Thursday, December 6, 2012

Pesticide Residues on Organic: What Do We Know?

Are there really less pesticide residues on organic crops?  The answer might not be as simple as you think.

A few weeks ago it was announced that for the first time in the history of USDA-Organic, there will be mandatory pesticide residue testing starting in 2013.  This was always a theoretical possibility, but a government audit of certifiers showed that it essentially never happened.  Now it will, at least to some extent (something like 5% of operations)

I wrote to the contact person at USDA to ask this question:

"will this new testing program look for any residues of the pesticides that are allowed on organic crop and thus applied frequently?"

Why Ask This Question?

Most consumers believe (erroneously) that organic crops are not sprayed with any pesticides at all.  That is not true, and the criterion for what can be sprayed on organic has nothing to do with relative risk - it is simply based on whether the pesticide is deemed "natural."  Knowing what is actually sprayed on organic crops, I was particularly interested in the copper-based fungicides because they are rather toxic by modern standards, and about Bt, protein insecticides because it would be helpful to calm people freaked out about Bt-biotech crops to be able to compare the exposure to this ultra-safe material when they probably consume farm more that is sprayed on crops vs when it is expressed by the crop.

Unfortunately, I learned that this new testing program is only there to encourage compliance with the organic rules, not to document anything about relative residue levels.  There will be no testing for organically approved pesticides.  In fact there won't be any public data-base generated and the sampling will be at the discretion of certifiers - not random.

This leaves us with the same situation we have had for a long time.  Organic advocates and marketers make regular claims about the advantage of organic with regard to pesticide residues, and yet there is no actual data to support that claim - at least not for the US.

But Didn't That Stanford Study Compare Residues?

Remember the recent "Stanford Meta-Study" comparing organic and conventional that stirred so much controversy?  They found lots of studies about nutrient content, but in their extensive search of the scientific literature they were only able to find 9 studies that compared pesticide residues in organic and conventional.  Only one of those was even from the US and it was from the mid 1990s.  It was based on a testing program at USDA called the PDP (Pesticide Detection Program).  While that group does an excellent job of monitoring pesticide residues on conventional crops, it has never looked for the pesticides most likely to be found as residues on organic - things like copper salts.  So even that one study that the Stanford group cited for the US was not a meaningful piece of data for residue comparison.  So much for the scientific literature as a source on this question.

Why Doesn't the PDP Test For Copper, Bt, Biologicals Etc?

I contacted the USDA scientists who run the PDP to ask why they don't test for things like Copper fungicides, Bts or other biologicals.  The answer was quite practical.  They use something called multi-residues methods (MRMs) with which it is possible to simultaneously test for 2-300 different synthetic pesticides in a single analysis run.  However, because of solubility issues and detection technology differences, many organic-approved pesticides cannot be extracted or measured by the same protocol.  To do the testing for these individual categories of pesticides would be far too expensive for the budget of that agency.  The random sampling method of PDP is also not well suited to getting enough organic samples for comparison.

Can We Compare Residues?  No.

So, here is where we stand on the question of pesticide residues on food.  The conventional supply is rigorously tested for the main products they intentionally apply as well as for any off-label or environmentally persistent products left over from the bad old days.  We get a data set every year which essentially says that there isn't anything to keep consumers from confidently buying that food.  The organic food supply is going to be tested to some degree for the first time, but we won't see any real summary of that data nor will we be able to compare it to conventional.  We also know that there won't be any data generated about the pesticide residues most likely to be present on organic.

Do We Know Anything About Pesticide Residues On Organic Crops?

There was a relatively small, but high quality pilot study conducted by the USDA as background for their new testing regime.  The authors were careful to point out the multiple reasons that their data is not really comparable to PDP (limited number of crops, smaller sample size not collected in the same fashion, fewer chemical tests conducted...).  What they did find was that there were definitely some synthetic pesticide residues detected on organic crops - mostly consistent with spray drift, accidental contact in packing houses, persistent environmental pollutants....  The levels they found were not problematic from a safety point of view, but that is just as true for the PDP testing of conventional crops.  This pilot program was like the PDP in that it used MRMs and so it didn't test for the majority of organic pesticides.   So, bottom line, we still have no real data about the most likely pesticide residues that occur on organic crops and we are unlikely to get any.

