by Karen Hall

Plastics. We use them every day. Some of us also wear them, in the form of jewelry, athletic shoes, polyester cloth, pantyhose (does anybody really still wear those?), glasses frames. Plastics are used in toys, signs, cars, construction materials. There are plastic parts in the printer on my desk, the phone that sits next to it, and the trays that sit under my house plants. I got an award several years ago and, you guessed it, it’s made of plastic.

Plastics are – literally – everywhere. Last week my husband Jeff and I spent some time traveling across farming country, and plastic bags, like small balloons, were hooked on stubble in every single windy cornfield. In deciduous trees, which are still bare in this part of the world, shreds of plastic bags fluttered almost everywhere.

Also, I recently saw a feature on television news that showed how much plastic has invaded our oceans. Go to YouTube and check out some of the videos. They’re horrifying. A few days later a friend told me her son recently sent her a photo of an Albertson’s plastic bag caught in a tree in Rapid City. I’m sure I frowned; there hasn’t been an Albertson’s store here since 2009. That got me thinking, though. What happens to all the plastic that we use, usually only once, then throw away?
Well, it turns out that not much happens to it. If it goes to a landfill, which is what happens with most plastic, it gets covered up by more trash and, eventually, dirt. And since it takes oxygen for most things to break down biologically, most things in landfills simply stay there. In whatever form they had when they got there. No biodegradation. Landfills are typically anaerobic environments. No oxygen, at least not enough for biodegradation.


Would it be better to let those bags fly away then? That’s a big old NO. Very little of the plastic currently produced actually biodegrades, meaning that organic processes happen to break the material down into basic substances that are no longer plastic or plastic-like, elements such as carbon, oxygen, sulfur and nitrogen.

Wait a minute, though. What about those plastic bags that were made with cornstarch? They call those “bioplastics” now. They were advertised as biodegradable, weren’t they? Well, yes. But how long does it take? Some take weeks, some take years. Some need high temperatures and water in order to break down. And when they do, they give off methane, which is a greenhouse gas that contributes to global warming. Some take a long time and leave behind a toxic residue. Sigh. And then there’s the issue that they’re made, in part, from CORN. In a world where people don’t always get enough to eat, we’re growing corn to make plastic.


What about plastics that are labeled “biodegradable”? Are they really? Maybe. Some contain additives that make them decay, but they need light and oxygen to do so. Again, not so much of either in the landfill.

So when you’re out with your county political party cleaning a roadside and you find one of those plastic bags that disintegrates into shreds when you try to pick it up, is it biodegradable? Probably not. The elements are working on it – light heats it up via radiant heat transfer and night freezes it, at least here in South Dakota. Wind whips it against whatever else is in the ditch and it tears into shreds. It’s not degrading in any biological way, just in a physical one. Not the same thing at all. Now it’s just much smaller pieces of plastic.

So, I asked myself, if there really ARE such things are biodegradable plastics, where do they go to biodegrade? Not many places, it turns out. The best way for those plastics to biodegrade is in a commercial composting facility. There are none in South Dakota, though some of our neighboring states do have them: Minnesota, Iowa, Wisconsin, Colorado. These facilities are hot: the biological processes, with help from the facility itself, bring wastes to a temperature of 140 degrees F and higher, which is necessary for some plastics to biodegrade. But that’s not all: the humidity must be high (greater than 80%, which happens almost never in western South Dakota), and specific microorganisms must be present. It became clear to me quickly that plastics that truly ARE biodegradable will probably not break down in a backyard compost bin or pile, at least not during my lifetime.


So I’ve come to the conclusion that almost all of the plastic that has ever been made is still with us, and still plastic. Think about that.

So what’s the answer? More in my next post.

Karen Hall, Rapid City Author