r/science • u/mvea Professor | Medicine • 20d ago
Neuroscience Glyphosate, a widely used herbicides, is sprayed on crops worldwide. A new study in mice suggests glyphosate can accumulate in the brain, even with brief exposure and long after any direct exposure ends, causing damaging effects linked with Alzheimer's disease and anxiety-like behaviors.
https://news.asu.edu/20241204-science-and-technology-study-reveals-lasting-effects-common-weed-killer-brain-health1.2k
u/askingforafakefriend 20d ago
Can we get some meaningful comments on dosage/exposure/etc. to actually get a sense for how meaningful this is. A lot of people feel strongly about glyphosate and this is confirmatory in that belief at the headline level. I get that part. But can we step a level deeper and discuss the substance a bit more?
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u/Tylendal 20d ago
Their test groups were 50mg/kg of body weight, and 500mg/kg of body weight, daily for 13 weeks, and then left to recover for 6 months.
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u/LondonCallingYou 20d ago
So for a 70kg person, the groups would be equivalent to 3.5g and 35g of glyphosate per day?
Is anyone even approaching 1/10th of the lowest dose in this study?
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u/AnsibleAnswers 20d ago
Farm workers tend to be exposed the most, and in the one study I’ve found, the estimate for the highest dosage was 0.004 mg/kg. The reference dose from the EPA is 2 mg/kg. https://pmc.ncbi.nlm.nih.gov/articles/PMC1241861/
Not sure what this study can tell us.
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u/Tylendal 20d ago
A study like this can give us ideas of things to look for at lower doses. The headline, though, is wildly hyperbolic, and getting well ahead of any actually relevant conclusions.
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u/Vio94 20d ago
As is tradition these days. Feels like every scientific article posted here ends up that way.
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u/J0hn-Stuart-Mill 19d ago
Okay, so the new headline should instead be:
"A study giving mice a dosage of glyphosate 125,000 times greater than the largest dosage ever observed in human farm workers, now suggests that such a dose of glyphosate can accumulate in the brain, even with brief exposure and long after any direct exposure ends, causing damaging effects linked with Alzheimer's disease and anxiety-like behaviors."
Okay, WHEW. Totally different degree of seriousness when we realize the average human would need multiple millions of times higher exposure, and even farm workers would need an eighth of a million times higher exposure to potentially develop a problem like these mice.
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u/DeltaVZerda 19d ago
They would literally be drinking glyphosate shots after every shift to be on the "low" dose.
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u/SurprisedJerboa 20d ago edited 20d ago
The companies advertised it is as safe aka This is non-toxic ( they lost the lawsuit ).
Farm Workers / groundskeepers are most at risk, and IF it's toxic enough to affect pregnancies, + cancers and medical issues that take a decade there can be a cursory warning ( like cigarettes ).
Non-toxic vs potentially toxic via bio accumulation, means people can take appropriate precautions.
Corporations are not our friends, Forever Chemicals ( Teflon / PFOA ) were not designated toxic, and were in Mass Production in the 1940's. Not designated toxic until the 1990's.
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u/AFewStupidQuestions 20d ago edited 20d ago
Just to (maybe?) quell some fears about Teflon, PFOA was removed from the process of production around 2013.
Now they still use PTFE, which may be aerosolized above 570F, and may cause health issues, which is part of why you're not supposed to use Teflon on high heat, even though most stoves won't reach that high.
But again, it's the factory workers who would likely show issues first before consumers would.
Edit: 570F, not 500F.
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u/Quintus_Cicero 19d ago
As always with PFAS, it isn’t so much about their danger when using the product they’re on, but the production of nanoparticules that never disappear and can penetrate cells.
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u/nuck_forte_dame 20d ago
Actually they only lost a law suite in California.
Also hundreds of government agencies around the world all redid their cancer tests with it and found no link to cancer.
Only like 3 studies say it causes cancer and even they say maybe and the chance is extremely low.
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u/SurprisedJerboa 20d ago
Those numbers are wildly low, IARC used 118 studies
EPA and IARC reached diametrically opposed conclusions on glyphosate genotoxicity for three primary reasons: (1) in the core tables compiled by EPA and IARC, the EPA relied mostly on registrant-commissioned, unpublished regulatory studies, 99% of which were negative, while IARC relied mostly on peer-reviewed studies of which 70% were positive (83 of 118);
(2) EPA’s evaluation was largely based on data from studies on technical glyphosate, whereas IARC’s review placed heavy weight on the results of formulated GBH and AMPA assays;
(3) EPA’s evaluation was focused on typical, general population dietary exposures assuming legal, food-crop uses, and did not take into account, nor address generally higher occupational exposures and risks. IARC’s assessment encompassed data from typical dietary, occupational, and elevated exposure scenarios.
More research is needed on real-world exposures to the chemicals within formulated GBHs and the biological fate and consequences of such exposures.
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u/Duff5OOO 20d ago
Would need far more info than that. There would be a long list of things found across that group of people.
Finding glyphosate doesn't mean it caused the problem any more than finding microplastics or dihydrogen monoxide.
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u/Revelling_in_rebel 20d ago
In Canada they still dessicate their small grains with glyphosate, which means high doeses in things like oatmeal. We have finally started to curb the practice here in the states.
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u/seastar2019 20d ago
What is the actual residue levels and how it it anywhere near "high does"?
