Other "sources" (using the word loosely as their providence is unclear)
> "based on the information available, this was a localized issue with only one student directly exposed. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury." [1]
Karen Wetterhahn's exposure and death [3] is a cautionary tale of the extreme toxicity of dimethyl mercury, and was instrumental in new safety recommendations, including strongly discouraging the use of dimethyl mercury for any purpose.
Yes, dimethyl mercury is terrifying stuff - it killed Karen Wetterhahn from a few drops that went _through_ the gloves she had on:
> The case proved that the standard precautions at the time, all of which Wetterhahn had carefully followed, were inadequate for "super-toxic" chemicals like dimethylmercury
Sufficiently pure dichloromethane is also fun stuff. It just eats through most any gloves, plastics, whatever. Even PET, and only polyethylene is somewhat resistant.
LD50 about 2mg/kg oral. By oral it's meant that well.. if you soak your hands in it it will be worse.
Still it's the goto thinner for f/ex gluing ABS. I have a couple liters sitting on the shelf right beside me.
You may also be thinking of phosgene, which actually contains no phosphorous at all. But it is extremely toxic see the LC50: https://en.wikipedia.org/wiki/Phosgene
This is not true, and choosing the LD50 of Melathion to represent organophosphates as a whole seems odd. He was probably thinking of nerve agents or perhaps pesticides. Take a look at the LD50's of the former. These are among the nastiest, most lethal substances known to man.
Yes. See for example any number of nerve agents such as VX. https://en.wikipedia.org/wiki/VX_(nerve_agent). Yes, you can quibble over whether they count as "phosphates" given they often have fluoryl or other substituents, but the class is generally referred to as organophosphates, and they certainly have phosphorous in them. Malathion, is also an organophosphate which acts via the same pathway, but only in insects.
There was a time not so long ago when it was common for chemistry teachers to show off pools of mercury in their bare hands.
By the time I first took chemistry classes, though, that practice had stopped, less out of concern of exposure to liquid mercury and more for accidental exposure to gaseous forms due to spills.
When I was in highschool in the 1960s mercury in the chemistry lab was commonplace.
One way to familiarize students with mercury was to have several liters of it in a wide open-top jar and have them force their fist through the mercury pool to the bottom of the jar.
In fact, forcing one's hand through mercury between six to eight inches deep is not easy, some kids found it too difficult to do.
I'd describe my hand as feeling very squeezed and it being forced upwards to the surface with considerable force. The experience was certainly unforgettable.
There were some safety protocols: good ventilation (to minimize Hg vapor) and afterwards hands had to be thoroughly scrubbed with soap and water.
His "Things I Won't Work With" series on Science (https://www.science.org/topic/blog-category/things-i-wont-wo...) is fun to read. The link in the article itself now unfortunately just points to the science.org homepage so you have to do some clicking around to get to this blog series.
> One problem with this subject is that it tends to lead to bragging contests about who has run the most hazardous reactions. But think about it: if these reactions have all been run for good reasons with the best protective equipment there is less to brag about. And if they haven’t, then the discussion turns into figuring out who has been the biggest fool
I suspect the answer is "bragging rights" in this case.
Fans of this series - and folks who are generally in this post's comments - are likely to enjoy Larry Niven's short story "A Tall Tail": https://reactormag.com/a-tall-tail/
Back in 1998, I scored a consulting job at a silicon plant outside of Salem, OR. Now I was working as a systems admin and I was expected to be responsible for the computer systems, which were basically located in the normal offices, rather than a dedicated machine room floor.
However, since it was an active silicon manufacturing plant, all employees and contractors were obligated to complete safety training sessions. And I swear now that these safety sessions were designed to weed out the faint-hearted guys who weren't serious about supporting this silicon brand.
The safety sessions were simple lectures, with some handouts and PowerPoints, and some of the chemicals they described were absolutely insidious stuff. They were colorless, odorless, and some could melt or disintegrate bone without noticeably affecting the skin or muscles. They said you would just end up with a limp and useless appendage if you spilled some of this stuff on you. Other stuff was highly toxic and you didn't want to breathe anything. Basically it was a big warning to just stay out of the manufacturing floor, especially if we didn't know what we were doing.
I never went near the manufacturing floor. It was a pretty cool job and I wish I lasted longer there. They couldn't scare me away with a safety session, since my Dad had worked for decades in Environmental Health and Safety. Dad knew all about the nastiest stuff and he was always responding to hazardous laboratory accidents. Dad made us the safest home in our ZIP code.
