Summary: No, it seems vegetable washes (a.k.a. produce washes) generally don't really help remove pesticides... but that isn't the point of them... but even at their main task of removing microbes, they may or may not be effective.
Are Pesticides the Real Problem?
We wash produce to remove a number of contaminants:
- Artificial Wax
- Microbes including bacteria and viruses
From a health perspective, the microbes should be a far greater concern than the trace amounts of pesticide remaining. (e.g. FDA recommendations don't even mention pesticides; they recommend washing to avoid harmful bacteria.)
According to one reviewer:
While I found lots of how-to advice on the Internet about removing pesticides, I didn’t find a single wash that claims to do so.
Now, this reviewer clearly didn't find Veggie Wash and FIT Fruit and Vegetable Wash, whose manufacturers have made those claims, but I am using this just to support the idea that produce washes aren't primarily aimed at cleaning pesticides.
Further discussion of the alleged dangers/safety of pesticides (at the dosages found on produce) probably deserves its own Skeptics.SE question.
Given the problem is broader than merely pesticides, I have included some studies below that don't look at pesticides, but I think are relevant in evaluating fruit washes.
Which Specific Case?
The question of how much cleaner the produce becomes is difficult to answer because of the diverse set of situations we could measure:
- The type of fruit wash.
- The type of pesticide/species of microbes.
- The type of fruit (compare washing firm-skinned tomatoes with soft-skinned peaches or high-surface-area grapes.)
- Whether the washing is done by the consumer or the producer - I have focussed on the consumer here. For producer issues, this is a good starting point.
So, we can't give a single, simple answer.
Some Data Points
Here are some data-points from individual studies:
This experiment looked at:
- Twelve pesticides - including DDE (a metabolite of DDT, that has been banned)
- Several four commercial produce washes: FIT, Fruit & Vegetable Wash, Organiclean and Vegi-Clean
- They were compared to detergent solution, to rinsing in tap water alone, and not washing.
- Several types of produce: lettuce, strawberry and tomatoes.
First, they checked that water removed pesticides. They found all but three types of pesticide were "significantly reduced". (I don't know what that term means in this case.)
Then they tried comparing the washes.
The mechanical action of rubbing the produce under tap water is likely responsible for removing pesticide residues. Mild detergents or fruit and vegetable washes do not enhance the removal of pesticide residues from produce above that of rinsing with tap water alone.
This paper looked at a couple of experiments variously involving:
- Dirt, Wax, a "cocktail" of organophosphorous and organochlorine pesticides, and contaminating it with Tryptone Soya broth and ground beef brothes.
- An unnamed (in the abstract) produce wash, with and without a paper towel.
- It was compared to water (with and without a paper towl), a produce brush and a chlorine solution.
- Several types of produce: waxed apples, unwaxed apples, cucumbers and lemons.
Water rinse and paper towel dry was found superior to all other methods tested.
any treatment that included wiping with paper towels showed increased effectiveness over similar treatments or controls
For the Tryptone Soya broth, the chlorine dip was better than water rinse and paper towel. For the beef contaminant, water rinse and paper towel was better.
The efficacy shown by paper towels usage in this diverse set of experiments is based on frictional removal of offending soils.
This measured actual produce being served at a university dining hall.
- It looked at any microflora they could culture. This one is not about pesticides.
- It compared before washing, after washing in water and after washing in Victory produce wash.
- It looked only at lettuce.
They find the high contaminated lettuces had less microflora on them when washed in the produce wash with water.
Our results indicate that Victory produce wash is effective in reducing indigenous flora on lettuce during food service preparation.
I note the authors had some caveats about the techniques used.
This looked at a number of different washing solutions.
- It looked only at strawberries.
- They strawberries were innoculated with 4 different viruses and bacteria. This one is not about pesticides.
- It compared warm and cool water, seven various chlorine, bleach and phosphate solutions plus Fit produce wash, Healthy Harvest, liquid and automatic dishwashing liquid, saline and vinegar.
While they didn't top the lists, the produce washes outperformed water:
The consumer-oriented produce wash Fit was very effective (>99%) in reducing the numbers of bacteria but not in reducing the numbers of viruses. Another wash, Healthy Harvest, was significantly less effective than Fit in reducing bacterial pathogens but more effective for viruses.
This study was trying to check that a particular result was reproduceable by trying it at three different labs.
- They looked only at tomatoes (but suggests the results will apply to " similar fruits and vegetables with rigid, smooth surfaces.")
- They contaminated the tomatoes with five different types of Salmonella. (This is not about pesticides.)
- They compared Fit produce wash, sterile water and "neutralizer broth".
Fit produce wash worked better than water or the neutralizer broth at removing Salmonella.
Treatment with PW resulted in reductions in the number of Salmonella 2 to 4 logs greater than those achieved with the sterile water or D/E neutralizer broth controls.
The Food Safety & Health department of the University of Wisconsin took one manufacturer's claims to task: FIT Fruit and Vegetable Wash: Do the Ads and Research Match?
They showed that the claims made by the company were based on experiments that did not match realistic situations, and that the cleanliness it implied might not translate to real-world benefits.
e.g. they claim that some experiments were done on glass containers rather than fruit, and that pesticides were applied immediately before harvest, which is not how fruit is normally consumed.
Fit's overall claim is to provide a convenient and more effective way to CLEAN fresh produce better than water alone. It make no claims for increased safety of quality. Fit may indeed clean produce better than water by removing wax and fingerprints. There is no available proof that Fit increases safety of produce.
There are plenty of studies of various aspects of the effectiveness of produce washes. It is clear that pesticides are not the only reason to consider them.
The results of the studies are somewhat mixed and almost contradictory, which may be due to the large number of differences between the situations. In the absence of a formal review of the literature (which I have looked for but didn't find), we might turn to organisations that evaluate such risks:
The US FDA Recommendation is to use running water.
Washing fruits and vegetables with soap or detergent or using commercial produce washes is not recommended.