Is Squash on the Dirty Dozen List? The Truth About Pesticides

December 11, 2025 •

4 min read

While the Environmental Working Group's (EWG) annual report often causes concern, it's important to know the facts about specific produce items. For decades, shoppers have used the 'Dirty Dozen' list to decide which fruits and vegetables to buy organic, but does conventional squash truly pose a risk?

Quick Summary

This article examines squash's status concerning the Dirty Dozen list, explains why it typically avoids the list, and provides practical advice for minimizing pesticide exposure when purchasing conventional produce.

Key Points

Not on the Dirty Dozen: Squash is not typically included on the Environmental Working Group's (EWG) annual Dirty Dozen list of produce with the highest pesticide residue.
Natural Protection: The thick, inedible rind on winter squash varieties acts as a natural barrier against pesticides, minimizing the risk of contamination.
Clean Fifteen Contender: Due to its low pesticide residue, winter squash often aligns with criteria for the Clean Fifteen list, though it may not always be explicitly named.
Historical 'Plus' Category: While not on the main list, some summer squash was temporarily included in a 'plus' category in the past for specific, highly toxic pesticide concerns.
Washing is Recommended: Regardless of its list status, all produce, including squash, should be thoroughly washed to remove surface dirt and residues, with baking soda solutions being particularly effective.
Context is Key: The Dirty Dozen lists are a guide for consumers to prioritize organic spending, not a reason to avoid any produce, which is a vital part of a healthy diet.

Understanding the Dirty Dozen and Clean Fifteen Lists

The Environmental Working Group (EWG), a non-profit organization, publishes a yearly Shopper's Guide to Pesticides in Produce. This guide is intended to help consumers make informed choices about which produce to prioritize buying organic. It consists of two primary lists: the "Dirty Dozen," which highlights conventionally grown fruits and vegetables with the highest pesticide residue levels, and the "Clean Fifteen," featuring those with the lowest. The EWG's methodology considers factors such as the number of pesticides found on a crop and the overall toxicity of those pesticides. The lists are compiled based on data from tests conducted by the U.S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA).

Where Does Squash Stand?

Squash, including both summer varieties like zucchini and winter varieties such as butternut and acorn, is not typically found on the annual Dirty Dozen list. In fact, winter squash was removed from the list in 2025. The primary reason for its absence is that squash, particularly the winter varieties, possesses a thick, inedible rind. This thick barrier naturally protects the inner flesh from absorbing pesticides applied to the crop's exterior. The practice of peeling or cooking off the outer layer further reduces potential exposure.

While squash is not a regular feature on the Dirty Dozen, it is important to note that the EWG has in the past created special "plus" categories for certain crops. For example, in 2013, summer squash and leafy greens were highlighted due to contamination with highly toxic pesticides, even though they didn't meet the primary Dirty Dozen criteria. This demonstrates that vigilance is still important, and the EWG's reports provide valuable context beyond just the main list.

The Role of the Clean Fifteen

Conversely, produce with low pesticide residue ends up on the Clean Fifteen list. Similar to winter squash, many fruits and vegetables on this list have a protective outer layer that is removed before eating, such as avocados, onions, and pineapple. For many consumers on a budget, consulting both the Dirty Dozen and Clean Fifteen lists can help them decide when to splurge on organic and when conventional is a safer, more affordable choice.

How to Minimize Pesticide Exposure on Conventional Produce

Even with produce not on the Dirty Dozen list, it is always a good idea to wash your fruits and vegetables thoroughly. For squash, washing is important to remove any surface dirt and bacteria. Here are several effective methods:

Rinsing with Water: Use cold, running water for 15 to 20 seconds. This is the simplest method and is effective for removing loose dirt and some surface residues.
Baking Soda Solution: Mix a solution of two teaspoons of baking soda per one quart of water. Submerge the produce and swirl for 30 seconds before rinsing thoroughly. Research indicates this can be more effective than just water for removing certain pesticides from the surface.
Salt Water Soak: Soak produce in a 10% saltwater solution for up to 20 minutes before rinsing. A 2017 study found this was effective at removing specific pesticide residues.

It is important to remember that washing methods are best for removing surface-level contaminants. For pesticides that have penetrated the flesh, washing is not as effective.

Comparison: Squash vs. Dirty Dozen Contaminants


Feature	Squash (Butternut, Zucchini)	Typical Dirty Dozen Items (e.g., Strawberries, Spinach)
Pesticide Residue Level	Typically low; often featured on the Clean Fifteen list or not included.	Consistently high levels of various pesticide residues detected.
Protective Barrier	Thick, inedible rind on winter varieties offers natural protection.	Thin, delicate, or edible skin, offering little to no protection against absorption.
Washing Efficacy	Washing, peeling, and cooking are highly effective at reducing pesticide exposure.	Washing is less effective, as pesticides can penetrate the delicate skin.
EWG Historical Record	Occasionally highlighted in a "plus" category, but not a recurring item on the main list.	Regularly appear on the Dirty Dozen list year after year.
Nutritional Value	Excellent source of Vitamin A, C, magnesium, and fiber, low in calories.	Often high in vitamins and antioxidants, but come with the trade-off of higher pesticide risk if conventionally grown.

Conclusion: Making Informed Choices

While squash is not a regular member of the Dirty Dozen, staying informed about pesticide concerns is crucial for all consumers. The EWG's lists are a valuable tool for prioritizing organic purchases, but they should not deter you from consuming a diet rich in fruits and vegetables, regardless of how they are grown. Whether you choose conventional or organic squash, proper washing can significantly minimize your exposure to surface-level pesticides. Ultimately, a balanced diet incorporating a variety of produce is the most important factor for good health.

For more information on the most current pesticide testing data, you can visit the Environmental Working Group's website, which publishes its updated shopper's guide annually. [https://www.ewg.org/foodnews/]

Frequently Asked Questions

Squash, especially winter varieties like butternut, has a thick, inedible rind that protects the inner flesh from absorbing pesticides. This natural barrier means that washing and peeling effectively remove any surface residues, keeping it off the list of most-contaminated produce.

Winter squash, such as butternut and acorn, has a thick, protective rind, making it less susceptible to pesticide absorption. Summer squash, like zucchini, has a thinner, more porous skin. However, conventional summer squash is also not a regular feature on the Dirty Dozen list.

For best results, wash squash under cold, running water for 15-20 seconds. For more thorough cleaning, you can soak it in a baking soda solution (two teaspoons per quart of water) for 30 seconds before rinsing.

Buying organic is a personal choice based on budget and priorities. The EWG's lists are a guide to help you decide which conventional items may pose a higher risk. Since squash has a low pesticide residue risk, many people choose conventional varieties to save money, opting to spend more on organic versions of produce on the Dirty Dozen list.

For pesticides that have been absorbed into the flesh of a fruit or vegetable, washing will not be effective. However, with thick-rinded produce like winter squash, the risk of significant penetration is very low. Peeling the skin provides an additional layer of protection.

The Dirty Dozen list is a useful tool but should be considered a guide rather than a definitive health decree. The EWG itself states that consuming a diet rich in fruits and vegetables, whether organic or conventional, is more important for health than avoiding conventional produce based on the list.

The Environmental Working Group (EWG) releases an updated shopper's guide annually. You can find the latest information on their official website.