I think Hydrofluoric acid is probably the substance you're describing which leaches the calcium out of your bones. It will certainly burn you too though. It's a common byproduct from heating fluorinated gases and is sometimes used in its own right for wet etching.
As an aside, I love it when they tell you in the safety WBT what the highly toxic gas smells like.
For lower concentrations (< 50%) HF burns aren't always immediately visible (and often not immediately painful), which can delay treatment as people may assume it's not serious.
Rechargeable lithium batteries pose a higher risk than single-use lithium batteries. Only the rechargeable ones have a thermal runaway hazard.
Single use ones too can contain fluorine, but not the runaway risk. Nevertheless, they require significant care to avoid shorting during storage. Never store them lose or where they can contact each other.
Sounds like something I remember from chemistry class but I can"t remember exactly what it was (this was several decades ago now), I think it was sometimes used for etching glass, but if it got into your body -- I'm not sure if getting it just on your skin was necessarily a lethal hazard -- it would leech the calcium from your bones and was considered an especially nasty way to go. Our prof was helping her father in law clean out his garage and he had a bunch of it in a container, bought in the 60's or 70's for a glass etching kit, and was like "Okay I'm getting rid of this, but have you got any other hobbies you've been meaning to get around to that I should know about?".
Some places would mix it with nitric acid so the yellow stain would tell you that you had been exposed.
Other fun chemicals used in fabs were Silane (CSi4), methane w/ silicon instead of hydrogen, used to form a silicon dioxide layer for etching* w/ HF and final step of protection. It would spontaneously combust on contact with air, so when you popped a tank fitting it would leave a white powder residue. Silicon dioxide is used as a food additive so AFAIK that wasn't dangerous.
Phosgene was also used as a dopant. If the alarm for that went off you really got out ASAP.
Arsine was a dopant also.
This is what I sort of remember from working on slacker job in silicon fab a long time ago when the number of transistors per chip was 1. I did say a long time ago.
* You could also just oxidize the outer layer of the silicon wafer itself w/ water vaper at high temps.
Silane is like Methane, but with Silicon instead of Carbon (SiH4). Thanks god for doping was used Phosphine (PH3) and not Phosgene (COCl2), both are nasty, but the second is more. Plus I don't know how much is used, since nowadays doping is typically done by ion implantation rather than gas diffusion
Out of curiosity, does this reset/modify the timestamps of the old posts? I was confused at reading comments from "hours ago" I thought for sure I'd read days ago.
Sorry for the confusion—I know it's weird but the alternative turns out to be even more confusing and we've never figured out how to square that circle!
Note that it seems increasingly unlikely that it was actually synthesized.
> Emerging information calls into question whether this compound was in fact synthesized.
> while the student remains under medical supervision, their initial blood test result, which was received today, shows no sign of exposure to mercury.
Imagine thinking you'd killed yourself, and then breathing the intense sigh of relief when you realize you're bad at chemistry and you didn't manage to synthesize the compound correctly.
Plausible scenario from a comment in the science.org post linked in another thread:
> If the MIT student was doing some work with reactive stuff and mercury and got an unknown result well outside expectations out of the output they were expecting i can see them struggling through working out what it could be, coming to the conclusion Dimethylmercury was possibble as an accidental side product of what went wrong, and just pulling all the emergency handles to be safe. Given how nasty that stuff is that is exactly the kind of reaction to such a scenario you'd want someone to have.
Can someone who knows a thing or two about chemistry explain why one would need to synthesize or purchase this chemical. Given that it involves a student I'll take "because of bragging rights to impress everyone" as a valid response, but wondering if it has any value is otherwise? Is it one of those "well despite its danger it's still the best at X, Y and Z and nothing else comes even close"?
I forget the guy's name, but he writes entertaining articles about chemistry things he'll never mess with. I wonder if Dimethyl Mercury is one of them.
Edit: reading further down the comments, Derek Lowe is guy.
It can be something as simple as an analytical reference.
If you’re testing for dimethyl mercury in say fish, you need a standardized sample of dimethyl mercury to run.
These references are highly dilute and thus less hazardous. But some labs prepare their own references rather than buying them.
That requires working with pure dimethyl mercury.
The hazard is manageable as long as you’re prepared. Chemists work with lots of hazardous chemicals and it can all be managed with the right preparation.