What Would Happen If We Could Get Information About Organic Residue Status?

If organic were subjected to the same level of random and comprehensive testing that is used for conventional, and if all its pesticides were included, it would almost certainly come out "dirty" by the absurd and irresponsible methodology employed by the Environmental Working Group to create its annual "dirty dozen list".  They just count detections without regard to the nature of the chemical in question or its concentration or its EPA tolerance.  If there ever were a comparable pesticide residue database for organic it would force a far more scientific discussion of which residues matter and which do not.  My guess is that both conventional and organic would come out as just fine for consumers to eat, but the "organic advantage" would disappear when both types of food had to be compared using scientifically sound assessments.

Bottom line.  Just eat your fruits and vegetables and whole grains.... enjoy them!

You are welcome to comment here, and/or to write me at

Organic produce image from Pculter's Photostream

Sunday, November 4, 2012

What Would A Real "Right To Know" About Food Look Like? Not CA Prop 37

If California Proposition 37 is really about a "Consumer Right To Know," then why is it talking about a few words in a tiny font on the back of a package?  Why are we only talking about one question (GMO or not) when there are so many more issues people could care about? Why are we talking about something that only involves selected types of food in only one state?  None of this sounds like a sincere or even rational way to let people "know" something about their food.  It also sounds so "last century!"

Why Accept Minimal Information?

The "information age" is unfortunately also the "disinformation age."  There are a host of sources out there saying all sorts of negative things about genetically engineered crops - things which are clearly at odds with the scientific consensus around the world.  In many cases the entities behind these critiques have much to gain in product sales or fundraising is consumers can be frightened about GMO foods.  That is certainly the case for many sponsors of Proposition 37.  A few words on a package is a very poor way for a consumer to come to "know" anything except what these entities want them to "know," which is "be afraid and buy what I'm selling instead."

In the internet, smart-phone age there would be so much better ways to allow people to actually get some knowledge about their food.  Most products have a bar code, a PLU sticker, or some other way to link to data.  Consumers could have an "app" or their mobile device that uses that code to take them to a wealth of product-specific information that could be accompanied with the background or perspective to move from some isolated factoid to actual "knowledge."  Alternatively, consumers could access the information on a computer or even on a terminal provided by the store.  The key is setting up an authoritative, current, user-friendly and independently verified place to go find reliable, unbiased information.

Who Should Do This?

I think this would be best run by a non-governmental, not for profit entity with no economic ties to food companies, biotech companies, anti-technology organizations, organic marketers.  It should have a transparent list of highly qualified technical advisors from academia.  It should have a group of communication experts who really understand how to present technical topics for a broad audience.  It should have advisors from the farming community and the commodity system who can tell those communicators how things really work in the largely unfamiliar realm of agriculture. It should have some seriously tech savvy people to set up the site(s).  Thought needs to be put into how to fund this because it is fair that the food and biotech industry help foot the bill, but in a way that does not give room for even suspicion of conflict of interest.  It may be that charitable sources can also be tapped.  If all the money spent on the Prop. 37 battle could have been used for this it could have been funded for years.

What Information Should Be Available?

The first thing that could be done is to make a very easy way for people to know whether any given crop does or does not even have commercial GMO varieties that could ever end up in the store.  Anti-GMO sites usually use graphics of crops which never have been and in most cases will probably never be GMO.  For instance, very few crops in the fresh produce arena are GMO.   This list could easily be maintained by for the "right to know' site with help from the USDA.

For crops that have been improved using transgenic methods, there should be an easy way to see what the traits are, how they work, why they are useful to farmers, what advantages they may have for consumers.  For each one there should be a balanced presentation of the issues that have been raised from a health or environment perspective and what data has been generated and reviewed to evaluate them.  This information is not something new, but it would be an advance to get it all into one place with independent credentials and easy access.  There should also be a clear description of the food ingredients that are most likely to include supplies from GMO plantings and how to recognize those on a label.

Finally, there should be a way to get information on a product-by-product basis using bar codes or other identifiers.  The information presented should probably be voluntary on the part of the company responsible for making the product, but it would also go through an independent review.

