“Traditional fruit-cleaning operations cannot wholly remove pesticides.” That’s the grim report from a recent research study in the American Chemical Society’s journal Nano Letters, and it’s causing a buzz in kitchens across the land.
For anyone who’s ever washed an apple and felt assured to take a bite, this is a stern reality check.
Here’s the deal: scientists employed advanced Raman imaging and discovered that pesticides not only reside on the skin exclusively, they permeate right through the skin and into the flesh of fruits such as apples. As Dongdong Ye, a professor of food science at Anhui Agricultural University, explained to The Guardian, “Rather than fostering undue apprehension, the research posits that peeling can effectively eliminate nearly all pesticide residues, contrasted with the frequently recommended practice of washing.” That speedy rinse under the faucet? It’s not doing nearly as much good as most people believe.
The science behind it is fascinating and a bit creepy. Pesticides are formulated to linger, rain and sunlight resistant so they can shield crops. That same persistence makes them difficult to get rid of at home. New methods such as surface-enhanced Raman spectroscopy (SERS) have determined that even after a good wash, pesticide molecules are still found not only on the skin, but buried deep in the flesh of the fruit (pesticide contamination via the fruit’s peel and into the outermost layer of pulp).
But what about all those home remedies vinegar soaks, baking soda baths, fancy washes? It turns out, they’re not created equal. In a series of experiments, exposure to a baking soda solution for 15 minutes was the only treatment that significantly lowered some pesticide residues from the surface (baking soda solution changed color to blue, signaling it was effective in cleaning pesticides off). The chemistry here is that baking soda, being alkaline, has the ability to break down some pesticide chemicals. But and it’s a big one this is only effective on surface-sitting pesticides. If the pesticide is absorbed or has penetrated, even the best soak won’t do the trick.
Vinegar and commercial washes for produce? They may eliminate dirt and some bacteria, but research indicates they’re not as useful as baking soda for pesticide residue removal (surface pesticide residues were removed most effectively by sodium bicarbonate (baking soda) solution). Even the baking soda process can’t compare to what’s already under the peel, though. As one study described it, “the overall effectiveness of the method to remove all pesticide residues diminished as pesticides penetrated deeper into the fruit.”
For fruits and vegetables that can’t be peeled leafy greens or berries, for instance things get more complicated. Washing under running water remains your best option, with reductions in pesticide residue ranging from around 40% to 77% based on the veggie and technique (running water resulted in the greatest removal efficiency of all techniques). Leafy greens, sadly, are particularly problematic because their big surface area and texture cause pesticides to linger so easily. Boiling and blanching may assist for some pesticides but not all and it varies with the particular chemical properties of each pesticide.
And then there are safety limits. The USDA and FDA conduct periodic testing on produce and report that 99% of foods they tested contained residues of pesticides in levels within legal tolerances, which they indicate are safe to consume (99% of foods tested had residues within legal tolerances). But other consumer groups, such as Consumer Reports, claim that these thresholds are not tight enough, particularly for children and those who consume lots of produce. Their latest review revealed that 20% of 59 various fruit and vegetable categories had pesticide residues at levels that were “significant risks” to consumers.
So what’s a health-conscious home cook to do? The evidence leads to a few obvious conclusions:
- Peeling is the most effective way to eliminate nearly all pesticide residues from fruits like apples, pears, and potatoes (peeling can effectively eliminate nearly all pesticide residues). Yes, you’ll lose some nutrients and fiber found in the skin, but you’ll also ditch most of the lingering chemicals.
- For fruits and vegetables that can’t be peeled, scrubbing under running water is still worth it. It won’t catch everything, but it does make a difference particularly for pesticides that haven’t penetrated far.
- Baking soda soaks can enhance surface pesticide removal for robust fruits and vegetables just don’t count on miracles for anything that’s already penetrated in (washing produce in a baking soda solution can eliminate 66.7–98.9% of pesticide residues).
- If you’re extra concerned, buying organic or from local farmers who use fewer or no pesticides is a solid option.
One additional note: though regulatory agencies deem the danger from pesticide residues in most fruits and vegetables as low, some individuals such as children, pregnant individuals, and individuals with certain health issues might wish to be particularly careful. As Michael Hansen, a senior scientist at Consumer Reports, put it, “This is more science showing that, yes, there are concerns. Don’t just think that washing is going to help you.”
At the end of the day, it comes down to making smart decisions. Whether you’re peeling your apples, soaking your grapes, or simply washing your greens thoroughly, having an idea of what really works and what doesn’t can help you get your kitchen as safe and healthy as possible.
