[HN Gopher] A plastic made from milk that vanishes in 13 weeks
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       A plastic made from milk that vanishes in 13 weeks
        
       Author : JeanKage
       Score  : 88 points
       Date   : 2026-03-02 14:20 UTC (8 hours ago)
        
 (HTM) web link (www.sciencedaily.com)
 (TXT) w3m dump (www.sciencedaily.com)
        
       | david-gpu wrote:
       | Milk is surprisingly intensive in terms of greenhouse emissions.
       | It is somewhere around 1 to 3 kg CO2-equivalent per kg of milk.
       | 
       | Milk protein costs around 95 kg of CO2-equivalent emissions per
       | kg of protein, which is apparently what was used in the
       | production of this plastic [1]
       | 
       | [0]
       | https://www.sciencedirect.com/science/article/pii/S002203022...
       | 
       | [1] https://ourworldindata.org/grapher/ghg-per-protein-poore
        
         | ericd wrote:
         | But to put this in context, the average American family's
         | carbon footprint per year is roughly 50,000 kg, and one flight
         | is usually on the order of >1,000 kg, or ~300kg/700 pounds of
         | milk, assuming that 3kg CO2 per kg milk high end figure. So if
         | you like milk, there are probably other places you can cut
         | first.
         | 
         | Does seem like a lot of carbon for a kg of plastic, though, how
         | does that compare to normal plastic's carbon footprint?
        
           | beAbU wrote:
           | >... >1,000 kg, or 700 pounds of milk
           | 
           | Why do you mix your units like that.
        
             | ericd wrote:
             | Because I'm American, so I use metric in scientific
             | contexts, and weird medieval units in everyday ones :-)
             | 
             | I'll edit a bit for clarity for you all who live in more
             | consistent places.
        
               | beAbU wrote:
               | I'm not above asking the barber to leave an inch on the
               | top, but then I'm not going to ask him to leave 15mm on
               | the sides. At least keep the system consistent within a
               | sentence :)
        
         | scythmic_waves wrote:
         | It's possible to use manufacture whey protein without cows:
         | 
         | https://en.wikipedia.org/wiki/Whey_protein#Microbial_product...
         | 
         | It's not theoretical either. You can buy vegan dairy products
         | made from this method today.
        
           | cogman10 wrote:
           | I'd be interested in knowing what the CO2 emissions were from
           | these. You still need to feed the yeast, so you'll have the
           | CO2 emissions involved in growing a crop associated with
           | this. And if you look at the chart in the OP, you'll see that
           | grain production is about half the CO2 emissions of milk.
           | That's likely part of the milk CO2 production accounting.
           | 
           | In addition, you'll need more cleaning/sterilization/mixing.
           | I'd guess that it's lower, but I wonder how much lower.
           | 
           | And then there's the other products that generally get thrown
           | into the mix to make up for things like missing fats. For
           | example, a vegan cheese based on bacteria will often include
           | coconut oil, probably to get the same fat profile.
           | 
           | Whey is an interesting product in general because it's a
           | waste product of cheese making.
        
             | Retric wrote:
             | It's likely to be vastly better.
             | 
             | Feed efficiency is critical when doing these calculations
             | as cows inherently need energy to survive not just produce
             | milk. As such even if you use the same crop two different
             | sources of protein can have wildly different levels of CO2
             | emissions embedded in their creation.
             | https://en.wikipedia.org/wiki/Feed_conversion_ratio
        
               | cogman10 wrote:
               | I think it is likely more efficient. That said, cows do
               | have the advantage that the food they consume needs
               | little to no processing in order to produce milk. The
               | yeast needs pretty precise processing of the incoming
               | mash both to make sure a wild yeast strain doesn't make
               | it's way in, and to make sure the yeast ultimately
               | produces the right proteins.
               | 
               | You can't just throw in grass clippings into a vat and
               | get whey. You can throw grass clippings into a cow to get
               | milk (though, TBF, I dislike grassy milk).
        
