Not So Dirty Dozen

Part 2

In the previous post of this series, I explained how apples, as a perennial member of the EWG Dirty Dozen, are not so dirty and are, in fact, surprisingly clean for a fruit that is in a constant battle with an array of natural pesty enemies.  We examined the Toxicology in that previous post.  Today we will look at the Analytical Chemistry and Nutrition of the issue.  We will again remember the famous quote from Paracelsus that “Only the dose makes the poison”.

Let’s return again to the 2016 USDA data on pesticides in apples samples.  It is again attached below.  Remember that 531 apple samples were tested for 201 possible pesticide residues.  Today we will focus on the LOD Range column.  This is the Limit of Detection or the lowest level at which that particular pesticide can be detected with the instrumentation the USDA is using.  It is usually measured in part per million or ppm.  Most of these are small numbers, usually three places to the right of the decimal.  An LOD of 0.003 ppm (as for 3-Hydroxycarbofuran, the second pesticide on the list) is actually 3 ppb or 3 parts per billion. What does this mean in real life?  Let’s take something simple like salt dissolved in water as a demonstration.  In the following table we will dissolve salt in water in decreasing amounts until we get to ppb.  We will start with a liter of water which is about 1 quart.

Salt WaterConcentration
1 gram1 literOne part per thousand
1 milligram1 literOne part per million (ppm)
1 microgram1 literOne part per billion (ppb)
2.5 grams2.5 million litersOne part per billion (ppb)
Photo by Kindel Media on

An Olympic sized swimming pool contains about 2.5 million liters of water.  If you put 2.5 grams of salt, about half a teaspoon, into an Olympic sized pool, that would be 1 part per billion.  The detection limit for 3-Hydroxycarbofuran is 3 times that or about one and a half teaspoons in an Olympic sized pool.  Just for an interesting comparison, the toxic dose of Botox is about 50 micrograms, very toxic.  Diluted in a swimming pool at 3 ppb, someone would have to drink 17 liters (about 4 gallons) to have a toxic dose.

The point that I want to make here is that the USDA methods are very very sensitive.  So, when the EWG says that the average apple sample contains four detectable pesticide residues, I want you to think of Paracelsus and of the Olympic sized pool.  What does it really mean that an exquisitely small amount of a pesticide has been found and that on average four barely traceable amounts of pesticides have been found?  This is an unfortunate twisting of the analytical chemistry of this situation that usually bypasses the lay consumer.  One would normally assume that if four pesticides are found in an apple then that must be meaningful in real life.  But if I told you that I had put a detectable level of botox in your swimming pool (assume an LOD of 0.003 ppm as for 3-Hydroxycarbofuran), you now know that unless you drank 4 gallons you would be fairly safe.  So, the key question, per Paracelsus, is what is the dose, and EWG does not tell us that.  In their Methodology, they indicate that they use six criteria to rank that year’s foods for inclusion in the list.  This might suggest a balanced approach based on a range of food characteristics.  But five of the six criteria depend entirely on the number of detectable pesticides in one way or another.  It is only the number and not the amount, or dose, that really is being considered.

To use just three quick examples, I looked down the list of pesticides in our apple list for the first 3 that had over 20% “defects” or positive readings.  They were Acetamiprid, Boscalid, and Chlorantraniliprole.  I found the average pesticide residue for the 531 samples and divided it by the EPA tolerance.  For the 3 pesticides the average was 0.58%.  That means that on average an American apple in 2016 had less than 1% of the maximum tolerated dose of each of those 3 pesticides.  It averaged about 9 ppb for each of these three high exposure chemicals.  That is an astonishingly low amount especially since over 20% of all those samples had detectable levels.  The EWG did not really consider how low the dose was in ppb or how low it was compared to the legal limit.  They only counted it as an exposure.  Paracelsus would have rolled over in his grave.

Photo by Sora Shimazaki on

I am reminded again of the legal term “De minimis”.  In common usage this means, “The law does not concern itself with trifles”.  This came to my attention when it was used against the Delaney Clause in 1992.  The Delaney Clause seemed like a very sensible piece of law when it was enacted in 1958.  It said in effect that if a substance were found to cause cancer in man or animal, then it could not be used as a food additive.  As the science progressed and became more sensitive, it was found that almost everything caused cancer at some dose (remember Paracelsus) in test animals and the court cases became increasingly silly attempting to prohibit substances in our foods.  Finally in 1992, the EPA started rolling back some restrictions on some pesticides on the basis of de minimis.  I’m sure you can see where this is going.  We have real threats to our health out there (COVID, smoking, alcohol, opioids, etc) and there are certainly environmental chemicals of concern, but when a wonderfully healthy apple has less than 1% of the tolerated dose of a pesticide residue, I suggest you eat two apples instead of one and not worry about residues.

