In the immortal words of Tom Petty: “I won’t back down”

By Christie Wilcox | August 15, 2011 9:00 pm

USDA OrganicIn the responses to my article on organic myths, I have been called an industrial shill, liar, and an organic hater. People have questioned my motives, saying I am a bioengineer or paid by Monsanto*. They have called for my head, or at the very least, the retraction of my article.

In most of them, my arguments were inflated, twisted, or flat-out re-written. I don’t think GMOs “are the only way to feed the world.” I don’t think organics are “trying to take over.” So, screw the myths. This time around, I’m just going to focus on the facts.

Fact #1: Organic farming uses pesticides – and yes, organic pesticides are bad for you, too.

My main point in the first myth I brought up was simply to say that organic farms do use pesticides, contrary to what many people think. Since none of the people attacking my article can disagree with this fact (since it’s 100% true), they have instead warped my argument, saying I claim that organic farms are “seething hotbeds of toxic pesticide use” or that I believe all “naturally occurring pesticides pose the same risk as same as [sic] synthetic ones” when “the truth is, they’re [sic] don’t.”

I didn’t say either of those things. I did say that you can’t automatically assume a natural pesticide is safer, which was my point with rotenone. But Jason Mark claims it’s unfair to use rotenone as an example as it’s now banned in the US - fair enough (turns out the National Organic Program re-approved it in 2010 despite mounting evidence of its links to Parkinson’s. So my point stands). He then goes on to say that he chooses organic because he wants “to eat food that I know doesn’t involve the use of chemicals that harm ecosystems and have been linked to human health impacts.” Similarly, a response to my post on the Rodale Institute’s website says that the consumer can confidently state that they “buy organics because they don’t use the kinds of pesticides that create public and environmental health hazards, harm pollinators and other indicator species, make farmers and farmworkers sick, and/or persist for years in the environment accumulating up the food chain.”

Oh, really?

Let’s look at the details, shall we? The claim is that organic pesticides and fungicides are better to use because they’re less dangerous for us – and though he accuses me of ‘cherry-picking’, Jason only briefly talks about the health side effects of copper sulfate and conveniently doesn’t talk about the dangers of the most widely used organic fungicide: pyrethrum, though he delves deeply into the dangers of synthetics.

So let’s pit the most used organics against the most used conventional ones for a moment. In the USA, the top synthetic pesticide used is chlorpyrifos while the top fungicide is chlorothalonil. Yes, they are nasty chemicals, which in high doses are known to cause some serious health effects. But what about the organic alternatives? One way to compare is to look at their acute toxicity, often represented by an LD50 value. LD50, “lethal dose for 50%,” represents the dose at which 50% of a population will die from exposure.

In rats, the LD50 for copper sulfate is 30 milligrams per kilogram of body weight – which is a lot1. But copper sulfate has also been shown to have chronic effects at lower doses of exposure. In animals, chronic exposure has led to anemia, stunted growth, and degenerative diseases1,2,3. Furthermore, copper sulfate has been shown to disrupt reproduction and development, including inhibition of sperm development, loss of fertility, and lasting effects from in-utero exposure3,4. Copper sulfate is also mutagenic and carcinogenic4. And because copper is a trace element, it is strongly bioaccumulated, meaning consistent low doses can lead to toxic levels3,5. In people, increased exposure has been linked to liver disease and anemia3,6.

What about chlorpyrifos? The LD50 is 95 to 270 mg/kg – 2.5 to 10 times less toxic than copper sulfate1. As for its chronic effects, dogs fed chlorpyrifos at high doses daily did show increased liver weight and cholinesterase inhibition, meaning potential for neurological toxicity. But the effects went away immediately when feeding was stopped, and no long-term health effects were seen in either the dog or a similar rat study7,8. Furthermore, no evidence of mutagenicity was found in any of four tests reviewed by EPA9. It’s also not considered carcinogenic – rats and mice fed high doses for two years showed no increases in tumor growth9.

