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PLA - poly(lactic acid) - is biocompatible to the point that it is used in medical implants. It breaks down into lactic acid, which the body produces itself dur
by semi-extrinsic 3y ago
PLA - poly(lactic acid) - is biocompatible to the point that it is used in medical implants. It breaks down into lactic acid, which the body produces itself during exercise and can safely metabolize.
Breathing smoke and dust from PLA is bad, because breathing any type of smoke or dust is bad. Wildfire smoke is bad, but wood is not a harmful chemical.
We actually do understand the chemistry of plastics. And to a very large extent they are very safe, primarily because they are incredibly stable and non-degradable.
Even the studies of e.g. BPA health issues point to very weak effects. You need to do meta-analysis on tens of thousands of individuals to have statistically significant effects, and even then they are weak and it's not easy to say whether you have successfully eliminated confounding factors.
And "BPA-free" plastics just use BPF instead, with very similar chemistry. The consumer-facing BPA fuss is primarily driven by companies that want to sell products; health agencies are primarily concerned with occupational exposure, which is 4-5 orders of magnitude larger in terms of dose per body weight. BPA is metabolized in the kidneys to the benign BPA-G and excreted in urine; a dose 250 000 times the EU dose limit is cleared by the body in 24 hours.
PFAS is a similar story. Over long timescales with stupid disregard for basic PPE, like cross country ski waxing trailers where people were breathing C8-dust without masks for a thousand hours per year, there has been clear health concerns identified. So people are saying "there is no safe lower dose limit" and companies are switching to chemicals that haven't been used in the same context so there is little to no data on exposure safety, and saying "this will be safer".
- droopyEyelids 3y agoWhat plasticizers, chain extenders, flame retardants, fillers, stabilizers, colorants, reinforcements, blowing agents, antistatic agents, and lubricants are used with PLA? I'm not asking to play 'gotcha' with your comment, but because when I've attempted to do my own research on this, I find it easy to get information on the polymer itself, but the polymer is never used by itself in a product. As far as I can tell, most polymers are not actually useful without a cocktail of additional chemicals added to them to change their physical characteristics. From my research, raw polymers tend to be extremely brittle and frangible, completely unrecognizable when compared to the products we use made from them. And those additional chemicals are extremely difficult to find information on. Like when they're used, what they are, etc.
- semi-extrinsic 3y agoOh this is a very good point. Type and amount of additives is very rarely specified, although you can find some info in the academic literature.
- alwa 3y agoAs a person completely naive to the finer points of plastics manufacture-do these additives tend to be drawn from a fairly small and well-understood universe of chemicals and combined in predictable ways, or is it a bit more DIY at the level of a specific manufacturing plant or product spec or batch run? I guess my mind is instinctively reaching for the ways FDA attempts to ensure food safety by compelling manufacturers to publish ingredient lists, and by maintaining registries [0] of hopefully-well-understood additives (and banning the rest, in historically dangerous categories like colorants). Sure from time to time agitators take that information out of context to whip up a scare about one ingredient or another, and sure some of the food that comes in from overseas has after-the-fact labeling that’s a little sus. But at least there’s an expectation that the information must exist and be legible. [0] https://www.fda.gov/food/food-ingredients-packaging/determining-regulatory-status-food-ingredient https://www.fda.gov/food/food-ingredients-packaging/determin...