Washing fruits and vegetables before eating them makes sense. Does soaking them in vinegar or baking soda meaningfully remove more pesticide residue, and improve our health, compared with simply washing them with water.
I wash my fruits and vegetables before I eat them.
That seems as common sense.
They've been grown outdoors, harvested, handled, transported, displayed and handled again. There may be dirt, microorganisms, agricultural residues or other things on the surface that I'd rather wash away.
So when I came across the Environmental Working Group's Guide to Washing Produce, I wasn't surprised that it recommended washing fruits and vegetables.
What caught my attention was how specific their recommendation is.
EWG recommends soaking produce in a solution containing one teaspoon of baking soda for every cup of water, or one part vinegar to three parts water, for five to ten minutes, followed by rinsing under running water.
Specific recommendations make me ask specific questions.
Why one teaspoon?
Why one part vinegar to three parts water?
Why five to ten minutes?
What Does the Evidence Actually Show?
EWG says its scientists reviewed “dozens of peer-reviewed studies” to determine how effectively four washing methods reduce pesticide residues: rinsing with water, soaking in water, soaking in baking soda solution and soaking in vinegar solution.
EWG did not perform dozens of produce-washing experiments, rather, its researchers conducted a review of experiments performed by others. Their peer-reviewed review included 47 studies covering 23 types of produce and 79 pesticides or metabolites. The researchers reported median pesticide reductions (rounded to remove decimal points) of:
- 30 % rinsing with water
- 34 % soaking in water
- 51 % soaking in baking soda
- 54 % soaking in vinegar
Their conclusion was that baking soda or vinegar/acetic acid produced a median reduction more than 15 percentage points greater than plain-water washing.
At first that seems like an easy conclusion. Why not choose the method that reduces more? Before deciding, I want to know something fundamental:
What was reduced?
A reduction in the amount of a chemical being measured isn't the same as removing that chemical from the food.
How Comprehensive Was the Search?
EWG's researchers searched PubMed for the scientific literature and then supplemented those results by examining references from the studies they found. The PubMed search produced 1,004 results. Thirty-nine studies survived the screening process, and reference searching added another eight, producing the final 47 studies.
PubMed is not the entirety of scientific literature. Relevant research could appear in databases covering those disciplines that isn't indexed in PubMed. That doesn't invalidate the review. It limits what we can say about its completeness. A broader search could include databases such as Scopus, Web of Science, Embase and agricultural databases such as CAB Abstracts.
I'd like a broader search, before considering a literature review to be complete.
What Are We Measuring?
There's a assumption inside the phrase “pesticide residue.”
A commercial pesticide product isn't composed solely of the active ingredient whose name appears on the label. Pesticide formulations contain active ingredients and other ingredients. Those other ingredients have traditionally been called “inert” ingredients, although inert should not be interpreted as meaning biologically or chemically irrelevant.
When an experiment reports that washing reduced a particular pesticide by 50%, I want to know exactly what was measured. Was the experiment measuring the active ingredient? Known metabolites? Other components of the formulation? The entire commercial product? Transformation products created as the pesticide degraded?
These are different questions.
If I begin with "A + other ingredients," and after washing I only measure A, if I find less of A, I haven't established what happened to everything else. Was it removed?
Degradation Is Not Removal
Researchers at the University of Massachusetts studied two pesticides, thiabendazole and phosmet, on apples. They compared the effectiveness of using tap water, commercial bleach solution, and sodium bicarbonate (baking soda) solutions.
The researchers measured the greatest reduction in the two parent pesticides after treatment with baking soda.
It's tempting to say that simply as removing more pesticide. Their results show something more complicated happening. The researchers reported that, in the presence of sodium bicarbonate, thiabendazole and phosmet could degrade, and that degradation assisted the washing process.
That matters. If a compound is physically washed off, we should think of the process as the pesticide has been removed. If a chemical reaction occurs, we're dealing with something different. Compound A is degraded into compound B + other transformation products. Degradation is not removal. The original compound has changed. If a laboratory analysis measures only compound A, the amount of A can decrease. That's not equivalent to what most assume is meant when we say “it removes pesticides.”
