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Comment by TehCorwiz | Hacker News Reader

Lots of medical and lab supplies, such as tubing, tools, and stents. For some applications glass is too fragile, metal can be too reactive. Even "inert" metals like titanium or nickel eventually develop bio-films.

Various plastics' combination of temperature stability at both high and low temps (cryo / autoclave), non-bio-reactivity (body doesn't attack or reject over short spans), and corrosion resistance makes plastics perfect for these situations. Especially wet situations. And since plastics can be fine tuned for application specific needs they can be iterated on quickly with a materials but not manufacturing process change in some cases.

My wife and I had this conversation a couple weeks ago asking this very question which ultimately boils down to: "Are plastics worth it at all ever?" And the answer we found, surprisingly, was yes.

edit: a typo.

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Sure, plastics are wonderful materials. The problem is that they are too good for their price. And that's the folly: plastics are simply too cheap.

Because of that, we treat plastic things as disposable, which is how most of plastic waste is produced.

There is a very simple way to address plastic pollution: make plastic expensive again. Even a minor measure like a 10-cent tax on a bag is disproportionately effective.

To put it in context, if you forgot how much we are willing to pay for a bag, stop by a bag store.

An expensive application of plastic (medical, etc) won't be affected much, if at all, by a plastic tax.

So I still don't know why we're not doing it big time. Oh wait, I do know, it's greed[1]. As usual, the profits from such misuse if plastics will be privatized, and the losses socialized (we'll all pay for cleanups with tax money and/or suffer from pollution).

[1]https://www.bizjournals.com/memphis/news/2019/01/08/plastic-...

Exactly! Thanks for the link. We were discussing this in the context of the reduction of oil consumption world-wide eventually leading to higher cost of plastics overall and which areas could it have a large effect.

This is actually a known economic problem that has been repeated with grazing commons in england and fishing reefs, plastics have a significant cost externality[1] that isn't being identified in current pricings and needs to be added by governments (or whatever) to account for their "real cost".

[1] https://en.wikipedia.org/wiki/Externality

Aren't plastics usually reasonable to burn as well? As in burning mostly produces CO2 and water? Or do common plastics contain some nasty atoms we dont want in the air in any way?

Plastics often are doped with heavy metals like molybdenum to affect mechanical properties like wear resistance, or bromine for fire resistance. Neither of which you want in your lungs.

Even putting aside the heavy metals, the assumption that they burn into CO2 is a hard one to accomplish in fact.

Done improperly, you end up with a very snokey, sooty smoke.

Done properly, you’re dealing with very high T, which is hard, and NOx production.

But, assuming you’re doing a good job... burn baby burn!

(Just separate out the per-fluorinates - HF is nasty)

They can be burned safely in an incinerator. Ad hoc burning can produce very toxic chemicals, though, including dioxins, hydrogen cyanide, vinyl chloride and furans. It could release lead. It depends on the type of plastic (PVC? Polyethylene? Polypropylene?). This is why it’s troubling to see people burning bags of trash and tossing in plastic bags and soda bottles as if they magically disappear.

This is a good rundown: https://www.directplastics.co.uk/about_plastics/post/whats-i...

MIT says... https://engineering.mit.edu/engage/ask-an-engineer/can-we-sa...

“When plastic is burned, it releases dangerous chemicals such as hydrochloric acid, sulfur dioxide, dioxins, furans and heavy metals, as well as particulate.”

To be fair, aren't soda bottles and plastic usually PET, which should not release nasty stuff? Or am I just misinformed?

See TehCorwiz' response below. It seems it never is JUST plastic.

PET and PP seem to be cleaner than styrenes, ABS or PVC but best I can gather PET releases antimony when burned.

I think for some of those things like medical tubing, if we didn't have plastics we would be using things like leather or tripe or sinew or other natural solutions (I'm not an expert here). Not to say plastic isn't better, but it's not the only way of doing it.

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