In an interview Dr. Patrick Moore claimed that:

You can drink a whole quart of it and it won’t hurt you.

He then declined the offer to drink a glass of the herbicide to prove his claim, saying:

No. I’m not stupid

Given the fact that Roundup can contain from 2 to 50% of Glyphosate, we are talking about roughly 20-470gr of glyphosate.

  • Would drinking a glass of glyphosate have no harmful effects at all? (be it short term or long term)
  • Have there been any studies with such large doses?
  • Are there any cases of humans ingesting such large doses, and if so, what where the effects?
  • Is this a duplicate?
    – Oddthinking
    Sep 29, 2015 at 12:19
  • 3
    @Oddthinking The question you're linking to is dealing with long term exposure, while this one IMHO questions the acute toxicity of glyphosate. I found a study, which I think answers this question much better than the answers in the question you're linking to. Sep 29, 2015 at 12:31
  • @Oddthinking I had read it before I post this, but it doesn't address huge doses (be it lab tests, or suicide attempts). While its title asks about effects on mammals in general, the question itself is focused on bioaccumulation. My question is focused on acute dose. While an answer in the proposed duplicate mentions large doses to rats it has no mention of human cases. Overall they are somewhat similar questions, but i dont think they are duplicates (the second answer in proposed dupe only tangentially addresses this question).
    – user
    Sep 29, 2015 at 12:40

1 Answer 1


There are several studies examining the intake of glyphosate, in many cases even deliberate intakes as a method of suicide. Most of these studies are not freely accessible (behind pay-walls), but in the abstract of the following study, you can find some numbers:

Acute poisoning with a glyphosate-surfactant herbicide ('Roundup'): a review of 93 cases.

  • The smallest amount of a 41% glyphosate solution leading to death was 85ml. If I get my math right, this should be about 60g of glyphosate and must hence at least be considered as a potentially fatal amount.
  • There are however also reports of ingestion of 500ml 41% glyphosate solution (about 350g) leading to nothing more than mild to moderate symptoms.

I don't have any sound right now, so I am a little but unsure about the amount he claimed to be able to drink. You quote it as 'a quart' (946ml), the subtitles translate it with 'a large glass' and your calculations of the amount of pure glyphosate do not match up.

In any case, since we are roughly within the same amounts that are mentioned in the study: Drinking a glass of glyphosate may give you anything from a sore throat to a lethal reaction.

  • 7
    Is it the glyphosphate, or is it whatever is mixed with it? For such wildly disparate effects, maybe the confounding factor isn't the thing they are researching. Water is safe when mixed with sugar, but not so much if mixed with arsenic.
    – JasonR
    Sep 29, 2015 at 12:43
  • You are right. I mistakenly assumed 1 quart = 1/4 of a litre (while it's 1/4 of a gallon). I will edit accordingly.
    – user
    Sep 29, 2015 at 13:02
  • 1
    @Tor-EinarJarnbjo Yeah isn't that where LD50 comes in?
    – ryanyuyu
    Sep 29, 2015 at 14:32
  • 3
    @Tor-EinarJarnbjo I believe user1955's point is that your answer makes it sound like it is strictly the glyphosate that causes the issue, while the abstract you link is clear that it's a glyphosate-surfactant mixture which was consumed. Toxic effects might be due to surfactant rather than glyphosate (hence different surfactants in different cases might lead to different outcomes). Or by analogy, you can't necessarily conclude anything about the safety of water itself by learning people had adverse reactions to a water-arsenic mixture.
    – R.M.
    Sep 29, 2015 at 14:46
  • 1
    As others have mentioned, other additives might be the cause of lethality. Unless that scenario is ruled out, there can't be a definitive conclusion that glyphosate is the cause of death. "surfactants probably contribute to the acute toxicity of glyphosate formulations,"
    – user
    Sep 30, 2015 at 10:40

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .