Thursday, June 21, 2012

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

Aflatoxin contaminated groundnut image from IITA Image Library

Tuesday, June 19, 2012

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

Produce stand image from Steve Savage

Wednesday, June 13, 2012

What We Have NOT Recently Learned About Pesticide Risk

A few weeks ago, the readers of various "Food Movement" and "Health" blogs (and unfortunately some news sources) were treated to a major dose of fear mongering.  It had to do with an old agricultural fungicide that was tested at an extremely high, non-contextual dosage in a scientific study that looked at "chemical effects on epigenetic change."  What the study demonstrated was interesting, but it's interpretation in various circles has been completely out of context.  For example, self-described "Health Ranger," Mike Adams of Natural News started off with the headline:

"Red alert for humanity: Chemical damage can be inherited by offspring through unlimited generations"

Under the section heading, "Why chemicals threaten the future of the human species," Adams concludes:"  we are, in essence, ChemHumans, forever imprinted with the toxic burden of all the tens of thousands of synthetic chemicals we have foolishly unleashed onto our world, our environment and food supply".  

What inspired this sort of "the sky is falling" rant?  A classic failure to put a scientific finding into any sort of rational perspective.

The Journal Article That Got This Started

On May 21st of this year, scientists from the University of Texas, Austin, and Washington State University published a paper in the prestigious journal, PNAS (Proceedings of the National Academy of Sciences).  It was titled: "Epigenetic transgenerational inheritance of altered stress responses."  Epigenetics is a relatively new field of science.  It is the study of heritable traits which are not produced by changes in the sequence of DNA, but rather by modifications of that DNA such as methylation.  Some of the same mechanisms are involved in how cells differentiate into different body parts even though all cells have the same total set of genes.  Many things can lead to Epigenetic change.  For instance it was found that there were inherited traits for the offspring of people in Sweden who experienced famine and that the traits were passed down several generations.   The recent PNAS study showed an epigenetic change related to exposure to a particular chemical - an old agricultural fungicide called vinclozolin.    Mother rats were exposed to a single, very large dose of that chemical.  This induced an epigenetic change, and the body weight and stress responses of the rat's offspring were altered in a way that was passed from generation to generation thereafter.  

This is an interesting finding, but it is important to be clear about what this study does and does not show.  It shows that a substantial chemical exposure can lead to epigenetic change.  It does not in any way demonstrate that this or any other chemical can do this at the doses that we humans would ever receive in real life.  To investigate the question of whether a chemical might actually have epigenetic effects on humans would require a "risk assessment," and the authors have stated that that they were not attempting to do that.  However; when interviewed, one of the authors, David Crews, theorized that environmental exposure to things like DDT in the 1940s lead to increases in obesity and autism.  This leads one to wonder why the experiment was not done using DDT.  Andrew Feinberg of the Johns Hopkins Epigenetics center says that the theory is premature and cautioned about overstating what has actually been demonstrated.  The PNAS authors have overstated their case, and unleashed a storm of unhelpful speculation.

Dose Matters

What Adams and many other writers classically (and irresponsibly) failed to do was to consider how much this experiment differs from real world chemical exposures.  Many chemical effects that occur at high dosages become irrelevant when the dose if low.  A high enough dose of many, ordinary, natural, chemicals (caffeine, capsaicin, even table salt) can kill rats in a lab study.  That does not mean that they pose any risk at the doses in which we often consume them.  The saying, "the dose makes the poison" is a bit of classic wisdom, but not something that a writer like Adams would consider (besides, a terrified readership makes better customers for the home delivered Organic and Non-GMO foods that Adams is hocking on his "informational" site).

Here Comes The Disinformation

I knew as soon as I heard about the PNAS article that people would begin to assume that this potential for chemically-induced epigenesis is a new worry with regard to pesticides.  After all, the study was done with an agricultural fungicide.  Fortunately, there is a great deal of publicly available information to demonstrate that the amount of vinclozolin that was given to these rats was huge in comparison to any relevant exposure for food consumers.

Understanding This Dosage

I wrote to the authors of the study to learn what actual dose of vinclozolin they had fed the rats (it was in an appendix I was unable to see on-line).  The dose was 100 milligrams per kilogram of body weight.  To put that in perspective, to give a 100 pound human female (45.4 Kg)  an equivalent dose to what the rats received, would require 4.5 grams of pure vinclozolin.  To visualize this a little, I weighed 4.5 grams of salt (see picture below).  That is a lot of any individual chemical to consume at one time!