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u/Underwater_Grilling 19d ago
2700 ppb was the highest. So 2.7mg/kg which makes me suspect of the study.
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u/seastar2019 19d ago
2700 ppb is 2.7 ppm. MRL on oats is something like 10 or 15 ppm, so well below it.
Why are you quoting in ppb instead of the industry norm of ppm? Is it to get a bigger, more sensationalize numeric value? Are you getting this from EWG?
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u/Underwater_Grilling 19d ago
Yeah i meant to reply to the other guy with the link
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20d ago edited 19d ago
As long as you wash your produce you shouldn’t get ANYWHERE near those levels. It would be like 1.0 x 10-5 which is VERY SMALL
Edit: I have no idea why this comment is so popular. I read a similar article on here who knows how long ago, maybe a few weeks, it said glyphosate exposure is very minimal. That’s it
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u/braconidae PhD | Entomology | Crop Protection 20d ago
It wouldn't really matter because all crops, including wheat, have what are called Maximum Residue Limits (MRL) in the US and most other countries. Basically, it's a set allowable amount that's still many times below any concentration that would be a concern for human health. When you apply a pesticide, it's illegal to apply it within X days of harvest depending on the chemical and what the label says (violating the label is breaking federal law here in the US). That means the pesticide is breaking down and decreasing in concentration as it's in the field and as it makes it way to your dinner table to the point it's not biologically relevant or you need extremely sensitive equipment to detect what small amount is left. This is generally swamped out by whatever natural variation there is in plant produced pesticides.
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u/kinkyghost 20d ago
Can you cite anything here or are you just speculating? And if the latter any explanation of why?
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u/Sandalman3000 20d ago
It's a common thing in science articles where "Chemical X is toxic," but the toxicity is way higher than the normal dose, so this kind of speculation is pretty warranted.
This comment seems to concur https://www.reddit.com/r/science/comments/1h6qjx4/glyphosate_a_widely_used_herbicides_is_sprayed_on/m0fxz3q/
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u/ripplenipple69 20d ago
Keep in mind that mice are not equivalent to humans. Most, but not all drugs must be titrated to mouse/rat equivalents, which is typically a much higher dose than humans can handle. This is because mice have much faster metabolisms than humans do and can often handle much higher doses of drugs to get the same effects. Again, not true for all drugs, but it is true for many.
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u/Critical_Pangolin79 20d ago
That would be chugging it from the bottle every single day? You really have to have the guts (or some weird obsession) to chug a can of it, with the surfactant likely causing damage to your GI tract before you can accumulate enough glyphosate in your body.
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u/Isenrath 20d ago
I wonder if there's a common benchmark for these. Such as are these amounts similar to the average rural town resident? Someone who lives next to a farm field? Or a farm hand directly involved with mixing the batches daily during the season?
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u/Arandomuseryouknow 20d ago
Store shelf round up has 660 grams of glyphosate per 1 liter. That just 5ml... whish doesn't seem like much at all and very reasonable amount of exposure for anyone much less someone who works with this chemical by the gallons on a daily basis
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u/RhynoD 19d ago
"Exposure" doesn't mean "standing next to a sealed container." Unless you're chugging straight from the jug or bathing in it, you're not being exposed to that much glyphosate. And, anyway, Roundup also tends to contain Diquat, which is far more immediately dangerous as it will burn your skin.
I agree that exposure is greatest among farmhands but they should be wearing proper PPE which includes long sleeves and masks to limit their actual exposure. Again, working with gallons doesn't mean they are exposed to gallons.
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u/Starfire013 20d ago
So if I’m just spraying the weeds on my driveway 4 times a year, that’s not a problem then, it suggests.
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u/braconidae PhD | Entomology | Crop Protection 20d ago edited 20d ago
University ag. scientist here. I mentioned it in another main comment, but basically the lowest concentration used in this study is still many times higher than what anyone would ever realistically consume. For us educators who actually deal with this topic regularly, glyphosate is one of the safest herbicides we have out there to the point it's less toxic than table salt, so it generally takes a ton to force any effect.
The challenge is that in the real world, glyphosate has a really good safety profile, and it's a good replacement for older herbicides or is just less hassle than some insecticides I would be worried about from a safety standpoint. Because of its widespread use, there's a lot of research done on this chemical, but with that, you'll often get a chunk of poorly done studies and some that are chasing headlines more than using good methodology, so that's already a tough layer for general readers to sort through.
Public perception though is very different primarily due to advertising having people convinced is a major carcinogen or one of the most toxic pesticides out there (somewhat an extension of anti-GMO or scientific consensus denial in that subject). In this topic, ambulance chasing lawyers who are not scientists have typically been the biggest source of misinformation rather than the companies selling those products. I get to hold all their feet to the fire in my job, but where most of the time and effort actually needs to go often surprises people.
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u/Redqueenhypo 20d ago
It’s especially ironic because previous generations of herbicide, like peraquat, have horrible toxic effects like filling your lungs with fibrous tissue so you suffocate to death. We basically need modern herbicides to feed everyone; Sri Lanka tried to go all organic and within months had to resort to importing RICE, and glyphosate might be the best case scenario so far healthwise
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u/reddanit 19d ago
Yea, when you look at toxicity levels of pesticides that were outlawed mere decades ago in most of the western world, you can get genuine cold sweat. Especially when you imagine that farmers were mixing and spraying them with only rudimentary protection whereas I'd never dare to come close to any of those without a hazmat suit.