As with copper sulfate, those who work with pesticides for a living have experienced acute toxic exposure to chlorpyrifos. Studies have also linked fetal and chronic exposure to neurological complications and cancer risk, but these studies are hard to interpret, as they rely on a biomarker which may overestimate exposure by 10 to 20 fold10. Unlike copper sulfate, chlorpyrifos does not build up or persist in body tissues, and thus is not considered have significant bioaccumulation potential11. In humans, chlorpyrifos and its principal metabolites are eliminated rapidly following a single dose, within a day or so12.

What about those fungicides? The LD50 for pyrethrum in rats ranges from 200 mg/kg to around 2,000 mg/kg. Those that get a lethal dose suffer from tremors, convulsions, paralysis and respiratory failure before they finally die1. The LD50 for chlorothalonil? Well, it’s more than 10,000 mg/kg. That was the highest dose tested, but the rats still didn’t reach the 50% death rate target1. Rats fed a range of doses of chlorothalonil by the EPA over time showed no effects on physical appearance, behavior, or survival13. Yes, in some other high-dose feeding studies, chlorothalonil showed the potential to act as a mutagen or carcinogen14. But so has pyrethrum, with exposure leading to increases in tumors in the lungs, skin, liver, and thyroid of mice and rats15.

Ecologically, pyrethrum is extremely toxic to aquatic life and slightly toxic to bird species16. Chlorothalonil is toxic to fish as well, but it is non-toxic to birds17. Perhaps the kicker is that pyrethrum has been shown to be highly toxic to bees and wasps, which are keystone species necessary for the pollination of crops and other plants18. Chlorothalonil, on the other hand, isn’t.

Tell me, do you feel like the organic alternatives are totally safe? Sorry, but organic pesticides do make farmers sick. They do bioaccumulate. They do harm non-target species.

Oh, and I forgot to mention: organic alternatives are applied in higher concentrations and more frequently because they’re less effective at controlling the species they’re meant to kill.

While it’s true that some organic farms may not use any pesticides, those organic foodstuffs in your supermarket are almost guaranteed to have used them, and liberally. As Tom Laskawy notes, “copper and sulfur in particular are often overused, especially among fruit growers.” As with conventional fruits and vegetables, most of what you’re getting at the supermarket is factory farmed. And as Michael Pollan and Samuel Fromartz, among others, have pointed out: factory farming is factory farming, even if it’s organic.

My point is, a pesticide is a pesticide. If it kills things, it does so for a reason, and you probably don’t want to go around eating it. Do I want to chow down on food coated with chlorpyrifos and chlorothalonil? Well, no, of course not. That’s why we screen for synthetic pesticide residues. However, we don’t screen for organic pesticide residues. Given what you just read, wouldn’t you want to know how much of those chemicals are ending up on your plate?

Of course, to be fair, the other most widely used organic pesticide is Bt toxin – which is, by just about any tests so far, non-toxic to people. That’s exactly why it was chosen for use in GMOs: because you can eat it all you want and it has no ill effects. But I’ll get into that more later.

Fact #2: Science has yet to support claims that organic foods are healthier.

In my second myth, I said that “science simply cannot find any evidence that organic foods are in any way healthier than non-organic ones – and scientists have been comparing the two for over 50 years.” I was attacked for this statement, with citations of studies that show increased nutritional quality in organic strawberries, tomatoes and milk. It’s true – you can find single, unrepeated studies which have found some nutritional improvements. But that’s not how science works. When scientists weigh in on a topic, they can’t just rely on single studies that support their view. Instead, they have to consider all the studies on a topic, and examine the results of each. That is exactly what a meta-analysis does.

I actually cited not one but two separate papers which summarize the studies to date on nutritional quality, one of which was a meta-analysis19,20. In both, the results were clear: any nutritional benefits are slim, variable, and not universal. In other words, overall, the science hasn’t supported any claims of unilateral nutritional benefits.