Examples Of What People Could Know

Lets consider some examples of how this system could help consumers actually know things about their food.  Lets say you want to buy some corn tortilla chips.  Corn is a crop which is mostly GMO since the 1990s.  Most of this crop is used for animal feed or for ethanol production.  A relatively small part of it goes into food ingredients like corn starch, corn meal, high fructose corn syrup an other things.  A very small part of the total corn crop is used for making corn tortillas and tortilla chips.

One manufacturer of tortilla chips might say that they contract for special corn hybrids that are particularly well suited to chip making, and they decided to use non-GMO versions of those because they thought there was a customer base that would be willing to pay a bit more for that.  Another manufacturer might say that they intentionally use corn from the normal, mostly GMO supply because that corn is less likely to have mycotoxins like Fumonisin which is related to the sort of insect damage which Bt corn prevents.  The informed consumer could then decide which chips they want to buy.

Or consider soybean oil.  A food manufacturer or restaurant may say that they have specifically chosen to use the high oleic acid soybean products that have been developed using biotechnology.  This is a more functional oil for many foods and also a healthier oil because it is a solution for avoiding trans-fats.   The manufacturer could also say that since these and other GMO soybeans are herbicide tolerant, it makes it easier for farmers to use "no-till" farming techniques which are better for the environment in many ways.  Another manufacturer may explain that they use US, GMO soybean products because they do not feel confident in the non-GMO soybean-based ingredients on the market which may come from places like China.

The independent entity would summarize the safety assessments of each trait by expert panels around the world and that information would be linked from the product-specific site so that a curious consumer could see what is known on that front.

A system like this would actually allow consumers the opportunity to know about their food in a meaningful way.  Proposition 37 would not accomplish that goal.

You are welcome to comment here and/or email me at
No on 37 Logo from

Sunday, October 28, 2012

USDA Organic Crops: New Data Shows No Net Growth 2008-11

Organic is often described as the "fastest growing segment of the food supply." Recent data fails to support that claim.  The USDA recently released its second major survey of the US organic farming industry with data from 2011.  The obvious question was "what has changed in the three years since the last big survey in 2008?"  The answers are somewhat surprising (see graph above and description below):

Farms: The number of farms growing most organic crops has dropped by 20-30% for most crops (not graphed)

Acres: Although the crop mix has changed, the total acres of USDA organic crops is only slightly up for fruit and somewhat down for other categories (nuts, vegetables, row crops)

Yields: The average yields for organic crop categories other than nuts are slightly up

Production: The actual production of organic crops in pounds is down for all but fruits which are up slightly

Price: The price of organic crops has risen rather significantly for all but row crops
There was too much incomparable data between the two surveys for hay and silage crops, so the following analysis focuses on human-oriented crops like fruits, vegetables, nuts and row crops like cereals and oilseeds.

Why Fewer Farms?

The fact that farms and acres are down while yields are up for many crops suggests that there has been some shifting of production to the more successful operations.  I plan to look at the state-by-state detail on this in the future.

Acreage Changes

The table below lists some of the organic crops that have seen the largest absolute or relative acreage increases in the last three years:

Nearly 5,000 acres of organic table grapes were added which was an 18% increase.  The 1000+ acre increase in blueberries by 2011 was a 60% increase over the 2008 level.  Other crops with large increases included sweet corn, broccoli, squash walnuts, flaxseed, dry beans and sunflower seed.

While there were some increases, there were also many crops for which the acreage dropped significantly over this time span (see table below).

Apples, tomatoes, lettuce, peanuts and both spring and winter wheat were the organic crops with the largest acreage loss.  For fruit crops overall, the acreage change was a net zero.  For nuts, vegetables and row crops, the net change for the category was negative.  For all these crops combined, USDA Certified Organic Acreage declined by 68,000 acres over these three years.  This is in stark contrast to the historical trends.  Between 1995 and 2008 the average increase had been 144,000 acres/year.  Arguably this could be the result of the major recession, but as we will see later, price increases in the same time frame do not fit that hypothesis.

