# Biodegradation of Plastics **URL:** \ **Category:** Factual Questions\ **Created:** [April 16, 2024, 2:00pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366 "2024-04-16T14:00:55Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [April 16, 2024, 2:00pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/1 "2024-04-16T14:00:55Z")
Inspired by a post in another thread: > [@We should go back to glass and metal containers](https://boards.straightdope.com/t/we-should-go-back-to-glass-and-metal-containers/1000329/38): > > And plastics are pretty benign in land fills. They take up space, like anything else in landfills, but they don’t cause any special problems. And bacteria are already evolving to eat plastic. I don’t think plastic is really a problem. Using up the oil to make it, on the other hand… We’ve only had plastics for a bit over a century. As noted by @puzzlegal, there are bacteria already evolving to eat it. Obviously, there are issues with plastics in water, too, and the whole question of microplastics in the ocean, and the potential health hazards there. I’m definitely not saying that we shouldn’t worry about pollution of plastics; but I am curious about whether we need to worry about the opposite problem, as well. Let’s say that bacteria continue to evolve to eat plastics, and we get whole families and genera of different varieties that eat different sorts of plastics in landfills or in the Pacific Garbage Patch. Maybe we even genetically engineer some bacteria specifically to eat plastics. How realistic is the danger that these bacteria start breaking down not just the plastics in landfills and the ocean, but in our homes, cars, and warehouses too? It seems like it could be a thorny problem. When Coca Cola has enough shipments of plastic 2 liter bottles decay en route, are they going to develop a new resin that’s decay resistant? And if so, won’t those bottles start filling up landfills? ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [April 16, 2024, 2:09pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/2 "2024-04-16T14:09:40Z")
> [@Babale](#): > > How realistic is the danger that these bacteria start breaking down not just the plastics in landfills and the ocean, but in our homes, cars, and warehouses too? I think it’s going to become an issue. I didn’t think it will be a big deal with shipping packaging, because that stuff has a short lifespan anyway. Lots of things are shipped in cardboard without problems, for instance, and cardboard is readily biodegradable. But i can see plastic pipes rotting out, or plastic insulation. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [April 16, 2024, 2:10pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/3 "2024-04-16T14:10:41Z")
> [@puzzlegal](#): > > But i can see plastic pipes rotting out, or plastic insulation. I’m thinking about all the plastic under a car’s hood, which is relatively exposed to the elements. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [April 16, 2024, 2:14pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/4 "2024-04-16T14:14:16Z")
Sure! In the long run, if there’s an ample supply of carbon, and access to water, something will eat the carbon. ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [April 16, 2024, 2:15pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/5 "2024-04-16T14:15:34Z")
Those things exist already. They’re called plants. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [April 16, 2024, 2:16pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/6 "2024-04-16T14:16:25Z")
> [@Schnitte](#): > > Those things exist already. They’re called plants AFAIK plants do not digest plastic? ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 16, 2024, 2:21pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/7 "2024-04-16T14:21:13Z")
> [@Babale](#): > > Let’s say that bacteria continue to evolve to eat plastics, and we get whole families and genera of different varieties that eat different sorts of plastics in landfills or in the Pacific Garbage Patch. Maybe we even genetically engineer some bacteria specifically to eat plastics. We don’t have to wait for bacteria to evolve to eat plastics – we can insert additives within the polymer chain to insure that they break down. > [@](#): > > **Biodegradable additives** are [additives](https://en.wikipedia.org/wiki/Polymer_additive) that enhance the [biodegradation](https://en.wikipedia.org/wiki/Biodegradation) of [polymers](https://en.wikipedia.org/wiki/Polymer) by allowing [microorganisms](https://en.wikipedia.org/wiki/Microorganism) to utilize the carbon within the polymer chain as a source of energy. Biodegradable additives attract microorganisms to the polymer through [quorum sensing](https://en.wikipedia.org/wiki/Quorum_sensing) after [biofilm](https://en.wikipedia.org/wiki/Biofilm) creation on the [plastic](https://en.wikipedia.org/wiki/Plastic) product. Additives are generally in [masterbatch](https://en.wikipedia.org/wiki/Masterbatch) formation that use carrier resins such as [polyethylene (PE)](https://en.wikipedia.org/wiki/Polyethylene), [polypropylene (PP)](https://en.wikipedia.org/wiki/Polypropylene), [polystyrene (PS)](https://en.wikipedia.org/wiki/Polystyrene) or [polyethylene terephthalate (PET)](https://en.wikipedia.org/wiki/Polyethylene_terephthalate). > > Most common synthetic plastics are not biodegradable, and both chemical and physical properties of plastics play important roles in the process of plastic degradation. The addition of biodegradable additives can influence the mechanism of plastic degradation by changing the chemical and physical properties of plastics to increase the rate of degradation.