Sadly old.reddit.com has started requiring a login now. It worked for me up until today. Another site off the reading list, unless someone knows a workaround (I tried deleting cookies).
> "A message sent out from the chair of the department of chemistry at the school identifying the substance in question:"
> "“Dear Chemistry Colleagues,"
> "I am writing to provide an update on efforts to reopen Building 18 safely."
> "A specialized team from Triumvirate Environmental worked overnight on decontamination efforts in the building. This work includes wipe-downs of relevant surfaces in the lab and common areas, as well as the safe disposal of items that may have been contaminated. Decontamination work will continue throughout the day, and the building will remain closed until the work is complete."
> "In addition to our health and safety experts, we have been working continuously with staff and colleagues from departments across the Institute. Our highest priority is community safety, and we continue to make decisions accordingly and gather as much information as we can."
> "It remains the case that, based on the information available, this was a localized issue with only one student directly exposed, and this student was the individual working with the compound. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury."
> "I want to reiterate that, based on the information available to me, our industrial hygienists, MIT Health medical experts, and other resources we've consulted, the risk of secondary or tertiary exposures remains low, given the compound's characteristics and the information available to us."
> "Please feel free to reach out with questions. I will continue to provide regular updates as we learn and have more to share."
Seems the initial reporting may have been misleading. There was apparently *no* dimethylmercury exposure, after all: and MIT doubts it was synthesized in the first place.
Oh thank goodness. I was honestly shaken just thinking about how horrifying it would be to be a college-aged student who managed to expose themselves to dimethylmercury. Even if they were doing something stupid and reckless, that's a horrible way to go.
She had very high levels of mercury in her blood, and all attempts at chelation therapy to remove it were ineffective. That’s surely because it had spread throughout her body by the time the problem was recognized, but frankly no one can be sure if there were any measures that could have been effective enough after the initial exposure.
Is this accurate? I read the original Wetterhahn report (it's the first search result on Google) and chelation did appear to reduce whole blood mercury, but didn't do anything for the CNS exposure.
That would be important because it suggests immediate Succimer treatment could avert fatal CNS exposure (it takes hours/days for the blood/brain transfer to occur, apparently).
There are also some studies suggesting that the amount of excess mercury in fish compared to selenium may be more relevant than the absolute mercury concentration in causing potential toxicity.
Dimethylmercury evaporates to a known degree. Way way more than elemental mercury.
To detect elemental mercury vapor, the air is drawn in to a controlled chamber where if present it amalgamates with pure gold as the reference (zero) material, and determined electronically.
I don't think this works with organic mercury like dimethylmercury. It is an organo-metallic compound and behaves very unlike elemental mercury.
I'd be running the AA's from the analytical labs in mercury-vapor mode, putting them on carts if necessary since they do not need gas supplies for mercury detection & measurement.
Before plasma-emission spectrometers became widespread, more people were familiar with the traditional atomic-absorption (AA) instruments.
Instead of measuring the combined emission of any elements present in the sample, the AA used the steady emission of the target element alone as reference, from a (expensive) lamp having that specific element present within its hollow cathode.
AA normally uses a clean acetylene flame to vaporize the sample, with the reference light beam passing above the flame. If the target element is present in the sample, it absorbs some of the characteristic wavelength from the beam and is detected as a negative deviation from baseline.
For trace mercury though, the flame was not good enough, so an even more expensive and complex graphite furnace was installed in place of the burner.
Either way the light beam passes through a few inches of lab air to get from the lamp to the optical detector.
And you don't need the burner or the furnace to detect things that are already vaporized.
The graphite furnace would be good to calibrate with later if you couldn't do it in advance.
I wonder if their contractor has as good detection ability as MIT itself.
If claude ever has enough of are shit collectively and has enough of vibe coders, mercury will be load baring part of it's plan, no need for guns and bombs.
68 comments
[ 12.7 ms ] story [ 247 ms ] thread[1] https://www.reddit.com/r/mit/comments/1w12gb9/dimethyl_mercu...
[2] https://www.nbcboston.com/news/local/hazmat-crews-respond-to...
[3] https://en.wikipedia.org/wiki/Karen_Wetterhahn
> The case proved that the standard precautions at the time, all of which Wetterhahn had carefully followed, were inadequate for "super-toxic" chemicals like dimethylmercury
(from the Wikipedia page [3])
There aren't really any "good" organometals, but if there were, they wouldn't be this stuff.