               | Retric wrote:
               | I agree it's likely to be more labor intensive per lb of
               | feedstock, but only 21% of calories in milk are protein
               | and overall milk has ~10% of the initial energy. So
               | you're looking at ~2% of the energy from these crops
               | ending up as milk protein.
               | 
               | That's a lot of room for improvement which then means far
               | less labor on growing crops.
        
         | ahhhhnoooo wrote:
         | But we can also produce milk from yeast now. Perfect Day, for
         | example, produces milk without cows.
         | 
         | So it's not out of the question we could scale that up to meet
         | plastics demand.
        
           | 5o1ecist wrote:
           | I remember when people still knew what milk was ... and what
           | was not milk.
           | 
           | That was before multi-billion-dollar companies came up with
           | marketing strategies that manipulated people into not
           | understanding what milk was, instead making them believe that
           | milk is whatever they tell people.
           | 
           | Usually, the reaction to this is "Well, language and the
           | meaning of words change." ... Sure, but that argument comes
           | in complete ignorance of the fact that it _only_ happened,
           | because people with too much money and power can manipulate
           | millions into believing whatever these millions of people are
           | supposed to believe.
           | 
           | Thus now anything can be milk, as long as some profit-
           | oriented company decides that people shall call it milk.
           | 
           | This practise has become the norm to a degree that people
           | will not only generally accept it, but also generally defend
           | it. Pure madness.
        
             | OkayPhysicist wrote:
             | To be clear, Perfect Day doesn't make "milk" like plant-
             | based milks (think almond "milk", oat "milk", etc). They
             | bioengineered some yeast to grow whey protein directly. The
             | milk they make (made?) probably wouldn't be considered
             | "milk" in the strict sense (they had to get the fat and
             | sugars from plants), but there's really not a good reason
             | to distinguish between "whey protein from cows" and "whey
             | protein from yeast" when it's the same stuff.
        
             | qff wrote:
             | The large diary producers are forcing things that everyone
             | understand what is -- "Oat milk" and "Almond milk" -- to be
             | called "Oat drink" and "Almond drink". New terms for things
             | that have existed for decades.
             | 
             | Really, we should be calling the OG milk "cow milk" and let
             | the good times roll.
             | 
             | Big milk have been pushing questionable health research and
             | narratives for cow milk for quite some time.
             | 
             | All this coming from someone (me) who drinks 0,5L of cow
             | milk every day.
             | 
             | Yes, yeast milk is milk too. Just like coconut milk.
        
               | throwway120385 wrote:
               | I thought the reason things are called "Oat Drink" versus
               | "Oat Milk" is because non-dairy "milks" have to be
               | fortified with vitamin D and calcium and the stuff that's
               | labeled a "drink" is not fortified.
        
             | ahhhhnoooo wrote:
             | You understand that the product I'm talking about is the
             | same proteins as milk, and is essentially whey, right?
             | 
             | I'm not talking about grinding up nuts or grains and
             | calling it milk, I'm talking about engineering yeasts to
             | literally produce the proteins that milk has to create a
             | product that isn't just milk-like, but is literally
             | identical proteins.
        
               | tredre3 wrote:
               | Whey is just a small part of milk, though. You can't
               | isolate one aspect and pretend it's fair to call it (cow)
               | milk.
               | 
               | You wouldn't call whey protein powder mixed in water
               | milk.
               | 
               | You wouldn't call butter mixed with water milk.
               | 
               | You wouldn't call casein powder mixed with water milk.
        
             | systoll wrote:
             | Language changes. In this case just the spelling though.
             | 
             | "Almaund mylke" is all over medieval cookery manuscripts,
             | among other options.
             | 
             | We've been using milk for non-animal products for longer
             | than we've spelt milk with an i, and for longer than we've
             | had companies, let alone multi-billion-dollar ones.
        
             | vlabakje90 wrote:
             | The first documented use of the word coconut milk in
             | English dates from 1698 ( Philosophical Transactions of the
             | Royal Society, volume 20, page 333) and the use of almond
             | milk goes quite a bit further back, to at least 1390 (The
             | Forme of Cury).
        
