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DBL%20Hendrix%20small.png College chemistry, 1983

Derek Lowe The 2002 Model

Dbl%20new%20portrait%20B%26W.png After 10 years of blogging. . .

Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases. To contact Derek email him directly: Twitter: Dereklowe

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June 11, 2014


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Posted by Derek

I noticed some links to this post showing up on my Twitter feed over the weekend, and I wanted to be sure to mention it. There's a recipe for "all-natural" herbicide that goes around Facebook, etc., where you mix salt, vinegar, and bit of soap, so Andrew Kniss sits down and does some basic toxicology versus glyphosate. The salt-and-vinegar mix will work, it seems, especially on small weeds, but it's more persistent in the soil and its ingredients have higher mammalian toxicity (which I'm pretty sure is the opposite of what people expect).

I hope this one makes a few people think, but I always wonder. The sorts of people who need this most are the ones least likely the read it, and the ones most likely to immediately discount it as "Monsanto shill propaganda" or the like. I had email like that last time I wrote about glyphosate (the second link above) - people asking me how much Monsanto was paying me and so on. And these people are also not interested in hearing about any LD50 data (which they probably assume is all faked, anyway). They're ready to tell you about long-term cancer and everything else (not that there's any evidence for that, either).

Going after this sort of thing is a duty, but an endless chore. I was also sent a link to an interview with some actress where she talks about her all-natural beauty regimen - so pure and green and holistic, and so very expensive, from what I could see. One of the things she advocated was clay. No, not for your skin. To eat it. It has, she explained, "negative charge" so it picks up "negative isotopes". Yeah boy. You'll have heard of those, maybe the last time you were And of course, it also picks up all those heavy metal toxins your body is swimming in, which is why a friend of hers told her that she tried the clay, and like, when she went to the bathroom it like, smelled like metal. I am not making any of this up. A few comments on that site, gratifyingly, wondered if there was any actual evidence for that clay stuff, but most of them were just having spasms of delight over the whole thing (and trading obscure, expensive sources for the all-natural lifestyle). So there's a lot of catching up to do.

Comments (27) + TrackBacks (0) | Category: Chemical News | Snake Oil | Toxicology


1. DCRogers on June 11, 2014 9:14 AM writes...

What a loser, everyone knows that the negative charges in clay pick up the *positive* isotopes!

The negative isotopes are excreted in the urine, duh.

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2. Chembry on June 11, 2014 9:21 AM writes...

WOW!! The knowledge, or lack thereof, about science in the general public never ceases to amaze me!

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3. Jeff Peterson on June 11, 2014 9:30 AM writes...

Yes, "spasms of delight" from down below as they pass the soil microbes and metals they've just ingested.

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4. DrugDeviser on June 11, 2014 9:31 AM writes...

Yes, "spasms of delight" from down below as they pass the soil microbes and metals they've just ingested.

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5. Dr. Ozz on June 11, 2014 9:33 AM writes...

"Nearly all chemists can stand adversity, but if you want to test a chemist's character, tell him dirt cures cancer."
-Abraham Lincoln

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6. Dr Manhattan on June 11, 2014 9:38 AM writes...

Derek, you left out mentioning the Vitamin D part "down there" and places where the sun doesn't normally shine. I also really liked the company that shipped products in a "mindful way with zero emissions". They walk it your house??

Stunningly ill-informed in so many ways! Looks to me like an infomercial (more like disinfomercial) for a number of small "Natural" product companies. Bet she got paid.

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7. Hap on June 11, 2014 9:51 AM writes...

Walking it probably isn't zero emissions either, particularly if it's a reasonable distance. I don't think they could hold their breath for that long for starters.

She may not have needed to be paid - people are willing to go long distances for ideas and beliefs, and it seems like the worse the idea, the farther people are willing to go.

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8. CMC on June 11, 2014 10:01 AM writes...

After reading the ingredients in a Eco-friendly plant killer being vinegar I have been using kitchen grade to eliminate volunteer growth in the cracks in my driveway. It is effective but empirically appears less concentrated as requires multiple doses vs dedicated plant killer but based on cost (especially of bulk no-name vinegar). Assume adding salt and soap would make more active but as indicated I am concerned NaCl can be persistent and fear run off into area I am attempting to have grass. Wish I still had access to a lab and would borrow some concentrated AcOH for hitting certain aggressive weeds.

