Do You Really Need to Worry About Pesticides on Your Kale?

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Bundle of Kale (Wikimedia commons)

Last week the Environmental Working Group (EWG) published its annual “Dirty Dozen List” and highlighted Kale near the top of it’s list of foods with “pesticide residue contamination.” They want you to buy your Kale as Organic.  EWG claims to base that recommendation on data from the USDA’s Pesticide Data Program (PDP), but a closer look at the actual data suggests a far different conclusion – that the Kale in our food supply is quite safe and that there is not the big difference between organic and conventional that they imply.

Since EWG gets much of its funding from large organic marketers, it is not surprising that their recommendation is to buy organic, but the 2017 PDP testing included 67 samples that were labeled as USDA organic (13% of the total for Kale).  Many of those organic samples had detectable residues representing 31 different chemicals, only one of which is approved for use on organic crops (Spinosad).

Now the levels at which chemicals were detected on the organic were very low and of no health concern based on the very conservative “tolerances” set by the EPA through its extensive risk assessment process.  However, the same can be said for the 455 conventional Kale samples tested the same year of.  The residues we are talking about here are hundreds to thousands of times below the relevant tolerance (see graph below).

In theory there wouldn’t be any synthetic residues on organic, but the USDA’s certification rule allows for “inadvertent” presence of synthetics at 5% or less of the EPA tolerance. (There is a separate USDA-Organic compliance testing program that looks for residues, and in that case the 5% rule applies).  98.9% of the 2017 PDP detections for organic Kale samples would meet that standard, but so do 98.1% of the residues on conventional samples.  Not so different, eh? In the graph above, only the red part of each bar would be a technical violation of the organic rules and none of the Kale detections for either conventional or organic exceeded the tolerance. Note that neither category is actually “dirty” based on a rational, scientific assessment.

Now, there were about three times as many residues/sample found on the conventional Kale, but the USDA does not even test for a great many of the pesticides that are approved for and regularly used on organic.  This would include “natural products” such as mineral-based materials (e.g. sulfur or copper compounds), petroleum oils, plant extracts, and biologicals).  Those sorts of products make up a substantial part of what gets applied to Kale. Thus, pesticides which are not part of the PDP testing make up 65% of the total pounds of crop protection agents applied to kale and 44% of the treatment acres (see graph below from the most recent available year of California use data).  Approval for organic is entirely based on what is considered to be “natural” and the USDA is quite clear that the classification is not about relative safety.

The acreage of Organic Kale has been increasing over the last 15 years and with it the use of the organic-allowed pesticides.  (See the example of sulfur use on Kale as linked to organic acreage in the graph below).

If the USDA tested for residues the natural product pesticides, the number of “detections” for organic samples would certainly increase. But as with the synthetics, the results would most likely indicate that this is a perfectly safe vegetable to consume whether or not it is organic.  Bottom line, the wisest thing for consumers to do is to ignore the fear-mongering of the EWG and simply enjoy a healthy diet including lots of this and other fruits and vegetables.

Inconvenient Truth: There Are Pesticide Residues On Organic

(Originally posted on Forbes 2/8/16)

A recent review article in the scientific journal Nature Plants makes the claim that organic produces "foods that contain less (or no) pesticide residues, compared with conventional farming."  That's not what the latest USDA-PDP (Pesticide Data Program) information about pesticide residues says. What that transparent source of tax payer-supported research indicates is that 40 different synthetic pesticide residues were detected on organic food samples at levels similar to what was seen for the comparable conventional food samples. In both cases the amounts are too small to be a health/safety concern, but this certainly does not fit the standard organic narrative.

Commodity breakdown of the food samples used
for pesticide residue testing in 2014

For the 2014 survey, USDA scientists collected just over 10,000 samples of 15 crops taken from ordinary retail food channels.  The scientists then used extremely sensitive laboratory methods to check for traces of hundreds of different chemicals.  409 of the samples were labeled as organic, and residues were detected in 87 of them.  Thus 21% of the organic samples had detectable residues representing 142 detections in 78 crop/chemical combinations.  That detection percent is lower than for conventional, but the PDP testing does not have the capacity to detect several of the most commonly used, organic-approved pesticides like sulfur, copper compounds, mineral oils or Bt.  Those materials can't be measured with the same technology used for the other chemicals, so the USDA has chosen not to test for them. If they did, the detection percentage for organic would be much higher.  One organic-approved pesticide that is measured by the USDA is called Spinosad, and it was detected on 13 organic crops as expected.  However, the other 40 of the 41 different pesticides detected on the organic foods were synthetic chemicals that are not approved for use on organic.

