If you spend time understanding the science behind Roundup and glyphosate, its active ingredient, you soon realize that this is a safe chemical compared to many other chemicals, even ones liberally used in the home. Why is it then that so many people fear Roundup?
Probably the biggest reason is great promotion by the anti-Roundup and anti-Monsanto crowd. That is one powerful force that brings one misleading article after another to the attention of a lot of people.
I think that another reason for this fear is our inability to understand very small and very large numbers. A recent research study found glyphosate in natural water systems, and I have seen it posted by several people as proof of a real problem that needs to be feared. If these people simply understood small numbers, they would not fear the report or Roundup.
Glyphosate in Our Water
A recent study found that 41% of the 140 groundwater samples tested in Spain contained glyphosate.
The abstract title is “Determination of glyphosate in groundwater samples using an ultrasensitive immunoassay and confirmation by on-line solid-phase extraction followed by liquid chromatography coupled to tandem mass spectrometry.”
The author of a news article about the study took the data from the study and came up with this title: “Glyphosate, despite its low mobility in soils, is capable of reaching groundwater. 41% of 140 groundwater samples from Catalonia, Spain, contained high levels, technically beyond the limit of quantification.” Note the “contained high levels, technically beyond the limit of quantification”
The levels are in the ng/L range – that is not high levels.
What does “technically beyond the limit of quantification” mean? It certainly does not mean the levels were too high to measure – you simply dilute the sample. And if the levels were so low that they could not be detected, then they are certainly not high levels.
More gobbledygook to help convince people of the terrors of glyphosate.
They did find glyphosate in 41% of the samples. That means 59% had no glyphosate – a much more positive way to report things.
For this discussion, I’ll assume the work was well done and the data is accurate.
Understanding Small Numbers
The average amount of glyphosate in 41% of positive samples was 200 ng/L. A number like 200 sounds like a lot, and we humans really can’t visualize a ng (nano-gram), so this seems like a lot. But how much is it?
200 ng/L = 0.000,000,2 g/L
You might know that a gram is about the weight of a paperclip, but that does not really help to understand this number because it is so small.
“The EPA Allowable Daily Intake (ADI) for glyphosate is set at 1,750 µg (1.75 mg) per kg of body weight. The EU ADI is just 0.3 mg per kg body weight.” (ref 2). I’ll go with an average of 1mg/Kg.
The daily safe intake for someone weighing 70 Kg (150 pounds) is 70 mg. If you were drinking the average contaminated water in Spain, you would need to drink 350,000 L before you would reach this safe level. Or putting it in terms everyone understands – 1,000,000 beer-sized bottles. And that is the daily allowance.
How Toxic is Water?
The above calculation is informative, but I left out one very important detail. Water is also toxic, with an LD50 of 90 mL/Kg body weight. The 70 Kg person discussed above would have a 50% chance of dying after drinking just 6.3 L of water. They would almost certainly be dead long before they could drink the 350,000 L of glyphosate-laced water from Spain.
Interesting, probably only to a biochemist, is the fact that water would never kill you. By drinking water, your body would get its sodium/potassium levels out of whack, and that kills you. The water itself is not toxic.
Glyphosate in Cheerios
The same kind of arguments have been made for food products, especially Cheerios. With claims that they are laced with Roundup.
The truth is that all food products contain some glyphosate. Even organic caged chicken eggs contained it. But the levels in food are extremely low. “Fourteen of the twenty-four food items tested contained less than 75 ppb of glyphosate, which is equivalent to 75 µg of glyphosate per liter of testing solution. This is well below the ADI of 1,750 µg per kg of bodyweight per day”.
Roundup and Glyphosate
Bayer, owner of Monsanto, has been releasing numerous products using the Roundup brand name. These do not all contain glyphosate, while others contain glyphosate and much more toxic herbicides. One type of Roundup now contains vinegar and no glyphosate. Gardeners need to clarify which product they are talking about when they use the word Roundup. This post is about the traditional product containing glyphosate.
Disappointed to see you pronounce the use of a nerve toxin as safe. Didn’t Monsanto once tell us that the toxin magically disappears after 10 days? Now we know it is in most of our water supplies and stores in our body and mother’s breast milk.
The bigger issue here is why do homeowners need to use a toxin- because they are too lazy to weed? Because they must have perfection? Because they don’t want to support native pollinators and honey bees?
I understand using it for highly invasive weeds that threaten entire ecosystems. But on lawns? On fields of food destined to feed humans? On soil that is filled with a rich biome? There are far better ways to serve our landscapes and our co-species.
And your take on science is a bit skewed: reading an abstract without understanding the methodology and all findings and pronouncing a toxic chemical as safe is reckless and dangerous.
You should really spend some time to get the facts right.
1) glyphosate is not a nerve toxin.
2) I am quite sure Monsanto did not say “toxin magically disappears after 10 days” – a chemist would never say that. If they used 10 days, then would have said it has a half life of 10 days – which is a completely different statement. Where is your reference that they said 10 days?
3) People do not use glyphosate on lawns because it kills the grass.
4) There would be no reason to spray it on soils.
5) Since I accepted the data in the abstract, there is no reason to read the whole paper. If I had critiqued or criticized the results I would have needed to read the whole thing. I also never said the data was correct – I simply accepted it for discussion.
6) I never ” pronouncing a toxic chemical as safe”, at least not in this post. I simply illustrated what the data is telling us. I used the opinion of the EPA and EU for the calculations – not my own opinion.
You, like so many other people who blindly believe Roundup is the devil, continually fail to read the information in front of you.
