Roundup in 75% of Air? What the Report Actually Says


Information without context is not knowledge

Last week the anti-biotech websites exploded with the news: “Roundup Weedkiller Found in 75% of Air and Rain Samples, Gov. Study Finds” and more scary-sounding titles like that.

My first response was to get a copy of the paper right away so I could read all about it and see the data. That would be pretty remarkable. But I could not access the paper at Environmental Toxicology and Chemistry. So how did all of these websites above and their scholarly journalists get the manuscript?

I contacted one of the original paper’s authors, Dr. Paul Capel, and asked for a copy and got one.  Apparently I was the first. Seems like those coming to the conclusions of the websites above were acting true to form– skimming an abstract and drawing a conclusion that best fits their desires.

So I actually read the paper! Want to know what it says?

In short– the conclusions from the websites above are cherry-picked nonsense.

First, the paper’s authors do this work because ag chemicals volatilize or become airborne on particulate matter.  I never realized to what extent, but wind, rain and other factors stir up otherwise latent chemicals and it is important to understand what is present.  The authors did such a survey.   They performed a survey in 1995 and 2007, at two separate sites in northwestern Mississippi that support 80% of the state’s agricultural harvest, mostly supporting corn and cotton.

The authors note that the region had similar area farmed between the two dates, but the management was quite different, the biggest differences being the introduction of GM crops and the discontinued use of several insecticides. They sampled air and rain in this agricultural region over a growing season to understand environmental flux of ag chemicals. The areas had similar rain patterns.  Samples were analyzed by using Gas Chromatography and Mass Spectrometry (GC/MS), so we’re talking sensitive detection.



The authors are obviously quite skilled at analytical chemistry, as they reliably detect glyphosate, atrazine, and a dozen other chemicals in air samples in 2007.  Glyphosate is detected in 75% of samples, atrazine about the same.  The authors even found Molinate, a compound that had not been used in four years– this is sensitive technology!

THIS is what the articles above discovered, that chemicals were detected in these samples. Detected? That means it is there, but it does not say how much is there. More on this later.

CONCLUSION 2: Herbicides changed

Figure 4 shows the difference in herbicides between 1995 and 2007. Peak applications are in May, as expected. What you see is that glyphosate becomes the main herbicide detected.  What the activist literature does not bother to tell you is that the increase in glyphosate substitutes for “other herbicides”. Atrazine levels decreased 36%. Trifluralin was present in almost every sample but its levels were 20 times lower than 1995. Essentially, glyphosate removed the need for other herbicides with higher environmental impact, a fact well documented (e.g. Duke et al., 2012).

Concentrations? Oh, and don’t forget to look at the y-axis units.  We’re dealing with nanograms per cubic meter. Considering these compounds are biologically relevant at the conservative level of milligrams per kilogram, we’re talking about levels millions to billions of times below any biological relevance.


What the data really show is that tiny amounts of ag chemicals can be detected (ng /m3), and that between 1995 and 2007 glyphosate substituted for herbicides with more potential impact.

CONCLUSION 3: Insecticides went down dramatically

Here’s another set of data that the dirty green media forgot to report, but more likely they didn’t read it because it was not in the abstract.  The trend from 1995 to 2007 shows a decrease in insecticide use.  In 1995 methyl parathion was heavily used in Mississippi on cotton (160,000 kg!). By 2007 its levels dropped twenty fold.  In 1995 there was high reliance on Chlorphyifos and malathion, and by 2007 the levels were down substantially, the authors citing “no local use”. All “other insecticide” levels were lower as well.

Why?  Why the decrease between 1995 and 2007?

The introduction of transgenic (GMO) Bt cotton and Bt corn, the two principle crops of the region.  Of course, the crazy “green” media forgot to take the blinders off to see that.


Insecticides detected in 2007 compared to 1995. You clearly see what may be attributable to the effect of Bt corn and cotton, that the GMO products work as claimed to decrease insecticide requirement. The authors do not explain the 4 Sept peak in methyl parathion.

Basically, the paper says that when you get into an ag area you can find ag chemicals, if you have sophisticated equipment and plenty of know-how.  The authors discuss that they sample two different sites with different crops growing, so that could affect data and account for some of the weirdness and spikes observed..  It does not change the take-home message that agricultural chemicals volatilize and persist in the environment, so it is best to minimize their use, use chemicals with less environmental impact, and choose seeds that require less chemical.

That is exactly what GM crops do, and exactly what the data shows. 

Some additional points to note:

1.  The use of “Monsanto’s Roundup” in the website titles above.  Glyphosate was detected. The test did not find “Roundup” and the authors do not say “Roundup” once in the manuscript cited.  Do you see a political agenda showing?

2.  The headlines above come from sources where the authors did not read the paper– it was not available, just the abstract.

3.  The same information outlets neglected to mention that glyphosate increases offset the use of other herbicides with more impact, that insecticide use was down, and that the levels were nanograms per cubic meter.

These are all important to note because is reveals how misinformed, ignorant and willing to deceive the anti-GMO media really is.  They are not out for science or truth, it is about an agenda.