Finding synthetic pesticide residues on organic is not unprecedented.  Earlier, larger surveys of organic conducted by the USDA and by Canadian Food Inspection Agency found un-approved residues in at least 40% of samples.  The normal explanation of this is that it represents inadvertent spray drift or cross-contamination in harvesting bins etc.  Many of the detections are at such low levels they fit those scenarios, but interestingly when I looked at the conventional detections for the same 78 chemical/crop combinations, the organic detections were only significantly lower in 26 cases, and the organic detections were equal to or higher than those in conventional for 30 cases (see chart below).

Note how for many chemical/crop combinations the level
detected in organic was similar to or greater than
that in conventional samples

For organic advocates and organic marketers this sort of information leaves one of two possibilities.  They can agree with the EPA and other responsible agencies that consumers need not be concerned about the low-level pesticide residues found in either conventional and organic food.  Alternatively they could choose not to believe those authorities and be forced to conclude that organic food is unsafe.  For consumers the logical take-home message is that between our rigorous regulatory regime and our responsible farming communities, we can enjoy a safe, healthy diet full of fruits and vegetables without having to believe that safety is only available at a price premium.

There are several ways that you can review this information for yourself.  The USDA published a "what consumers need to know" document, a fact sheet, and a 230 page summary.  They also make the raw data available for download (as long as you are up for processing a 2.2 million row, 98MB table).  I like to take advantage of all that detailed, transparent data, and I will be publishing a more complete, independent analysis soon.

Twenty-three percent of the detections in organic were of old organochlorine or organophosphate insecticides or their metabolites (e.g. DDT, monocrotophos...). These are persistent environmental contaminants (they have been banned for decades). These chemicals are found in both organic and conventional samples at levels in the low part per billion range. This is an unfortunate artifact of pre-EPA history, but fortunately not a current health threat.  Three point five percent of the organic detections were for currently-used carbamate and organophosphate insecticides (Oxamyl, Carbaryl and Chlorpyrifos and Dimethoate), but all at levels well below current safety tolerances.  Seven point seven percent of detections were of neonicitinoid insecticides, and 9% were synthetic pyrethroids.  Other insecticides made up 3.5% of the detections.  Fifteen different fungicides represent 25% of the detections. There were detections of two different herbicides, 2 of a miticide and 3 of an insecticide synergist. Again, these detections are, for both organic and conventional, at levels too low to be of concern.  Indeed, what the the data demonstrates is how far below.
The reason that the USDA has been conducting its Pesticide Detection Program since 1991 is to monitor how well the system is working to insure that farmers can control damaging pests and still supply food that is safe for consumers.  What the data has consistently shown is that these goals are being met and that consumers can confidently enjoy a healthy diet rich in fruits and vegetables.

However, an organization called the Environmental Working Group has severely mis-used these data year after year to construct what they call their "dirty dozen list."  They are funded by many of the big players in the organic market (Organic Valley, Stonyfield Farms, Earthbound Farms, Applegate, Klean Kanteen, Dr. Bronner Soaps, Beauty Counter, Juice Beauty, Brown Advisory, Nature’s Path, Annie’s), and their goal is to frighten consumers away from conventional food and towards organic. The problem is that their non-scientific approach of simply counting detections regardless of the level or identity of the chemical would classify organic as "dirty" as well.  Consumers should simply ignore the disinformation that comes from EWG and consider not supporting the companies that fund them.

