Does boiling food reduce pesticides?

Answered on August 19, 2014
Created August 29, 2012 at 8:16 PM

If I boil conventional potatoes, will this reduce the pesticides? What can I do to reduce the pesticides? What negative effects will pesticides have on my health?

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on August 29, 2012
at 10:17 PM

I found this website which lists the common pesticides found on conventional potatoes: http://www.whatsonmyfood.org/food.jsp?food=PO

Apparently the most common potato pesticide is chlorpropham. And while studies tend to show the risks of chlorpropham in the amount consumed in food are probably low (1), it never hurts to play it safe. Cooking potatoes reduces chlorpropham a little bit (2,3), but since most of the chloropropham in potatoes is found in the peel, peeling potatoes reduces it the most (4).

Imidacloprid is next. While it again doesn't appear imidacloprid is a huge risk in the amounts found in foods (5), I'm much more wary of it than chlorpropham. One study found that washing tomatoes reduced Imidocloprid by about 66% (6). Another study found that washing and cooking various vegetables (none of them potatoes) greatly reduced imidacloprid (7). Finally, another study on mallow found that boiling mallow significantly reduced imidacloprid, with much of the pesticide potentially being transferred into the water (8). Once again, a greater amount of imidacloprid is likely found in the peel (9).

Azoxystrobin is fungacide also apparently common in potatoes. Again, doesn't appear to be super bad (11), but I still wouldn't want to eat it. One study found cooking zucchini reduced azoxystrobin a little bit (10). Interestingly, the book "Pesticide Residues in Food and Drinking Water: Human Exposure and Risks" claims that photolysis is a mjor means of azoxystrobin degradation, meaning sun exposure reduces the fungacide.

Okay, we've looked at the more common pesticides, but what about the dangerous ones? O-phenylphenol is a bad one in my opinion. Cooking fruit has been shown to degrade it a bit (12). Also, since O-phenylphenol is often added after the plant has grown to prevent spoiling during transport I'm willing to bet the potato peel often houses much of the chemical.

Boscalid: boiling spinach has been shown to reduce boscalid (13). Washing, peeling, and cooking carrots reduces baoscalid significantly (14).

Thiobenzadole does not appear to be reduced much by cooking (15,16). Some studies have reported that thiobenzadole has a greater affinity for the skin and gets partitioned there at a greater rate (17). So peeling potatoes will likely remove much of the thiobenzadole (18).

Studies on meat have found that cooking may reduce many of the nasty organochlorine pesticides (19,20). One study on potatoes found the same thing and added "acidic solutions were more effective than neutral and alkaline solutions in the elimination of the organochlorine compounds under investigation" (21). So perhaps add some vinegar or lemon juice to the boiling water you cook with? This same study found cooking also reduced organophosphates in potatoes as well.


Organic potatoes will certainly be better. But if you do buy conventional potatoes, I think peeling them and boiling them will go a long way in reducing possible pesticides (22).

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on August 29, 2012
at 09:15 PM

I don't know about boiling them, but washing fruits and vegetables for 30 seconds, under running water, drastically reduces, if not eradicates, pesticides


on August 30, 2012
at 12:35 PM

According to the EWG, potatoes are one of the 'dirty dozen'. I'm guessing it's because potatoes will, as they grow, absorb anything that's in the dirt--pesticides, fungicides, herbicides, as well as any other contaminants that might be there. As such, I would doubt that boiling potatoes would help much. Based on the other answers, I would guess that some other conventionally-grown veggies would be fine boiled to reduce contamination.



on August 29, 2012
at 09:46 PM

Yes. But I can't say if the reduction would be sufficient or significant to change anything. Any time you heat up a chemical you speed up the rate at which it degrades. So boiling food will by definition reduce the concentration of any pesticides present. But it may not make much of a real change to affect anything.



on August 29, 2012
at 09:23 PM

Some pesticides just stay on the surface and some get inside, I'm not sure what they use on conventional potatoes. If they are just on the surface, peeling should get rid of all of it, but it is inside, it is there to stay, I don't think boiling would eliminate chemicals.

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