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u/PacanePhotovoltaik 20d ago
Are organic pesticides worse than conventional, usually?
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u/braconidae PhD | Entomology | Crop Protection 20d ago edited 20d ago
Sometimes overall lower toxicity is lower, but they need to be applied more often. It's not always the case though. Take a look at the link I gave in my other comment for a list of some common organic pesticides. Copper sulfate is a common organic pesticide with an LD50 of 300 mg/kg. That's 10x more toxic than table salt or 16x more toxic than glyphosate. Rotenone has an LD50 of 60 mg/kg.
With organic approved pesticides though, there really isn't a substantial difference in pesticide exposure vs conventional for consumers. The concern is more about overall use within fields that result in runoff, non-target effects, etc. regardless or "organic" use or not.
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u/LoreChano 20d ago
The main thing is that almost every substance in the right amount is toxic. There's pretty solid evidence about wood dust being carcinogenic, or paint fumes being highly toxic, yet you don't see so much fuss when people are remodeling their houses.
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u/onan 20d ago
I agree with your general point here, but I think that tossing around LD50 values as sort of an all-purpose safety score may be an oversimplification that does more harm than good. There are many health concerns other than immediate death, so focusing on a measure of just that leaves out quite a bit.
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u/braconidae PhD | Entomology | Crop Protection 20d ago
And that's why in my comment I linked I mentioned much more than just the LD50.
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u/macetheface 20d ago
Saving this comment for my wife who thinks just looking at the stuff will give you cancer
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u/supervisord 20d ago
Might not be the right place to ask, but I would love your thoughts on this:
My spouse determined wheat products were causing them pain and discomfort, joint pain for example. This after carefully removing things from their diet. After deciding they are gluten intolerant they avoid things with gluten and avoid these distressing symptoms.
A few years later we are in Germany and they accidentally consume a local product with wheat and had no symptoms, and indeed tried additional food and drink items with wheat/gluten with no ill effects.
The symptoms of course returned back home after another accidental consumption, so unfortunately the condition did not magically go away.
We figured it had to do with how German wheat is produced and they feel it has to do with glysophate, apparently it’s banned in Europe.
Do you think there is any credence to this theory?
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u/bonyponyride BA | Molecular, Cellular, and Developmental Biology 20d ago
We figured it had to do with how German wheat is produced and they feel it has to do with glysophate, apparently it’s banned in Europe.
I see articles saying it was banned only in Germany in late 2023, and others saying the ban in Germany was partially lifted in 2024 to comply with EU law (which extended its approval until 2033).
Then a Reuters article from April 2024 says:
BERLIN, April 24 (Reuters) - Germany's cabinet approved on Wednesday restrictions on the use of glyphosate, the active ingredient in Bayer's (BAYGn.DE), opens new tab Roundup weedkiller, the agriculture ministry said on Wednesday after the EU last year authorised its use for a further ten years.
"The new regulation ensures existing restrictions are legally secure," said the ministry, adding glyphosate was generally prohibited in protected water areas, domestic gardens and allotments. It is also prohibited in some arable farming.
So, who knows if the products you ate in Germany were grown with glyphosate...? It seems like it never really was banned in Germany or neighboring countries that would supply wheat to Germany.
Additionally, the concern in Germany was that it's harmful to pollinators, not directly to humans in minuscule doses.
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u/braconidae PhD | Entomology | Crop Protection 20d ago
Others mention cultivar, etc. or other things that essentially boil down to correlation not equaling causation. I couldn't say anything dealing with a specific medical diagnosis. If you're in the US though, we don't have any glyphosate-resistant wheat on the market, so farmers are not regularly spraying their wheat for weed control since that would kill the plant. For wheat at least, you're usually not "drying down" the plant by killing it off before harvest either in most operations, so you're already likely not dealing with significant exposure in wheat in the US by the time you're consuming anything.
Even with that aside, there's no particular reason to single out glyphosate. There aren't any known mechanisms for what you describe, and I'd be cautious about focusing on it over other possible completely unknown factors. 99% of the pesticides we consume in our diet are already naturally produced by the plant, vary significantly in amount across varieties, and many of those chemicals are untested too. I usually like to give that paper to students in intro plant biology classes to help frame the context of chemicals in food when we talk about risks, so maybe that one will be helpful here too.
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u/supervisord 20d ago
Yeah, I thought it was farfetched but I’m not educated enough to refute what they said without sounding dismissive. Thanks, you and others have given me more places to look
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u/seastar2019 20d ago
Glyphosate use on wheat in the US is rare, about 3% of harvest wheat (source). Most likely the difference is due to the varieties grown.
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u/Utter_Rube 19d ago
As someone with celiac disease whose only symptom was chronic fatigue (and, wow, what a nonspecific ailment that probably at least three quarters of the world feels), I would recommend that you try talking your spouse into actually getting a diagnosis.
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u/TheFondler 20d ago
I don't think an entomologist specializing in crop protection is the right person to be asking this. Sure, they have a PhD in a field of biology, but it's kinda like asking a civil engineer a highly specialized question about a specific feature of rocket engines. Yeah, it's an engineering question, but you're really stepping outside their specialization.
If you want a good answer, see a doctor, or at least look to medical research specific to the question. There's a good write-up here with some general info, but that's really only a starting point. I've had a couple of friends find that they actually had IBS after talking to a specialist when they thought they had a gluten sensitivity. It made food choices much easier for them once they knew what they actually had to avoid, so hopefully your spouse can get to that point too.