[[1]](https://en.wikipedia.org/wiki/Biodegradable_additives#cite_note-:2-1) Biodegradable additives can convert the plastic degradation process to one of biodegradation. Instead of being degraded simply by environmental factors, such as sunlight ([photo-oxidation](https://en.wikipedia.org/wiki/Photo-oxidation_of_polymers)) or heat ([thermal degradation](https://en.wikipedia.org/wiki/Thermal_degradation_of_polymers)), biodegradable additives allow polymers to be degraded by microorganisms and bacteria through direct or indirect attack. [Biodegradable additives - Wikipedia](https://en.wikipedia.org/wiki/Biodegradable_additives#:~:text=Common%20enzymes%20involved%20in%20microbial,depending%20on%20the%20environmental%20conditions). The problem is that hardly anyone is doing this now. I suspect a lot of the problem is that nobody wants their biodegradable package to start degrading before it’s been used. And, of course, it costs more. But it seems like a relatively simple solution to a hugely threatening problem. There have been attempts to use intense UV to start the breakdown of non-biodegradable plartics. I’ve spoken with scientists working on this. But trying to get people to cooperate and to get funding is an uphill battle. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [April 16, 2024, 2:49pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/8 "2024-04-16T14:49:57Z")
That’s the premise of a sci-fi book I read years ago: > **[Mutant 59 by Gerry Davis and Kit Pedler](https://www.fantasticfiction.com/d/gerry-davis/mutant-59.htm)** > > Mutant 59 by Gerry Davis and Kit Pedler - book cover, description. TL/DR: Things go very badly when a bacterium bioengineered to eat plastic escapes into the wild to find a smorgasbord. ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [April 16, 2024, 3:05pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/9 "2024-04-16T15:05:17Z")
> [@Babale](#): > > AFAIK plants do not digest plastic? I was responding to the [post above mine](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/4). ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [April 16, 2024, 3:10pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/10 "2024-04-16T15:10:09Z")
> [@Schnitte](#): > > I was responding to the [post above mine](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/4) She was referring to the carbon that’s inside plastic, not any carbon ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [April 16, 2024, 3:33pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/11 "2024-04-16T15:33:05Z")
I don’t think there’s a FQ answer. Personally I find it implausible that bacteria would be _that_ effective at breaking down plastics, without significant bioengineering on our part. There are a lot of hurdles for evolution to pass. …I would be delighted though. As many catastrophic problems as fast plastic decomposition it would cause, we’d deserve it. ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [April 16, 2024, 4:49pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/12 "2024-04-16T16:49:12Z")
Since plastics are complex molecules typically including a lot of carbon, isn’t there a chance that any plastic-eating bacteria would exhale carbon dioxide as a waste product? In that case, it might be environmentally preferable to keep the carbon sequestered in landfills rather than release it into the atmosphere. ---
**Author:** ![Max\_S](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Max\_S](https://boards.straightdope.com/u/Max_S)\ **Post date:** [April 16, 2024, 5:07pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/13 "2024-04-16T17:07:59Z")
> [@Babale](#): > > there are bacteria already evolving to eat it. FQ: which bacteria are you referring to? Are you asking if existing genera could pose a threat to manmade structures, or if some future bacteria might? ~Max ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [April 16, 2024, 9:14pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/14 "2024-04-16T21:14:13Z")
> [@Max\_S](#): > > FQ: which bacteria are you referring to? Probably _Ideonella sakaiensis_. [https://letstalkscience.ca/educational-resources/backgrounders/plastic-eating-bacteria-natures-recyclers](https://letstalkscience.ca/educational-resources/backgrounders/plastic-eating-bacteria-natures-recyclers) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 16, 2024, 9:35pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/15 "2024-04-16T21:35:53Z")
Just a reminder here that “plastic” isn’t a substance. It’s a whole very large category of many very different substances. Even if some bug evolves to digest polyethylene, that doesn’t mean that it’ll be able to eat vinyl, or acrylic, or styrene, or polycarbonate. And things exist that digest wood, too, and have for æons, but that doesn’t mean that wood is now useless as a material. Plenty of wood things last for centuries. ---
