Do You Really Need To Worry About Pesticide Residues On Your Food?

Some of the healthy fruits and vegetable we can enjoy (Image from Wikimedia)

Many Americans have concerns about pesticide residues on food – particularly for fruits and vegetables. In contrast with that oft-communicated perception, the safety of our food supply is well documented. One reason for this disconnect is that there are activist groups (non-governmental organizations) that consistently promote the idea that consumers should buy organic versions of certain crops in order to avoid pesticides. A recent study documented how that sort of message induces some lower income Americans to simply avoid fruits and vegetables all together. The truth is that our food supply is extremely safe because farmers are careful to use pesticides in ways that don’t lead to residue problems at the consumer level and because of rigorous regulation followed by farmers over the last several decades.

The common perception of organic as a safer option in this regard is also at odds with reality. The United States Department of Agriculture (USDA), which oversees organic certification, clearly states on its National Organic Program website: “Our regulations do not address food safety or nutrition.” Organic farmers can and do use pesticides from an approved list, but that list is not based on safety criteria. Organic growers are limited to natural chemicals and to a limited list of synthetic materials. As with any crop protection material, the EPA has the responsibility to evaluate and regulate their safe use. That oversight is why consumers can confidently enjoy both conventional and organic foods.

In this post I will describe the testing, regulatory and training systems that are in place in the US to protect consumers from risks associated with pesticide residues. I will also describe the intense monitoring system that demonstrates year-after-year that this system is working.

All farmers face challenges from a variety of pests and although they use a number of methods to manage those threats, pesticides are a critical part of that “toolbox.” The broad category “pesticide” includes certain chemicals that occur in nature as well as various synthetic chemicals. There are also pesticide products based on living biological agents. The responsibility for pesticide regulation is with the Environmental Protection Agency or EPA. It determines how pesticides can be used safely, based on their particular intrinsic properties, and by restrictions on how and when they can be used.

EPA Risk Assessments

Before any new pesticidal product can be sold in the United States, an extensive list of toxicological tests must be performed and reported to the EPA. The company that makes or which will sell the product is responsible for the cost of this testing, but most of the work is performed in contract labs that are closely audited by EPA. The tests evaluate many different facets of potential toxicity for human and environmental health, both in terms of short-term effects (acute toxicity via consumption, by skin exposure, by inhalation exposure…) and long-term effects on development, organ health, reproduction, and potential carcinogenicity. In addition, a great deal of data has to be generated to show what happens to the chemical over time on the food, and in the environment in terms of its persistence, movement, and breakdown into innocuous ingredients. It costs on the order of $286,000,000 and can take more than 10 years to generate all of this required data. EPA then uses these data to conduct an extensive “risk assessment.” Based on that assessment, EPA develops “label requirements” specifying how, on which plants, when, and how much of the pesticide can be used. These risk assessments cover issues of worker safety, environmental impact and also what sort of residues might be left by the time the crop is harvested, and any potential risk to human health.

Some safe, delicious apples ready for harvest in western Washington this summer

Pesticide Tolerances (or MRLs)

With regard to pesticide residues at harvest, EPA designs the label requirements to make sure that any residues still present when the food gets to the consumer are below what is called a “tolerance.” (Outside the US this is called an MRL or maximum residue limit). The tolerance is set to insure that there is a substantial margin of safety (typically 100-fold) between the allowed residue and any level to establish reasonable certainty of no harm to humans. EPA then sets limits on how much of the pesticide can be applied and how close to when the crop is going to be harvested so that the tolerance is unlikely to be exceeded when farmers use the product.

These tolerances are very conservative limits and represent such small amounts that they can be difficult to envision. For instance, a tolerance might be five (5) parts per million. That can be visualized as to two drops of water in a five (5) gallon carboy. Some tolerances are set as low as one part per billion (e.g. one drop in 528 carboys). In summary, tolerances are extremely small levels of pesticide residue, set as a conservative standard for human safety, and customized to the specific properties of the each chemical.

Training

In order to be allowed to apply pesticides, farmers have to be trained and certified about how to comply with the chemical-specific label requirements. They have to maintain that training through on-going classes.

Is the System Working?

Every year, as part of a USDA effort called the Pesticide Data Program (PDP), thousands of food samples are randomly gathered from normal food channels and consumer markets. The samples are taken to labs where each sample is screened for the presence of hundreds of different chemical residues. The data that the USDA generates is transparently published both in raw and summarized form. Year after year, what the data show is that the system is working! The vast majority of samples have either no detectable residues or residues that are below the assigned tolerances – mostly far below. The fact that a small residue can be detected does not mean it is of concern. Modern analytical chemists have the ability to detect chemicals at very low levels. The reason that the numbers below tolerance are still published is not that they are of concern, but rather as transparent documentation that these products should be of little concern to consumers and regulators.  Several governmental agencies evaluate this information each year and confirm that consumers can confidently enjoy their food supply without concern about pesticide residues. The results were just released for 2015 and again document how well the system is working.  The FDA also has a residue testing program from which it concludes, "Results in these reports continue to demonstrate that levels of pesticide residues in the U.S. food supply are well below established safety standards."  California does its own residue testing and concludes, "California tests show low or no pesticide levels in many fruits and vegetables." Similar residue testing is conducted in Canada and the EU with equally encouraging results.  With this overwhelming body of evidence, how can the fear of residues persist?