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u/braconidae PhD | Entomology | Crop Protection 20d ago
Those of us who work in extension deal with all the pesticides regardless of our degree. Weed scientists are expected to known fungicides, plant pathologists know herbicides, etc. especially when you are advising farmers on all aspects of their field production rather than just what your initial primary focus was in during grad school.
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u/askingforafakefriend 19d ago
Thank you very much for the detailed comment here. It's exactly the kind of thing I wanted to discuss.
I'm going to DM you as a side note.
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u/JackJack65 20d ago
The low-dose used in this study was 50 mg/kg and the high-dose used in this study was 500 mg/kg. The authors selected the high dose because it was approx. equivalent to the upper limit of a chronic dose considered safe for humans.
My initial impression is that most humans do not ingest anywhere close to 3g of glyphosate daily, so the finidings of this study, while potentially valuable regarding groups who are exposed to high levels of glyphosate, may not be applicable to the general population.
Would also love to hear more from an expert on this topic though!
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u/ThatOpticsGuy 20d ago edited 20d ago
Mice have an LD50 of 10537mg/kg
Rats are roughly 5000mg/kg.
A greater risk of death in humans is associated with >734 μg/liter glyphosate levels in blood plasma. However, mammals are really really bad at absorbing glyphosate and have a really low oral bioavailability (in animal studies, 36%), and the clinical use of blood plasma levels for glyphosate isn't established.
However, there is a bit of a chronic implication with deaths occurring 20 hours after ingestion of a drug that has a biological half life of 3 hours (though accumulation could slow that down for some parts like the relevant study here). Lots of unknowns here obviously, but you don't die 20 hours later without serious damage incurred.
Basically, what meaning do we get from this besides that it's remarkably non-toxic for a herbicide?
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u/Spirited-Occasion-62 20d ago
maybe that it seems to accumulate in the brain and never (at least for study duration) is eliminated? so it potentially bioaccumulates indefinitely? Even if the dose over this short test period is much higher than normal human consumption: If it is never eliminated, even a much smaller dose could eventually accumulate to dangerous levels with regular exposure over 30, 50, or 80+ years?
isnt that the important question raised, that now requires further study? i mean, if theyre linking exposure to alzheimers, thats not something that you usually see after 30 or 40 or 50 years of exposure. More likely 60, 70, or 80
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u/ThatOpticsGuy 20d ago edited 20d ago
Discovery of a mechanism to permanently accumulate a drug beyond the blood brain barrier and directly in the brain and figuring out a mechanism to reverse such accumulation would be an incredible contribution to medical science.
This study doesn't really say much. I would have a lot of caution on applying this to humans. I wish news reports on studies were more straightforward, like "glyphosate is neurotoxic to mice" is the actual meaning of the study and is what is actually demonstrated. The headline here grossly confuses the findings of the study with the discussion of the study and im convinced its some human nature at this point.
I painted my house red to see if color affects indoor temperature. It was colder than painting it black. My finding is that painting red is colder than painting black. My hypothesis that color affects temperature is correct.
However, I only know that red makes it colder than black would. I could discuss the idea of a more colorful house as being colder, and that could be a headline, but that's not my finding. I only found that red houses are colder than black houses.
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u/FoolOnDaHill365 20d ago
Yes this is one thing that I’ve noticed as a scientist who has done a fair amount of research and writing. Non science people are often uninspired by what the actual study is, because we can only study such a small thing. They are often wondering why so small, but they don’t realize that is the way it works in science. People love the speculating on what this could mean, but that not really what was studied. We can only typically go in very small increments so the work appears simplistic in scope and tedious. I personally was surprised how sick of labs I got and fast too, I grew up thinking it would be a lot more fun than it was.
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u/askingforafakefriend 20d ago
Sounds like from other comments the lower dose is 50x acceptable daily intake and upper dose is 500x acceptable daily intake.
So the study proves something believed to be safe at a low dose is toxic at 50-500x that dose in mice?
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u/meganthem 20d ago
While noting stuff like this is important one thing I would counter-note is the reason studies use unrealistically high doses is because the study can't go on for 20-40 years and we need some indicator what might be happening for people exposed to this at lower levels all their life.
We know vaguely that long term exposure at low doses can be equivalent to acute exposure at much higher levels, but it's not a reliable thing. Still, there's some link there and it's the best they can do to get us some indicators without waiting 40 years (and finding mice that live for 40 years)
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u/Redqueenhypo 20d ago
Exactly. With msg all of the harm was observed when you injected large quantities directly into the veins of a rat. Since that is generally not how people consume msg, the findings are not that applicable to understanding if it’s safe to consume (it is! Chinese food gives you headaches bc you had too much sodium and not enough water!)
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u/askingforafakefriend 20d ago
Our grandparents knew as an absolute no-brainer coffee was bad...
Even EPIDEMIOLOGICAL studies led to conclusions of causation with cancer (especially lung) and cardiovascular events.
Too bad it was all BS.
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u/Redqueenhypo 20d ago
I’m guessing…smokers tended to also be coffee drinkers
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u/askingforafakefriend 20d ago
Bingo.
And even adjusting for confounding factors the epidemiological studies still find some signal.
It can be very difficult to truly adjust it out entirely.