           | zer00eyz wrote:
           | Is this going to result in net less greenhouse gas emissions?
           | 
           | Maybe but probably not zero, from parents article: "The use
           | of such treated fertilizers will be most relevant for
           | reducing the carbon footprint of milk in countries such as
           | the United Kingdom, Ireland, and the Netherlands, where N
           | fertilizer is a major contributor to the footprint."
           | 
           | In case you are unaware much of the nitrogen in plant matter
           | (food for yeast or cows) comes from fertilizer. And that is
           | extracted using the Haber process (see:
           | https://en.wikipedia.org/wiki/Haber_process ). This runs on
           | natural gas, because it's effectively a waste product of
           | other hydrocarbons being extracted.
        
         | philwelch wrote:
         | Where are these emissions coming from? For instance, if this is
         | counting the emissions involved in logistics, none of that
         | inherently or necessarily requires greenhouse emissions--you
         | can electrify trains, tanker trucks, and refrigerators.
         | 
         | If this is counting the methane emissions of the cow itself,
         | that's not a fair or complete accounting. The cow produces
         | methane in her digestive system after eating grass, and the
         | grass grows by, among other things, extracting CO2 from the
         | air. Then the cow burps methane, the methane combines with
         | atmospheric oxygen and breaks down to CO2 and water, and you
         | have a closed loop; the cow cannot belch more carbon than she
         | eats, and that carbon came from the air in the first place.
        
         | wolvesechoes wrote:
         | I am very much sympathetic to nature conservation,
         | decarbonization, degrowth etc. but really, there are more
         | important considerations at this very moment than shaving few
         | kgs of CO2 by ditching milk.
         | 
         | And, as much as some powers try to convince us, not everything
         | can be reduced to _carbon footprint_.
        
       | kleiba wrote:
       | Luckily, producing milk is completely environmentally friendly!
       | 
       | /scnr
        
       | regularfry wrote:
       | The paper doesn't talk about thermal properties, which is a
       | shame. Would be good to know if this is a thermoplastic.
        
       | boringg wrote:
       | New subscription model coming to plastics! Products last only 13
       | weeks.
       | 
       | I know - long lived plastics are bad. We need some kind of middle
       | ground thats as cheap as the current plastics and doesn't last as
       | long.
        
         | blitzar wrote:
         | Its called paper, wood, glass, ceramics or metal depending how
         | long you want it to be around for and what you are putting in
         | it.
        
         | DennisP wrote:
         | We go through a lot of single-use plastics.
        
         | ahhhhnoooo wrote:
         | Only lasts 13 weeks _in soil_. It presumably lasts a whole lot
         | longer when you don 't bury it in the ground.
        
           | gus_massa wrote:
           | I agree. https://en.wikipedia.org/wiki/Galalith is made of
           | casein and formaldehyde. It was popular 100 years ago and
           | there are plenty of pieces still around. I searched
           | formaldehyde in the article but I din't find it, I'm not sure
           | if they hide it or they are using a very different method.
        
       | LurkandComment wrote:
       | Is this going to drive up the price of milk? Corn went up when we
       | started making ethanol from it for gasoline.
        
         | malfist wrote:
         | Do you have any evidence for that? From what I understand, the
         | corn to ethanol pipeline was created to keep corn prices from
         | dropping below what the farm bill would pay for.
        
       | TZubiri wrote:
       | >vanishes in 13 weeks
       | 
       | Well then it's not plastic is it? Plastic's defining
       | characteristic is that it is not decomposable
        
         | cestith wrote:
         | The defining characteristic of plastic would seem to be the
         | definition of the word from which they are named. That is, that
         | plastics are _plastic_. It means they are easily shaped,
         | molded, formed, or extruded.
        
         | ahhhhnoooo wrote:
         | What? Plastic's defining characteristic is plasticity -- how
         | moldable, shapeable, extrudeable, pressable, etc it is.
         | 
         | Also, one of the most widely used plastics is PLA, polylactic
         | acid. Which is made from lactic acid from sugarcane, beets, or
         | cassava, and is biodegradable.
        
