Fake Banner
    Do You Really Need To Buy Organic To Avoid Pesticide Residues?
    By Steve Savage | September 9th 2012 11:48 PM | 12 comments | Print | E-mail | Track Comments
    About Steve

    Trained as a plant pathologist (Ph.D. UC Davis 1982), I've worked now for >30 years in many aspects of agricultural technology (Colorado State...

    View Steve's Profile
    Last week, a meta-analysis from a highly credible academic source (Stanford University, its medical school and nearby institutions), raised serious questions about the often-touted nutritional advantage of organic food.  They digested the contents of 237 peer reviewed articles comparing organic and conventional foods and diets.  They concluded that "the published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods."  

    This drew a great deal of attention and organic advocate defense.  Because even though Stanford is affectionately known by alums such as me as "the farm," it is certainly no ag-school promoting the status quo.  Instead, it enjoys a very strong reputation for research excellence.   It isn't easy to dismiss these findings.

    Many commentators, confronted with the highly credible de-mythification of the nutritional advantage of organic, jumped to the paper's slight evidence supporting a 30% reduction in exposure to pesticide residues as a way to justify paying extra for organic. Does the science really support that claim?  No.

    What I found disappointing about the Stanford study was the weakness of its analysis of differences in pesticide residues.  First of all, of the 9 papers it analyzed on this topic, only one was based on US crops.  Seven were about European food and one was from Australia.  The single US study used data from the 1990s.  Since that time there have been significant declines in the usage of older, more toxic pesticides.  

    The Stanford-associated authors drew the cautious conclusion that "consumption of organic foods may reduce exposures to pesticide residues...", but they didn't do anything to put that statement in perspective.  In fact, their analysis was only a comparison of the number of pesticide detections with no consideration of which pesticides were detected at at what levels.  Without that information, one can easily be counting,  as equivalent, chemical residues that could differ by a factor of a hundred thousand or million in terms of relative risk.   The Stanford group may have been limited by doing meta-analysis instead of original research, but in any case this sort of "detection counting" is the same egregiously misleading "analysis" that is committed each year by the Environmental Working Group in compiling their "Dirty Dozen List."  

    How Would You Best Answer Questions About Pesticide Residue Safety

    The truth is that at least for the US, there is a perfectly good way to answer the question, "Should we be concerned at all about pesticide residues on our conventional food?"  There is a publically available, fully transparent, downloadable data-set that provides exactly the information needed to get those answers. Each year, a group in the US Department of Agriculture (USDA-AMS) conducts a huge effort called "The Pesticide Detection Program." (PDP).  They collect thousands of samples of food commodities from commercial channels throughout the year, and then take them back to the lab and analyze each for hundreds of different pesticide residues.   It is effectively a "report card" on the entire food production system about how well it protects consumers from undesirable pesticide exposure.

    I've been working for a while to do a rigorous analysis of the latest available PDP data from 2010.  It has been a daunting task, because it is a nearly 2 million row, 85MB document. It contains a great deal of useful information in a form not easily accessed or understood by the public.  However; once this is data iscrunched; it is easy to see why the USDA, EPA, FDA conclude that consumers have no need to worry about the safety of their food supply from a pesticide residue point of view.

    A graph of the cumulative distribution of detections for all crops tested in 2010

    The graph above shows that the vast majority of the residues that the USDA scientists detect are at less than one part per million (1 milligram/kilogram).  There really are not very many chemicals, synthetic or natural, that are of concern at these levels, but fortunately the USDA data does identify what the chemicals were and one can find out about them by searching for an MSDS (Material Safety Data Sheet).