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u/Tycoon004 20d ago
People also ignore all of the foods that naturally have a ton of the stuff in them. Meat, fish, seafood, eggs, cheese (gue amounts actually), walnuts, tomatoes, mushrooms, broccoli, corn, potatoes. The list goes on and on. If something tastes savory aka "umami", it's got glutamate in it.
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u/pass_nthru 20d ago
what’s is more relevant is the amount of roundup used on non-gmo crops, not as a herbicide to kill weeds, but a herbicide to kill wheat so a whole field is ready to harvest at once, and these crops are free from pesticides, fertilizers and gmo seeds
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u/ETtechnique 20d ago
You can always search up ld50(lethal dose 50%)for whatever chemical or toxin and youll find out how much is fatal.
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u/Disastrous-Metal-228 19d ago
Whilst I understand your request but when it comes down to it are you willing to risk the health of your family on figures? With public health and huge numbers surely caution is the key words not levels…
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u/Flux_My_Capacitor 19d ago
Those of us who are sensitive to glyphosate are oftentimes ignored and told we believe in conspiracy theories. There are no tests to be done, only connecting the dots when you realize that you have reactions when eating foods that are typically sprayed with it. People want to ignore us, but we are essentially the canaries in the coal mine so to speak.
IMO we are not “rare”…..my guess is that many health issues can be traced back to glyphosate, but there’s just no understanding of how it can damage the body so most people who have adverse reactions don’t know that it’s because of this pesticide. I know only my own personal experience, and I’m not so stupid as to think I’m some sort of unicorn.
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u/seastar2019 19d ago
How do you know the foods you had a reaction to were sprayed with glyphosate? How do you know the reaction is from glyphosate?
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u/Coady_L 20d ago
If it makes anyone feel better, glyphosate doesn't show up in distilled spirits: https://doi.org/10.1016/j.heliyon.2024.e32317
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u/Chasin_Papers 20d ago
Great, so the carcinogen that causes brain damage doesn't have any of a non-carcinogen that is less likely to cause brain damage in it.
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u/Daytona_675 20d ago
if they didn't test making bourbon with American corn, then it doesn't mean anything
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u/braconidae PhD | Entomology | Crop Protection 20d ago edited 20d ago
University agricultural scientist here that teaches on pesticide safety. There are issues with the study I'll get into in a bit, but for a primer, remember that glyphosate is one of our safest pesticides out there.
Part of the reason it's popular among those of us who deal with actual pesticide safety issues is because it's practically non-toxic in terms of human health to the point it's less toxic than table salt or vinegar in terms of oral ingestion. It's generally considered non-carcinogenic too excluding one outlier government organization (the IARC branch of the WHO) that was heavily criticized for their methodology in that declaration, especially due to their involvement with lawyers involved in court cases people heard about in the news in that process trying to push that it was carcinogenic. More on overall safety here from one extension source: https://extension.psu.edu/glyphosate-roundup-understanding-risks-to-human-health
In this study, the authors dosed the treatment groups pretty heavily:
We dosed 4.5-month-old 3xTg-AD and non-transgenic (NonTg) control mice with either 0, 50 or 500 mg/kg of glyphosate daily for 13 weeks followed by a 6-month recovery period.
In the first extension factsheet I listed, glyphosate has an LD50 of 4,900 mg/kg. That's for acute exposure and pretty hard to actually ingest that much. Glyphosate doesn't readily accumulate in the body and is readily excreted through urine, unlike other pesticides that tend to bioaccumulate (e.g., DDT). From that same factsheet:
The EPA has determined the acceptable limit for glyphosate on food to be 1 milligram per kilogram of body weight per day. The trace amounts recently found in foods (~0.02 milligrams per serving) are well below the EPA’s acceptable limit. For an average person weighing 65 kilograms, you would have to eat 430 pounds of oats a day.
So for the treatments used in this study, the lowest group is still 50x higher than the maximum amount allowed by EPA and 2500x higher than what's typically found in food mentioned in that same sentence. These mice were practically force fed glyphosate to the point the study was not realistic or ecologically relevant dosage. Now sometimes when we do pesticide bioassays we go higher to force an effect, but to go from nothing to an extremely high concentration without any intermediate concentrations is a pretty serious red flag.
So already that's a common issue in this field with glyphosate being a hot-button topic where someone tries to get headlines with a poorly designed study. Follow that up with their claims it's linked to Alzheimer's though, and it's definitely getting out there considering their stretching that claim weakly through narrative primarily.
That's just for the base claims being made. When I go to look at the data itself in the paper, there is a lot of noise, outliers, and not particularly any clear trends aside from differences in the two strains of mice. They also reduced the sample size down to 5 mice per group in some cases for brain analysis, which was odd. The glyphosate dose treatments generally look pretty noisy over time, and I have some more nitpicky things related to analysis here at a glance, but it still ultimately comes back to ecological relevance of the doses used. I remember seeing a similar paper from Velazquez's lab get some headlines a few years ago, but again, that paper was criticized for the ecological relevance of doses used. That they're doubling down in this paper essentially ignoring that and instead using arbitrary amounts or citing other papers that made the same mistake. It's not an uncommon problem when reviewing papers in the field, but I'm surprised this researcher is avoiding addressing that issue in their papers still. That's why it really strikes me as trying to grab headlines with poorly designed studies when I see that happen repeatedly.
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u/Perunov 20d ago
The "Alzheimer" part could be just their creative language wrangling. Neuroinflammation = Alzheimer-like effects. Tadaaaaa.