This becomes interesting with phosmet. The researchers did not detect phosmet in the sodium-bicarbonate wash solution. They attributed this to its rapid degradation under the alkaline conditions.
What happened to the phosmet?
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Note: Phosmet is a chemical compound, an active pesticide ingredient. It is not, by itself, the entire pesticide product. There are three things to keep separate:
- Phosmet — a chemical compound, C₁₁H₁₂NO₄PS₂, organophosphate insecticide, that can be an active ingredient in pesticide products.
- A pesticide product containing phosmet — formulated to contain phosmet plus other ingredients.
- Phosmet degradation products — chemical compounds produced when the phosmet molecule chemically breaks down or transforms.
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Finding less phosmet establishes that less of the original phosmet molecule remained. It does not tell us where the pesticide-related material went or what compounds were present afterward. To answer that, I would need a different kind of analysis.
Before treatment, measure: parent pesticide + relevant degradation products
After treatment, measure both the produce and the wash water for: parent pesticide + degradation products
That's essentially a mass-balance question: What did we start with, what did it turn into, and/or where did it go?
I have not found evidence that the apple study performed that type of analysis. The study measured the parent pesticides and investigated their degradation behavior. I have not found quantification of resulting degradation products before and after washing that account for the whole. That doesn't make the experiment invalid. It means we need to be precise about what the experiment actaully established.
Killing It Isn't the Same as Removing
There's a useful analogy from another area in which I've worked: mold remediation.
Some attempt to treat mold with products intended to kill it. Whether a particular treatment kills mold is a separate question from whether it removes mold.
Imagine that I wanted to evaluate such a treatment and measured only viable mold spores.
Before treatment, I detect 100 viable spores.
After treatment, I detect 85.
I could accurately report, Viable mold spores decreased by 15%.
I could not accurately say, “The number of mold spores decreased by 15%.”
I could not conclude, there is now 15% less mold present.
Some of those spores are no longer be viable. They're still there. In mold remediation, killing mold and removing mold are different goals. Mold that is no longer viable does not disappear, and may still contain allergens and biologically active components.
The measurement should match the question. The same reasoning applies here.
If baking soda causes a pesticide to degrade, measuring less of the original pesticide does not by itlsef. establish that an equivalent amount of pesticide-related material was physically removed from the fruit. It establishes, there is less of the original compound.
Then comes the question: What did it become?
Are the degradation products less toxic? More toxic? About the same?
Do they remain on the produce? Do they enter the wash water?
Are they removed during the final rinse?
Those aren't arguments. They're questions. They're important if chemical degradation is part of the mechanism being credited with reducing pesticide residue. The EWG review itself recognizes this issue. Its authors call for additional research, examining metabolites formed during household cleaning and food preparation and their toxicity.
That acknowledgment is important. If the purpose of washing is to reduce a potential health risk, then percentage reduction in the parent pesticide isn't necessarily the final metric we care about. The question is what remains, and whether the resulting produce is meaningfully safer to eat.
Fifteen Percent of What?
A percentage doesn't tell us the significance of a reduction.
Imagine that a particular fruit contains 100 units of a chemical at a level that represents a meaningful health concern. If water reduces that to 70, and another treatment reduces it to 50, the additional reduction might be considered significant.
Now imagine the starting concentration is below a level associated with meaningful risk. Reducing it another 15 or 20 percentage points produces little meaningful health benefit. The percentage reduction hasn't changed. Its significance has.
Before deciding that I need a more elaborate procedure for washing my produce, I'd want to know: How much pesticide am I being exposed to? At what concentrations? How does that exposure compare, with concentrations associated with adverse health effects? How much does the additional reduction achieved with baking soda or vinegar change that risk?
A study demonstrating a greater reduction in the concentration of a measured chemical does not, answer those questions. Even the word reduction deserves a closer look.
