Latest Glyphosate Smear Misses 80% of Context
Monday, August 08, 2022
If you are suspicious of glyphosate (aka Roundup) because it seems to keep popping up in the news, let me recommend the most recent debunking of the most recent smear-piece in that particular Luddite campaign to sow ignorance and panic.
Writing for the Genetic Literacy Project, a great resource for this kind of thing, horticulturalist Kevin Folta performs a lengthy and thorough debunking of the Guardian piece, which headlined "'Disturbing:' Weedkiller Ingredient Tied to Cancer Found in 80% of US Urine Samples."
For those pressed for time, let's highlight Folta's quick review of two very important missing pieces of context.
First, the safety of glyphosate is very well-established. On this point, Folta lauds the conciseness of a recent reevaluation of glyphosate by Canada's health department:
Glyphosate is not genotoxic and is unlikely to pose a human cancer risk... No pesticide regulatory authority in the world currently considers glyphosate to be a cancer risk to humans at the levels at which humans are currently exposed.Second, there is the small matter of how much of this chemical has been detected and what that might mean.
For the curious -- or anyone in need of a real exposé -- Folta gives a bird's-eye view of the past reporting of the activist hack now posing as a journalist at the Guardian.... What is the high level found in the CDC report?
"[A]nalytical chemists can [detect] glyphosate at a level comparable to ... about three minutes in 32,000 years." (Image by Billy Williams, via Unsplash, license.)
We don't know. The CDC assessment did not measure how much was there, it only noted if it was detected above an analytical threshold. Present/absent, 1/0, yes/no. Not how much. The author sets up the paragraph talking about high levels when there are no quantitative data. Deception again. Note that no other agency and no other review of glyphosate has found levels of glyphosate in urine or blood anywhere near those suggesting health risk. So, the sleight-of-hand here serves only to promote uncertainty and fear.
What level would pose a danger? What is a "detection"? Analytical chemists have devised amazingly sensitive protocols to detect glyphosate in aqueous solutions like urine. In this case, they can detect 0.2 nanograms per milliliter. That's 200 parts per trillion. What does that mean? That means analytical chemists can confidently say that they detected glyphosate at a level comparable to 200 seconds in one trillion seconds -- or about three minutes in 32,000 years. Amazing! [bold added]
-- CAV
2 comments:
I would be VERY curious about what they're calling a detection. The issue is that there are detection limits and reporting limits. The detection limits are what the process can detect; anything less is too low a concentration to be confident that you have a real detection (signal to noise ratio gets too high). Reporting limits are what the lab can say they can detect. Labs need to run standards of known concentrations at specific intervals to ensure that they can get the readings they say they're getting. They also spike samples with known quantities of the chemical they're looking for to see if they can get those readings back--sometimes the material being tested (called the matrix) can cause problems (for example, clays are notorious for hanging on to heavy metals, giving an artificially low reading). At high concentrations they often have to dilute samples, which reduces precision, but that's not really a factor here. Anyway--as you get close to the detection limit, the reporting limit becomes a major concern. If the reading 2 ppt, but the variance inherent to the process is +/-3 ppt, you don't have 2 ppt--you have somewhere between 0 and 5 ppt.
If this sounds complicated, it's actually a lot worse than I'm making it sound. It takes a minimum of a year to get someone up to speed on sampling routine stuff--metals, chlorinated solvents, fuel spills, and the like. Sampling exotic stuff, at the limits of our ability to detect things? It's beyond difficult. It takes highly trained experts to just collect the sample, much less ship it.
Without providing adequate data on the sampling techniques it's impossible to know if these results are accurate. To give a plausible scenario: I give a urine sample every year as part of my HAZWOPER physical, and no one has ever monitored me during this process. If I was outside waiting and admiring their garden, and they just sprayed it with weed killer, and I don't thoroughly scrub before peeing in the cup, I will spike the sample with this chemical. For that matter, storing my urine in the same container as a farmer's, with improperly closed lids, can be enough. Or if the nurse doesn't change gloves between running the samples. At 2 ppt, I'd expect a Clean Hands/Dirty Hands protocol at minimum (which is a royal pain so people tend not to do it).
To be clear, I'm not saying the numbers are definitely wrong. I'm just saying that people who aren't used to the process of collecting samples tend to over-estimate accuracy of sample results given in isolation. There's a lot that can affect the final number, and the closer you get to the detection limits the more important that information is to evaluating the numbers.
Dinwar,
Thanks for mentioning these additional potential pitfalls.
If the authors of the "study" couldn't be bothered to report levels, why assume they got everything or anything else right?
Gus
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