If you really want a more in depth look, check out Erin Prosser’s detailed explanation of the research. She concludes that the science is mixed at best, and even if organic foods are nutritionally superior, “it won’t be by much, meaning it may make no substantial difference in terms of your health.”

Fact #3…

Ok, my third myth got attacked on two fronts that are so separate, I feel the need to address them independently. So, instead of Fact #3, I have 3a and 3b.

Fact #3a: Certified organic farms don’t have yields that equal conventional ones.

Organic farming – and by organic farming, I mean farming that is officially organic through some certification process – has lower yields than conventional. At least, that’s what a 21-year study published by Science in 2002 found – that organic farming methods produced 80% what conventional farming methods did21. A 2008 review of the literature found organic yields were 50 – 75% of those of conventional farms22. An even more recent meta-analysis puts the value at 82%23. In fact, only one study to date has said that organic methods get average yields higher than that.

This is the paper by Badgley and colleagues which many claim shows organic farms produce just as well as conventional ones24. But that’s not what the paper says. The paper models whether or not organic farming can feed the world based on different yield percentages. The lowest yield they test for organic farming: 91%.

Where did the 91% figure come from? The authors averaged the yields from 293 studies they found looking at organic production. But the paper flat-out states that it considers a wide variety of agricultural systems in this analysis. The authors explicitly state that by organic, they are not “referring to any particular certi?cation criteria” and that they “include non-certi?ed organic examples.” They don’t just include a few – of their 293 ‘organic’ comparisons, 100 are not certified organic, including ones which likely used synthetic pesticides and GMOs25. The paper’s methods, math and modeling have been critiqued strongly by two separate sources 25,26.

Even still, I never, and still don’t, make any claim that sustainable agriculture can’t have the same yields as conventional farming. It definitely can. But you have to broaden the definition of “sustainable”, as Badgley et al. did, to include non-organic methods.

For example, a recent study found that alternative management strategies outperformed both conventional and organic methods. These strategies, like no-till methods, demonstrated greater production efficiencies than either conventional or organic, and even had greater average yields27.

Do yields matter? Yes, they do. While we can argue left and right about whether hunger and famine now are a matter of production or politics, when the planet reaches 9 billion people or so in 2050, production will matter. That’s not to say that lower-yielding methods can’t be used in areas of abundance, or where people can afford it. But to feed nine billion mouths, we are going to have to be careful and efficient in our use of land if we are to produce enough food without destroying what little habitat is left for the world’s other species.

Fact #3b: GMOs aren’t evil, and yes, they might even do some good for the world.

By far the most passionate responses to my post centered around the issue of GMOs. I would argue that the rumors about my stance on GMOs have been greatly exaggerated. After all, I never claimed that “organic agriculture can be redeemed if only its definition can be broadened to include GMOs,” or that “genetic modification is all benefit and no risk.”

Do I think GMOs have the potential to up crop yields, increase nutritional value, and generally improve farming practices while reducing synthetic chemical use? Yes, yes I do. I’m not alone on this – the science supports me.

GM crops have been in fields and on the market for decades now, and studies are starting to weigh in on their benefits. A recent review of results of farmer surveys found that of 168 comparisons between GM adopters and non-adopters, 124 show positive results for the GM adopters, 32 indicate no difference and only 13 show negative yields – and that these increases were highest in developing countries28.

Most of the yield increases have come from the use of Bt crops. I specifically called out organic proponents on the hypocrisy of using Bt toxin liberally but not being willing to consider a GM Bt variety. As Jason Mark says, this means I claim that “there’s no distinction between spraying Bt and placing it directly into the plant” – but that’s not true at all. Of course there’s a difference. The GMO is the better solution. Studies have shown that spraying insecticides have a much stronger, negative effect on biodiversity than the use of transgenic crops29, which is particularly important when you consider that Bt crops have reduced pesticide use by 30% or more30. Furthermore, the pesticide use reduction wasn’t just in GM Bt fields – planting Bt varieties benefited non-GM growers, allowing them to reduce pesticide use and produce more crops31.