LD50 about 2mg/kg oral. By oral it's meant that well.. if you soak your hands in it it will be worse.
Still it's the goto thinner for f/ex gluing ABS. I have a couple liters sitting on the shelf right beside me.
Holy hell. I would've have believed it was possible for a non-biological substance to be so toxic.
From https://en.wikipedia.org/wiki/Cyanide_poisoning
> A fatal dose for humans is on average 1.52 mg/kg of body weight
Assuming 80kg(175pounds), that's like 120mg of Cyanide.
There is probably even more nasty stuff.
You may also be thinking of phosgene, which actually contains no phosphorous at all. But it is extremely toxic see the LC50: https://en.wikipedia.org/wiki/Phosgene
I guess it's a biological product, but it's certainly not "living".
Then there's carfentanil and similar which are deadly only at much higher 100 microgram levels.
By the time I first took chemistry classes, though, that practice had stopped, less out of concern of exposure to liquid mercury and more for accidental exposure to gaseous forms due to spills.
One way to familiarize students with mercury was to have several liters of it in a wide open-top jar and have them force their fist through the mercury pool to the bottom of the jar.
In fact, forcing one's hand through mercury between six to eight inches deep is not easy, some kids found it too difficult to do.
I'd describe my hand as feeling very squeezed and it being forced upwards to the surface with considerable force. The experience was certainly unforgettable.
There were some safety protocols: good ventilation (to minimize Hg vapor) and afterwards hands had to be thoroughly scrubbed with soap and water.
https://www.chemistryworld.com/opinion/a-risk-not-worth-taki...
(Well, the poor woman, then, this article ...)
> One problem with this subject is that it tends to lead to bragging contests about who has run the most hazardous reactions. But think about it: if these reactions have all been run for good reasons with the best protective equipment there is less to brag about. And if they haven’t, then the discussion turns into figuring out who has been the biggest fool
I suspect the answer is "bragging rights" in this case.
However, since it was an active silicon manufacturing plant, all employees and contractors were obligated to complete safety training sessions. And I swear now that these safety sessions were designed to weed out the faint-hearted guys who weren't serious about supporting this silicon brand.
The safety sessions were simple lectures, with some handouts and PowerPoints, and some of the chemicals they described were absolutely insidious stuff. They were colorless, odorless, and some could melt or disintegrate bone without noticeably affecting the skin or muscles. They said you would just end up with a limp and useless appendage if you spilled some of this stuff on you. Other stuff was highly toxic and you didn't want to breathe anything. Basically it was a big warning to just stay out of the manufacturing floor, especially if we didn't know what we were doing.
I never went near the manufacturing floor. It was a pretty cool job and I wish I lasted longer there. They couldn't scare me away with a safety session, since my Dad had worked for decades in Environmental Health and Safety. Dad knew all about the nastiest stuff and he was always responding to hazardous laboratory accidents. Dad made us the safest home in our ZIP code.
As an aside, I love it when they tell you in the safety WBT what the highly toxic gas smells like.
Single use ones too can contain fluorine, but not the runaway risk. Nevertheless, they require significant care to avoid shorting during storage. Never store them lose or where they can contact each other.
Other fun chemicals used in fabs were Silane (CSi4), methane w/ silicon instead of hydrogen, used to form a silicon dioxide layer for etching* w/ HF and final step of protection. It would spontaneously combust on contact with air, so when you popped a tank fitting it would leave a white powder residue. Silicon dioxide is used as a food additive so AFAIK that wasn't dangerous.
Phosgene was also used as a dopant. If the alarm for that went off you really got out ASAP.
Arsine was a dopant also.
This is what I sort of remember from working on slacker job in silicon fab a long time ago when the number of transistors per chip was 1. I did say a long time ago.
* You could also just oxidize the outer layer of the silicon wafer itself w/ water vaper at high temps.
Sorry for the confusion—I know it's weird but the alternative turns out to be even more confusing and we've never figured out how to square that circle!
> Emerging information calls into question whether this compound was in fact synthesized.
> while the student remains under medical supervision, their initial blood test result, which was received today, shows no sign of exposure to mercury.