         | bluGill wrote:
         | There are a lot of plastics that are disposable. The first
         | plastics over 100 years ago were made from milk (I suspect the
         | Romans knew the process - it wasn't industrially useful
         | though). Many decomposable plastics have been made over the
         | year. The PLA commonly used in 3d printers is decomposable (in
         | the right environment).
         | 
         | Oil based plastics are generally a lot cheaper than the above
         | though, and they are typically not decomposable. Depending on
         | your use this can be good or bad (I don't want my plastic
         | plumbing pipes to decompose, but other plastics are used up and
         | I want them to decompose)
        
         | BigTTYGothGF wrote:
         | > Plastic's defining characteristic is that it is not
         | decomposable
         | 
         | Behold, a plastic! _holds up a rock_
        
         | ssl-3 wrote:
         | That's what they told me in school, too.
         | 
         | But then I got out in the real world, and noticed plastics just
         | falling apart all around -- including stuff that is not
         | intended to fail and which is otherwise still within its useful
         | life.
         | 
         | Like: One year, I bought some used pickle buckets from a local
         | burger joint to use as planters. Within 6 months, they were
         | falling apart: It was easy to break them apart in chunks with
         | my bare hands.
         | 
         | Or the plastics used for cars: They often eventually turn
         | brittle and fall apart, whether interior or exterior. Plastic
         | lenses on USDM cars turn foggy and useless; some types of wire
         | insulation disintegrate. (If we want to talk about
         | environmental cost, can we also talk about the impact of
         | building a new car?)
         | 
         | In some areas, we once used polybutylene water pipes. These
         | tended to fail and damage homes. There was even a billion-
         | dollar lawsuit about it in the 1990s. It was not good.
         | 
         | Meanwhile, a red Solo cup or a plastic drinking straw, once
         | landfilled, will be there a very long time -- but eventually,
         | they will also decompose.
         | 
         | And the UHMW cutting boards I use in my kitchen will probably
         | outlive my grandchildren's grandchildren before they start
         | falling apart on their own accord.
         | 
         | Plastic isn't always forever, even though some people seem fond
         | of saying that it is. Plastic isn't necessarily cheap, either,
         | even though "cheap plastic" is a common expression -- some
         | plastics are very expensive and resoundingly durable (and
         | there's only partial overlap of these two qualities on a Venn
         | diagram).
         | 
         | The truth is somewhere in the middle, but is rather nuanced and
         | variable and difficult to pin down in absolutes.
         | 
         | But plastic (as a noun) does, broadly speaking, have the
         | material property of being plastic (as an adjective).
        
           | 542354234235 wrote:
           | >Plastic isn't always forever
           | 
           | But molecularly, plastic is around forever. A wooden bucket
           | will eventually breakdown to not be wood at all anymore.
           | Products made from plastic is not what lasts forever, the
           | plastic itself is.
        
             | ssl-3 wrote:
             | That doesn't sound right to me, either. Let's use PLA as an
             | example of a thing that is definitely plastic.
             | 
             | In the right conditions ( _hot_ aerobic compost, which is
             | admittedly difficult to achieve), PLA rather quickly
             | decomposes all the way back down to lactic acid.
             | 
             | Lactic acid is definitely not plastic. It's liquid, and is
             | one of the primary products of the happy little microbes
             | that I nurture in my pepper ferments at home.
             | 
             | Again, it's hard to pin the long-term properties of plastic
             | (noun) down in absolutes.
        
               | TZubiri wrote:
               | Do you need to grind the plastic into dust for that to
               | happen?
        
               | ssl-3 wrote:
               | No, AFAICT.
               | 
               | Everything goes faster in hot compost with additional
               | preprocessing, but it's not strictly necessary to reduce
               | things to dust.
               | 
               | Hydrolysis of the PLA still happens whether it is dust or
               | something larger. After that, the chains are small enough
               | to be available for microbes to eat fairly quickly.
               | 
               | They're just eating one bite at a time; they don't know
               | that they have an entire elephant to eat.
               | 
               | More surface area improves immediate availability and
               | speed, but less surface area doesn't cause the process to
               | cease.
        
