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?
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.
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.
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.
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.
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?
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.
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.
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.
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.
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.
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.