Neha Pathak, MD, FACP, DipABLM: Welcome to the WebMD Health Discovered Podcast. I'm Dr Neha Pathak, WebMD's Chief Physician Editor for Health and Lifestyle Medicine.
Today we're exploring the best ways to keep our shopping carts safe and reduce the pesticides on the produce that we're eating. We'll discuss how testing is done, why some fruits and vegetables are always high on the Environmental Working Group’s annual Shopper’s Guide, what makes something part of the Dirty Dozen or the Clean 15, and the confusion around swapping chemicals that might be new but not necessarily harmless.
We'll translate all of that data into practical, budget-friendly strategies and help you decipher what organic labels actually mean — and when it makes sense to splurge on organic produce versus when you can stick to just conventional produce. If you have ever had questions or concerns about what you are feeding yourself and your family, this is the episode for you.
First, let me introduce my guest, Dr Alexis Temkin. Alexis is a PhD who supports EWG’s consumer databases, policy, and research in the areas of personal care and cleaning products, pesticides, and tap water.
She began her research career at Columbia University Medical Center working as a lab technician studying the molecular mechanisms responsible for environmental influence on gene regulation. As a doctoral student at the Medical University of South Carolina, she studied how exposure to environmental chemicals during development can influence adult obesity and metabolic syndrome. Welcome to the WebMD Health Discovered Podcast.

Alexis Temkin, PhD: Thanks so much for having me.

Pathak: So before we jump into our conversation today — and I will tell you I am an avid follower of EWG's work — I'd love to ask about your own health discovery working with the Environmental Working Group, and what led you to the work that you're doing.

Temkin: Yeah, so when I was in graduate school, I was in a program in a lab that was really invested in studying how exposure to environmental chemicals, particularly during development — so thinking about pregnancy or early life, like childhood — could influence disease states or health outcomes later in life.
And I was actually at that time studying a chemical that I didn’t really know a lot about. There weren’t a lot of great resources in terms of where this chemical might be found. It happened to be a chemical that was used during the Deepwater Horizon oil spill cleanup. So that was sort of my research focus.
But it was a chemical that was used in a lot of other products, and actually the Environmental Working Group’s database was one of the best sources for understanding where we find different chemicals in our life, particularly in cosmetics or cleaning products. So that was how I became familiar with the Environmental Working Group. I thought I really wanted to transition my research from in the lab to something that might be more useful in terms of translation — from what I was learning about how chemicals can impact health — to the general public. That’s how I got here. And now I work on a variety of different things that are all related to exposure to chemicals and health outcomes.

Pathak: That’s really helpful. So that gives us a little bit of a background on what the Environmental Working Group is trying to do. Can you help us understand a little bit about the Shopper’s Guide to Pesticides in Produce? Why was that particular product created?

Temkin: Yeah, so the larger EWG work is really centered around different tools that consumers can use to help reduce exposures to environmental chemicals, right? And that covers cosmetics, cleaning products, as well as tap water. But pesticides is something that the group really has been working on for a long time.
A lot of that work in terms of consumer education or consumer tools centered around pesticide exposure reduction is the Shopper’s Guide to Pesticides in Produce. This is pretty much an annual report that has been released by the organization since 2004. So it’s been quite a long time.
The emphasis, or initial reasoning, for why they put the report together came out of a lot of work in the mid-1990s that was highlighting issues about pesticide exposure and health, particularly for infants and children. There was a National Academies report in the early ‘90s that really highlighted that the way pesticides were regulated didn’t necessarily consider what we know about children being more vulnerable or susceptible to health outcomes based on chemical exposures. It also didn’t necessarily consider unique dietary patterns of children.
So there was this foundational report that raised concerns about pesticide exposure. And then similarly, there was legislative action in the mid-1990s that tried to overhaul the way pesticides were regulated — for instance, understanding that chemicals might impact the endocrine system and health outcomes associated with hormone functions. Those weren’t really considered in current regulatory status.
So this came out of that, as a way to help people reduce pesticide exposure. What it is, is a list of 47 fruits and vegetables ranked based on their overall pesticide contamination. That data actually comes from monitoring by the United States Department of Agriculture. They release testing data every year based on samples of thousands of fruits and vegetables, covering hundreds of pesticides. We analyze that data to look at rankings or indicators of pesticide exposure — like how often a pesticide is found, what that concentration is, what the toxicity might be — to develop the ranking scheme. That becomes the Dirty Dozen list (fruits and vegetables with the most pesticide residues) and the Clean 15 list (produce with the least amount).