Production (actual pounds)

With changes in farms acres and average yields, the key question is what happened to the total production of organic crops that could then flow to consumers?  Once again this is a mixed story.  Some crops have seen significant increases in production (see table below).

Crops like grapes, oranges, peaches, sweet corn, carrots, squash, rice and winter wheat all saw increases of over 20 million pounds over the three years.  Many of these increases were dramatic on a percentage basis.  However, there were also many crops that saw dramatic decreases in production (see table below).

Organic apples declined by nearly 190 million pounds.  Tomatoes, Lettuce, and Corn also showed major declines.  Overall, for all the categories combined, there were 7.3 million less pounds of organic foods in 2011 than in 2008.

Imports, which were not captured in this survey, also contributed to the supply of organic foods available to US consumers from 2008 to 2011.   For some vegetables and fruits, there were likely major supplies from Mexico and other sources.  For grains, any increase in supply likely comes from much more distant origins.  These including countries for which many observers have doubts about the credibility of the certification system.

Prices: What Do These Crops Cost?

Moving from 2008 to 2011, the prices per pound that organic farmers received were higher, often significantly higher.  These changes do not correlate well with production changes, nor do they fit the scenario that recession-driven limits on consumer demand had much effect on prices for organic in market.  Most fruit crops saw price increases over these three years, and even more vegetable crops did as well (see table below)

All nut crops realized price increases including peanuts which saw a major overall production drop and almonds which saw a production gain (see table below).

The only real losing category for organic crop prices over these three years was row crops (see particularly spring and winter wheat in the table above).  Again, these crops are much more subject to long-distance competition from places like China and India.  During these three years, conventional row crop farmers in the US saw significant commodity price increases, but the organic producers did not.

Any Big Conclusions?

Considering the major, crop-to-crop differences, I'm reluctant to draw too many big conclusions at this point.  All that is clear is that there has not been much if any overall growth in the US, Certified Organic crop sector over the last three years except in terms of cost.  I will be sending this analysis to many contacts who are knowledgeable about the organic sector and I hope to get some perspective from them and from readers of this post on the various sites where this is posted.   There are almost surely crop-by-crop and region-by-region stories behind what can be seen from these data.  If you know some of those stories I hope you will either share them in the comments here or via email at

Comments on the Form of the Data
(This section is for data wonks.  Read on if you are interested in this detail)

There has been very little if any comprehensive coverage of this new survey in the mainstream press or even in the pro-organic blogosphere.  I'm guessing that this is because it is pretty hard to do the analysis.  I'm not saying that the USDA has intentionally made this difficult to do, but if they wanted to make it difficult, their presentation would have been a good strategy.

First of all, there was a big difference between the two surveys.  In 2008 it included both USDA Certified and USDA Exempt Organic farms.  The latter is a category for farms with less than $5,000 in annual sales which don't have to go through a formal certification process and which can only use the label "Organic" not "USDA Organic."  In 2011, only the USDA Certified Organic farms were included.  Fortunately, the 2008 data has tables breaking out the data that way (tables 23 to 26 at this link).

The data set is designed for PDF format, so even though there are CSV versions that can be opened in Excel, the set-up of the tables requires work to put it in a form that can be conveniently compared between the years.  Also there are unit changes for some crops between the years (e.g. hundred weights vs tons).  For this analysis I converted everything to pounds, but I'd like to have someone check the math.

Particularly at the state level, many data cells are marked "(D)" meaning that the number of farms is too small to show the data because it would give away too much detail about specific operations.  Thus, for instance, organic cotton production dropped by 60% between 2008 and 2011, but the data for value and number of farms was not given.   Similarly, barley production data was not published.

The ups and downs of the organic commodities do not seem to correlate with those for the total crop in these two years (2008 and 2011).

Monday, October 22, 2012

Can the Damage from Agenda-driven Junk Science be Undone?

Unfortunately, junk science can be generated by people with agendas, and the editorial process does not always prevent it from getting the undeserved legitimacy of publication.  In extreme cases the legitimate scientific community responds, but can it undo the damage?  Recently a group of scientists led by Gilles-Eric Seralini of the University of Caen published a feeding study which purported to find tumorigenic effects of GMO corn and glyphosate. It was so blatantly flawed in design and interpretation that it elicited a rapid and overwhelmingly negative response.  