Bt crops not only increase yields and decrease pesticide use – they increase biodiversity. Three separate meta-analyses have confirmed that Bt crops benefit non-target species including bees and other insects29,32,33.

Have GM crops failed their debut? No, they haven’t. “There is now considerable evidence that transgenic crops are delivering significant economic benefits,” writes Clive James in a review of transgenic crops published in Current Science. His final sentence unequivocally states that “improved crop varieties are, and will continue to be the most cost effective, environmentally safe and sustainable way to ensure global food security in the future.” A 2010 review study found that “results from 12 countries indicate, with few exceptions, that GM crops have benefited farmers.” Similarly, a review examining 155 peer-reviewed articles determined that “by increasing yields, decreasing insecticide use, increasing the use of more environmentally friendly herbicides and facilitating the adoption of conservation tillage, GM crops have already contributed to increasing agricultural sustainability.”

That’s not to say all GM crops are stunning examples of the potential benefits of GMOs. Herbicide resistant crops are perfect examples of how GM technology can be used poorly. I don’t like Roundup Ready corn any more than my critics. How anyone could have thought that making a crop resistant to an herbicide (thus ensuring that we use MORE of this herbicide) was a good idea is beyond me. But I’ve been told not to judge organic pesticides by rotenone, so how is it fair to judge the future potential of all genetic engineering by Roundup Ready crops?

While Tom Laskawy says that in listing the potential benefits of GMOs, I have transgressed from “science to science fiction” and that most of the GM varieties I mentioned “don’t even exist in the lab”, every one of them is being or has been produced (hence the links) – including virus-resistant sweet potatoes, high-calcium carrots, high-antioxidant tomatoes, vaccine-producing fruits and vegetables, and allergen-free foods. He’s right that they don’t exist commercially, but how can they when all GMOs are universally demonized?

The real problem is that although GMO technology can be used to produce large social and ecological benefits, most GM crops developed to date have been designed to benefit Big Ag. This trend will only continue if the public keeps its negative attitude towards GMOs. I don’t like Monsanto any more than you do – so why let them control how GM technology is used? If there was more public pressure and desire for socially and ecologically beneficial GMOs, more scientists could get involved and use the technology better.

That’s what happened when the Rockefeller Foundation funded researchers at the Swiss Federal Institute of Technology’s Institute for Plant Sciences. The result was Golden Rice – a vitamin-A rich variety that the foundation had hoped to freely give to third world countries to help fight malnutrition34. The Swiss were working on a iron-rich variety, too, until widespread protesting of GMOs in Europe pressured the foundation into not renewing the institute’s funding.

Do I think all GMOs are perfect? Of course not. But should they be considered among the many different farming practices which may contribute to better farming in the future? Absolutely.

Fact #4: Farming practices of all types should be considered and weighed for their merits independent of labels.

The dichotomy between organic and conventional is misleading at best, and dangerous at worst. There is so much variation in each category that they are almost meaningless, except when it comes to our wallets.

I’m not pro factory farming. Nor am I pro organic. As Benton et al. write in their review of conventional, organic and alternative farming methods:

“rather than creating a misleading contrast by dividing farming systems into either organic/extensive and conventional/intensive there needs to be greater recognition that future farming has the potential to maintain yield whilst becoming “greener” by further optimizing inputs and practices to reduce environmental impacts”

Andy Revkin said it far better than me in his recent commentary on the destruction of GM wheat in Australia:

“It’s clear to me that genetics, intensified agriculture, organic farming, crop mixing, improved farmer training, precision fertilization and watering, improved food preservation and eating less wastefully and thoughtlessly will all play a role in coming decades — each in its place”

The central point of my mythbusting article, and of this one, is that the future of agriculture needs to examine all potential methods and determine if they are right for a given area. Landscapes are different – growing crops in Africa isn’t the same as growing crops in the Midwest, and if we universally apply the same methods globally, we are destined to fail both in terms of efficiency and sustainability. It is only through the breakdown of this arbitrary and variable distinction between methodologies and integration of a variety of practices that we will achieve our ultimate goal of a bright future both agriculturally and ecologically.

