Plastics are commonly portrayed as environmental villains. It is alleged that they never biodegrade, and therefore persist indefinitely in the environment. A few years ago it was even claimed, absurdly, that there are giant floating islands in the oceans, described in some quarters as “twice the size of Texas,” consisting of plastic.

None of that is true. Kip Hansen provides a useful corrective at Watts Up With That:

The simple fact is that plastics do degrade in the environment, especially in the ocean (and lakes, streams, rivers). When real scientists went out to investigate the marvelous Pacific Garbage Patch imaginatively described by Charles Moore, they found — well, almost nothing.

There is an enormous amount of “missing” plastic that some environmentalists claim must be floating in the ocean, somewhere. In fact, the “missing” plastic has been consumed–if you will, recycled:

As we have seen, floating plastic in the sea rapidly breaks down into smaller and smaller pieces — being exposed to sunlight and the motion of the waves. When the size of the pieces reaches a seemingly critical point, smaller than 1 mm, the plastic disappears. Simply put, it has been known for the last ten years or so that the missing oceanic plastic is eaten. Not just by fishes, although certainly some is ingested and re-excreted by fishes, but actually consumed as food by microorganisms.

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The tiny animals actually consume the plastic itself, much in the same way that they ate the oil from the Deepwater Horizon Gulf of Mexico Oil Spill. (Scientific American magazine ran this piece: “Meet the Microbes Eating the Gulf Oil Spill”. ) The same principle involved in the melting of crushed ice vs. cubed ice operates here: the smaller bits have a greater surface area compared to their total volume, and at a critical size, the microorganisms eating away at the surfaces just eat it all up. The natural pathways for the degradation and biodegradation of plastics have been known since 2008-09 or so, splashed about in the major journals. This is not secret information.

So you can rest easy. Plastic is not forever. Does that mean that we should dump plastic objects into the ocean? Obviously not. Hansen concludes with some common sense observations:

Bottom Line: It is a Scientific Urban Legend that “plastics are forever”. Most plastics both degrade and biodegrade in the environment — whether in the oceans or in landfills. Some plastics — such as PVC — resist degradation and thus are useful as building materials replacing such things as metals in plumbing and lumber in siding and building. The “floating rafts of plastic garbage”-version of the Great Pacific Garbage Patch is a pernicious myth that needs to be dispelled at every opportunity. The “missing 99% of the plastic in the oceans” has been eaten, mostly by bacteria and other microbes. These little critters will continue to eat the plastic and if we reduce the amount of plastic going into the oceans, they may eventually eat it all up. Microbes are also eating up the plastic in landfills — albeit, much more slowly. Take Home Message: Kindergarten rules apply at all stages and areas of life: Pick up after yourself — clean up your own messes. We need to do all we can to keep every sort of trash, including plastics, contained and disposed of in a responsible manner – this keeps it out of the oceans and the rest of the natural environment. Plastics are valuable and should be recycled whenever possible into useful and valuable commodities, such as replacements for lumber in decking, shipping pallets, etc. Volunteerism to clean up beaches and reefs is effective and worthwhile. Responsible outdoor recreation, including boating, includes keeping your trash (and especially plastics) under control and disposed of properly ashore.

If anyone ever advocates capital punishment for those who throw trash off the decks of cruise ships, I’m in. Sometimes, when talking to an environmentalist who goes on and on about global warming, etc., I like to change the subject and talk about littering and what can be done to stop it. Litter (including plastics) is, in my view, the most serious environmental issue, albeit one that never seems to be of much interest to environmentalists who can raise much more money by talking about global warming.