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9. Dr Manhattan on June 11, 2014 10:08 AM writes...

Hap, yeah, I thought about the walking part also having emissions, but it was too good to pass up as a snarky comment. Since we are scientists, we know there really is no way, thermodynamically, to move objects without some energy and emissions. Maybe they use those negative charges to eliminate emissions??

Everyone who reads this blog and becomes ill goes to the doctor, and doesn't ask their taxi driver for medical advice. ("Say, Mr. Bickle, what do you recommend for cardiac arrhythmia?")

Following her advice may actually may work out better for the human race in the long run, as people who actually use her recommended "products" will become Darwin Awardees, eliminating themselves from the gene pool.

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10. DannoH on June 11, 2014 10:14 AM writes...

Pour straight bleach on your weeds. It kills them dead too, and really cheap. And you can do your your white laundry with it! Also if you mix a little with the natural pond water you drink you are less likely to get the runs. Win Win Win!

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11. oldnuke on June 11, 2014 10:30 AM writes...

Pour sodium arsenate on the weeds. Hey, arsenic comes out of the ground, that makes it natural, right? gr

Bet the weeds are dead for 25 years or so, like the old Triox vegetation killer used to do.

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12. Semichemist on June 11, 2014 10:58 AM writes...

Wondering if the "metal" smell had anything to do with GI bleeding caused by eating friggen clay. Best make sure that stuff is food-grade first...

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13. molecular_architect on June 11, 2014 11:54 AM writes...

I have an even better one for you. According to Gwyneth Paltrow, water has "feelings". She has a coffee table book filled the the research of some "scientist" to back her up!

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14. Anon on June 11, 2014 12:52 PM writes...

Does Play-Doh count? It says 'non-toxic'...

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15. dave w on June 11, 2014 1:15 PM writes...

I remember seeing a package of "organic bentonite" intended as a "mud pack" for skin application - I'm not sure of the benefit of applying bentonite - i.e., finely divided SiO2 - to the skin, but with respect to the "organic" term, there's no way it can apply....?!

(It's not "organic" in the general sense of "derived from biological sources", or in the chemist's sense of "cotains covalent carbon", or the agricultural sense of "raised without using chemical pesticides" - it's basically powdered rock!)

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16. Colonel Boris on June 11, 2014 2:17 PM writes...

Black Spider Monkeys clearly bought into this idea:
Negative isotopes would be awesome, though. I'm assuming they have negative mass and can help power an Alcubierre drive.

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17. metaphysician on June 11, 2014 2:45 PM writes...


Sure as hell isn't non-toxic to *me*. Crack open a can of Play-Doh in the same room as me, and I'm sneezing in seconds.

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18. Moody Blue on June 11, 2014 3:20 PM writes...

Yes those negative charges in the clay also have negative mass and thus is very effective in weight loss treatment!

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19. Anonymous on June 11, 2014 3:26 PM writes...

Eating clay has been around for a long time.

That's the small slap upside the head for the so-called scientists writing the comments above. Clay eating, as practiced by spider monkeys, macaws, and a number of Andean peoples, and others is reported about binding various alkaloids in your food (e.g. bitter potatoes in the Andes) to the clay, so that you don't get poisoned. You've obviously got to pick the right clay so you don't poison yourself with all the cations bound to the clay, but if you've got the right stuff, it will help you stay alive and get nutrition out of plants that are otherwise poisonous.*

As for the actress, of course her claims are all, well, crap. She's taken a real thing, pulled it totally out of context and started experimenting with it. Of course she got it wrong, but I'm a little surprised that people who get paid to do much the same thing (anyone here a natural products chemist?) are heaping scorn on her, rather than pointing out what's wrong with her recommendation and where it might be worthwhile.

*why eat poisonous potatoes and other poisonous plants? Again, IIRC, the bitter potatoes grow better at higher altitudes, so they are a useful crop at really high altitude, but only if you've got the clay to help get their load of phytotoxins down to subclinical levels. As for how macaws and monkeys figured the trick out, well you've got me. I guess they have a better experimenters than, say, actresses are. Or something.