The Scientific Community Responds

In an unprecedented move, the French academies of agriculture, medicine, pharmacy, science, technology and veterinary studies released a joint statement calling the Seralini paper a "scientific non-event" and the overall assessment that:  

"This work does not enable any reliable conclusion to be drawn."   

This follows a similar critique by the German, Federal Institute for Risk Assessment (BfR) which concluded:

"The study shows both shortcomings in study design and in the presentation of the collected data.  This means that the conclusions drawn by the authors are not supported by the available data."  

This sort of rapid rejection by such an agency was also unusual.  Today, ANSES, the French agency responsible for risk assessments with biotech crops, published an opinion that: 

"The study's central weakness lies in the fact that the conclusions advanced by the authors are not sufficiently supported by the data published."  

While these statements are in the civil and precise tone of scientific communication, they amount to as much of a "smack down" as is possible from the restrained, academic and regulatory communities.  The currency of respect in the scientific community is solid data from objective, well designed, well executed, and properly interpreted experiments.  The "Seralini study" met none of those standards and should rightly be ignored by the broader society unless someday confirmed by more objective research.  Unfortunately, that is not a likely scenario.  

How This Controversy Will Play in the Anti-Science World

It is far more probable that this "cancer link" will become another permanent entry in the lexicon of anti-GMO "evidence."   It will join toxic lectins-in-potatoes, Monarch butterfly toxicity, and Indian farmer suicides as endlessly repeated, mythic narratives in the echo-chambers of groups and publications which oppose crop biotechnology.  It matters little how much good, respectable research has been published to document the safety of biotech crops, such as review of 12, independent, long-term feeding studiespublished in the same Journal as the Seralini study just this April.  It matters little how many major scientific bodies conclude that biotech crops are safe.  To those who have bought into the conspiracy thinking, this will stand as irrefutable evidence that they have always been right to oppose this technology.  All criticism of the Seralini study will be written off as part of the grand, profit-driven conspiracy to kill everyone with GMO crops.

The Real Fallout From Fear-Mongering

It would be bad enough if something like the Seralini study simply contributed to the unnecessary angst amongst consumers around the world.  It also has very real political, economic and practical effects.  For instance brand conscious food companies have used their leverage to prevent the development of GMO versions of potatoes, bananas, coffee and other crops because they fear controversey.  Apple growers worried about the market response are opposing the introduction of a non-browning apple even though it was developed by one of their own fruit companies.  French activists destroyed a government-run field trial of a virus-resistant root stock which could have made it possible to produce good wine on sites that have become useless because of contamination with sting nematodes and the virus they vector.  California voters have the potential to pass a seriously flawed "GMO labeling" initiative next month that could only serve the purposes of the lawyers and "natural products" marketers who created it.  More importantly, European and Japanese importers of wheat essentially blackmailed the North American wheat producers into blocking biotech wheat development because those companies were nervous about consumer response in countries where GMO angst is so high.  This has delayed by decades not only specific desirable trait development, but also what might have been an enormous private investment in a crop that is critically important for feeding a lot more people than just those in those rich countries.  There is a huge cost of "precaution" based on poor science.

You are welcome to comment here and/or to write me at

Trash can image from Montgomery Cty Division of Solid Waste Services

Monday, October 8, 2012

When Increased Pesticide Use Is A Good Thing

recent study published in Environmental Sciences Europe has attracted attention because it documents a net increase in pesticide use on genetically engineered crops in the US.  The author, Chuck Benbrook, is certainly qualified to consider pesticide issues, and I have had positive interactions with him over the years; however as an organic advocate he has a very different perspective on pesticides than I do.  Chuck is certainly not alone in his assumption that pesticide use is,  by definition, something undesirable.  That is an assumption that deserves to be challenged.  There are some patterns of pesticide use that are problematic, but there are many more in which the pesticide serves a positive purpose that far outweighs any associated risks.

