thinking.

Prioritizing organic for Dirty Dozen items — particularly strawberries, spinach, kale, and other consistently high-residue produce — addresses the highest-residue exposure points in a typical diet first. For Clean Fifteen items, conventional options present lower concern based on the testing data and may represent a practical budget accommodation where needed.

Washing all produce — conventional and organic — is worth doing regardless of source. For conventional produce, washing with plain water reduces surface residues meaningfully even if it doesn’t eliminate them. For items where electrolyzed water devices are accessible, the research by Studziński et al. suggests they offer meaningful improvement over plain water washing.

For produce with thick, inedible skins — avocados, pineapples, onions, mangoes — the skin provides a barrier that reduces the residue load on the edible portion. These items consistently appear on the Clean Fifteen for this reason.

Varying the produce in a diet across different items and growing seasons distributes potential residue exposure across different compounds rather than concentrating it in a small number of high-consumption items. No single produce item needs to be avoided entirely — informed prioritization across the full diet is a more sustainable and practical approach than categorical avoidance.

Data Worth Having

Pesticide residue in conventional produce is a well-documented reality — not a speculative concern. The USDA tests for it, the data is publicly available, and the patterns it shows are consistent enough to inform practical decisions without requiring a complete overhaul of how produce is purchased.

The Dirty Dozen gives you the highest-priority items to address. Organic certification gives you the most direct available response for those items. Washing — particularly with more effective methods — reduces what’s addressable on the surface. And understanding what washing can’t reach is the piece that makes the rest of the picture make sense.

The references used in this article are a starting point — we encourage you to read further and draw your own conclusions.

Ready to keep going? Browse our Mindful Eating articles to build a clearer picture of what’s in your food and how to evaluate it.