What About the “Dirty Dozen List?”

Unfortunately, each year there is an organization called the Environmental Working Group (EWG) that takes the USDA PDP data and grossly misuses it to create a “Dirty Dozen List.” Instead of looking at how detections relate to carefully developed tolerances, EWG essentially treats all detections as significant – an approach that has been completely rejected by independent experts in the field of toxicology. EWG then recommends that certain crops be sought out as organic. Similarly misguided recommendations to purchase organic are published Consumer Reports. This makes no sense, since organic is not a safety certification. In fact, organic crops often have the same sort of low-level, detectable residues of pesticides as conventional (example data from the US and Canada). This point is conveniently ignored by these organizations.

In conclusion, we have a system in the US that both enables farmers to control pests and which protects consumers so that they can enjoy healthy foods without worrying about pesticide residues.

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

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Ten Thousand New Reasons Not To Worry About Pesticide Residues

(Originally posted on Forbes 3/1/16)

Each year, the farmers around the world who produce our food (fruits, vegetables, grains) get the equivalent of a “grade” on a giant “group project.”   For 2014 they got another A+ as they have for many years.  The “test” entails thousands of food samples, which the USDA collects from normal US food channels and then scrutinizes for pesticide residues using extremely sensitive laboratory testing methods. They are checking for any detectable residues (41% of samples have none) and whether any of the detectable residues exceed the conservative “tolerances” set by the EPA (99.6% of the samples met that exacting standard). This means that our regulatory/farming system is working extremely well! Farmers are able to produce crops without the inefficiency and quality issues associated with excessive pest damage, and consumers are able to safely enjoy what they grow. The official conclusion from the USDA is “These Pesticide Data Program data show that, overall, pesticide residues found on foods tested are at levels below the tolerances established by the U.S. Environmental Protection Agency (EPA) and pose no safety concern.”

Chemical pesticides are only one part of the pest control regime, but an important one. The chemical pesticides in use today are predominantly low in mammalian toxicity, but for all pesticides the EPA sets detailed rules for how they can be used (e.g. maximum rates, periods of time before harvest…). These are designed to ensure that any residues that remain at the consumer level are below a “tolerance” based on a rigorous, multi-factorial risk assessment by the EPA. The tolerance is generally 100 times less than a dose that could cause any ill effect.  The allowed residues are also lower than the levels of natural pesticidal compounds that many crops make to defend themselves.

The 2014 USDA “test” is called the Pesticide Detection Program or PDP, and it has been conducted every year since 1991. For 2014 tests were done on 10,750 samples including 21 types of fruits or vegetables, two grains, two types of infant formula and salmon. The scientists detected a total of 22,890 specific pesticide residues of which 98.5% were below tolerance or at such low levels they couldn’t even be properly quantified (see table below).

I appreciate the fact that the USDA makes this data available and transparent. It allows us to see that not only are most of the residues below tolerance, a great many of them are more than 10, 100 or even 1,000 times lower than the tolerance (see column chart below - all to the left of the center bar are no-issue detections, but 84% are far below).

There are some minor differences between crops. In the two charts below, the light green bars show how many of the detections in a given crop were below tolerance, and the dark green bars show what percent were 10 or more times lower than the tolerance. The samples of infant formula had, happily, either no detections (dairy-based formula) or a few detections that were between 1000 and 5000 times lower than the very low tolerance (soy-base formula, 7 of 527 samples). Oats and rice also had few detections and those at very low levels.

Unfortunately, the very transparency which documents the safety of our food is grossly misused by an organic industry-supported organization called the Environmental Working Group. EWG conducts its own “analysis” of the data in which they completely ignore how the detections differ from one another and how they relate to the tolerances. Their choice to represent as “dirty” any residue, no matter how low or non-toxic, conveniently ignores the fact that similar pesticide residues are also regularly detected on the organic options that they promote. Hopefully they will refrain from such irresponsible fear-mongering this year.

So, at the risk of being like a parent who only focuses on an A- on a report card of all A+s, I looked in detail at the 1.5% of residues were of any potential concern. For the few detections that exceeded tolerance, most were only marginally higher and thus of very minor concern.  There were some residues detected for which there was not a tolerance for that specific crop, but in most of those cases the levels were lower than the tolerances for other crops.  The EPA also tests for some old, long-banned pesticides notorious for their environmental persistence. There were 18 detections of such materials, including three from organic samples.  Of those 18, 17 were at extremely low levels and only one was very significant (0.46ppm monocrotophos in a squash sample from Mexico).  All in all, I could only find 11 residue examples of moderate concern, which is an amazingly small number (0.045%).  I have posted a much more detailed analysis on Scribd.  If anyone is interested I'll be happy to email you that full summary.

So once again, the take-home message is that we have another 10,000+ reasons to confidentially enjoy our American food supply.  My congratulations to those who produce it for us.

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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

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