Research

U of T Professor Douglas Stephan of Chemistry weighs in

The City of Toronto enacted a new bylaw this summer requiring retailers to charge customers for plastic bags, resulting in many of us toting our own canvas and other reusable bags to the grocery store. We wondered how bad plastic bags actually are. To find out we spoke to Professor Douglas Stephan of Chemistry. He holds the Canada Research Chair in Catalysis and New Materials.

How bad are plastic bags for the environment?

The issue is that the vast majority of plastic bags—except for the paint, the coatings that are on them for the branding—will not biodegrade. These are polyethylene bags for the most part. Polyethylene is basically a solid form of oil—it’s made from the byproducts of oil refineries. The process takes small ethylene molecules, which are two-carbon chains, and links them together into a big long chain. So you have these long chains of carbon atoms that basically are chemically inert, with the exception of under extreme conditions—they are flammable. But they’re not going to age well. There are no bugs that will consume plastic. They’re going to be around a long, long time. That’s the problem.

The other side of that question, as I understand it at least, is simply the sheer numbers. Five hundred billion bags are used worldwide each year. Ontarians use 7 million plastic bags a day.

So the new bylaw will potentially make a real impact.

Absolutely. The other thing it does is bring to the forefront a green mentality. It makes people think about ways they can avoid needless use of stuff. At the same time it would be nice if they could address the packaging industry, but that’s a tougher one. I notice an inordinate amount of cardboard and  packaging when I take out the recycling. An awful lot of it could be avoided.

I’ve done a lot of traveling to Europe. It is routine there for people to carry bags to the store. They have been doing this for ten years or more. In some sense, North America is behind.

But there’s economic impact to phasing out the use of materials. It has to be done slowly and carefully.

Is biodegradable plastic on the horizon?

There are people working on biodegradable plastic. But the target application is probably not grocery bags. There are already polymers that will biodegrade over a relatively short period of time. For example, sometimes when you get stitches, they are made from a polymer holds your skin together while it heals. Gradually it will degrade and the stitches eventually dissolve. These kinds of medical applications are perhaps a more critical use of new materials than applications like plastic bags.

Are we moving toward abandoning plastic?

We are not going to abandon plastics. Synthetic materials are a very important part of our material world—but we’re not talking here about bags, about the gratuitous use of plastic. For example, plastic is used in all kinds of electronics. The notion of going to a paperless society is based on supporting material—flexible electronics on very readily available polymers. There are all kinds of applications for new polymers.

What is your research about?

We are targeting new technologies to produce polymers. We’re focused on the technology for production more than the actual material that ends up being produced, but we work in concert with polymer chemists.

Tags: Behind the Headlines, clean technology, Douglas Stephan, Environment