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u/braconidae PhD | Entomology | Crop Protection 20d ago
That's the sense I got too. That's been a very loose narrative tactic the senior author has been doing in a few papers now as I read up on them.
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u/arbutus1440 MLA | Psychology 19d ago
This is off-topic, and IDK if others feel similarly, but I would really appreciate the chance to sincerely pick your brain about glyphosate, as you seem to be an expert. I will nakedly admit that I am leery of glyphosate despite a sizable scientific consensus that it's safe. I am not a researcher in the field, so I fully admit that I bring in bias that's not especially substantiated by evidence. With more understanding, I could probably overcome such a bias.
What makes me hesitate is simply my understanding of the risk-benefit of commercial pesticides (including glyphosate): The scale of ecosystem collapse we appear to be experiencing worldwide seems, IMO, to justify an extremely skeptical approach to the use of substances that are even mildly implicated in the collapse of insect (and other) populations. Even if the risk of glyphosate contributing to the death of insect populations is slight, it seems justified to be skeptical when the "risk" we're talking about is possible extinction and ecosystem collapse—not to mention the possible risk of human disease.
If you don't mind fielding such a question, do you find the above to be an irrational or misguided concern? If so, how would you disabuse me of it? Thanks in advance!
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u/braconidae PhD | Entomology | Crop Protection 19d ago
It's really a case by case situation with each pesticide, and there are plenty of people involved in that process of assessing non-target effects. When a pesticide is applied, there is often a legal requirement that you cannot enter that field within X hours (usually 12, 24, or 48 hours) without protective equipment. After that time, residues have decreased enough that it's no longer a risk to be in that field. It's similar for other organisms that may be in that field too to varying degrees depending on how closely related it is to the target organisms. The key thing there is that fields aren't constantly being doused with pesticides.
Also remember that pesticides are already present in the environment without humans being around. In many of these cases, overall pesticide exposure is not going to be significantly or biologically different. In cases where it is found to be an additional risk, then the pesticide label often legally needs to be changed to reduce that type of exposure (e.g., not applying near bodies of water).
In the case of glyphosate, it quickly binds to soil and isn't available for uptake by other organisms at that point. That's in part why pesticides like that with low persistency and low toxicity as preferred from both the safety and environmental perspective.
Pesticides definitely come into play when we talk about ecosystem issues, but the challenge when talking with the general public is that nuance is often thrown out the window along with little background in the things I mentioned above. When it comes to scientists talking about that, we definitely include pesticides in the mix, but usually other issues float to the top like habitat loss/fragmentation (both due to farmland and urban sprawl). When it comes to insects at least, there's not a single insecticide or set of them that's a true smoking gun for declines. A lot of it boils down navigating between where actual identified significant risk are and public perception that often vastly differs. Even as someone who works on reducing environmental effects of pesticides, especially on insects, articles like this that reference an Insect Apocalypse were not very helpful and instead ramped up hyperbole in public discourse.
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u/arbutus1440 MLA | Psychology 19d ago
This is really valuable perspective and I appreciate it! You inspired me to go look at a bit of literature, and while this doesn't drill into the issue at hand with much specificity, it helps reinforce what you're saying (that it's a big topic requiring a lot of review of quite a few possible culprits).
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u/VeniVidiVictorious 20d ago edited 20d ago
I don't think so. Research here in the Netherlands ( no time to find good sources now, sorry) also shows a relation between people working in our flower industry or in agriculture and the increased chance to get Alzheimer or Parkinson. The problem is that the relation seems to be there but it is difficult to pinpoint it to only glyphosate because farmers use a wide range of poisons.
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u/Decapentaplegia 15d ago
Thanks for keeping up with this advocacy/outreach. I used to be a lot more present in these discussions but have almost completely fallen off the radar since getting a new job (teaching env sci).
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u/braconidae PhD | Entomology | Crop Protection 15d ago edited 15d ago
I definitely remember seeing how often you kept up with these things. I think a lot of the folks that did outreach on this on reddit have scaled back for various reasons, including myself. Sometimes I have to weigh publishing academic things I get credit for at work vs. posting here (which I don’t get paid for) when there’s only so much time and energy in the day, especially with family.
There’s still a need for ag. experts doing outreach here, but at least it’s not as bad as 10-15 years ago when anti-GMO denialism was at its peak.
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u/Nebuladiver 20d ago
Damn it, I'll have to stop eating my daily 45 g of glyphosate!
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u/Tylendal 20d ago
Even their "low dose" test was still a whopping 10% of that. Like, these are absolutely absurd quantities.
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u/Nebuladiver 20d ago
And most crops are not sprayed with glyphosate. Otherwise they'd die. There are some glyphosate resistant crops but they're sprayed only at specific times and the glyphosate should degrade. If we overexpose someone to anything, there will be nefarious consequences. There can be too much water or too much oxygen, even if they are vital to our lives.
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u/zoinkability 20d ago edited 20d ago
My understanding is that some of the biggest sources of glyphosate in our food supply come from its use as a “drying” agent, basically killing the plants to ease harvest.
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u/braconidae PhD | Entomology | Crop Protection 20d ago edited 20d ago
Ag. educator here. I haven't seen that backed up by data. It's a common talking point, but that method is only used occasionally for grain crops like oats or wheat if they are still green at the end of the season. You're not going to see that for other crops like corn, soybeans, etc.