What About the Pesticides Inside the Apple?
The apple experiment revealed something else. After 24 hours, approximately 20% of the applied thiabendazole and 4.4% of the applied phosmet had penetrated into the apples. The baking-soda wash couldn't remove those internal residues. Thiabendazole, a systemic pesticide, penetrated approximately four times deeper into the apple peel than phosmet.
This raises a question:
How much of the pesticide residue we're exposed to is available for washing to remove?
If a meaningful portion has penetrated the fruit or vegetable, then optimizing the surface-washing procedure addresses only part of the exposure. That doesn't mean washing is pointless. It means we need to understand which problem washing is capable of solving.
Five to Ten Minutes?
There's a detail in the apple study that caught my attention. EWG recommends soaking produce in its baking-soda or vinegar solution for five to ten minutes.
In the apple experiment, using a 10 mg/mL sodium bicarbonate solution, researchers reported that it took 12 minutes to remove surface thiabendazole, and 15 minutes to remove surface phosmet.
“Remove” requires qualification, as the researchers found that degradation of the parent pesticides occurred in sodium bicarbonate.
That doesn't prove EWG's five-to-ten-minute recommendation is wrong. Complete reduction of the measured parent pesticide isn't required to achieve a useful result. One experiment involving two pesticides, on apples, cannot establish an ideal washing time for every pesticide and fruit and vegetable.
It does make me ask: Where did EWG's recomendation of five to ten minutes come from?
The studies EWG reviewed used soaking times ranging from 1 to 60 minutes. Vinegar/acetic-acid concentrations ranged from 0.15% to 10%, while baking-soda concentrations ranged from 1.25% to 10% in the studies reporting concentration. EWG's researchers themselves noted that some of the concentrations studied were higher than typical household use and therefore limit generalizability.
Their consumer guide gives us a simple recipe. It may be a practical compromise. I'd still like to know the evidence supporting those particular numbers.
Laboratory Apples Aren't Grocery Store-bought Apples
We need to be careful about what an experiment represents.
In the apple experiment, researchers applied thiabendazole and phosmet to organic Gala apples at controlled concentrations, and measured what happened under controlled conditions.
It doesn't tell us what is on the apple I bought at the grocery store. Real agricultural exposure involves the pesticide formulation used, application method, concentration, weather, number of applications, time between application and harvest, degradation, storage and post-harvest processing.
The EWG review included both field studies and experiments in which researchers artificially applied or “spiked” produce with pesticides. That doesn't make the experiments bad. It tells us what question they answer.
What Problem Are We Trying to Solve?
We've traveled quite a distance from: Should I wash my apple?
That question is easy for me: Yes.
The harder question is:
Do I need to soak my apple in a prescribed concentration of vinegar or baking soda for five to ten minutes because doing so meaningfully reduces a health risk from pesticide exposure?
To answer that, I'd need to know:
What pesticide residues are actually present on and inside the produce we buy?
At what concentrations?
What is the health significance of those concentrations?
How much is accessible to washing?
How much does ordinary water remove?
How much additional exposure does vinegar or baking soda eliminate?
When a measured pesticide decreases, how much was physically removed and how much was chemically transformed?
If it was transformed, what did it become?
Where did those transformation products go?
Were the complete pesticide formulations considered, or only selected active ingredients and metabolites?
And finally:
Does the washing treatment produce a meaningful improvement in human health, compared with washing the produce with water?
What Harm Is There in Doing More?
There is an understandable response to all of this: Why not use baking soda or vinegar anyway? Even if the benefit is small, what harm could it do?
We don't know that it does not cause any harm. The evidence we've examined doesn't establish that soaking produce in these solutions is dangerous, and I don't want to create a new fear as we question another.
“More” isn't always better.
If sodium bicarbonate reduces the concentration of some parent pesticides by causing them to degrade, chemistry is occurring. We can't leap to the conclusion that the new compounds are being created, that everything produced by those reactions, is harmless and irrelevant just because the measured parent pesticide decreased.