Why Even Bt Crops Were About Alternative Pesticide Use, Not "Reduced" Pesticide Use

Throughout the history of biotechnology in agriculture, I have been uncomfortable with the way that many of its advocates claim that "reduced pesticide use" is one of the primary arguments for the use of the technology.  First of all, even the Bt crops which even Benbrook credits for reduced foliar sprays (Bt cotton and European Corn Borer resistant corn) were not actually about eliminating pesticide uses - they were about delivering a different kind of pesticide efficiently via the plant itself.  In fact in the Western Corn Belt, the introduction of Bt corn lead to yield increases because much of this new "pesticide use" via the seed was on acres which were normally untreated in the past.  The various caterpillar pests of corn and cotton are real challenges for crop production and they are not going to go away.  Pesticides, whether delivered via chemical applications or plant expression, are good and useful tools because they preserve yield and thus increase the efficiency of all the other inputs to the crop (land, water, fuel, fertilizer, labor...).  

Some Perspective On Scary Sounding Big Numbers

It is an unfortunate reality that most people don't know how to think about very large or very small numbers.  The gleeful interpreters of Benbrook's study from the Food Movement (e.g. Tom Laskawy at Grist) leap on evidence of an impressive sounding number of increased pounds of pesticides used on biotech crops. 404 million pounds sounds like something huge, but not when put into the perspective of the area involved.   This 404 million pound figure is Benbrook's overall estimated increase on the hundreds of millions of acres of biotech crops over the 15 year period between 1996 and 2011.  That works out to something like four ounces per crop acre per year. Even if it were four times that value, it would represent 0.00002 pounds per square foot.  Just for additional perspective, an organic vegetable crop might easily be treated with several copper fungicide applications at the rate of six pounds/acre each season.  

When It Comes To Pesticides, There Are Pounds And There Are Pounds

To his credit, Chuck Benbrook points out that "in light of its generally favorable environmental and toxicological properties, especially compared to some of the herbicides displaced by glyphosate, the dramatic increase in glyphosate use has likely not markedly increased human health risk."  Benbrook knows what many people do not, which is that pesticides differ from one and other by orders of magnitude in terms of their various toxic properties to us and to non-target organisms.  Thus, any time that one hears about an increase or decrease in pesticide use, it is crucial to ask what chemistries are involved.  For instance, the biotech corn hybrids that have been introduced with resistance to Corn root worm (actually a beetle) have been a plant-delivered pesticide alternative that reduced the need for some older organophosphate chemicals which are more problematic than most modern insecticides.  For resistance management purposes and for secondary pests, there is actually the need for increased use some alternative soil insecticides or seed treatments.  Once again, the constant goal is to adequately control economically important pests, and over time to do so with lower and lower risk options.

Why Increased Herbicide Use Can Be A Very Good Thing

When it comes to herbicides, increased "pesticide use" can be a very good thing from an environmental perspective.  In the early eighteenth century, an English agronomist named Jethro Tull began promoting "horse hoe husbandry" which was essentially the innovation of planting crops in neat rows and using mechanical devices like plows and harrows to control the weeds growing in between.  It revolutionized agriculture, but also put farming on a track towards serious environmental impact.  Plowed soils are susceptible to erosion which leads to declining soil quality, sedimentation of waterways, and ultimately to movement of soil-associated fertilizer and pesticide residues into surface water.  In later, mechanized agriculture, plowing was also associated with significant fuel usage. Probably the single most important advance for sustainable farming has been the elimination of plowing and other soil disturbances which is achieved through methods such as "no-till farming."  The introduction of herbicides in the 1960s, farmers, equipment companies and chemical companies began to develop ways to grow crops without tillage (no-till).   Herbicide tolerant crops greatly enhanced farmer's ability to adopt these methods since the mid 1990s.  This is clearly a case where "more pesticides" means a better environmental outcome.  This is exactly what is going on as an result of the increase that Benbrook documents.  It is a good thing and a positive result of biotechnology.