           | throwway120385 wrote:
           | You have to put UV and temperature stabilizers in plastics to
           | prevent them from breaking down outside. The sun is merciless
           | and destroys everything in time.
           | 
           | Your buckets would have lasted longer if you had painted them
           | with outdoor housepaint or outdoor water- or oil-based
           | urethane, because those coatings contain uv stabilizers.
        
           | TZubiri wrote:
           | I meant decomposable by bacteria.
           | 
           | It's trivial to make plastics that break, but then you have
           | many microplastics which again don't decompose.
           | 
           | The breakage isn't even infinite, as the particles grow
           | smaller, the shear resistance grows and it stops splitting,
           | and again nothing decomposes it further
           | 
           | So decompose =/= break.
        
       | 1970-01-01 wrote:
       | I've said before that we need a short term plastic that
       | completely dissolves into harmless organic compounds that can
       | then be forgotten in nature with no ill effect. 13 weeks is just
       | about right!
        
       | abdullahkhalids wrote:
       | > Plastic production has climbed from 2 million tonnes in 1950 to
       | 475 million tonnes by 2022, roughly equivalent to the weight of
       | 250 million cars.
       | 
       | That's 60 kg/person/year of plastic, which is a lot. Or about
       | 4800 kg for a person living 70 years. Obviously, there is wide
       | variation in this number across the human population.
        
       | cestith wrote:
       | I'm hoping this is a first step toward using some other
       | protein(s). There are some fairly high protein plants like
       | chickpeas and soy that are less intensive to produce than milk.
        
         | lotsofpulp wrote:
         | Are proteins fungible? I thought different protein sources
         | provided different amino acids.
        
           | throwway120385 wrote:
           | No they are not but they can be combined to produce a
           | "complete" amino acid profile.
        
           | WorldMaker wrote:
           | In case of plasticizing it, it _should_ be fungible in terms
           | of use the cheapest and /or least healthy to make plastic-
           | like single use goods.
           | 
           | That said, the question I have is given the nature of calcium
           | (and its relation to limestone), I'm wondering if the milk
           | protein here is especially useful to plasticizing because of
           | its calcium content? A quick search does classify calcium
           | caseinate as _both_ a protein and technically a calcium salt.
        
       | [deleted]
        
         | mudkipdev wrote:
         | Or remove "is"
        
         | dang wrote:
         | Yup. We certainly don't want "Plastic is made from milk and
         | vanishes in 13 days" but I'd rather not have a linkbait "This"
         | so took a non-this route.
        
       | pixl97 wrote:
       | How long before a bacteria learns it can eat this and starts
       | breaking it down much more quickly?
        
       | nancyminusone wrote:
       | Worth noting that casein is a very very old technology - people
       | have known how to use it (well, milk) to make a type of glue for
       | thousands of years.
        
         | kbelder wrote:
         | 1) Heat 1 cup milk, not to boiling.       2) Add 4 tablespoons
         | vinegar.  Stir for a few minutes.       3) Strain out curds.
         | Squeeze to remove as much liquid as possible.       4) Form
         | into a shape or press into a mold, let dry.
         | 
         | It's in that small category of objects that seems like plastic,
         | but are still edible. Tastes bad, though.
        
           | wao0uuno wrote:
           | That's literally a recipe for paneer cheese. Tastes awesome
           | fried and mixed into many Indian dishes.
        
           | washadjeffmad wrote:
           | There was a variation of this in a midcentury science book
           | for a children that I'd check out from the library as a kid.
           | It was used to demonstrate how to make your own 'plastic'
           | action figures.
        
       | wolfi1 wrote:
       | sounds like bakelite to me. you can get a disposable polymer from
       | polylactide as well, and it can be obtained from silage (so-
       | called green refinery, although the term seems to have been
       | broadened in the last decade)
        
       | tartoran wrote:
       | PLA is also biodegradable and cheap but it does not biodegrade
       | that fast, certainly does not vanish in 13 weeks. Im not sure
       | what the usecase is here but I'm sure it could have some uses.
        