**Author:** ![Max\_S](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@Max\_S](https://boards.straightdope.com/u/Max_S)\ **Post date:** [April 16, 2024, 9:58pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/16 "2024-04-16T21:58:07Z")
I was going to point that out but it isn’t clear to me whether we’re discussing some hypothetical fast-acting decay, or what. Like from the OP, I don’t think anything around now is going to cause Coca Cola canisters to fall apart en route to the retailer. The timeline for _I. sakaiensis_ colonies to break down a thick layer of polyethylene seems to be on the order of years. ~Max ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [April 16, 2024, 10:17pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/17 "2024-04-16T22:17:47Z")
An organism that can degrade a material may only do so at appreciable rates under narrow temperature and humidity conditions. See wood, above. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [April 17, 2024, 3:10pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/18 "2024-04-17T15:10:57Z")
A lot will depend on the conditions. If the bacteria evolve to consume PVC in sunny, wet conditions, then buried pipes aren’t going to be in much danger. I sort of doubt a bacterium that evolves to consume one type of plastic is going to automatically going to be able to eat all other plastics. More likely whatever enzyme it uses is going to be effective on a small set of plastics with a certain chemical makeup. I would imagine that if PET starts being eaten by bacteria, they’ll just find a coating or something to inhibit their growth for some reasonable period in the plastic. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [April 17, 2024, 7:41pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/19 "2024-04-17T19:41:24Z")
Yes, but i expect over time most of the plastics will succumb to something. And i did say that i thought it unlikely we’ll have to worry about the single-use container getting our soda home, it’s things that are supposed to last decades, like pipes, that might be problematic. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 17, 2024, 8:19pm UTC](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366/20 "2024-04-17T20:19:40Z")
> [@puzzlegal](#): > > Yes, but i expect over time most of the plastics will succumb to something. They do physically break down into very tiny pieces, which is what they call _microplastics_. The problem is that beyond that you have to break down the chemical bonds to return material to the various cycles. But polymer chains are unwilling to do this easily, especially PFAS, which are saturated with fluorines, and the C-F bond is hard to pull apart. Polyethylene is arguasbly the simplest and most “vanilla” of polymers – it’s backbone of carbon atoms with a couple of hydrogens attached to the unsaturated arms of that carbon chain. But even PE takes a long time to break down under conditiomns in the outdoors. > [@](#): > > PE is highly recalcitrant and inert material hence it is very difficult to degrade in the environment even after buried for several years as landfill. A polyethylene sheet showed only partial degradation and negligible weight loss when kept in moist soil for 12–32 years [[77](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#ref-CR77)]. The recalcitrance of PE is due to its water insolubility, the hydrophobicity because of presence of linear backbone of carbon atoms, degree of crystallinity, and its high molecular weight [[86](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#ref-CR86), [111](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#ref-CR111), [114](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#ref-CR114)]. # Biodegradation of polyethylene: a brief review - [Sunil Ghatge](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#auth-Sunil-Ghatge-Aff1), - [Youri Yang](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#auth-Youri-Yang-Aff1), - [Jae-Hyung Ahn](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#auth-Jae_Hyung-Ahn-Aff2) & - [Hor-Gil Hur](https://applbiolchem.springeropen.com/articles/10.1186/s13765-020-00511-3#auth-Hor_Gil-Hur-Aff1) [_Applied Biological Chemistry_](https://applbiolchem.springeropen.com/) **volume 63** , Article number: 27 (2020) > **[Biodegradation of polyethylene: a brief review - Applied Biological Chemistry](https://link.springer.com/article/10.1186/s13765-020-00511-3)** > > Plastic waste management and recycling became a serious global issue as it affects living beings from all the ecosystems. Researchers investigated biodegradation of polyethylene (PE) by measuring changes in various physico-chemical and structural... That’s why intentianally putting in occasional “speed bumps” of other organics along that chain helps break it down – the long chain fractures at those points, allowing chemical reactions to take plavce there. And the chains aren’t so long. [Next page](https://boards.straightdope.com/t/biodegradation-of-plastics/1000366.md?page=2)