You are welcome to comment here and/or to email me at savage.sd@gmail.com

A Note To Rachel Carson On The 50th Anniversary Of “Silent Spring”

What looks like it might be an original copy from 1962

Dear Ms. Carson,

On this, the 50^th anniversary of the publication of your book, “Silent Spring” I’d like to tell you about the remarkable legacy of your book.  Many things have transpired over the last five decades that would give you considerable satisfaction. Unfortunately, I must also explain to you why many people today don’t understand how profound those changes have been.

Your Positive Legacy

The biggest change since 1962 has been in our societal appreciation of the need to carefully evaluate the environmental and health attributes of chemicals that we use for the control of agricultural pests or the vectors of human disease.  Whole new fields of science have developed to understand such risks (environmental toxicology, environmental science to name two).  Whole new regulatory bodies (Environmental Protection Agency, EPA) and processes (chemical registration) have been instituted to translate those risk assessments into sound policy.  DDT, which was central to your 1962 warning, is long-gone, as are scores of other, old pesticides that cannot meet high, modern, safety standards.  Billions of dollars have been invested in the discovery, testing, and introduction of new, low-risk pest control methods and practices. The net effect of all of this is that not only are our springs well-accompanied with bird songs, we also enjoy a safe, affordable and diverse food supply beyond anything one could have imagined in 1962.  I’m sure that when you took the risk of publishing your book, you hoped that it would initiate this sort of positive change, and that is certainly what has happened.

Your Legacy Obscured

Unfortunately, there are some today who seem to have a vested interest in convincing us that your legacy has not been this positive. Whether it is to sell certain products or to garner attention or contributions, these voices continue to promote a “sky is falling” narrative. When you wrote 'Silent Spring,' you employed highly emotive language, vivid mental images, and a good degree of hyperbole.  Such over-the-top prose was justifiable because you had to overcome the deep-seated complacency of your age. Today, many groups continue to employ that same literary style when talking about food and agriculture issues.  By doing so, and by engendering unnecessary fear among consumers, they effectively deny people the confident enjoyment of life and food that would otherwise have been another part of your legacy. I am confident that you hoped to initiate change, not to inaugurate a perennial state of alarm.

A Prime Example of Your Positive Legacy

Each year the USDA conducts an extensive sampling and testing program for the American food supply.  It essentially serves as a “report card” for agricultural pesticide safety, both in the US and in countries from which we import foods.  What the report clearly shows is that consumers have no need to be concerned about pesticide residues on their food.  The extremely low levels detected are virtually all well below even the conservative tolerances set by the EPA and mostly millions of times below toxic doses.  These results speak volumes about the positive impact of your book. 

A Prime Example of Your Positive Legacy Denied

There is an organization called the Environmental Working Group (EWG), which takes that same set of data and quite effectively uses it to frighten consumers.  They do so by ignoring almost all the actual information in the USDA report.  They ignore that differences between chemicals as if we had learned nothing about what to look for in 50 years.  They ignore the actual levels detected as if we have forgotten the ancient Greek understanding that "the dose makes the poison."  Finally, they ignore the carefully set EPA tolerances as if over all these years, we have learned nothing about how to evaluate risk.  Unfortunately, their message is widely disseminated by a credulous press and believed by a great many consumers.

Real Environmentalism

Your book is widely credited as a major contribution to the development of the modern Environmental Movement.  That is, indeed, a very positive result of your influence. A strong segment of that environmental movement continues to make significant contributions to society.  That part of the movement acknowledges that there has been positive change that you helped to initiate and to which many entities have contributed over the years.  The segment of the Environmental Movement that effectively denies positive change does no service to your legacy.

You are welcome to comment here and/or to email me at savage.sd@gmail.com

'Silent Spring' book image from Sterling College

A Curious Silence: The Environmental Working Group and Mycotoxins

The Environmental Working Group (EWG) tells us:

"The mission of the Environmental Working Group is to use the power of public information to protect public health and the environment."  

If you look at their website, a great deal of what they do involves warning people about various "toxic risks."  They publish an annual "dirty dozen" list ranking crops by pesticide residues.  They have a major effort to identify purported risks from chemicals in cosmetics and sunscreens.  They look at toxic things in drinking water and in pet food.  They have an extensive "Chemical Index" with toxicity ratings.  But there are some very important toxins about which EWG is completely silent.