Benbrook Is Almost Certainly Underestimating The Increased Pesticide Use On US Row Crops

The USDA pesticide use reporting, on which Benbrook relied for much of his analysis, ended during the Bush administration around 2006.  This is unfortunate because it failed to capture a substantial increase in pesticide use that has occurred in response to the unprecedented increase in agricultural commodity prices since 2007/8.  US row crop agriculture has always been a relatively low-use chemical market from an agricultural chemical perspective.  For the big US crops like corn and soybeans, there have historically been very few sprays of insecticides or fungicides.  US and Canadian wheat production involved even fewer.  In Europe, between high yield potential, crop subsidies, and wet weather, pesticide use is vastly higher on wheat and other crops than in the dominant US row crops.  However, in recent years as corn, soy and wheat prices have risen to levels several times higher than in the past, American farmers have been able to economically justify in-season sprays of fungicides and insecticides to prevent pest-related losses that would have simply been tolerated in the past.  The chemicals that they are using for these sprays are in the "not scary" category, and thus their usage is a good thing for the critical role that the US and Canada play in the global food supply.

To reiterate, pesticide use or its increase are not automatically undesirable things.  It depends on what is the alternative and what is the nature of the particular pesticide in question.  Plant biotechnology is just one important tool in the bigger tool box of agriculture.  Sometimes it allows farmers to use a more attractive pesticide option (Bt Sweet Corn would the be best example of this).  Sometimes it helps them with the adoption of sustainable practices that depend on relatively low risk herbicides.  For farmers, biotechnology and pesticides are not an either/or.  They are often partners.

Sprayer image from the USDA
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Sunday, September 23, 2012

Pesticides: Probably Less Scary Than You Imagine

 The word "pesticide" conjures up negative, scary images. These images come from old organophosphate insecticides of the 1960s that killed fish and birds and caused farm worker illness.  These are sorely outdated images. What most people don't know is how much safer the new generations of pesticides are.  In fact, scores of old materials have been withdrawn from the market or banned long ago.  The new products are mostly compounds with extremely low mammalian toxicity and benign environmental profiles.  Today's pesticides are not your grandfather's or even your father's pesticides. Fortunately, you don't have to take my word for this.  There are some excellent sources of public data on this topic. These  products emerged from an on-going chemical discovery effort involving billions of dollars of investment over decades.  

Pesticides From A Consumer Perspective

One source of information about pesticides is a huge, annual sampling and testing exercise that the USDA carries out to look at what pesticide residues can be found in the food supply.  I have previously posted an analysis of that that data set from 2010 (latest available).  It shows that the residues that can be detected on US foods are at such low levels relative to conservative tolerances, there is no reason for US consumers to worry about them.  

What Sort of Pesticides Are Farmers Using Today?

When a recent, Stanford, meta-study cast doubt on the nutritional advantage of organic foods, some consumers stated that it is still worth it to buy organic because it doesn't have pesticides.   Many, perhaps most, consumers believe that organic means "no pesticides." This is simply not true - though it is a convenient fiction for some marketers and advocates. There are many pesticides that are allowed to be used on organic crops.   

One of the best ways to look at what is being used in both conventional and organic farming is to look at the extensive and transparent, California Pesticide Information Portal (CalPip).  California has a tremendous diversity of crops and also a very large share of the organic market.  It is a source for data which comes from mandatory reporting of all commercial pesticide use in the state.  CalPip posted two lists of the top 100 pesticides used - one based on total pounds applied and one based on the total number of acres treated.  I created a list that combined the two without the surfactants or other spray additives.  That left 104 materials.  I then looked up the publicly available, MSDS documents (Material Safety Data Sheets) to get the acute toxicity (oral ALD50) for each of the products (see graph below).  

The EPA defines a range of toxicity categories from I to IV, with IV being the least toxic (essentially non-toxic to mammals, but their terminology is classic regulatory-cautious).  On a weight basis, the largest share of pesticides used in California in 2010 fall into the least toxic category (62%).  The blue part of the bar includes products which allowed for both organic and conventional farms.  
About 1/3 of all the pesticides used in California in 2010 fall into the "slightly toxic" or "moderately toxic" categories.  Note that there are organic products in these toxicity categories as well.  Most of the organic pesticides in categories II and II are copper salts (copper sulfate, copper hydroxide...).  These are old products which the EPA still allows with some restrictions because of copper's issues with toxicity to aquatic invertebrates and environmental persistence.  Conventional growers can control the same plant diseases that organic growers treat with coppers using various category IV products which are less toxic which have benign environmental profiles.   Why would organic growers use pesticides with somewhat more risk issues than conventional?  Because the criterion for organic approval has nothing to do with safety as such.  It is all about whether it meets a certain definition of "natural."   As we will see later, categories II an III are not all that scary, but it is worth noting that organic does not automatically mean better from a pesticide perspective.
Note that only 0.2% of the commonly used chemicals in California fall into the "Highly Toxic" category, and those are used under strict limits to prevent any form of unwanted exposure.  Just for interest sake, however, Vitamin D3 would fall into this category if it were a pesticide.