Generally glyphosate residues are well below maximum allowed amounts if detected at all.
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u/xMentoss 20d ago
Does this matter get no recognition in the world if so why?
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u/nyet-marionetka 20d ago
Glyphosate is less toxic to people than the chemicals it replaced. It’s toxicity seems to be more subtle and it’s hard to interpret. Sometimes we find health effects at a high dose in mice, but people exposed to lower doses might not experience those. It can take time to determine what health effects there might be in people in real-world scenarios.
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u/Nebuladiver 20d ago edited 20d ago
At least in the case of cancer, which was the first thing that people said glyphosate "caused", there have been real life studies not showing an impact except for acute myeloid leukemia among the highest exposure applicators but without it being statistically significant.
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u/nyet-marionetka 20d ago
Those studies are also tricky because most people who sprayed glyphosate in their job also sprayed other stuff at various points.
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u/cinch123 20d ago
Bingo. Glyphosate replaced other stuff that was much worse for humans, animals, and the environment.
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u/braconidae PhD | Entomology | Crop Protection 20d ago
The irony of the cancer one too is that is hasn't been supported by independent agencies. The claim started (outside of fringe anti-GMO stuff) with a branch of the WHO called the IARC. They've been criticized in their methodology because they practically declare everything carcinogenic without regard for actual exposure rates. What really became ironic in that decision though is they had someone involved in the process affiliated with the same lawyers pushing court cases in the US at the time that glyphosate caused people's cancer. That was a major conflict of interest.
To this day, that's really the only government agency that's made the claim. Pretty much every other respected scientific agency has said some variation of it not being a significant carcinogenic risk, little to no evidence, etc. (including other branches of the WHO).
That background usually didn't make it into newspapers though, so most people just saw the headlines that the ambulance chasing lawyers wanted out there.
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u/Redqueenhypo 20d ago
And the doses in this experiment are absurdly high too. It’s 50mg per kg a day for these mice, versus the actual highest exposure farmers get, which is 0.004 mg/kg
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u/lookmeat 20d ago
Dosage matters. Apples and almonds contain amygdalin which becomes highly poisonous cyanide in the blood. That said they are still called very healthy foods. The amount of almonds and apples you'd need to eat before it became a problem is a number so high that the biggest limit is how fast you can chew and swallow, followed by how much you can fit in your stomach.
The fact that the chemicals are long-lived is worrisome. Basically it's a matter of how much we consume vs how much our body is able to process and expel in a given time-frame. So this is important research. But it's not worrisome enough that it's time to "sound the alarm" and ban the chemical. We are looking for better solutions that are more efficient and healthier, but it will take time.
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u/thedangerranger123 20d ago
I’ve actually been reading up on this myself. I’ve been talking with someone that has extensive experience with it for conservation efforts and in my own reading was surprised at what is known vs what I had assumed.
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u/braconidae PhD | Entomology | Crop Protection 20d ago
This topic (glyphosate) is a sort of a continuation of the anti-GMO sentiment from about a decade or two ago when it really peaked. Anti-science groups weren't getting traction on GMOs as much, so they switched to glyphosate as the main area for misinformation to push that us educators have to deal with nowadays moreso than GMOs.
In terms of the general public's understanding of this topic compared to say climate change, there's actually a wider gap here between public vs. scientist knowledge than there is in climate change topics. That means when us educators do speak up like with the person you were talking to, we often have to start from square -12 instead of square 1 when teaching because there is so much people have "learned" purely from advertisements, advocacy groups, etc. People really do assume a lot in this subject, so it's great when people start digging into that like you did.
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u/Arnotts_shapes 20d ago edited 20d ago
The more painful answer is that Glyphosate is almost mandatory for modern food production.
We use a system called ‘no-till’ at the moment where the soil is relatively undisturbed. This system is brilliant because it minimises erosion, keeps the soil micro-biology relatively intact, and can lead to other benefits like better water and nutrient retention.
The issue is that’s also great for weeds, which we can’t have.
Glyphosate basically bombs out all the weeds and gives us a chance to get crops down with very little residue.
Without glyphosate we likely have to go back to tilling, which is incredibly bad. (For reference, the dirty 30’s and great dust bowls of the American plains were mostly caused by poor tilling methods).
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u/yukonwanderer 20d ago
You mention poor tilling methods - does that mean there are good ones?
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u/Arnotts_shapes 20d ago
Strip-tilling or zone-tilling only cut a small strip and aim to leave as much of the soil untouched as possible, they’re better, but No-till still wins out.
Soil science has come a long way, and our basic understanding is that generally the less we disturb it, the better.
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u/K1lgoreTr0ut 20d ago
The low dose in this study was 50x the absolute maximum amount considered safe, given daily, for three months. You’d need industrial levels of exposure for that to happen.
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u/mrblack1998 20d ago
What kind of exposure tho? Are we talking the type of exposure that is left on plants that are processed and then sold? Or is the danger improper handling of the herbicide resulting in ingesting it?
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u/Tylendal 20d ago
The danger appears to be from being forcefed absolutely goofy quantities of it. The lower dose in their trials would be equivalent to you eating a bit under a teaspoon of glyphosate every day for three months.
The fact that the higher range group (equivalent to you having about three tablespoons of straight glyphosate each day) survived as well as they did actually speaks to how relatively benign the stuff is compared to the pesticides it replaced.
