The Dangers of Dimethylmercury (2019)

It is worth explaining just what is wrong with it. Mercury of course is a toxic compound, but kids used to crack mercury thermometers in their mouths and suffer no consequences. Pressure gauges came with exposed tubs of mercury and you would get some on your hands and it was fine, even kind of fun to play around with. Felters famously felt symptoms after careers of using it, usually blamed on long term inhalation, but it required a long time and lots of exposure to get to that point. Many people received dental amalgams with mercury bases and while there has always been a conspiracy theory about it, it has never been acutely toxic enough to be mainstream—the shift to other composites has instead been driven by comfort (metal fillings conduct heat and cold at an unnatural rate) and aesthetics (the new composites are white instead of silvery).

The basic reason is that the body does not eat metal and does not know what to do with it largely. Even with the metals that the body uses, like cobalt, it wraps every atom of cobalt in a big old ring of carbon and that's Vitamin B12.

Dimethyl mercury, is different from normal mercury, in a similar way. The methyl groups are organic groups that your body is much more willing to absorb and process. So the latex is not protecting you nearly as much because latex is this organic natural filter that lets things through... But also your skin is not protecting you because this stuff can seep into your skin via those methyl groups, your cells are just like “oh you look interesting I can take you into my chemistry.”

So yeah, milligrams are all it takes, tiny trace amounts: but the reason that you don't think of it being quite that dangerous is that your exposure to the liquid metal version is an exposure to a form that your body is uniquely unsuited to process or absorb. Water off a duck's back. Even though the water contains neurotoxin, it just rolls right off. Even, in our case, when ingested. But add these little methyl groups, methylmercury and dimethylmercury and really any organic mercury molecule, it gets real bad real fast because it's no longer rolling off our backs, it's soaking into our feathers.

There is always some risk in handling chemicals, even more so making new ones from scratch.

This does not so much attract those driven by risky behavior, rather those who can tolerate the risk remaining after effective mitigation.

With toxic chemicals it's good to have a safety culture.

Historically, with more common toxins like benzene, it was often handled without gloves up to at least the mid 1970's when the effects of long-term exposure became more widely recgonized.

Regardless from the very beginning benzene had always been handled with no smoking, lighters, or open flames, and with a respirator when the operator deemed necessary.

Most days gloves were just plain never worn except for well-recognized major immediate hazards like pure sulfuric acid, and disposable gloves had never become a consideration since they were plain latex which is not very chemically resistant, too thin & skin-tight, basically as the name implies "surgical" gloves for physicians & nurses to maintain a more sterile enviroment and protect the patients from contaminants on the workers' hands, not as much to protect the workers themselves.

Industrial nitrile gloves were already up to today's standards but these were orders of magnitude more costly than medical disposables, much thicker, not tight at all, can last for years and be easily slipped on & off quickly for instance every time an entry needs to be made in a lab notebook without taking the chance of touching the notebook with any contaminated gloved hands ever.

Workers were expected to take very good care of their prized modern nitrile gloves so they would be ready every time when needed, unfortunately this was so seldom that often they couldn't find their personal gloves quick enough, and poured the sulfuric without using them anyway.

Or perhaps even more risky, using someone else's gloves, other than the specific pair they had been issued and expected to provide dedicated care & maintenance of along with their personal respirator. You didn't need these things most of the time, but when you did nothing else would do. And you never knew how contaminated someone else's PPE might have been.

By the 1980's litigation was alarmingly through the roof everywhere and toxic chemicals are a very difficult-to-defend target.

Mandates came down for workers to wear nitrile gloves for every single chemical with any kind of hazard at all. Materials like acetone, dilute acids, brine solutions etc. that had been handled safely without gloves for generations now triggered the requirement. Some operators who seldom wore gloves now needed to wear them most of the time from that point forward. If you wore them all the time it was felt you were protected all the time. Culture changed. It became a no-brainer.

Cue the arrival of disposable nitrile gloves, the full-strength originals were just too expensive for everyday use. The inflation from 1971 to 1976 had made sure of that.

Culture changed further. Eventually the appearence of a gloved hand holding a test tube is no longer a red flag that it likely contains one of the very few (in most labs) highly toxics that truly require the most extreme care.

Today I've got workers going through pallets of disposable gloves for every pair of traditional personal nitriles.

Other companies haven't issued personal gloves of any kind for decades, nitrile or not.

And I never dreamed the doorknobs and keyboards on the office machines would become so suspect for toxins compared to how it was before gloves became ubiquitous. Lab notebooks today might be safer to handle only with gloves and not enter non-chemical offices.

Remember PPE stands for "Personal Protective Equipment" and its not very personal if it's a throwaway and can be treated like an afterthought rather than a personal possession.

This methylmercury fatality could likely have been prevented if the disposable nitriles had never arose.

No doubt the victim would have been wearing the thick non-tight original gloves instead, which might have provided protection anyway even though the nitrile composition is just not completely impermeable to this particular toxin. Would have to safely discard the contaminated non-disposable gloves also since this is a lingering hazard rather than something like an aggressive acid which can be washed off the gloves afterward.

The high-dimensional surface of "threat to life" vs. molecule structure is super, super, non-convex.

Like H2O -> yay, H2O2 -> die, H2 + O2 -> fire

Like methanol -> die, ethanol -> fun, propanol -> die, butanol -> die, heptanol -> die, octanol -> die

I had a drop of molten steel fall on my bare skin, doing welding, the worst I experienced was a bit of pain and a small 1st degree burn that didn't require treatment and didn't leave a scar. I heard that with the proper technique it is possible to put scoop molten steel with your bare hands without burning yourself (not that I recommend it, obviously).

Metal tends to bead up (high surface tension), and the Leidenfrost effect offers temporary protection. I may be wrong but I suspect you are more at risk of burning yourself in a kitchen than in a steel mill. I would be more scared of a deep fryer than a crucible.

Also, molten steel radiates IR and glows obviously, so you can usually tell when it's about, and doesn't stay molten and remain a silent, persistent danger.

Though from what I’ve heard about solid through sand buckets, and pitted face-shields, and contents of lab fridges, I’d think GP a bit optimistic.

Anything specialty is probably specified by the researcher, and ordered and paid for by the staff person handling grant administration.