Next, I went to the data from the USDA's Pesticide Detection Program (PDP), the large sampling effort they conduct each year to find out exactly what pesticide residues occur in foods of various types (the same data set perennially misused by the Environmental Working Group to make their "Dirty Dozen" list.  During the years 1995 to 2008, trace vinclozolin residues were detected 1,058 times in crops like strawberries, table grapes, and green beans.  The average quantity of the fungicide detected was 0.13 parts per million.  It is better to look at the entire distribution of results.    The highest level of vinclozolin ever detected was 5.2 parts per million in one batch of strawberries in 1998.  Even if our imaginary 100 pound person ate strawberries from that worst-case batch, they would have to eat 1,923 pounds of them at a sitting to get the 100 mg/kg dose the rats got in the PNAS study.  The graph below shows the entire distribution of pounds of produce needed to deliver the study dose to a 100 lb human from actual residues.

Clearly, there is no reason to think that real-world exposure to pesticide residues might cause the sort of epigenetic changes seen in the PNAS study.

What Would An Actual Risk Analysis Entail?

To do a risk analysis of this epigenetic phenomenon, vinclozolin would need to be fed to the rats at a series of different, lower doses in order to find the "No Effect Level."  It is almost certain that actual human exposure to vinclozolin in food is far, far below that level.  There is no rational reason to believe that pesticides like vinclozolin are "threatening the extinction of the human species."  Instead, they are making it possible for growers to provide us with food of high quality at a reasonable cost.  Vinclozolin served that role for a while; but not any more in the US.

A Short History of Vinclozolin

Vinclozolin was discovered by the German company, BASF in the 1970s and first registered for use in the US in 1981.  It was a fungicide that was active on a specific group of plant diseases caused by fungi such as Botrytis and Sclerotinia.  Every consumer that buys fresh produce has probably seen Botrytis which produces as a powdery mass of grey spores as it rots things (see effected strawberries below - Image from University of Florida).  Botrytis is one of the major causes of food wastage both before and after harvest of many crops.  There were not many very effective fungicides for these diseases in the 1980s, so the introduction of vinclozolin was welcomed by growers.  It was used for a period, but it has since been replaced by even better and safer options.

Vinclozolin is essentially non-toxic in acute, mammalian testing.  Rats can consume 50 times as much vinclozolin as in the PNAS study with no short-term effects.  However, over time, as EPA risk analysis became more and more comprehensive and risk tolerances were adjusted to safer and safer standards, it turned out that vinclozolin had some issues at high doses.  In an abundance of caution, actions were taken to make sure that risk was extremely low.  At first, certain uses of vinclozolin were restricted and extra worker safety standards were required.  Eventually, the manufacturer decided to simply withdraw the product and its use was phased out.  You can read the details of that history on the EPA website. Vinclozolin was never documented to cause any actual health problems, but it is a good example of our highly protective regulatory progress over time.  You can see how vinclozolin use declined in California in the graph below.

So, as interesting as this PNAS study is (a very high dose of a chemical can lead to epigenetic change), it is not a reason to conclude that this phenomenon is any sort of threat to human existence or the cause of a host of ills.  If chemically induced epigenetic change does occur, it is probably only relevant for vastly higher chemical exposures than ever occur with agricultural pesticide residues in food.   Humans can actually be exposed to far higher doses of certain nasty, natural chemicals like mycotoxins or certain phytochemicals.  Those would actually be a logical classes of chemicals to study for real-world epigenetic effects.

This recent PNAS article does not change the reality that we do not need to fear agricultural pesticide residues in our food, and that such fears only serve the economic interests of fear-based marketers.

You are welcome to comment on this site or to email me at  "Scream" image from Christopher Macsurak

Friday, June 8, 2012

Mixed Messages in the Latest Data in the FAO Food Price Index

Yesterday (6/7/12) the Food and Agriculture Organization of the UN (FAO) released it's indices for food prices in international trade.  Most of the news coverage was up-beat because May showed the largest drop in some time.  For instance the allAfrica website had a headline, "FAO Food Price Index Drops Sharply."  It was a 4% drop; however that comes after several months where the index stayed flat and failed to show the sort of major correction that occurred after the last spike (2007-9).  Even with the drop in May, the index is still nearly as high as it's highest level in that previous spike.

Perhaps I'm doing some "glass half full" thinking, but what concerns me is that May's drop comes mainly from changes in only two of the components.  There was a serious drop in the dairy component of the index which really dominates the overall story for May (see graph below).

Indeed, the dairy index is dropping at exactly the same rate as it did in the last correction - just a few months later.  Some news sources highlighted this contribution, but not most.

Sugar also dropped quite a bit over the past two months, but neither sugar or dairy are "typical" in terms of their pattern vs other important commodities.

What concerns me is that the cereals index (see below) is so stubbornly high.  It's drop in May was really quite insignificant and does not even undo the increase that occurred in April.  These are prices that make life very difficult for grain dependent, poor nations around the world.

The meat index, which exhibited the most dramatic spike in 2010-12, shows little sign of correction at all.

The oils index dropped some in May, but once again not enough to erase the increases that have occurred over the last 6 months.

Many who have written about the latest index data do make a very good point.  All it would take was news of some major weather issues for the 2012 crops that are now growing, and May's progress could easily be reversed.

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