I use Roundup sparingly on invasive plants in my area. If you are not on the ban bandwagon you will be villified on online garden groups. Many of the responses are based on emotions and not on data. Its nice to have someone with a science degree weed through the misinformation.
Hi Susan:
Who is the someone with a science degree?
Thank you for the article. I appreciate you taking the time to do these. Very well done and informative.
Thanks for a much needed article.
I appreciate your science based analysis. BUT, your use of the phrase “anti-roundup, anti -Monsanto crowd. . . . one powerful source” seems to suggest a political bias on your part.
-Don McCatty
Royal Oak, MI
What should I call people who are against Monsanto and Roundup and are unwilling to accept any of the scientific data?
When you consider how widely used these chemicals , the results are not concentrated . There have been numerous scientific studies for many years about the harmful effects of these chemicals. IT may not be so bad if just a few people on the planet were using them , but that isn’t the case. IN fact , where I live in Oregon , a health warning was issued this summer discouraging people from swimming , fishing and letting their dogs swim in the river because of the high levels of glosphates found in the water from run off and other factors.
And those studies have found very few if any harmful effects.
Just because there is a health warning does not mean there is a health issue. Politicians do what the public wants, not what the science shows them. But I would like to see a reference to the closure information if it contains the levels found. I’ll bet they are extremely small.
I’d share this post but, as a Canadian living in France, I’d probably be kicked out of the country.
I have, however, stocked up on glyphosate!
Good job!
I think there are lots of legitimate concerns surrounding Roundup, including the domination of our agricultural systems and regulatory capture by an ever shrinking handful of companies, the effects of spraying ‘lab-safe’ compounds at landscape levels and, possibly, health effects on people who apply Roundup under actual rather than ideal field conditions. As a result folk are uncritically receptive to studies like the one you’ve dissected which sound like they might show harm in a more viscerally understandable way (‘it’s everywhere and it’ll give you cancer’). My fear is that the demonisation of Roundup means we’ll go after the wrong target. If we carry on as usual with industrial agriculture but simply slot another compound into the place of Roundup then matters will certainly not improve and might be worse.
1) re:”spraying ‘lab-safe’ compounds”. Glyphosate has been field tested for many years. A recent study of works who are exposed daily to the chemical found no health risks. We are well beyond lab safe.
2) Glyphosate has been off patent for many years and is now made by a dozen or so companies. So we have an expanding group of companies – not a shrinking one. Besides this has nothing to do with the safety of a chemical.
The next big change in agriculture will be the development of much better plants that produce the pesticides internally. A whole new set of potential problems, but a huge potential for mankind.
I guess I didn’t make myself clear enough. I was agreeing with you that many people wildly over interpret and misinterpret findings about glyphosate. I spend quite a bit of time pointing out in my own circles that various studies held up to prove that it is the root of all evil do no such thing, and often that the ‘safe’ alternatives being proposed (salt, paraffin!) are far more harmful.
However I also think it is important to understand why otherwise rational people act this way concerning glyphosate, and I do think that it is because it is acting as a lightning rod for wider (and legitimate) concerns about the agriculture industry. As you say, many of these concerns have nothing to do with the safety of a single herbicide, but that was my point.
I think glyphosate has become the centre of this attention as the poster child of Monsanto. It may be out of patent (as I am aware, having used various herbicides in my job), but Monsanto’s attempts to keep control of it through licensing of Roundup Ready seeds have only made it more closely associated with them.
The point about landscape-level dosing with pesticides is not my own, but was recently made by the UK’s top science advisor on the subject in Science (the journal). Hardly the anti-Monsanto crowd. You can read it at http://science.sciencemag.org/content/357/6357/1232.
Incidentally, plants that produce pesticides in their own tissues have been availabe for many years, such as Bt cotton. The same effect had been achieved by seed coatings with neonicotinoids – on the verge of being banned in Europe outside greenhouses due to a huge weight of evidence that they damage pollinator populations.
It is an interesting question – why are some people so against glyphosate? I think a lot of it has to do with a lack of understanding of basic chemistry and science. In their minds all chemicals are bad. Concepts like the importance of dose and correlation are not understood. Add to this the extensive source of misinformation through the internet – any fool can be an expert. Unfortunately, the groups against glyphosate are much better at promoting their position, both in quality of reports and in quantity. It really comes down to marketing – which group is the better marketer?
Then we have the big movement against any type of establishment which is ready to eat up any info about the evils of big business. Don’t people understand that most jobs are directly or indirectly dependent on big business?
Re: “plants that produce pesticides in their own tissues have been availabe for many years” – actually millions of years – it is the only way plants don’t get eaten. But I do understand your point about Bt cotton.
I’m certainly one that takes an evidence based approach towards Roundup (and GMOs) and I’ve used Roundup myself to fight weeds. It’s pretty clear that it’s safe.
But I do have concerns about overuse leading to Roundup resistant weeds, much in the same way overuse of antibiotics have led to antibiotic resistant bacteria. Has anyone looked at whether or not this is happening?
It is definitely happening and is a large potential problem. But it is not due to GMOs.
These are very important questions. It is well known that weeds can evolve resistance to herbicides quite quickly if they are exposed to high doses of herbicides. There is some evidence of weeds becoming resistant to roundup where it has been used the most heavily, this is why there is so much interest in finding alternatives such as Dicamba (which has many other problems). Here for example is a summary published in the Journal Weed Science in 2012 of the problems with weed resistence to herbicides http://www.bioone.org/doi/full/10.1614/WS-D-12-10001.1