Lets' find out.
Until we do, I don't think “What harm could it do?” is evidence that a procedure is beneficial.
There's another cost:
Every additional health recommendation requires something from us.
Buy this.
Measure this.
Mix this.
Soak for this long.
Rinse this way.
Do it every time.
It takes time and effort, and it can leave people with the impression that eating an apple without performing the procedure exposes them to a danger they could have prevented. Before adding another health ritual to people's lives, I think we should establish for sure that it solves a meaningful problem, significantly.
If It Ain't Broke, Don't Fix It
There's an old saying, "If it ain't broke, don't fix it."
EWG's guide says there is “no one-size-fits-all solution” because different produce and pesticides behave differently. It says ordinary water washing reduces pesticide concentrations. Perhaps its simplest recommendation is its best: “Clean your produce, then eat it.”
I'm not convinced that the evidence establishes that everyone needs to buy distilled white vinegar, measure baking soda, prepare a solution, and soak produce for five to ten minutes to meaningfully improve their health.
I'm not arguing that doing so is harmful.
It brings me back to the question I started with:
After answering all of those questions, is there evidence that soaking my fruits and vegetables for 5–10 minutes in EWG's prescribed concentration of vinegar or baking soda meaningfully improves my health compared with simply washing them under water?
I haven't found that evidence.
One last thought about water
Even “wash it with water” raises a question.
One of the studies I examined tested a chlorine solution. In the apple study, researchers used a Clorox bleach solution containing 25 mg/L available chlorine for two minutes. They found that it was not effective at removing the two pesticides they tested, thiabendazole and phosmet.
Another study involving diazinon and chlorpyrifos on perilla leaves and broccoli found chlorine water produced greater pesticide “removal and/or degradation” than soaking or washing in water. That phrase, removal and/or degradation, brings us right back to a question in this article: Did the pesticide leave the food, or did the chemistry change?
That's relevant because municipal tap water contains a disinfectant such as chlorine or chloramine. I haven't investigated this question enough to conclude that washing produce with tap water creates a meaningful problem, and I wouldn't turn tap water into another thing to worry about.
If I already have filtered or reverse-osmosis water available, I'd use it. It removes another variable, without adding another complicated procedure.
Make Life Better — What You Can Do
My takeaway is simple. Use common sense.
Wash your fruits and vegetables. With water.
If filtered or RO water is available, use it. If it isn't, don't make washing produce with tap water another thing to worry about.
Then eat them.
About the Author
Daniel Stih is an engineer, environmental consultant, author and Certified Microbial Consultant whose work focuses on investigating environmental conditions, evaluating evidence and solving problems involving healthy indoor environments.
While living in Oregon, Daniel volunteered with the Northwest Coalition for Alternatives to Pesticides (NCAP), where part of his work involved reading, organizing and archiving press coverage used in the organization's research.
In his environmental consulting work, Daniel has also investigated homes and businesses following accidental pesticide exposures, including incidents involving pesticide companies spraying the wrong building, applying the wrong product or inadvertently mixing products. His work has included coordinating laboratory testing for residual pesticide contamination and helping develop mitigation and cleanup strategies.
That experience taught him that pesticide exposure and cleanup are not always as simple as identifying a single active ingredient or determining whether its concentration has decreased. The formulation, residues, surfaces involved, application circumstances and what remains after cleanup all matter.
References:
Reducing pesticide residues on produce: a scoping review of household produce washing methods. https://www.frontiersin.org/journals/environmental-health/articles/10.3389/fenvh.2026.1768399/full?utm_source=chatgpt.com
Effectiveness of Commercial and Homemade Washing Agents in Removing Pesticide Residues on and in Apples. https://pubs.acs.org/jafcau/article-abstract/65/44/9744/1367159/Effectiveness-of-Commercial-and-Homemade-Washing?redirectedFrom=fulltext&utm_source=chatgpt.com