The Missing Toxins

The extremely important class of toxic chemicals that is completely absent from the EWG website is Mycotoxins.  You can go to the search engine on the site and enter words like: mycotoxin, aflatoxin, fumonisin, ochratoxin, vomitoxin... and find absolutely nothing.  What makes this silence so strange is that mycotoxins are known to be some of the most dangerous substances to which people can be exposed, particularly in food.  If one of EWG's primary purposes is to "protect public health" it seems odd that they would not say one thing on their web site about this extremely well-documented risk.

Beth Hoffman, an information technology writer, raised an interesting issue today in an article in Forbes.  She was discussing the huge disparity between what government and academic scientists say about pesticide safety and what the Environmental Working Group says with its "Dirty Dozen" list.  She says, "But at its core, the argument for and against lists like the Dirty Dozen is a question of trust."

The EWG clearly distrusts the scientific/regulatory consensus.  But should consumers trust the EWG?

Should we trust an organization that either ignores or fails to recognize a real and present risk when they are telling us that there is significant risk where science says there is not?  EWG says it "provides practical information you can use to protect your family and community."  How can we trust that statement if EWG provides zero information about chemicals which are not in the "you just never know" category, but in the "clearly documented as toxic and carcinogenic" category?

What Are Mycotoxins?

Mycotoxins are potent, natural chemicals which are produced by certain fungi.  These fungi can, under various circumstances, grow on food and feed crops either while they are growing in the field, or later during the storage and/or drying of certain commodities.  The most important example is a toxin called aflatoxin which is produced by some strains of the fungi Aspergillus flavus and Aspergillus parasiticus.  These organisms can grow on things like peanuts, tree nuts, and corn.  It can also grow on hot chili's or figs while they are drying if that is done improperly.  It can occur in imported spices like nutmeg.  It has been found in imported chocolate.  It is thousands of times more toxic than most pesticides, and it is one of the most potent carcinogens known.  It is estimated that aflatoxin is the a major  cause of cancer deaths world wide.  Unfortunately, this mainly occurs in the third world, and even places like China are just now beginning  to address the issue.

Why Haven't Most People Heard of Aflatoxin or Other Mycotoxins

In the developed world, extraordinary efforts are made to keep food mycotoxin levels in general, and aflatoxin levels in particular, low enough to make our food safe.  The system works well enough that it does not come to the public attention very often.  This success is based on the same sort of science-based regulation and testing that are designed to insure that pesticide usage is safe.  The system of mycotoxin exclusion generally does a great job, but occasionally something slips through - mostly incidents involving pet foods or imported products from regions of the world that don't have adequate safety practices in place.

Just as an example, nut crops like peanuts and almonds can potentially become contaminated with aflatoxin, usually because of insect damage.  In our food system, the individual, shelled nuts that go into something like peanut butter or roasted almonds are put one-by-one through a light-based screening process to reject any individual nut with even the possibility of contamination.  Peanuts and other nuts sold in-the-shell cannot be screened to that degree.  EWG could instruct consumers to avoid in-the-shell nuts to protect their family. It has also been shown that eating green plants like spinach gives us chlorophyll which can bind aflatoxin in the gut so that it never gets into our blood stream.  EWG could recommend that one eats a salad with peanut butter sandwiches just to be safe.  EWG could talk about which imported foods might be most likely to have aflatoxin.  These examples would be practical guidance about real risks.  On such issues, the EWG has long been silent.   Contrast this with the proactive efforts by the Bill and Melinda Gates Foundation to address mycotoxin issues in the third world.  Yet this major oversight is not the only reason to distrust EWG.