Pathak: And are these fruits and vegetables that are grown in the U.S.?

Temkin: So the way that the USDA collects their data is to be representative of what shoppers or consumers are going to find on their grocery store shelves. Depending on the produce and the season when that produce is collected, the sampling tries to span at least one year, sometimes two.
So, if you’re looking at apples, for instance: if they’re collected in the fall, a lot of them might be domestic. If they’re collected at other times, they might be imported. But overall, it’s supposed to be a representation of what U.S. consumers find on their store shelves. We import a lot of fruits and vegetables, so the USDA does cover those as well. We treat those samples equally as a kind of average or national representative sample.

Pathak: So then let’s dig into terms that I think a lot of people have probably heard about: the Dirty Dozen and the Clean 15. I’ve had a lot of friends talk about some of the recent media coverage around what they’re going to change. Can you tell us a little bit about what is on the Dirty Dozen list, and then what are some of those fruits and vegetables on the Clean 15?

Temkin: Yeah, so as I mentioned, these two lists are the top end and the low end of the 47 fruit and vegetable ranking. There are other produce items that fall in the middle. One of the reasons the lists were created was to help people reduce pesticide exposure.
One option is choosing organic produce all the time. We know that when studies assess switching to an organic diet, you see reductions in pesticide residues. But that’s not really a reasonable option for everyone all the time. So the goal was to separate these lists: the Dirty Dozen (conventional produce with the most pesticide residue) and the Clean 15 (conventional produce with the least).
If people are eating a lot of items from the Dirty Dozen list — their favorite foods, for example — buying those organic when possible might be a way to reduce pesticide exposure. The Clean 15, on the other hand, are lower-residue items, so eating those conventionally might not increase exposure as much.
Things on the Dirty Dozen include a lot of fruits: strawberries, apples, peaches, cherries — as well as leafy greens like spinach, kale, and mustard greens.
On the Clean 15, you’ll find items like pineapples, avocados, onions, mushrooms, papayas, bananas, and cauliflower. We have guides listed on the website, as well as printable PDFs you can carry with you to the grocery store.

Pathak: So once something is on that list — closer to being a conventional produce item that is “clean” — does that mean it still has the potential in the future to get onto the Dirty Dozen list? How do these changes happen? Is it differences in farm practices? Is it just the way that a fruit or vegetable has to be harvested that makes it more high risk for having a lot of pesticide residue?

Temkin: It's a great question. So there are probably a few reasons that influence how things might shift on the list from year to year. I would say over time there haven’t been really large shifts in the group of produce that end up on the two lists, and I don’t think anything has ever swapped from the Dirty Dozen to the Clean 15 or from the Clean 15 to the Dirty Dozen. They might move toward the middle of the list or something like that. Part of that is actually due just to data availability. The USDA data is truly a really wonderful monitoring system, and it’s some of the best data that we have about pesticides in food.

But the way it’s set up is, for instance, because they’re collecting so many samples and doing so many analyses, sometimes the data is always about two years behind. So even the most recent data — those fruits and vegetables were collected in 2022, pretty much. So there’s a little bit of lag in data, and not every produce is collected every year, so some data might be older than others.

Usually when we get new data, that might influence where something moves. But also some fruits and vegetables are just, I think, more pesticide-intensive in terms of their growing practices. They’re more susceptible to certain pests. So whether or not the pesticides are the same, we’ve seen shifts in different types of insecticides that are used. You might see reductions in one class but increases in another. That seems to be somewhat consistent overall when you’re thinking about total pesticide contamination on the different crops.

Pathak: So then tell us a little bit about what you mean by toxicity scoring. You’re looking at this list, you’ve identified a variety of pesticides or insecticides that might be contaminating these products. What are some of those chemicals of concern? What are the big categories?

Temkin: Yeah, so really across the fruits and vegetables sampled from the USDA that we looked at — and this covers about 53,000 samples of fruits and vegetables — I think about three-quarters of them have detectable residues in general. If you look just at the Dirty Dozen, that’s much closer to 95% of those samples having some level of pesticides detected.

That does vary from crop to crop. But what we know — and one of the reasons why we’re concerned about overall pesticide exposure — is that while many of these pesticides meet the regulatory standards, so they’re not exceeding those levels set by the EPA, there’s definitely a disconnect between the way chemicals are regulated and what some research might show in terms of health effects. For example, academic research studying the impact of these pesticides on animals has found health effects that weren’t necessarily considered by regulators. Those usually impact neurological development or reproductive and endocrine (hormone-mediated) health outcomes. So there’s this disconnect there.

