What vegetable has the least pesticides?

December 11, 2025 •

4 min read

According to the Environmental Working Group (EWG) analysis of USDA data, conventionally grown sweet corn is among the vegetables with the lowest detectable pesticide residues. Choosing produce with naturally low pesticide levels is a smart strategy for health-conscious shoppers on a budget who can't always buy organic.

Quick Summary

The Environmental Working Group's annual Clean Fifteen report, based on USDA testing, identifies produce with the lowest pesticide residues, helping shoppers prioritize organic purchases. Vegetables with low pesticide levels often have natural defenses like thick peels or require less chemical treatment during growth. Sweet corn, onions, and asparagus are consistently on the list of lowest-pesticide produce.

Key Points

Sweet Corn is Cleanest: Sweet corn consistently ranks among the lowest in pesticide residues, thanks to its protective husk.
Peel Provides Protection: Vegetables like onions and asparagus have low pesticide levels because their outer layers are peeled or they have natural defenses.
Processed Produce is Cleaner: Frozen sweet peas, which are shelled before processing, show minimal pesticide residues.
Buy Organic When Necessary: The Clean Fifteen guide helps consumers prioritize organic purchases by indicating which conventional items are low-risk.
Thick Skin Matters: Vegetables with thicker skins or rinds, such as onions and cauliflower, generally have fewer residues on the edible parts.
Health Benefits Outweigh Risks: Consuming conventionally grown produce is healthier than avoiding fruits and vegetables entirely due to pesticide fears.

Understanding the Clean Fifteen

Each year, the Environmental Working Group (EWG) releases its Shopper's Guide to Pesticides in Produce, which includes the "Dirty Dozen" and "Clean Fifteen" lists. These lists are based on an analysis of recent USDA test data and are designed to help consumers make informed choices about which produce to buy organic and which is relatively safe to buy conventionally grown. The Clean Fifteen specifically identifies the produce with the fewest pesticide residues. While the lists serve as a useful guide, it's always recommended to wash all produce thoroughly before consumption.

The 2025 Clean Fifteen: Vegetables with Minimal Pesticides

Based on the latest data, several vegetables consistently rank among the cleanest, exhibiting very low to no detectable pesticide residues.

Sweet Corn: Consistently at the top of the list, sweet corn is naturally protected by its husk, which prevents most pesticides from reaching the edible kernels. Less than 2% of tested sweet corn samples showed any detectable pesticide residue.
Onions: The outer layers of an onion are typically peeled away before consumption, providing a protective barrier. Tests have shown that very few pesticide residues penetrate to the edible portion.
Frozen Sweet Peas: Unlike snap peas, sweet peas are tested after shelling, and the pod's protection, combined with processing, results in extremely low residue levels.
Asparagus: This vegetable naturally contains compounds that can help break down some pesticides, making it resistant to certain chemical residues. Roughly 90% of tested asparagus samples had no detectable pesticides.
Cabbage: Cabbage produces natural insect-repelling compounds that reduce the need for extensive pesticide use. Most sampled cabbages show no detectable residue.
Cauliflower: As a recent addition to the Clean Fifteen, cauliflower has shown very low residue levels, with almost half of tested samples having no detectable pesticides.
Mushrooms: Typically grown in controlled indoor environments, conventionally grown mushrooms generally have low pesticide residues.
Carrots: While some pesticides are detected on carrots, especially on the greens, the overall residue level on the root vegetable itself is low.

Factors Affecting Pesticide Residue Levels

The amount of pesticide residue found on a vegetable depends on a variety of factors, including its growing environment and physical properties. Understanding these factors can help you make more informed decisions about your produce.

Physical Protection

Vegetables with thick, inedible outer layers or peels are naturally more protected from pesticide spray that might be applied to the surface. For example, the thick husk of sweet corn and the peel of an onion prevent most residues from reaching the edible parts. This is a primary reason why these items consistently appear on the Clean Fifteen list.

Natural Resistance

Some plants have evolved their own defense mechanisms against pests, reducing the need for chemical intervention. Cabbage, for instance, produces natural compounds called glucosinolates, which deter harmful insects. This natural resistance means farmers can use less aggressive chemical treatments, resulting in lower residue levels.