A Serious Issues With the Way That EWG Does Its Analysis

An analogy might be helpful here.  Domesticated dogs come in a huge range of sizes from tiny Chihuahuas to huge Mastiffs.   They also come in a huge variety of personalities, from breeds which you could easily trust with a baby to those which have been bred for aggressiveness and which have been known to maim and kill people.  If anti-dog activists were to propose that any dog should be avoided and that people should move to towns that exclude all dogs, most people would dismiss the idea as ridiculous.  This is; however, directly analogous to what EWG does with pesticide residue data and their "solution" of buying organic.  The amounts of pesticides that the USDA finds on foods in its residue testing program can vary by 1000-fold or more - actually much more than the range of dog sizes.  The intrinsic properties of the different chemicals that are detected also differ even more than the differences between aggressiveness in breeds of dogs.  Yet what EWG does when it makes its dirty dozen list is to treat every residue detection the same.  This is just like our fictitious anti-dog activist who says that all dogs represent a equivalent risk, or that you just never know about any dog.  Why should anyone trust this method to analyze risk?

Beth, the Forbes writer, gives indications that she tends to distrust the scientific/regulatory consensus.  I wonder if she has thought about whether she should trust the EWG? Do you trust an organization uses a seriously over-simplified analysis of one category of chemicals while ignoring toxins of far greater concern?  Or might it make more sense to trust science backed up by government and academic scrutiny?

You can comment here and/or you are welcome to email me as savage.sd@gmail.com.

Aflatoxin contaminated groundnut image from IITA Image Library

How The USDA Unwittingly Aids EWG's Pesticide Disinformation Campaign

Each year, the Agricultural Marketing Service of the USDA (USDA-AMS) conducts an extensive sampling and analysis of items from the actual US food supply to determine what, if any, pesticide residues are present at the consumer level.  This information is published each year, and the actual raw data is also available for download.  The data for 2010 was just recently released.

What Does The Data Actually Tell Us?

For 2010, as for preceding years, the data demonstrates is that pesticide residues are only present at very low levels, usually dramatically below the conservative "tolerances" set during the risk analysis by the EPA.  This is quite remarkable considering that pesticide use on crops depends on many thousands of independent decisions by many thousands of individual farmers both in the US and in dozens of countries from which we import food.

This year the USDA provided several summaries in an effort to be clear about what they have found.  In this year's press release one finds the following, unambiguous statements:

The 2010 PDP report confirms that food does not pose a safety concern 

based upon pesticide residues.  

Statement from the EPA “The data confirms EPA’s success in phasing- out pesticides used in children’s food for safer pesticides and pest control techniques.  The very small amounts of pesticide residues found in the baby food samples were well below levels that are harmful to children.”  

Statement from FDA: "Based on the PDP data from this report, parents and 

caregivers can continue to feed infants their regular baby foods without being concerned about 

the possible presence of unlawful pesticide chemical residues." 

Statement from the USDA: "Age-old advice remains the same: eat more fruits and vegetables and wash them before you do so.  Health and nutrition experts encourage the consumption of fruits and vegetables in every meal as part of a healthy diet..."

Unambiguously positive assessments like this can also be found in the main data summary, the "What Consumers Should Know" highlights, and in the "Questions and Answers" link.

What Does The Press Tell Us?

As a typical example, CNN starts with the headline, "Watch out for the 2012 'Dirty Dozen," and continues, "Apples and celery are still agriculture's dirtiest pieces of produce according to the Environmental Working Groups annual "Dirty Dozen" report."  It's version of the baby food findings are, "For the first time this year, the USDA also collected data on pesticide residue in baby food, finding many of the studies samples to be contaminated with organophosphate pesticides."

How can CNN report something so radically different than what the USDA said?  They simply are repeating what the Environmental Working Group has said in its press release of 6/19 and make no effort to compare it with the official document.

HuffPost Healthy Living starts with the headline, "Dirty Dozen: EWG Reveals List of Pesticide-Heavy Fruits and Veggies."  Nowhere in this article is there even a reference to what the USDA, EPA and FDA said about the data.  It simply passes along the EWG interpretation as if it were gospel. 

This is the mainstream media.  You can well imagine what is said on various organic and Food Movement sites and blogs.

In contrast, Jon Hamilton writing for an NPR blog uses the headline, "Why you shouldn't panic about pesticide in produce."  Jon notes that the EWG sends a "mixed message," saying "you should be concerned about pesticide residues in fruits and vegetables, but not so concerned that you stop eating these foods."  Rather than simply parroting EWG, this writer demonstrates some journalistic mettle by interviewing a scientist at McGill University who can provide some perspective.  He also demonstrates that he read at least some of the USDA documentation by quoting specific numbers on apples and the non-alarm assessment for the baby food data.  Such efforts at balance are unfortunately rare.