    A comparison of the detected chemicals vs natural toxins and foods

    When most people hear the word, "pesticide" they imagine something quite dangerous.  What they don't know is that over the last several decades, the old chemicals have been steadily replaced by much less hazardous ones that have emerged from a multi-billion dollar discover effort.  That is why 36.6% of the residues detected in 2010 were for chemicals that are less toxic to mammals than things like salt, or vinegar or the citric acid in your lemons.   73 percent of the detections  were for pesticides that are less toxic than the vanilla that is in your ice cream.  90.5 percent of the pesticides detected were less toxic gram per gram than the ibuprofen that is in the Advil tablets that tens of millions of people take on a regular basis.  95.4% of the detected residues were from chemicals that are less toxic than the caffeine that is in your coffee each morning.  "Pesticide" does not equal "danger."

    The appropriate way to look at residue data

    Even so, the best way to answer the question, "should I worry about pesticide residues?" is to compare what was detected to something called the "EPA tolerance."  Companies that want to register new pesticides or to continue to use older ones spend well over $100 million dollars and several years of research to characterize the hazards (or lack thereof) that are associated with each chemical.  These are used to inform a sophisticated, EPA-driven  "Risk Assessment" process that determines if the chemical can be used and with which restrictions (e.g. how long the use must stop before the crop is harvested.)  The "tolerance" that comes out of this process is designed to set a maximum level of that pesticide residue that should be detected in practice. This value includes a generous safety margin (on the order of 100x).  Anything that is detected which is below the tolerance is not of any concern.  The tolerances are set specifically by chemical with differences for each crop to reflect  differences in the amount people would eat and which crops tend to be consumed the most by children.  

    What Does The Residue Testing Say?

    The reason that the USDA can look at their data and make strong statements about safety is that the residues they find are virtually all below the tolerances, mostly far below (see graph above.)  Only 7.8% of the residues detected in 2010 were even within the range of 0.1 to 1 times the tolerance.  More than half were less than 1% of the tolerance (see graph above).

    The Stanford study cited a 30% reduction pesticide residue detections which is essentially meaningless in the context of the miniscule risk associated. Unfortunately, many consumers have been convinced that there is a risk where there isn't one.  They have gotten this from misleading promotion of organic as "pesticide-free" when it isn't, and by the scaremongering of groups like the EWG. The net effect of consumer concern about pesticide residues, driven by distorted messaging, is a reduction in fresh fruit and vegetables consumption (see graph above).   After some modest increases in fruit and vegetable per capita consumption in the 80s and 90s, those trends have ceased or even been reversed.  How much of that is related to disinformation about the risks associated with pesticide residues?  It is hard to know.  

    This new study, even if it is from Stanford, does not provide consumers meaningful guidance on the question of whether they should spend more to avoid pesticide residues.  The more relevant USDA data says that they don't need to hesitate to buy and consume "conventional" foods.

    You are welcome to comment here or to email me at savage.sd@gmail.com.  Graphs are based on USDA-AMS pesticide data and USDA-ERS produce trend data.


    The thought that comes to mind "its the food chain stupid" and relates that regardless of detectable or non-detectable levels on the food putting pesticide into the environment is making an impact on the overall health of the food chain. Oh, by the way,we are part of the food chain. Estrogen disruptive pesticides are fat soluble and can be stored in body fat. We now are at about 1 in 3 with incidence of cancers. Any way we can reduce the environment and bio-load the better. Also, the definition of nutrition used in this meta analysis is somewhat limited in that is strictly referring to macro and micro nutrients. There are now a whole other set of elements that have nutrient value. These are known as phyto-nutrients, phytochemicals, phytosterols or phytohormones that have important activity that can be higher in foods grown in soil with more organic matter and not strictly fertilizers found in industrial farming.

    While you are absolutely correct that phytonutrients are hugely important and contribute a great deal to health and wellness, I'd like to emphasize that these nutrients do occur in all plants, regardless of how they are grown. Furthermore, all phytonutrients are not created equally. For example, the phytoestrogens commonly found in soy (a cure-all touted by most vegetarian/vegan types) are well known to exacerbate cancer (specifically breast and ovarian) and have been shown to increase the aggressiveness of already progressively degenerative hypothyroid diseases, like Hashimoto's. Furthermore, they have a huge influence on reproductive processes and can wreck absolute havoc on female reproductive organs, even to the point of leading to permanent damage/scarring and infertility. Just because its in a plant doesn't mean its good for you. *Caveat...these are broken down during fermentation, so eat all the tempeh and miso you want!

