Odile Madden knows a lot about plastic. A materials scientist with the Smithsonian’s Museum Conservation Institute, she has spent the past eight years studying plastics found throughout the Smithsonian’s collections.
Odile spoke with John Barrat about her work and her belief that plastics, like all materials created or adapted by humans, will evolve.
In 2015, Odile Madden embarked on a collaborative study with researchers at Western University in Ontario to examine microplastics that pollute two key waterways in the Great Lakes: Lake Ontario and its outlet to the Atlantic, the St. Lawrence River. The results of that study were published recently in the Marine Pollution Bulletin.
What are microplastics?
Microplastics are pieces of plastic that either started out smaller than a half centimeter in size or they’ve broken down to that size or smaller. Many people seem to see microplastics as evidence that ‘plastic lasts forever, it never goes away.’ In my job working with museum artifacts, I see that plastic really does not last forever.
What did you learn about microplastics in the Lake Ontario/St. Lawrence River study?
Our team found that the highest concentration of plastics in the Lake Ontario environment is directly related to the most densely populated areas onshore. It looks like the plastic deposition in the lake environment is more related to the source of the plastic rather than the water currents and the storm patterns carrying the plastic around or the shape of the shoreline that can collect it. Population density is more important in describing the source of the plastic than the geography or the water flow patterns that disperse the plastic.
Did that surprise you?
It did a bit. In 2013, I took a research trip to Alaska with other scientists and a group of artists. We were looking at very remote shores in Alaska and finding huge amounts of plastic on some of these shorelines—but not because a lot of people lived there. A spit of land off the Alaska coastline was collecting plastic because of the currents and the way they flow around the Gulf of Alaska. It was interesting to see how water currents carried plastic a long way and how the plastic was deposited along the shoreline. We hardly saw a soul in the six days we were out on the boat. In that case, the plastic is being carried to places far from the source.
In the Great Lakes environment, I was interested to see that the most densely populated areas seemed to have the most effect on where the plastic was found, rather than where the environment was carrying the plastic.
Maybe that has something to do with the fact that a lake is a more closed environment than the open ocean. It also seemed to affect the kind of plastic that was found.
In Alaska we found types of plastic that float, like polyethylene, polypropylene, and plastic foams. It had to be carried a long, long distance to land where it did.
In Lake Ontario, our team found both plastics that float and plastics that don’t float. There was a large proportion of polyethylene nurdles—the small plastic beads from which larger objects are molded.One interesting find was a significant amount of polyurethane, which has become popular as a household and industrial glue and gap-filling foam, as well as a packing material.
We also found that some of the plastics that would be expected to float were actually found in the sediments on the lake bottom. We’re still studying how floating plastic gets pulled and held down on the bottom.
Most people tend to think of plastic as an environmental evil, but you’ve said in the past that you don’t find that viewpoint particularly productive. What is your own attitude toward plastics?
As a materials scientist, I study plastic as a material, and I spend a lot of time studying the technology by which it is shaped into things. So I look at synthetic materials as substances made by people that are shaped into objects with a goal in mind. They have a motivation, a desire for something, and they have some amount of capability that they use to make the material into objects that they can use. That’s very much about choice. And materials are just stuff. Stuff is not evil.
When creating any new material, it is normal, probably inevitable, to discover some deficiencies along the way. Correcting those deficiencies is important if a type of material is going to be successful. This is as true for plastics as it is for metals, ceramics, paper, and so on.
Do you think our use of plastics will change in the future?
I believe that plastic will continue to sort itself out because it is a new material. When I look back at other materials through history and how they’ve evolved, I see examples where some have evolved into less unhealthy options.
Celluloid, a name for an early plastic called cellulose nitrate, is my favorite example of a kind of plastic that evolved from something very unsafe into something safer. One of its characteristics is that it is extremely flammable. It can combust without air and even burn under water. It is very hard to put out a cellulose nitrate fire.
Celluloid was used for motion picture film around the turn of the 20th century and to make novelty items such as comb and brush sets, shirt collars, all sorts of objects. It had this tendency to ignite quite spectacularly, and there were fires in factories and movie theaters that injured and killed many people. Celluloid was a huge, obvious public safety hazard. But people weren’t willing to do without motion pictures or these personal items.
But over the course of 50 or 60 years the use of celluloid evolved. Traveling on public transport with motion picture film made of celluloid was forbidden. Projectionists in movie theaters became licensed and were trained how to handle this kind of film. Movie theater projection rooms were engineered in ways that could contain a fire should one start.
All the while, new materials were being developed to substitute for celluloid, but it took about 50 years to adopt substitutes such as cellulose acetate, which wasn’t particularly stable but wasn’t as flammable as celluloid. Today, polyester film, which doesn’t have that flammable property, is the base of choice for modern motion picture film.
This is an example of a plastic improving upon its deficiencies over time such that it becomes safer. I think that trend will continue as we work to overcome things we don’t like about today’s plastics—like pollution.
So in a historical context, problems with plastics don’t end in world destruction, they end in solutions?
There are more than 7 billion people on the planet. It would be very difficult to destroy all of us. That doesn’t mean that plastic will not cause some suffering along the way. But I hope and think it will continue to evolve into something that’s more acceptable.
As we go forward, understanding the kind of plastic that makes up the pollution has ramifications for how we manage it, either by regulation, filtration, collection or design of the plastic. Before we can do that we need to understand what kinds of plastic are finding their way into our waters and how they are polluting them.
Posted: 3 April 2017