Growing Methods

The way a crop is cultivated plays a significant role in its pesticide exposure. Mushrooms, which are often grown indoors in controlled, sterile environments, require fewer external pest controls than crops exposed to the elements. Additionally, whether a vegetable is grown on a vine, on a tree, or in the ground can impact its susceptibility to pests and pesticides.

Comparison: Least vs. Most Contaminated Vegetables

To put the Clean Fifteen into perspective, here is a comparison with some of the items typically found on the Dirty Dozen list, which represents produce with the highest levels of pesticide residue.


Feature	Clean Fifteen (e.g., Sweet Corn, Onions)	Dirty Dozen (e.g., Spinach, Strawberries)
Pesticide Residue	Very low to no detectable residues.	High levels of multiple pesticides detected.
Physical Protection	Often have thick, inedible outer layers (husks, peels).	Typically have thin, edible skins or are eaten whole.
Growing Environment	Some are grown in protected or controlled environments (e.g., frozen peas, mushrooms).	Frequently grown in open fields, making them more susceptible to pests and diseases.
Natural Defenses	May have natural pest resistance (e.g., cabbage, asparagus).	Often lack strong natural defenses against a wide range of pests.
Washing Effectiveness	Simple washing or peeling effectively removes any residual surface pesticides.	Residues can penetrate the thin skin, making them harder to remove with just water.

Navigating Your Produce Choices

For those on a budget or with limited access to organic produce, the Clean Fifteen offers a practical guide for prioritizing your grocery purchases. While buying organic versions of all produce is ideal for minimizing pesticide exposure, it is not always feasible. The most important takeaway is that consuming more fruits and vegetables, regardless of whether they are conventionally or organically grown, offers significant health benefits that outweigh the risks of pesticide exposure. By focusing your organic budget on Dirty Dozen items like spinach and strawberries, and choosing conventional options for Clean Fifteen vegetables, you can still reduce your overall pesticide load effectively.

Conclusion

For consumers concerned about pesticide exposure, understanding which conventionally grown vegetables are lowest in residues is a valuable tool for smarter shopping. Year after year, data from the Environmental Working Group confirms that vegetables like sweet corn, onions, and asparagus are among the safest choices, offering a low-risk option without needing to purchase organic versions. These vegetables benefit from natural defenses or growing conditions that minimize pesticide use, making them a budget-friendly way to maintain a nutritious, healthy diet. Regardless of your purchasing choices, always remember to wash your produce thoroughly to remove any surface contaminants.

For more information on the testing methodology and the full lists, you can visit the Environmental Working Group's website.

Frequently Asked Questions

While avocados (technically a fruit) have topped the list for lowest pesticide residue, conventionally grown sweet corn is reliably one of the vegetables with the least amount of detected pesticides due to its protective husk.

Yes, conventionally grown produce from the Clean Fifteen list is generally considered safe to eat, as testing shows these items have very low to no detectable pesticide residues. Washing all produce is still recommended.

Vegetables can have fewer pesticide residues for several reasons, including natural defenses against pests, protective outer layers or peels, and controlled growing environments (like mushrooms). These factors reduce the need for extensive chemical treatments.

No, washing with tap water can significantly reduce surface pesticide residues, but it does not remove all residues, especially those that have been absorbed by the plant. For low-residue items like those on the Clean Fifteen, this is usually sufficient.

Buying organic is a personal choice. While a vegetable on the Clean Fifteen list has low pesticide residues, organic farming offers additional benefits, such as supporting environmentally friendly practices and protecting farm workers from chemical exposure. If on a budget, you can prioritize organic purchases for items on the Dirty Dozen instead.

The Clean Fifteen is a list of produce with the lowest pesticide residue, making them safer choices to buy conventional. The Dirty Dozen is the opposite, identifying produce with the highest pesticide residues, for which buying organic is often recommended.

Yes, frozen sweet peas have consistently ranked on the Clean Fifteen list with low pesticide residues. Testing is done on the edible portion of the vegetable, and the processing involved further ensures minimal residue.