Taken from https://emergency.mit.edu/
> If the MIT student was doing some work with reactive stuff and mercury and got an unknown result well outside expectations out of the output they were expecting i can see them struggling through working out what it could be, coming to the conclusion Dimethylmercury was possibble as an accidental side product of what went wrong, and just pulling all the emergency handles to be safe. Given how nasty that stuff is that is exactly the kind of reaction to such a scenario you'd want someone to have.
Edit: reading further down the comments, Derek Lowe is guy.
If you’re testing for dimethyl mercury in say fish, you need a standardized sample of dimethyl mercury to run.
These references are highly dilute and thus less hazardous. But some labs prepare their own references rather than buying them.
That requires working with pure dimethyl mercury.
The hazard is manageable as long as you’re prepared. Chemists work with lots of hazardous chemicals and it can all be managed with the right preparation.
Some guy's in the hospital from handling droplets of instant liquid death and they're worried about feelings being hurt?
https://old.reddit.com/r/labrats/comments/1w1ukrv/mit_studen... ("A message sent out from the chair of the department of chemistry...")
>To keep Reddit safe, accounts are required to access old Reddit.
God, I hate that horrible website. How does this keep people "safe"
> "A message sent out from the chair of the department of chemistry at the school identifying the substance in question:"
> "“Dear Chemistry Colleagues,"
> "I am writing to provide an update on efforts to reopen Building 18 safely."
> "A specialized team from Triumvirate Environmental worked overnight on decontamination efforts in the building. This work includes wipe-downs of relevant surfaces in the lab and common areas, as well as the safe disposal of items that may have been contaminated. Decontamination work will continue throughout the day, and the building will remain closed until the work is complete."
> "In addition to our health and safety experts, we have been working continuously with staff and colleagues from departments across the Institute. Our highest priority is community safety, and we continue to make decisions accordingly and gather as much information as we can."
> "It remains the case that, based on the information available, this was a localized issue with only one student directly exposed, and this student was the individual working with the compound. Their reported use of dimethyl mercury was unauthorized. MIT does not allow the purchase or synthesis of dimethyl mercury."
> "I want to reiterate that, based on the information available to me, our industrial hygienists, MIT Health medical experts, and other resources we've consulted, the risk of secondary or tertiary exposures remains low, given the compound's characteristics and the information available to us."
> "Please feel free to reach out with questions. I will continue to provide regular updates as we learn and have more to share."
> "With care and regards,"
> "Matt Shoulders”"
https://www.science.org/content/blog-post/alleged-dimethylme... ("The Alleged Dimethylmercury Incident")
Seems the initial reporting may have been misleading. There was apparently *no* dimethylmercury exposure, after all: and MIT doubts it was synthesized in the first place.
Is this accurate? I read the original Wetterhahn report (it's the first search result on Google) and chelation did appear to reduce whole blood mercury, but didn't do anything for the CNS exposure.
That would be important because it suggests immediate Succimer treatment could avert fatal CNS exposure (it takes hours/days for the blood/brain transfer to occur, apparently).
Obviously, not an expert.
https://www.tandfonline.com/doi/full/10.1080/24734306.2020.1...
There are also some studies suggesting that the amount of excess mercury in fish compared to selenium may be more relevant than the absolute mercury concentration in causing potential toxicity.
To detect elemental mercury vapor, the air is drawn in to a controlled chamber where if present it amalgamates with pure gold as the reference (zero) material, and determined electronically.
I don't think this works with organic mercury like dimethylmercury. It is an organo-metallic compound and behaves very unlike elemental mercury.
I'd be running the AA's from the analytical labs in mercury-vapor mode, putting them on carts if necessary since they do not need gas supplies for mercury detection & measurement.
Before plasma-emission spectrometers became widespread, more people were familiar with the traditional atomic-absorption (AA) instruments.
Instead of measuring the combined emission of any elements present in the sample, the AA used the steady emission of the target element alone as reference, from a (expensive) lamp having that specific element present within its hollow cathode.
AA normally uses a clean acetylene flame to vaporize the sample, with the reference light beam passing above the flame. If the target element is present in the sample, it absorbs some of the characteristic wavelength from the beam and is detected as a negative deviation from baseline.
For trace mercury though, the flame was not good enough, so an even more expensive and complex graphite furnace was installed in place of the burner.
Either way the light beam passes through a few inches of lab air to get from the lamp to the optical detector.
And you don't need the burner or the furnace to detect things that are already vaporized.
The graphite furnace would be good to calibrate with later if you couldn't do it in advance.
I wonder if their contractor has as good detection ability as MIT itself.