Friday, February 11, 2011

"Organic" Food, Part II

Last time I discussed whether "organic" foods contain more nutrients than conventionally-grown foods. When reports started coming out that there was no reliable scientific evidence that "organic" foods were more nutritious, "organic" food proponents immediately fell back on their other two claims: "organic" foods contain fewer toxins and "organic" farming methods are better for the environment. The primary argument for fewer toxins is centered around the use of pesticides. Let's look at this in more detail.

The second claim: Do "organic" foods contain fewer toxins than conventionally-grown foods?

Before we address the presence of toxins applied as pesticides, first let us consider toxins that plants can acquire from their environment. Researchers studying "organically"-grown tomatoes found that they contained over fifteen times as much cadmium and ten times as much lead (both of which are harmful to human health) as conventionally-grown tomatoes.[1] Also, mycotoxins (mouse-over for definition), such as fumonisins and patulin, are reported to be higher in "organic" foods due to the limited use of fungicides.[2]

On to pesticides. There is a misconception that "organic" farmers don't apply any pesticides. The reality is that they don't apply any synthetic pesticides. The use of botanical pesticides, which are defined as "natural pesticides derived from plants" [3], is still allowed. Here is an incomplete list of such botanical pesticides which are currently allowed under the current definition of "organic" food in the U.S. [4]:
What is surprising about this list is that many of the compounds listed are toxic to humans, not just insects (rather than elaborate on each one, I've just provided links in the list above to toxicity information). But because they're natural and because they're believed to biodegrade more quickly [7], it's okay to spray those poisons on your food. However, the notion that "organic" pesticides biodegrade more quickly than conventional pesticides has more to do with inadequate testing methods than with scientific fact.[8] Additionally, about 25–30% of "organic" crops test positive for the presence of synthetic pesticides.[9]

On top of that many proponents of "organic" foods like to claim that botanical pesticides don't result in resistance like synthetic pesticides do. That's just silly. Overuse of any single chemical to kill a population of living things will almost always result in resistant strains—especially if you're dealing with organisms with high population numbers, like bacteria, fungi, weeds, or insects. In fact cases of resistance have already been reported for some of the botanical pesticides listed above.[10]

The argument that botanical pesticides are better because they're natural doesn't necessarily hold water. There are plenty of natural poisons—even in plants that are eaten by humans:
It has also been claimed, though I can find no hard evidence (so make of it what you will), that due to the use of animal manure, "organic" foods are more likely to be contaminated with E. coli, Campylobacter, Salmonella, etc.[13] This is not a risk with conventionally-grown foods since there are no bacteria in synthetic fertilizers.[14]

The answer: No.


[1] Rossi, F., et al. (2008) "Health-promoting substances and heavy metal content in tomatoes grown with different farming techniques." (full text .pdf) Eur. J. Nutr. 47:286–92. Note that "organic" tomatoes were also lower in vitamin C and lycopene than were conventionally-grown tomatoes.

[2] See Urban Myths of Organic Farming.

[3] Organic Foods Production Act of 1990 [as amended through Public Law 109–97, Nov. 10, 2005], Title XXI, § 2103 [7 U.S.C. 6502], Clause 2. Available here as a .pdf. Note that while botanical pesticides are defined as being derived from plants, there is no stipulation that they be mass produced in plants. I don't know whether "organic" farmers buy synthetically produced botanical pesticides, but a loophole exists that allows them to (see debunks the organic fantasy garden 106363.html).

[4] Actually, there are some botanical pesticides which are not allowed for "organic" farming, such as piperonyl butoxide from sesame seeds, nicotine sulfate from tobacco, strychnine from the poison nut tree, and deguelin (cubé resin) from lancepods. See National List of Allowed and Prohibited Substances, §205.602: "Nonsynthetic substances prohibited for use in organic crop production".

[5] I can't, for the life of me, figure out why copper sulfate is allowed as a fungicide in "organic" farming—it's not plant derived, it's mined. Thus it's a purely chemical soil amendment; there's nothing biological (i.e. organic) about it.

[6] The items in this list were derived by performing a Google search for the term 'botanical pesticides' and then aggregating the ones which were mentioned or discussed most often.

[7] However, organophosphates, the class of insecticides and herbicides most commonly used today, also rapidly degrade when exposed to sunlight and air. And they pose negligible risk to consumers (see

[8] See food lies d**ned lies  dr oz 106392.html.

[9] See food#Safety and pesticides. I'll speculate more on why I think this happens in the final post.

[10] Resistance in: capsaicin, azadirachtin, pyrethrin (many), veratridine (first result), rotenone (just an insect-derived cell line, not actual insects), myristicin, spinosad, and Δ-endotoxins.

[11] Yes, people eat these. They do it to get high. And people in Australia lick the poisonous cane toad to try to get high off the bufotoxins it secrets from its skin. (This doesn't actually work, though—the toad skin has to be smoked.)

[12] Again, toxicity information is provided in the links. Incidentally, there is one mammal which can consume iris roots without getting bloody diarrhea: the raccoon.

[13] Dennis Avery asserted this, claiming data from the CDC. However, the CDC has denied supplying him with such information. See organic foods. For food poisoning reports, go to and search for "organic".

[14] All cases of contamination with food-poisoning-causing organisms from conventionally-grown foods happens post-harvest.

Image attribution:

Wheatgrass sprouts are by Dean Ayres, available at

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