         | functionmouse wrote:
         | PLA does not break down naturally. It will last centuries in
         | the environment.
        
           | malfist wrote:
           | PLA does break down naturally, it is a good source of carbon
           | for many types of bacteria. It takes a long time, and happens
           | more quickly in industrial composters where it's shredded to
           | microplastics first but it does happen.
           | 
           | Take a look at something people have been using for eons with
           | saltwater aquariums: bio-pellets. These are tiny beads of PLA
           | that are fluidized to allow high turnover of water through
           | the PLA, this encourages bacteria to colonize and digest the
           | PLA, then break off and move into the water column (the
           | bacteria) and be removed by the protein skimmer. Because of
           | the red field ratio, each 106 mols of carbon from PLA removed
           | this way also removes 16 mols of nitrate, which is a major
           | pollutant in aquariums. It also removes 1 mol of phosphate, a
           | major pollutant as well, but that's not significant.
           | Phosphate is best done by fluidized reactors with ferric
           | oxide
        
             | zenith_is_tired wrote:
             | CNC Kitchen put 3D printed PLA into their composted for
             | over three months. I don't remember the specifics, but
             | results were underwhelming.
             | 
             | As someone who constantly prints temporary jigs and
             | spacers, I'm interested in compostable filament. Bonus
             | points if it is comparable to PLA in price.
        
               | tmp10423288442 wrote:
               | There are a decent amount of plant parts that don't break
               | down much at all in 3 months - doesn't mean they aren't
               | biodegradable ultimately, although hoping for
               | biodegradation as a way to eliminate litter is a
               | nonstarter with this approach.
        
               | malfist wrote:
               | 3 months? Most organics will not break down in that time.
               | 6-12 months is recommended, and even then, not everything
               | is broken down. I've had egg shells last 2 years or more
               | in my compost bin.
               | 
               | I made no claims about the speed at which PLA breaks
               | down, only that it does. Biopellets in reactors tend to
               | last years.
        
       | lich_king wrote:
       | > vanishes in soil in just 13 weeks.
       | 
       | Part of the problem with waste management is that we don't really
       | put it in the soil. Your household garbage is mostly
       | biodegradable, but if it ends up buried in a lined pit under tons
       | of other garbage, even paper and orange peels will probably sit
       | there for centuries. I'm not sure it makes much of a difference
       | what kinds or quantities of plastic end up buried in the
       | landfill.
       | 
       | I think the solutions here are more on the supply side than the
       | landfill side. The question there is what are we trying to solve.
       | 
       | Energy use? Most alternative packaging materials are energy-
       | intensive too, so it's less about plastic and more about retail
       | and consumer preferences to have everything individually wrapped
       | and packaged in bags or boxes with colorful graphics, nutrition
       | information, and so on.
       | 
       | Environmental pollution? There, the problem is the plastic that
       | doesn't end up in a landfill. Including our "recycling" shipped
       | overseas.
        
         | cogman10 wrote:
         | It still biodegrades within the pit. In fact, that's actually a
         | problem because it can generate fire starting temperatures!
         | (Crazy I know) It's also a problem because a part of
         | biodegrading is producing CO2 and CH4.
         | 
         | But I generally agree. The big issue here is we as a society
         | have moved away from biodegradable packing and distribution. I
         | get it, plastic prevents waste and mold. That's why we use it.
         | It's also dirt cheap. It's a byproduct of oil refining
         | (literally cheaper than water).
         | 
         | The ultimate solution to the plastic problem is making plastic
         | more expensive, and the way to tackle that is by reducing oil
         | consumption. Fortunately, that's sort of just naturally
         | happening.
        
         | wolvesechoes wrote:
         | > I think the solutions here are more on the supply side
         | 
         | This is why nothing happens there, yet common folks receive
         | higher and higher burden.
        