Kevin is a public scientist that enjoys illuminating hot-button scientific issues for non-scientists using an evidence-based approach. Kevin is always uncomfortable referring to himself in the third person.

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37 comments on “Roundup in 75% of Air? What the Report Actually Says
  1. Organic activists HATE Roundup (glyphosate) precisely because is effective.

    There was a time – believe it or not – when Roundup was ALLOWED in restricted circumstances in organic production. But that was back when the organic movement was still being led by fulltime organic farmers who had farms to run.

    Now, under the mostly urban elitist leadership of the organic movement, Roundup is the Devil incarnate! And Roundup-Ready crops are the Phantom menace.

    Great job exposing the truth Kevin. Pretty soon organic activists will hate you too.

    • Micah P says:

      Elitist? Because we don’t want chemical spraying and environmental and biodiversity degradation to continue to the extent that is allowed through GMO crops. Elites run companies like Monsanto, not grass root campaigns seeking to increase the amounts of local and organic foods grown while keeping small farms operational, ethical, and profitable.

  2. Eric Bjerregaard says:


  3. Keith Hayes says:

    Nice summary of the article, Kevin. I have this bookmarked!

  4. MaryM says:

    Very helpful, thanks for actually reading the paper. I’m shocked–shocked I say–to think that some of the folks propagating the misinformation haven’t had a chance to do so.

  5. Sanjay says:

    Some years ago I was involved at the analytical biochemistry side with consulting for a grocery store in California that had been convinced by some bright spark to invest in a mass spec so they could demonstrate for their customers how much cleaner the organics were than the non-organics. The store was then perplexed that, basically, they weren’t. But of course it was a dumb idea: the pesticides are generally volatile and distribute nicely on everything in the store quite rapidly. The MS was mothballed.

  6. Chris Preston says:

    Kevin, AMPA is a metabolite of glyphosate produced when glyphosate is metabolised by soil organisms and some plants, not something added to the formulation.

    • Kevin Folta says:

      Thanks Chris. In my flurry to get this out I was thinking POEA. Just saw a bunch of letters. Will fix!

  7. Lucy says:

    At this level of sensitivity I would loooove to see how they performed controls. Chromatography uses the very same chemical it’s trying to detect as reference standards. So there is a potential for cross-contamination.
    I mean, just run a sample of air from the lab to make sure the things they are detecting are not wafting from a bottle of reference standard at a nearby bench.
    BTW here is a link to the paper:

  8. Rickinreallife says:

    Kevin — I presume the graphics in your article are copied and pasted directly from the study report, i.e. those graphics were created by the study’s authors themselves, correct?

    • Ewan R says:

      The figures in the article do appear to be what Kevin has posted.

      One thing you don’t discuss, Kevin, is the wildly different sampling sites – the earlier sampling was done at quite some distance from any agricultural field (specifically to avoid pesticides). The later sampling was done practically within a soy field (3m from it and surrounded by rice and soy fields (2 types the early sampling was situated to avoid) – thus comparing the two years doesn’t really paint an accurate picture of changes in pesticide use – to do this you’d want, I’d assume, to be 500m away from any ag production and see what happened there (one would assume most chemicals would be reduced in quantity detected (at least those one might see sprayed on or around rice/soy fields) thus painting an even more different picture (again, this is an assertion rather than being backed by evidence, but it seems so obvious as to not really require a massive body of evidence to at least bring it up) of quite probably vastly reduced quantities of ag chemicals in the air *in general* (the pendimethalin for example, shows quite a hefty spike in the later sample date, but this is likely (I’d guess) due to application ~3m away from the sample site rather than being indicative of any major increase in use).

      • Kevin Folta says:

        Right on Ewan. They were not at the same location, same distance, you name it. Even the weather was quite different.

        It is easy to dig in on this one, but I think what the authors are going for is a survey of change over time. What does a snapshot of this location look like compared to this one? That seems to be the case. They don’t overstep the data in trying to reconcile similarities and differences.

        I think we need to just take this for what it is, some data from two locations about stuff detected in air and rain with sensitive equipment.

        • Ewan R says:

          Indeed, I’m likely overextrapolating in the other direction, I have no beef whatsoever with the research itself, just any interpretation of it (despite the fact I then go and apply my own spin… humans are odd critters) given the sampling differences – I guess I’m just struck predominantly that it paints a far more optimistic picture than even a simple “yes but glyphosate is less toxic than all that other crap” does… and certainly (as you highlight) a more optimistic picture than the “OMG Glyphosate kidneys lumpy rats!” reaction which appears to be the norm.

          • Kevin Folta says:

            Sometimes a manuscript is like making sausage– you don’t want to know how it was made. This group does a lot of this kind of work. They probably had two datasets from the same general region that showed the shift.

            I actually am meeting with one of the authors next month. I’ll find out!

  9. Jessica says:

    Can you post a link to the article please? Thank you so much!! Thanks for your critique.

    • Mike says:

      In this case, he’s referring to multiple articles. Links aren’t necessary in this situation, and are in fact detrimental as the articles are themselves written in order to be linkbait. There’s no need to feed linkbait containing bad/no science. They should be easy enough to find with a standard search.