    Karen,The phytochemicals you are talking about occur in all plants, organic and not.  They are important, often cancer fighting etc, but many of them are also toxic at lower doses than typical pesticides.  Many are also "endocrine disruptors."  They are fine at the doses we consume.  Pesticides are just present at much lower doses.   
    Steve Savage
    There are no words to say how much I appreciate this analysis. You have succinctly said what I've been trying to explain to my non-scientist friends and family for years! I would only suggest adding a link to the list of allowable pesticides and herbicides in organic farming. Many people think its all about crop rotation and paired planting, which may be true in grandma's garden but is certainly not the case in regards to what you see on the shelves at Whole Foods. My mantra has always been and will remain: if you're that worried about it, peel your fruits and wash your veggies...case closed. Thanks again for the great analysis!

    I found this article via Google. Interesting. There is surprisingly few information available on pesticides and pesticide residue on the Web while the consumer demand for it is high, and the market for organic/bio food is going to the stratosphere in the West. No wonder people are listening to enviro alarmists and religious folks instead of scientists: they aren't defending themselves.

    I do have some issue with the definition of "toxicity" you use, though, which leads you to conclude pesticide levels on consumer food are inoffensive. I guess it is about death in mammals or the LD50.

    The problem is that a substance can cause serious harm in somebody without necessarily causing death. Think bioaccumulation, carcinogenic properties, effects on the neural system, etc.

    Alex,I agree that acute oral toxicity is only one of many important measures of risk.  That is why a comparison to the EPA tolerance is so important.  It is designed to consider all the different factors in the risk assessment as well as the demographics of who consumes each crop (e.g. children).  It is a very tough standard, so it is sort of remarkable that thousands of farmers in the US and outside are able to consistently deliver food with residues below those levels.  
    Steve Savage
    Thank you for responding to my comment though you missed the main point. There is research studies on how various types of organic and permaculture techniques and soils and how they effects the value of herbs and plants. Here is one:
    It is interesting how certain research studies get a lot of press while other do not. Welcome to the world of research and corporate money.

    I think this is not just an outstanding piece but also it has prompted the best and most thoughtful string of comments I've seen here in a long time. Thanks Steve!

    One of the problems with the Stanford study is that they more or less set up a strawman (nutritional value) then proceeded to strike it down. Most people are not buying organics because they think it's more nutritious - they buy it because:
    they believe it to have less pesticide residue (and depending on which country they are in that's quite likely true)
    organic farming techniques are far better for soil health
    generally speaking they believe that buying organics helps support local farmers more - again quite likely as organic produce often does not travel as well

    If they are buying it to avoid residues, then they are still wasting money.  The residues that are present on conventional are not of concern, and the organic could definitely have residues of the copper fungicides that are used on them.  The PDP does not test for copper or for some of the other things that organic growers use, so you don't really know how much is there.  However, bottom line you are far better off eating any kind of fresh produce because of all the beneficial chemicals they contain
    Steve Savage
    Interesting that the article showed a decline in consumption of fresh produce...I would ask where that study hails from? Is it based on purhcases from market chains? I think there has been a large increase in buying local, farmers markets, CSA and even "grow your own" movements, which might account for the decline in what appears to be "consumption of fresh fruits" when in reality Americans are simply purchasing somewhere else, growing their own, or sharing with a neighbor.

    The data on consumption comes from the USDA-Economic Research Service.  I would love to believe that produce consumption is improving in ways that are not tracked well, but it is doubtful.  The decline or stagnant trends also occur in commodities that few people could ever grow for themselves because of weather etc.  Some commodities are going up a lot like strawberries.
    Steve Savage