And then also, we sometimes see that exposure in actual people. When you have studies that look at urine or blood samples to measure pesticides and then compare them to health outcomes, those exposures — which reflect what the general population is exposed to — can be associated with health effects. Typically those include harm to the nervous system, impacts on fertility, and reproductive issues like preterm birth.

Some pesticides are more well studied than others. That’s definitely true for organophosphates. There’s one chemical called chlorpyrifos, which was associated with reduced IQ and cognitive function in people, particularly when exposure happened during pregnancy. That class in general — organophosphates — is known to be harmful to the nervous system.

A positive thing is that we’ve seen reductions in those pesticides detected in foods compared to the 1990s or early 2000s. But we do see this replacement of insecticides with other chemicals, typically called pyrethroids or neonicotinoids. Originally they were thought to be a little safer, but as science catches up with regulatory changes, we’re learning there may be similar health effects.

There are also many pesticides found in food that we have very little data for in people. We might know they’re present, but we don’t have epidemiological studies to link them to health effects. That’s one of the reasons we take this approach of asking: how can you reduce your overall exposure while still consuming lots of fruits and vegetables — which we know are associated with health benefits and should be prioritized over a diet high in ultra-processed foods?

Pathak: So what if you do end up having to buy a conventional item that’s on the Dirty Dozen? Are there best practices for washing that can help minimize your exposure?

Temkin: Certainly none of the items on the Dirty Dozen should be avoided, per se. Right? I also think in general the recommendation of eating a variety of fruits and vegetables is really important. So those items on the Dirty Dozen shouldn’t be avoided.

There are often options in the frozen section — especially for some fruits — where organic versions might be more affordable than fresh organic versions. So there are a few ways consumers can work with this list to make decisions based on their choices, what they’re eating, and what’s available at their stores.

As for best practices for washing fruits and vegetables: the first thing is definitely to wash them. Washing fruits and vegetables is more important than worrying too much about which method is best. The FDA and CDC recommend it for food safety, and it also helps reduce pesticide levels.

The USDA data is interesting because they do wash produce before testing. So some of the residue levels are after washing — which means the levels could be higher if you don’t wash. Typically, running under water for about 15 to 20 seconds is a good recommendation. Some studies show adding baking soda or vinegar to water may be a little more effective, but even water alone will give you the biggest reduction to begin with. So definitely wash your produce, then consume it — that’s the base advice.

Pathak: What are some of your best practices with different types of fruit?

Temkin: For sturdier fruits like apples, I usually run them under water while also scrubbing or rubbing them individually for 15 to 20 seconds. This idea kind of came out of COVID handwashing recommendations — like singing “Happy Birthday” to make sure you hit that time — or you can just count.

Berries are harder. I typically run them under water and then dry them on paper towels. Drying is really important because if water is left on them, they tend to mold quickly. Some people recommend soaking berries, but I haven’t tried that. Full disclosure: I’m more of a vegetable consumer than a fruit eater — I don’t have a big sweet tooth — but I know kids love berries, so that’s always a journey in figuring out the best prep.

You mentioned organophosphate-based pesticides earlier. The work we’re doing and the information we’re sharing — how do I see practices changing? I think one of the most important things to mention is that although we’re talking about a consumer guide, the real burden of food safety and safe pesticide use should fall on regulatory agencies.

That goes for many different types of chemicals we’re exposed to. There are personal choices and modifications people can make, but ultimately government regulation and chemical manufacturers should be responsible for proving safety.

We have seen some encouraging progress. For example, organophosphates like chlorpyrifos — allowable levels in food were recently revoked due to evidence of harms to children’s developing brains. But we still see issues with how the best available science is applied in regulatory spaces. Children’s health isn’t always considered, and epidemiological or academic studies showing effects at lower doses than regulatory “allowable” levels aren’t always given enough weight.

So yes, improvements have been made to get some of the most harmful pesticides off the market. But the newer pesticides haven’t been as well studied. There’s always this lag — chemicals are approved and used widely, then studied later.

Pathak: That triggers another question for me around what people can do once they’ve brought some of these products into their home. With skin versus non-skinned fruits or vegetables — is there a benefit? For example, with bananas, we know you peel them. With potatoes, we know there are health benefits to eating the skin. How do you think about skin on some of these fruits and vegetables?