  10. Jeff Graham says:

    There are certainly many questions about what these data mean and if the quality of sampling and analysis was proper and sufficient. I do not have ready access to the full paper so my comment is limited to what is reported in the Supplemental Tables I could access from the Wiley site.

    Glyphosate product formulations generally consist of glyphosate as a water soluble salt of some form (potassium, isopropyl amine, etc.) plus inert materials to enhance uptake through plant foliage. Given that glyphosate is applied as a salt, the vapor pressure is so exceedingly small that volatilization from plant surfaces and soils seems quite unlikely. Glyphosate also binds soil voraciously.

    Inspection of supplemental Table 3 reveals an interesting and significant piece of information. In the case of glyphosate the authors report detection in rain and only in the particle phase of the air sample. They did not measure or could not detect in glyphosate in gas phase samples.

    It seems logical to reliably infer then that the source of glyphosate detected in this study was not from compound volatilization per se, but from glyphosate on soil and plant on particulate matter dispersed in the air that was sampled.

    • Kevin Folta says:

      That’s probably correct Jeff. It seemed strange that it would volatilize, and maybe that’s my interpretation. It is likely what is detectable in air as particulate bound. They do say that rain removes 100% of it (probably in that table too). The real complete typeset article is not out yet, but Karl does have a preprint and hopefully will post it soon.

    • Silvia B says:

      Yes, this confirms other older studies on the sampling and detection of glyphosate in air samples. Very low vapor pressure and strong soil binding makes it always non-detect in gas phase (no volatilization), detected only in particle phase, i.e. soil dust that is caught by filters. I actually have a paper on this somewhere in my office, need to fish it out, it was a field study comparing various passive/active samplers and their ability to detect glyphosate.

  11. Artie says:

    The problem is big agriculture, GM crops should not have to be the answer… nor chemicals.

    • Mike says:

      There’s that “big” word again. >95% of American farms are still family owned and run. Also, name one food (or anything outside of abstract concepts) that isn’t made of chemicals.

      • Good point Mike. Never before in history has technology been rejected on the basis that the companies developing and delivering it were “too big.” I’m not even sure anti-GMO organic activists know what they mean when they use the term “big agriculture.”

  12. Drake says:

    You realize you are an activist too, right? Your tone is confrontational and condescending and you’ve taken as many liberties with interpretation of the data as the “green” literature you so disparagingly lament. This isn’t “new” data that the “greens” were just pulling from the abstract – the USGS released this work in 8/2011. You may have gotten an advanced copy of a single publishable unit – but it is nothing special that you contacted the author. Also, you might be interested to know that the full work includes a data set for Iowa, something worth mentioning as it is part of the two peer-reviewed articles already published from this work.

    • Drake says:

      The other works already published from this data are: “Occurrence and fate of the herbicide glyphosate and its degradate aminomethylphosphonic acid in the atmosphere,” published in volume 30 of Environmental Toxicology and Chemistry and in “Fate and transport of glyphosate and aminomethylphosphonic acid in surface waters of agricultural basins,” published online in Pest Management Science.

    • What liberties would those be, Drake? Don’t just hand-wave, tell us how you think he misinterpreted it in detail.

    • Kevin Folta says:

      Hi Drake!

      Let’s talk activism. An activist is someone that works to promote, slow, or direct social, political, economic, or environmental changes. I guess with that definition my SECONDARY job is activist, as I am trying to shape social and environmental changes through the implementation of the scientific method.

      My FIRST job is using the tools of science to identify evidence about the nature of our physical universe. So identifying those facts and then applying them to make the world a better place is sort of the purview of the public scientist.

      I know it is nothing special that I contacted the author. What is important is that nobody else did– yet they were willing to scare the wits out of greenie-weenie website readers with the information.

      Glad you looked up their other work. These authors have quite a history together. I’m actually meeting with Dr. Capel in April in Minnesota.

  13. Eric Bjerregaard says:

    Artie, How will folks be fed without big farms and other businesses. “The problem” There are no others?

  14. Midiot says:

    Forgive me if I’m blind……but does this article NOT include a link to the study in question ? Wasn’t that the point ?
    I apologize if it’s there…..I cannot find the link.

  15. Midiot says:

    One more note……if this indeed a gov’t study, why is it not free to read ?
    ….I will be emailing Paul Capel for a free copy.

    • Kevin Folta says:

      I can send you a copy if you send me an email. Also, I’ll be interviewing Capel about this in person in early May.

  16. Daws says:

    Can you clarify what the quibble is about in additional point 1? I was taken to understand that Glyphosate is simply the active ingredient in roundup?

  17. Reba Smith says:

    As a being at the top of the food chain, I feel that sensitive equipment and measurements are in order. This does not negate the results or implications for me.

  18. Eric Bjerregaard says:

    Of course not Reba, I would never expect correcting the context and exposing the bias of the anti gmo sites. to effect your “feelings” Kevin was not advocating not using sensitive equipment. Just noting the lack of significance of the concentrations.

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