Why Does The EWG's Version Get So Much Attention vs The USDA's?

Although sensationalism, low journalistic standards, and limited scientific background are certainly involved in the largely uncritical magnification of the EWG's message by the press (and particularly the blogosphere), I'm afraid that UDSA-AMS is partially to blame.  Don't get me wrong, they do a rigorous collection and analysis of the data.  They are extremely clear in what they conclude with sound reasoning.  They are definitely transparent and unbiased in their presentation.  What what USDA does not do is provide a summary version of the data that is easily digestible by ordinary readers, including typical members of the press.  EWG provides a simple list with a one dimensional ranking.  It is a gross and misleading simplification, but that makes it easy to relay as if it was a real analysis.  Unfortunately, the summaries that the USDA presents are extremely detailed, extremely long, and not easy to interpret even for someone who wants to.  Let me explain.

A Document That I Doubt Many People Really Read and Digest

The annual summary document for each year's PDP data is huge, in the range of 200 pages as a pdf (it is hard to tell, the appendices are numbered independently).  It starts with 28 pages of background on methodology and summary of sample types etc.  Then there are 9 pages of a historical appendix.  Finally the actual data begins in a 77 page appendix, but this is organized by chemical - nothing that most people would even begin to relate to.  For each chemical there is no information about whether that product is something toxic or not, nor is there information on any other dimension of its environmental profile.  To get that, someone would have to search for an MSDS and maybe an EPA RED - none of which are easy for any layman to interpret.  All this table lists are the number of samples, the number and percent of "detections,"  the range of those detections in PPM, the LOD (limit of detection), and the EPA tolerance (an extremely conservative level set by an elaborate risk analysis). Most people would have no idea what to do with those numbers.  In fact they show that the vast majority of "pesticide detections" are at levels well below the tolerances, but it is tedious to do the comparisons by eye and there is nothing in the table to give the message of how far below any level of concern the vast majority of samples are actually shown to be.  I'm not surprised that no independent journalistic interpretation of these data occur.

Below the chemical-by-chemical summary there are dozens of pages summarizing commodities other than fruits and vegetables.  That is followed by an appendix J which unhelpfully simply compares the "percent detections" for imported and domestic samples (a summary level as seriously unhelpful as that by the EWG).

Finally, at the very end of this huge document there is a crop-by-crop summary with the same data columns as for each chemical (#samples, #detections...) which has the same tedious requirement to compare detections and tolerance that are all usually numbers to several decimal points.  I have never seen anyone in the press do much if anything with this data set.

What Does This Report Need?

To be fair, USDA-AMS has amassed such a huge body of data.  It is difficult to summarize it in a way that is intuitively meaningful.  Their bottom line conclusion, "produce is safe," is a perfectly valid, but some visual representation could go a long way towards getting that message across.  I acknowledge that this is difficult.  I have made some attempts to do so in the past.  I plan to do so again with this year's data, but that will take time.  The same would be true for even an ambitious reporter, while simply reporting what the EWG says allows less ambitious reporters to keep up with the instant news cycle.

A Mountain of Data

It is a wonderful thing that the USDA makes the effort to analyze so many samples of so many crops and looks for so many different chemicals.  The downside is that this generates a database that is beyond what most of us even know how to process.  The file that one can download with the raw data has been getting bigger every year and has now reached 85MB.  I'm used to dealing with large files, but none of my ordinary software can deal this this.  I've gotten my son to write a program in RUBY to parse the data and only give me the tiny fraction which contains "detections" and discard the millions of rows of data that effectively say, "we didn't find this chemical in this sample."  I'm going to ask him to modify the program this year with some additional summaries.  

When and if I get this done, I plan to make this available to anyone interested in doing an actually meaningful analysis of the data and to explore ways to present it graphically in ways that can compete with the egregiously trivialized "analysis" done by EWG.  

You are welcome to comment here, and/or email me at savage.sd@gmail.com

Produce stand image from Steve Savage