Animals

The Shocking Truth About Biodegradable Plastics

Plastic makes our lives much more convenient, but it takes a very, very long time to decompose. How long does it take, and do biodegradable plastics solve this problem?

Related on TestTube:
Why You Should NEVER Throw Away Batteries
Which is Actually Better for the Environment: Paper or Plastic?

Plastic is an umbrella term used to describe any number of synthetic materials that can be molded into shape while soft and turn rigid. The first plastic material to hit the market was bakelite, which was invented by chemist Leo Baekeland in 1907, and from that point on--thanks to low cost and versatility--society was forever changed. Since plastics are not natural, bacteria don't digest them, and and they don't biodegrade. They just degrade from being exposed to things like UV radiation and friction from oceanic currents. By definition, for something to be biodegradable, it needs to be broken down by bacteria or other living organisms, so is a truly "biodegradable plastic" even possible?

According to the International Union of Pure and Applied Chemistry, a material can biodegrade in one of three ways:

1. Primary: Chemical alteration of the substance's property
2. Environmentally Acceptable: Biodegradation of only the undesirable properties of that compound.
3. Ultimate: The compound is completely broken down to either fully oxidized or reduced simple molecules like water, carbon dioxide, etc.

Per these guidelines, biodegradable plastic has compounds added to it which are supposed to enable bacteria to break them down. There's also bioplastic, which is a plastic that's made from a renewable source of biomass, like corn, vegetable oils, peas, or even microorganisms. The most common form of bioplastic is polylactide acid or PLA and is made out of corn. Unfortunately, in order for PLA do biodegrade, it needs a certain kind of bacteria at just the right temperature. These are not found in landfills, (where most plastic bags end up), but require treatment at one of 42 commercial composting facilities in the U.S. On the other hand, some biodegradable plastics are capable of biodegrading in landfills, but end up breaking down into methane gas -- which is technically a "simple molecule", but also happens to be a greenhouse gas.

So it looks like the concept of "biodegradable plastics" has been an oxymoron all along. A recent study from Michigan State University found absolutely no difference between regular plastic bags and additive-treated plastic bags and bottles as we know them. Of course, there are plenty of plant and fiber-based containers on the market which aren't just biodegradable, but actually compostable. Of course, the best strategy is to minimize how much trash you create, so recycling and reducing your trash is always the easiest way to ensure your lifestyle has the least impact on the environment.

Learn More:
How long does it take for plastics to biodegrade? (How Stuff Works)
"Drop a ketchup bottle on the floor, and you'll be thankful for polyethylene terephthalate, or PET, the nearly indestructible plastic used to make most containers and bottles."

Time it takes for garbage to decompose in the environment (New Hampshire Department of Environmental Service)
"Time it takes for garbage to decompose in the environment: Glass Bottle: 1 million years, Monofilament Fishing Line: 600 years."

Do Biodegradable Plastics Really Work? (Mother Jones)
"Just how long does it take for conventional plastics to completely break down?"