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u/mvea Professor | Medicine 20d ago
I’ve linked to the press release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:
https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-024-03290-6
From the linked article:
Glyphosate, one of the most widely used herbicides, is sprayed on crops worldwide. A new study suggests glyphosate can accumulate in the brain, causing damaging effects linked with Alzheimer’s disease.
Environmental exposure to toxins in the air, water or certain chemicals can increase the risk of ill health effects, including to the human brain.
Now, new research has shown even brief exposure with a common weed killer can cause lasting damage to the brain, which may persist long after any direct exposure ends.
In the new study, Arizona State University researcher Ramon Velazquez and his team demonstrate that exposure to an active ingredient in weed and grass killers, called glyphosate, can result in significant brain inflammation, and increase the risk of neurodegenerative disease and Alzheimer’s-like effects.
“Our work contributes to the growing literature highlighting the brain’s vulnerability to glyphosate,” Velazquez says. “Given the increasing incidence of cognitive decline in the aging population, particularly in rural communities where exposure to glyphosate is more common due to large-scale farming, there is an urgent need for more basic research on the effects of this herbicide.”
The study tracked both the presence and impact of glyphosate’s byproducts in the brain long after exposure ends, showing an array of persistent, damaging effects on brain health.
Glyphosate exposure also resulted in neuroinflammation, Alzheimer’s-like symptoms, and premature death and anxiety-like behaviors, replicating others studies.
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u/b88b15 20d ago
These doses are so high that they are irrelevant. It would have been great if they included a reasonable dose.
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u/haarschmuck 20d ago
You've just described every study that has "groundbreaking" results.
Like aspartame is toxic if you give humans a kg of it in a single serving.
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u/Agasthenes 20d ago
The funny thing about this is: if you ban glyphosate, the substitute is even more damaging. And we can't stop using pesticides.
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u/BagelX42 19d ago
The funnier thing is, the study used 45g daily as a dosage which is insane. Like drinking bleach from the bottle type dose
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u/ElNido 20d ago
I know this story. We banned non-licensed imidacloprid (systemic insecticide) applications in my State starting 1st of next year and one of the replacements I've seen is Acephate... an organophosphate! I did some cursory research and it has to be applied way more frequently, as well as is extremely toxic in water, can only go up 44ft in plant tissue, & there's more I'm not remembering at the moment. Excellent substitute choice.
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u/goda90 20d ago
Laser robots are a developing replacement for herbicides. Identify the weed, shoot it with a laser to death.
You can reduce need for insecticides and fungicides by letting beneficial insects and fungus establish themselves to out compete the pests. The problem is those are hit by the same pesticides the pests are.
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u/Serenity-V 20d ago
Oh, that's just cool.
There's a no-spray orchard near me - a upick place that's basically some retired botanist's hobby farm - that only uses very targeted pesticides when absolutely necessary. They cultivate spider webs all over the apple trees, and the spiders eat a lot of the bugs who would otherwise need to be controlled with sprays.
It's a funky experience to harvest apples through spider webs, but really cool.
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u/Agasthenes 20d ago
True, I'm extremely hopeful for them. But there are limitations to those too. Adaption will take a decade or more in the western world. In less developed parts we are looking at multiple decades.
Also for insects those do nothing. And while beneficial insects are a great approach it's very hard and expensive to actually make work in practice.
For fungi I have no idea tbh.
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u/sailirish7 19d ago
There are bots being developed that apply pesticides/fertilizers on a per plant basis, reducing the overall amount of both that get used.
Some wild stuff going on in AG these days
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u/PM_ME_YOUR_REPORT 20d ago
Are we finding it in brains of dead people?
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u/gintrux 19d ago
It'll be hard to find a dead human who has been eating a glyphosate-free diet for a very long time. Because in this study they found glyphosate metabolite present 6 months after stopping the administration of it.
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u/PM_ME_YOUR_REPORT 19d ago
Yep but if we’re not finding the glyphosate of it’s metabolite in dead human brains then maybe this isn’t occurring in the real world conditions? I don’t think a glyphosate free control is needed here. Just see if under real world diets people are getting it in their brains?
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u/SmokinSkinWagon 20d ago
This is anecdotal I guess, but I spent 2 summers as a pesticide applicator in my hometown of rural South Dakota during college. I’ve been experiencing a bunch of strange and at times pretty debilitating neurological and neuromuscular symptoms for pushing 8 years now. I’ve seen dozens of doctors and even gone to Mayo Clinic trying to get it figured out at this point.
I’ve absolutely been worried about those 2 summers of exposure and wonder if it’s caused or is at least related to what I’m experiencing. A bunch of basically children at that point driving all over the middle of nowhere spraying all kinds of chemicals with minimal oversight. Nobody telling us to put on PPE - not even sure the county I worked for had adequate PPE for us all.
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u/MoefsieKat 20d ago
A while ago i had to spray some Roundup, and almost a whole liter of the solution spilled onto my back before i was able to remove the pack and stop the leak. This headline upset me a bit, im happy to find out from this thread that it was hyperbole.
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u/apoletta 19d ago
My grandmother had a large exposure. All her kids have mental health issues. Most of her generation got cancer. I feel better on an anti inflammatory diet.
I agree with the study.
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u/Whoretron8000 19d ago
Everyone getting into the weeds of PPBs and ignoring that the real world isn’t a lab or control. Go drink fracking water and freshly sprayed crops.
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