Temkin: Yeah, so at least in the way that the USDA tests their fruits and vegetables, they peel, you know, the inedible peels — something like on a banana or an avocado, the papaya. Some fruits and vegetables with those inedible peels do tend to end up on the Clean 15. So that certainly could be one reason why they might not have as many pesticides detected in the edible portions of those fruits or vegetables.

We know that a lot of items, like you mentioned, potatoes or apples, usually have a lot of fiber, and some of the more beneficial nutrients are found in the peels. There are also studies that show peeling them can reduce pesticide levels even further.

But I think this kind of goes back to the balance: consuming a lot of fruits and vegetables may outweigh the risk of some of the pesticide concerns. So I think a good wash of skinned fruits and vegetables, rather than peeling them, is probably the best option.

I also know some people don’t really like the peel or skin sometimes, so it does come down to preference a little bit. But yeah, I would recommend a good wash and probably keeping the skin on.

Pathak: And then when it comes to cooking, does that change anything? So for potatoes, if you’re baking an apple pie — when we think about it from an infectious disease standpoint, you think of your cooking method. Cooking something is going to reduce the risk of having bacteria on it. So what do you know about what happens to pesticides through various cooking methods?

Temkin: Yeah, so there have definitely been some studies that have looked at this. Typically, you might see reductions in pesticides in items that are cooked. Sometimes, though, they might lead to, for instance, transformation products or something like that with heat that aren’t necessarily measured, detected, or fully understood in terms of their toxicity.

One other item, for instance, is potatoes. This is an instance where sometimes when they’re fried, they can produce another sort of byproduct that has potentially carcinogenic properties from one of the pesticides on them. So I think it’s probably a world where we’re not totally sure for all pesticides, especially just ’cause there are so many of them.

But in many cases, a lot of them are reduced by cooking. And so for items that you eat raw, that might also be a consideration for potentially purchasing organic items.

I think there have been a couple of studies that even with potato consumption — which, you know, are probably always consumed cooked to some degree — you can see measurable levels of this one pesticide called chlorpropham, which is really common on potatoes. It actually prohibits sprouting during storage, and it’s found in high concentrations on a lot of them. But there are correlations with levels of that pesticide detected in people, depending on whether or not they eat potatoes. So that’s to say it doesn’t reduce exposure completely.

Pathak: This has been such a helpful conversation. I really, really appreciate your time. I’d love to give you the final few moments for, one, information about how people listening can access the full guide and, two, your tips on the best ways to use your guide in everyday life.

Temkin: Yeah, so ewg.org/foodnews is where you can find the guide, as well as the Dirty Dozen, the Clean 15 list, and just a lot more information in general about pesticides and which pesticides are found on which fruits and vegetables. You can also get those little pocket guides to take with you to the grocery store.

And again, the best way to use this guide is in a way that aligns with how you already shop. Thinking about consuming a lot of fruits and vegetables in your diet is definitely first and foremost.

Items on the Dirty Dozen — if they’re purchased a lot or really are favorite foods, or maybe during sensitive windows of development, like pregnancy or early life — considering buying those options organic, as accessible, might be a way to reduce pesticide exposure.

And then items on the Clean 15 are conventional items that are lower in pesticide residues. So maybe not necessarily needing to buy organic versions when those are available — consuming those can help ensure you’re not increasing your pesticide exposure as much.

Pathak: That’s really, really helpful, and I want to thank you again so much for your time.

Temkin: Thank you so much. This was a great conversation.

Pathak: My key takeaways from this discussion are:
Number one, certain types of produce like strawberries, spinach, and apples routinely carry the most pesticide residue.

It’s useful to use tools like EWG’s Shopper’s Guide to help you make the best choices for you and your family when it comes to the types of produce you are buying.

Finally, regulations often lag behind the science. This means that personal choices do matter, and using tools like EWG’s Shopper’s Guide can help us minimize our exposure to certain chemicals while still maintaining a healthy, plant-rich diet filled with delicious fruits and vegetables.

To find out more information about Alexis Temkin, the EWG, and their work, make sure to check out our show notes.

Thank you so much for listening. Please take a moment to follow, rate, and review this podcast on your favorite listening platform. If you’d like to send me an email about topics you are interested in or questions for future guests, please send me a note at [email protected].

This is Dr Neha Pathak for the WebMD Health Discovered Podcast.