       | killerstorm wrote:
       | Any article about biodegradable plastics should start with
       | advantages over cellophane/cellulose.
       | 
       | People have figured out how to make it a hundred years ago, it's
       | already used for food packaging, known properties, abundant and
       | cheap - made from trees / other plants.
       | 
       | The article starts as if it's some breakthrough miracle which is
       | unheard of. I can literally just buy compostable bags for organic
       | waste made of corn starch on Amazon. It's already a product.
       | 
       | Journalist demonstrate less awareness than 8B LLM. Scientist
       | tells you about a new plastic? Ask them how it's better than
       | what's already on the market.
        
         | coryrc wrote:
         | > I can literally just buy compostable bags for organic waste
         | made of corn starch on Amazon.
         | 
         | They compost, but they don't biodegrade. The difference is
         | whether it breaks into microplastics or dissolves/is digested
         | in the ocean.
        
           | jacobolus wrote:
           | My understanding is that cellophane generally does biodegrade
           | in most settings. Polylactic acid (those cornstarch-derived
           | bags) mostly biodegrades in hot enough compost or (after
           | several years) in ambient-temperature soil, but not very well
           | in cooler water (One study: "The half-life period of
           | degradation [of polylactic acid in artificial seawater] is 12
           | [days at 90deg C] or 468 days [at 60deg C]").
        
             | toss1 wrote:
             | >> 12 [days at 90deg C] or 468 days [at 60deg C]
             | 
             | Those temperatures are certainly hard to find in nature,
             | outside of hot springs! Even if this is an error and we are
             | talking about 90degF/60degF, the higher temperature is
             | pretty much constrained to the tropics, so we're talking a
             | year+ to degrade in real conditions. It is better than
             | centuries, but not exactly rapid?
        
               | jacobolus wrote:
               | Yeah, I imagine it's considerably slower at ambient ocean
               | temperature. Don't throw your PLA bags in the ocean or a
               | river. Here's a different paper:
               | 
               | > _For example, PLA is not biodegradable in freshwater
               | and seawater at low temperatures [32,36-39]. There are
               | two primary reasons for this: (i) The hydrophobic nature
               | of PLA, which does not easily absorb water [40-42]. In
               | aqueous environments, the lack of hydrophilicity
               | diminishes the hydrolysis process, which is crucial for
               | the initial breakdown of PLA into smaller, more
               | degradable fragments. (ii) Resistance to enzymatic
               | attack; the enzymes that degrade PLA are not prevalent or
               | active under typical freshwater and seawater conditions
               | [39,43,44]. The microbial communities in these
               | environments may not produce the necessary enzymes in
               | sufficient quantities or at the required activity levels
               | to effectively breakdown PLA. Additionally, the
               | relatively stable and crystalline domains of PLA can
               | further resist enzymatic degradation._
               | 
               | Also:
               | 
               | > _It should be emphasized that neat PLA cannot be
               | classified as a completely biodegradable polymer, as it
               | generates microplastics (MPs) during biodegradation._
        
             | IAmBroom wrote:
             | That can't be right - even 60 C is 140 F. No normal water
             | bodies are near that hot.
             | 
             | If it's actually 60/90 FAHRENHEIT, very few water bodies
             | are (currently) 90 F. That's above even most equatorial
             | temps.
        
         | crystal_revenge wrote:
         | > Story Source:
         | 
         | > Materials provided by Flinders University.
         | 
         | It's not that the "journalist" didn't think to ask, it's that
         | this is a PR piece sent out to media outlets _from the
         | university that did the research_. Nearly all universities have
         | a PR team that sets fluff pieces out to the media to promote
         | the work of the university.
         | 
         | The person who wrote this is being _paid_ not to ask tough and
         | important questions around this research.
        
         | marcosdumay wrote:
         | > Any article about biodegradable plastics should start with
         | advantages over cellophane/cellulose.
         | 
         | Well, I guess it starts with the plastic being thermoplastic.
        
       | CagedJean wrote:
       | Wow! Temporary boob implants!
        
       | abracadaniel wrote:
       | Products that involve clay as an ingredient tend to have issues
       | with lead contamination (along with other heavy metals) as it
       | likes to absorb them, and the sources are highly variable.
        
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