The Truth About Bioplastics

Photo: flickr/Andyrob
Biodegradable plastics are going mainstream, but how green are they?

Plastics have been getting their fair share of bad press lately, especially those ubiquitous grocery bags. Critics argue they’re made with fossil fuels, take anywhere between 100 to 1,000 years to break down and create a massive litter problem worldwide.

Enter biodegradable plastics, eco-solutions for consumer items such as bags, plastic wrap and take-out food containers and cutlery. While still in its infancy, insiders estimate the ‘alternative’ plastic product industry could capture up to 20 percent of the plastics market over the next decade.

So, if traditional plastics are “bad,” these greener alternatives must be good, right? Well, it’s not quite that simple. Here’s why.

Biodegradable plastics

While conventional plastics such as polyethylene and polystyrene are derived from fossil fuels, bioplastics, such as polylactic acid (PLA), are made from renewable resources such as starch from corn or sugar cane. Biodegradeable plastics (not to be confused with bioplastics), which break down under certain circumstances, can be derived from either agricultural or petrochemical sources.

In fact, biodegradeable plastics have been used in niche applications for years (consider dissolvable medical sutures, now a $300 million industry). But the consumer items have a shorter history. In the early 1990s, biodegradable plastic bags and plates, made of conventional polymers, such as polyolefin, mixed with a starch compound, were touted as a green alternative. Unfortunately, these products fell short of consumer expectations: While the starch component biodegraded, the plastic remained, albeit in much smaller bits.

And therein lies an important distinction: the meaning of the terms biodegradable and compostable. While a material can be labeled biodegradable (referring to the process whereby microorganisms cause decomposition and assimilation), it may not necessarily be compostable, the process by which material biodegrades to produce carbon dioxide, water and humus within a specified period of time. (This is what happens to organic waste that is processed in a municipal compost system or in your backyard composter.)

Confused? It gets worse. Beyond ‘biodegradable’ and ‘compostable’, today’s next generation of greener products may be labeled as oxo-biodegradeable, hydro-biodegradable, photo-biodegradable or water soluble, which speaks to the chemical process by which these materials break down. 

The bottom line is, not all biodegradable plastics are created equal and there are a lot of misleading claims out there. Fortunately, you don’t need a chemistry degree to sort it all out.

Just look for the “Compostable Logo,” designed by the New York City-based Biodegradable Products Institute (BPI) and the U.S. Composting Council. It identifies products that meet industry standards to break down quickly and completely in a municipal compost facility.

A not-so-perfect solution

If you think that opting for “green” plastics on a day-to-day basis is a way of doing your part to help address our growing landfill problem, think again.

“When they [consumers] hear the term “biodegradable” they think that somehow things are going to magically disappear no matter what they do, ranging from littering to putting them in landfill,” says Steve Mojo, executive director of BPI. “The reality is, none of that happens.”

Why? Because landfills are essentially built to “entomb” waste, preventing exposure to air, moisture and sunlight. So even biodegradable waste won’t break down very much in a landfill (and the products that claim they will cite dependency on variables such as oxygen and microbial activity). That’s why newspapers found in landfills are still readable 35 years later.

“The notion of making plastic bags biodegradable and then sending them to landfill is really oxymoronic,” says Mojo. Which is why consumers should look for compostable, not biodegradable products, he says. “By calling things ‘compostable’, you signal to the consumer that this is something you need to handle differently.”

How to handle

“If you don’t have [access to] a commercial composting system, you might as well not bother” with biodegradable plastics, says Joanne Fedyk, executive director of the Saskatchewan Waste Reduction Council . “[Composting] is what [these products] are created to do and if you put them in the landfill, they won’t break down any more than plastic will.”

Simply put, biodegradable products belong in the green bin, not the trash, and certainly not the blue box (biodegradable plastic and recycled plastic don’t mix).

But not all municipalities have access to commercial organic diversion programs yet. According to Statistics Canada, in 2006, 30 percent of Canadians composted kitchen waste via a curbside collection system (the figure was only slightly higher for yard waste, at 38 percent).

So dealing with our growing waste problem is less about plastic versus bioplastic and more about getting back to the basics.

 “In order to minimize what you send to the landfill, you need to reduce, reuse, recycle and divert to compost,” says Mojo.