Links to the critiques of my first article:

*As for the attacks of my career and character, I can say without any hesitation that exactly 0% of my PhD funding comes from any kind of agribusiness. I study the population genetics and evolution of lionfish – you know, those frilly fish that are horribly invasive in the Atlantic. So no, Monsanto and bioengineering companies aren’t interested in what I do. If anyone really wants to know, my research funding and interests are freely disclosed and readily available on my website. And if anyone would like to contribute to said funding (bioengineering company or otherwise), there’s a nice contact form that you can use to get in touch with me. It’s a rough time to be studying science – I’ll take whatever funding I can get!

NOTE: I accidentally switched the uses of Copper Sulfate (actually an organic fungicide) with Pyrethrum (actually an organic insecticide). Oops! The points still stand, though – if you look at the information I provided, the organics are much more acutely and chronically toxic.

References:

  1. EXTOXNET: Extension Toxicology Network. A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Michigan State University, Oregon State University, and University of California at Davis. http://pmep.cce.cornell.edu/profiles/extoxnet/index.html
  2. Clayton, GD and FE Clayton, eds. 1981. Patty’s industrial hygiene and toxicology. Third edition. Vol. 2: Toxicology. NY: John Wiley and Sons.
  3. TOXNET. 1975-1986. National library of medicine’s toxicology data network. Hazardous Substances Data Bank (HSDB). Public Health Service. National Institute of Health, U. S. Department of Health and Human Services. Bethesda, MD: NLM.
  4. National Institute for Occupational Safety and Health (NIOSH). 1981- 1986. Registry of toxic effects of chemical substances (RTECS). Cincinati, OH: NIOSH.
  5. Gangstad, EO. 1986. Freshwater vegetation management. Fresno, CA: Thomson Publications.
  6. New York State Department of Health. 1984. Chemical fact sheet: Copper sulfate. Bureau of Toxic Substances Management. Albany, NY.
  7. American Conference of Governmental Industrial Hygienists, Inc. 1986. Documentation of the threshold limit values and biological exposure indices. Fifth edition. Cincinnati, OH: Publications Office, ACGIH.
  8. Hayes, WJ and ER Laws (ed.). 1990. Handbook of Pesticide Toxicology, Vol. 3, Classes of Pesticides. Academic Press, Inc., NY.
  9. US Environmental Protection Agency. June, 1989. Registration Standard (Second Round Review) for the Reregistration of Pesticide Products Containing Chlorpyrifos. Office of Pesticide Programs, US EPA, Washington, DC.
  10. Eaton, DL et al. 2008. Review of the Toxicology of Chlorpyrifos With an Emphasis on Human Exposure and Neurodevelopment. Critical Reviews in Toxicology 2008 38:s2, 1-125
  11. New York State Department of Environmental Conservation. 1986. Draft Environmental Impact Statement on Amendments to 6 NYCRR Part 326 Relating to the restriction of the pesticides aldrin, chlordane, chlorpyrifos, dieldrin and heptachlor. Division of Lands and Forests. Bureau of Pesticides. Albany, NY.
  12. Nolan, RJ et al. 1984. Chlorpyrifos: Pharmacokinetics in human volunteers. Toxicol. Appl. Pharmacol. 73: 8-15.
  13. U.S. Environmental Protection Agency. 1984. Chlorothalonil: Fact Sheet Number 36. September 30, 1984. Washington, DC.
  14. Sweet, D.V., ed. 1987. Registry of Toxic Effects of Chemical Substances Microfiche January 1987. NIOSH, Washington, DC.
  15. United States Environmental Protection Agency (US EPA). Office of Prevention, Pesticides and Toxic Substances . Carcinogenicity Peer Review of Pyrethrins . February 22, 1995. Washington, D C .