With that segue, let’s turn to nutrition here.  The EWG suggests that for the Dirty Dozen we find alternatives such as other healthy foods without residues, or find organic alternatives.  These may seem reasonable but are also generally unnecessary.  In this situation as in many similar ones, we need to consider the tradeoffs.  What do we gain and lose by taking or not taking an action?  As it happens, apples are cheap and nutritious.  They have lots of vitamin C, lots of fiber, and lots of potentially healthy phytochemicals that can act to prevent chronic diseases.  There is very little difference between traditional and organic apples except the price.  So, I suggest buying twice as many traditionally grown apples.  If you opt for trading for another fruit, will it be as nutritious or as cheap or as available?

There is one deep concern that I have about this type of food recommendation and others in my field share my concern.  It is fairly elitist.  Who can afford to make these dietary changes?  It is folks who read or listen to this sort of information and have the time, money, and access to easily make these changes.  Consider other folks from other backgrounds with limitations on access, time, and money.  This type of information seems classist, pointless, or simply induces some level of guilt that they cannot provide for their children properly.  Some poor soul may take a quick look at those 12 fruits and vegetables and decide that it would be safest to stop eating any fruits or veggies.  Is that our message?

An additional point I would like to make is how this sort of thing is covered in the press.  This is an example of how a quick sound bite that seems fairly healthy can find its way into numerous media outlets with little critical review.  CNN covered this year’s Dirty Dozen with a fairly positive review.  They get a quote from an EWG toxicologist and used a slick graphic supplied by EWG.  They followed up with several typical EWG talking points concerning specific pesticides.  Only one contrary voice was quoted and EWG was allowed to respond.  The usual advice is given to eat organic alternatives and choose local foods.  In fairness to CNN and other outlets, the Dirty Dozen has a high gloss PR image and is very smooth with its statements and supporting experts.  They make it very easy for publications to put together a seemingly objective piece with little extra work that meets the deadline.  Most of the other media posts that I can find online are from very like minded outlets supporting chemical-free foods, and organic, and vegetarian groups.  Not surprisingly, they gave rather favorable reviews.  WebMD did a much nicer job.  In addition to the EWG toxicologist, they got perspective from an industry group and from a dietitian and professor.  She raised several points similar to mine and stressed eating a lot of fruits and vegetables.

Photo by Maria Lindsey Content Creator on

My point here is that this is a hard area to report objectively in.  As an editor, you receive a nice glossy press release that supports good health and points to the usual bad guys such as agricultural chemicals.  How deep do you need to dig on that?  And readers love it and with some quick quotes from “both sides” and you are good to go with pretty pictures and graphics supplied by the press release.  And you meet your deadline.  Editors have my entire sympathy.

But this leads me to my final point and why I bothered to bring this rather minor issue to the attention of my (few) faithful readers.  In our time when it is so easy to create and distribute this sort of misinformation, what is happening to things that we thought we held dear?  Does a balanced view really matter compared to a glossy PR piece?  Does true expertise in a field hold any sway at all in a public discussion?  Is science just a thing to be twisted politically so that “Trust the science” is now held in derision?  Does the loudest voice always win?  Will we actually believe the small voice from the back of the room that says, “But, mother, the emperor has no clothes?”

In this one small area in which I have some expertise, I declare that the Dirty Dozen is largely BS and should be considered de minimis.   Stick to the big issues, truth, mercy, and justice, and eat your fruits and vegetables, all of them, lots of them, without guilt.

4 thoughts on “Not So Dirty Dozen

  1. Marty,
    This was great to read! I have been resistant to going with organic, because I really did not think it was necessary. Good to see some easily understood info that is substantial and can be shared with others.
    Of course there may be a few who are hypersensitive to the small amount of chemicals, but I would expect it be a de minimis group… 🙂

    Liked by 1 person

    1. Yes, there are some allergies out there, even to apples themselves. Organic pesticides can also be fairly nasty. Lime sulfur stinks pretty badly and you won’t want to touch it. I personally would not touch neem oil.


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