How Toxic Are These Different Categories?

It is not that easy for most people to relate to these EPA category descriptions, so it is useful to make comparisons between pesticides and familiar chemicals in foods and pharmaceuticals (see graph below).

Vitamin C is something which many people take in large, 250-1000 mg doses on a regular basis.  Fifty-five percent (55%) of the pesticides used in California in 2010 were less toxic than Vitamin C. Sixty-four percents (64%) were less toxic than vitamin A.  Seventy-one percent (71%) were less toxic than the vanillin in ice cream or lattes. Seventy-six percent (76%) of the pesticides were less toxic than prozac and 89% were less toxic than the ibuprofen in products like Advil.  Ninety-seven percent (97%) of California pesticide use in 2010 was with products that are less toxic than the caffeine in our daily coffee, the aspirin many take regularly, or the capsaicin in hot sauces or curries.  This is not the sort of image that most people visualize when they hear the word "pesticides."

Of course, acute oral toxicity is only one of many dimensions of the EPA risk assessment that is behind all product registrations and reviews.  That is why, from a consumer health point of view, the comparison of residue levels to a tolerance is the most appropriate statistic by which to judge consumer safety (it factors in various forms of chronic exposure and the nature of the crop itself..).   People are also concerned about combinations of chemicals, but our diets contain more complex combinations of natural plant-made chemicals at much higher concentrations.   The beneficial aspects of eating things like fresh produce far outweigh any concerns about the pesticide residues that are in either organic or conventional foods.

What About Farm Workers or the Environment?

The people who tend our crops are certainly exposed to pesticides far more than any consumer.  What about them?  If one looks at the data for exposure via skin or breathing, a similar pattern emerges to that for oral toxicity - modern chemistries are low in hazard and thus in risk.  There are also label restrictions that prevent workers from being exposed to the more hazardous materials (e.g. what protective clothing is required and how long after a spray before anyone can re-enter the field).  All the registered pesticides are also extensively studied in terms of their effects on "non-target" organisms and their environmental fate.  The rules for how any given pesticide can be used (the label requirements) factor in worker and environmental risk.  Once again, the sort of issues that were common in the 1960s are not at all reflective of the modern situation.  Some organically approved pesticides have their own worker and environmental issues which are also mitigated by the same sorts of EPA label restrictions.

Are Pesticides Really Needed Anyway?

Yes, they certainly are.  Farmers use many other methods than pesticides to control pests (I'll be writing about that soon), but without pesticides our farms would be far less efficient in terms of resource-use-efficiency (land, water, fuel, fertilizers, labor).  That is why both organic and conventional farmers often need to use pesticides.  Again, the organic pesticide list was not created based on its risk profile, so there are many cases where the conventional options are as low or lower in risk than the organic option.  

So, overall, the “its all about pesticides” argument for buying organic is not compelling in a modern time-frame.  If someone wants to spend the extra money for organic, that is their choice. Someone who does not want to by organic should feel neither guilt nor fear about that decision.  It is a choice that is well supported by the science.

Spraying image from the USDA-ARS.  Graphs by Steve Savage based on CalPip Data.  I'm also happy to share my data files with those that are interested.  You are welcome to comment here and/or to write me at

Sunday, September 9, 2012

Do You Really Need to Buy Organic Foods To Avoid Pesticide Residues?

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.

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).

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 (see graph above).   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."

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, may be a reduction in fresh fruit and vegetables consumption (see graph below).   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?  A study by the Hartman group found that some consumers said they reduced their produce purchases specifically because of the "dirty dozen list."  The question needs more research.

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  Graphs are based on USDA-AMS pesticide data and USDA-ERS produce trend data.