  16. Casida, J. E., ed. 1973. Pyrethrum, The Natural Insecticide. Academic Press, New York.
  17. Shelley LK, Balfry SK, Ross PS, Kennedy CJ. 2009. Immunotoxicological effects of a sub-chronic exposure to selected current-use pesticides in rainbow trout (Oncorhynchus mykiss). Aquat Toxicol 92:95–103.
  18. Cox, C. 2002. Pyrethrins/Pyrethrum Insecticide Factsheet. Journal of Pesticide Reform 22(1) 14-20.
  19. Dangour, A., Lock, K., Hayter, A., Aikenhead, A., Allen, E., & Uauy, R. (2010). Nutrition-related health effects of organic foods: a systematic review American Journal of Clinical Nutrition, 92 (1), 203-210 DOI: 10.3945/ajcn.2010.29269
  20. Rosen, J. (2010). A Review of the Nutrition Claims Made by Proponents of Organic Food Comprehensive Reviews in Food Science and Food Safety, 9 (3), 270-277 DOI: 10.1111/j.1541-4337.2010.00108.x
  21. Mader, P. (2002). Soil Fertility and Biodiversity in Organic Farming Science, 296 (5573), 1694-1697 DOI: 10.1126/science.1071148
  22. Kirchmann, H et al. 2008. Can Organic Crop Production Feed the World? ORGANIC CROP PRODUCTION – AMBITIONS AND LIMITATIONS. 39-72, DOI: 10.1007/978-1-4020-9316-6_3
  23. Mondelaers, K et al. 2009. A meta-analysis of the differences in environmental impacts between organic and conventional farming. British Food Journal, 111(10); 1098-1119. DOI: 10.1108/00070700910992925
  24. Badgley, C et al. Organic agriculture and the global food supply. Renew. Agric. Food Syst. 22, 86–108
  25. Avery, A. 2007. ‘Organic abundance’ report: fatally flawed. Renewable Agriculture and Food Systems, 22: 321-323
  26. Gelfand, I., S. S. Snapp, et al. 2010. Energy Efficiency of Conventional, Organic, and Alternative Cropping Systems for Food and Fuel at a Site in the US Midwest. Environmental Science & Technology 44(10): 4006-4011.
  27. Carpenter JE. Peer-reviewed surveys indicate positive impact of commercialized GM crops. Nat Biotech 2010; 28:319-21
  28. Wolfenbarger LL, Naranjo SE, Lundgren JG, Bitzer RJ, Watrud LS, 2008 Bt Crop Effects on Functional Guilds of Non-Target Arthropods: A Meta-Analysis. PLoS ONE 3(5): e2118. doi:10.1371/journal.pone.0002118
  29. Naranjo, S. E. 2009. Impact of Bt crops on non-target invertebrates and insecticide use patterns. CAB Reviews: Perspectives in Agriculture, Veterinary Sciences, Nutrition and Natural Resources 4: No 11 (PDF)
  30. Hutchison, WD et al. 2010. Areawide suppression of European corn borer with Bt maize reaps savings to non-Bt maize growers. Science. 330: 222-225.
  31. Duan, J.J. et al. 2008. A meta-analysis of effects of Bt crops on honey bees (Hymenoptera: Apidae). PLoS ONE 3, e1415.
  32. Marvier, M. et al. 2007. A meta-analysis of effects of Bt cotton and maize on nontarget invertebrates. Science 316, 1475–1477
  33. Ye X et al. 2000. Engineering the provitamin A (beta-carotene) biosynthetic pathway into (carotenoid-free) rice endosperm. Science 287:303-305
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About Christie Wilcox

Dr. Christie Wilcox is a science writer and postdoctoral scholar at the University of Hawaii. She is renowned in the science blogosphere for her delicate balance of contemporary science and scientific perspective seasoned with just the right amount of wit. Her award-winning posts have landed on the pages of major media outlets including The New York Times and Scientific American. To learn more about her life and work, check out her webpage or follow her on Twitter, Google+, or Facebook.

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