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20. Hap on June 11, 2014 3:45 PM writes...

People here talked about montmorillonite clay as a catalyst for acetal/ketal cleavage under mild conditions, so if it acts as a mild solid acid, and the alkaloid salts get sequestered inside the clay instead of your stomach, that would make sense. You'd probably have to be somewhat careful where you got it, though, since if it contained heavy or toxic metal ions, then you might be trading one poison for another. Depending on the alkaloid, that might still be a good trade if you couldn't avoid eating the potatoes.

I guess doing it now would depend on the identity of what you were looking to remove. Here, I would assume most contaminants are nonpolar, and so it probably wouldn't do much good, and could hurt if the clay has toxic metals in it.

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21. a. nonymaus on June 11, 2014 5:12 PM writes...

I guess they like their Kaopectate old-school. At least the eventual X-ray of their impacted colon will have nice contrast.

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22. AussieChemist on June 11, 2014 7:34 PM writes...

Hi All,

Whilst I agree on the overall issue being raised here I don't think the website assessing the two mixtures has appropriately used the toxicity data. The number quoted for acetic acid is for GLACIAL acetic acid. The fact that the acetic acid is anhydrous is likely what results in the toxicity not that it is acetic acid (compare dermal vs oral). Glacial acetic acid is not vinegar. Though no one is likely to drink the equivalent in vinegar the same comparison could be used for toxicity of phosphoric acid vs drinking coke.

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23. WyoWeeds on June 11, 2014 8:51 PM writes...

Hi AussieChemist,
I'm the author of the original post comparing the vinegar mix with glyphosate. You make an excellent point that I hadn't thought of, and it made me pretty nervous that I was spreading misinformation... So I did some re-calculating. It took a fair bit of looking to find an MSDS with toxicity values for a 5% vinegar product, but I did find one here:

The LD50 for an already mixed 5% white vinegar solution is listed as 66,200 mg/kg. This is dramatically greater than the glacial acetic acid; however, when you account for the amount that is applied (an entire gallon), things come out pretty much the same for the acute oral toxicity as I calculated earlier.

1 gallon of a 50 grain white vinegar weighs ~8.3 lbs at room temperature, or 3.76 kg. 3.76 kg of the 5% white vinegar would be enough to kill 56 rats (only slightly different than the 59 rats calculated from the glacial acetic acid).

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24. AussieChemist on June 11, 2014 9:27 PM writes...

Hi WyoWeeds,

Thanks for the update as I, like you, don't want to be spreading misinformation. I'm not toxicologist but this still doesn't seem right to me. This new toxicity number assumes toxicity due to chemical nature of acetic acid rather than the anhydrous nature of glacial acetic acid. The updated value doesn't account for this as it appears to be obtained by the simplistic view - 3310/0.05 = 66200 mg/kg likewise the dermal number for the rabbit 1060/0/05 = 21200 mg/kg. Practically put 100mL of vinegar poured on your skin will yield quite different results to 5mL of glacial acetic acid poured on your skin. Same amount of acetic acid but markedly different results (Please don't try this). Same goes for ingestion.
What this all says about the MSDS you found I'm not sure.

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25. dearieme on June 12, 2014 9:41 AM writes...

As our civilisation sinks, the wise can do little except chuckle at the antics of the foolish.

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26. Scarodactyl on June 12, 2014 10:24 AM writes...

@15: Bentonite isn't made of silica (SiO2), it's made of clay minerals, mostly montmorillonite ( (Na,Ca) 0.33 (Al,Mg)2 (Si4O10 )(OH)2 ┬ĚnH2O).

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27. Matt on June 12, 2014 8:41 PM writes...

Acetic acid is actually a fine non-specific herbicide, in 20% concentration or thereabouts. You can buy it already at that concentration for application at some horticultural suppliers. It's fast acting and non-persistent in the environment, though that is also a major limitation -- no sustained action.

Some experimenting around the yard shows that other light aliphatic acids, e.g. formic and propionic, are also very effective. Presumably acetic is sold for this purpose because it's cheap, familiar, and there is no major change in effectiveness switching to other acids.

Salt, on the other hand, is not only effective in killing weeds but in ruining the soil for a lifetime. It's about as "green" as heating your home by burning old car tires.

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