[KennyBlanken]

> The immediate danger seems to abated, fortunately,

The "it will explode leveling a couple city blocks" danger seems to be abated, but instead it's spraying an insanely toxic chemical out into the open, which will likely have health repercussions for residents for decades?

Thousands of gallons of toxic chemicals don't just disappear.

[__david__]

On the plus side, it's a chemical that was discovered more than a century ago so scientists have accumulated a lot of knowledge about it. So far no studies were able to link it to cancer. It also doesn't significantly build up in the body over time (like heavy metals do). It's 3x heavier than air so it shouldn't spread too far away. The main issue is they want to try to keep it from getting into storm drains or into the ground water.

I've heard from others that it's readily absorbed by water. That's bad in the ground water case, but it seems it might be a positive when trying to clean up a (contained) spill.

It appears to me to have a relatively high lethal dosage (my back of the napkin calculations are saying a 200 pound human would have to orally ingest almost a liter of it to reach the LD50 dosage--but again don't quote me on that number because I am not an expert and could have very easily messed up the math or the concept of a lethal dose).

So, while I agree there might be unknown long term issues, it does appear to be a relatively low probability of that since it seems to be on the less pernicious side.

[fc417fc802]

You've got the right idea with the LD50 but the catch is that if it ignites it produces things that are acutely toxic in relatively small quantities.

[gus_massa]

It probably polymerized completely and it's a giant block of nasty looking solid plastic, that perhaps can be lifted with a crane (with some support, in case it has cracks or something).

In some plastics the monomer is toxic, but the polymerized form is safe. (I think it was use for windshields for planes, so once polymerized it was probably safe to touch at least.)

In this case it was an uncontrolled reaction so I'm not sure if someone knows the exact current composition of the goo, so I strongly recommend to avoid licking it.

[amluto]

> In some plastics the monomer is toxic, but the polymerized form is safe.

This is common. Isocyanates are a common example — isocyanate monomers are nasty, and the very light ones are very nasty. They’re used to make polyurethane, polyurea and such, which are quite nontoxic in polymerized form.

In applications where the unreacted isocyanates are used by anyone other than professionals (e.g. two component varnishes), the manufacturer may go out of their way to use more expensive but less toxic variants.

[compass_copium]

Correct, PMMA is completely harmless. MMA is an incredibly common adhesive, and is in probably a dozen things in the room you are sitting in in its polymerized form.

[DannyBee]

MMA is not very toxic. It has the same LD50 as vitamin C. Table salt and baking soda are twice as toxic as MMA, for example.

Additionally it is almost certainly not in vapor form at 100 degrees. In sunlight it will also polymerize to a solid pretty quickly.

As such you'd practically have to drink it inside to hit the ld50.

The explosion would be much worse than a release of liquid or vapor based MMA during the day, and here it almost certainly solidified at this point

[amluto]

MMA can apparently cause some issues that are more subtle than death. I would MUCH rather eat 1g of vitamin C than 1g of MMA.

Also, vitamin C is not volatile, so there is no risk of inhaling it as a gas.

[DannyBee]

Sure it can. So can Vitamin C though.

The overall point remains the same: the toxicity, both short and long term, of MMA, is comparable to lots of everyday substances that are both commonly eaten and inhaled.

It just isn't that toxic as far as chemicals go. That doesn't mean it would be like great for you but calling it "highly toxic" is tremendously overblown and doesnt serve anyone well to claim.

Let's save the highly toxic claim for things that actually deserve it. We don't have to sensationalize everything. I maintain my view that the explosion would likely be much much worse than the odds of significant respiratory damage from MMA.

Also note the sensationalization also causes placebo effect. People miles away started claiming "their lungs hurt" when

1. There was no leak

2. Even if their was and it was a conspiracy or whatever, your lungs have ~no pain receptors and your chest/pleura/etc would generally not hurt from MMA overexposure. Your throat would and your skin would, depending on concentration. But nobody complained about skin irritation when the is basically no way to end up with one without the other.

Etc.

Sensationalization of this hurt people so far more than the actual issue!

[fc417fc802]

It produces highly toxic byproducts when it burns thus the exposure concerns.

[amluto]

Got a source for that? I searched a bit and found so evidence that its combustion products are notably hazardous. I did find an SDS stating that MMA’s combustion products do not have special hazards.

[fc417fc802]

I do not! Sorry, digging stuff up is a chore. It's possible I confused it with a different acrylate molecule. However glancing at an MSDS for it gives me the impression that exposure can result in a variety of acute symptoms and is quite serious. It would appear to be a severe irritant with the potential to cause an allergic reaction. In general it seems like fairly bad news.

Given how toxic a number of the other acrylates are, how indiscriminate the chemistry of partial combustion tends to be, and how reactive MMA is, I would certainly assume the worst about burning it until proven otherwise.

[amluto]

> insanely toxic

Some quick searching suggests that it’s toxic but not even close to “insanely toxic”. And it’s not persistent in the environment.

If you want a genuinely nasty chemical, check out methyl isocyanate, which is some two orders of magnitude more acutely toxic.

[bell-cot]

I'll see your CH3NCO, and raise (CH3)2Hg -

https://en.wikipedia.org/wiki/Dimethylmercury#Safety

- considerably more deadlier, and the mercury an element - so no clever chemical reactions can break it down into innocuous CO2, H2O, and N2.

[amluto]

True. But methyl isocyanate has the regrettable property that it was quite useful, to the point that there was a crappy, poorly maintained factory with tanks of it on site, with extraordinarily regrettable results.

https://en.wikipedia.org/wiki/Bhopal_disaster

[Vaslo]

Opened a small round bottom flask of this when I worked in the lab. Closed it immediately when I felt burning in my eyes as did others around me.

It’s toxic but not insanely toxic. Isocyanates, phosgene, gaseous cyanides - now those are insanely toxic