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I am not an anti-plastic guy. My ability to do my job relies heavily on high performance plastics in the products I use every day. If not for some of the advanced chemistries that have been developed over the last century, the world would be a much different place. In some ways for the better, but in many ways much worse. Anyway, this is all to say that my views on chemistry and plastics are nuanced.
I am, probably unsurprisingly, very against plastics that end up in the environment. My affinity for clean waterways, trash-free trails and animals without bellies full of plastic has led me to spend a lot of time thinking about plastic waste. That pondering has turned to microplastics recently, or more accurately to micropolymers. The difference may not be obvious. Simply put, all plastics are polymers, but not all polymers are plastics. Several natural products, such as cellulose and rubber, are polymers, but they are unable to be processed like a commercial plastic material until they are altered from their natural form.
I’ve specifically been thinking about three ways that micropolymers may be entering the environment.
Old hat: Tire wear particles
It turns out that tire wear particles, or TWP, may be the oldest form of micropolymer pollution in our natural environment. The history of the tire is one of trial, error and human suffering from an abundance of very uncomfortable rides. Once vulcanization became widespread, the tire industry took off (vulcanization being the process of heating natural rubber in the presence of sulfur and other additives to cross-link and strengthen the material).
My affinity for clean waterways, trash-free trails and animals without bellies full of plastic has led me to spend a lot of time thinking about plastic waste.
Unfortunately for the natural world, the evolution of the tire and (along with it) every kind of over-the-road transportation over the last 100 years has led to more TWP pollution. According to Bridgestone Americas, modern tires "can include natural rubber, synthetic rubber, steel, nylon, silica, polyester, carbon black, petroleum, etc." In other words, when small pieces of TWP end up on our roads, these complex, engineered materials will not degrade in the environment and are likely to end up in waterways and/or moving up the food chain.
The more obscure: Street sweepers
Micropolymers from street sweepers are a small issue compared to tires or clothing, which I’ll get to later. But it is one I’d never thought of until very recently. I had the pleasure of hearing Damon Carson, founder and president of repurposed MATERIALS, speak this fall and he mentioned that street sweeper brushes that are always being decommissioned due to wear. His company has found a second use for these brushes as scratch posts for cattle and horses. A creative reuse story for sure. This story got me thinking, though, about what is happening to all that plastic as they wear down.
It actually seems that street sweeping may be one method to control micropolymer pollution from entering waterways rather than contributing to it; a potential rare bright spot in this battle. One study in Science of the Total Environment, for example, concluded that "street sweeping is an effective measure for reducing the load of TWP, metals, and PAH [polycyclic aromatic hydrocarbons] on the road surface, and for preventing these pollutants from reaching stormwater."
Great news, right? Well, like everything, I’m sure it’s not quite that clean cut. I’d be very surprised if some micropolymers and other pollutants being brushed by street sweepers (including the small particles from the brush itself) aren’t becoming airborne in the process and finding their way back out into the environment. This is just one in a large stack of items that we should innovate around.
The frustrating: Synthetic fiber pollution
Most people probably own north of 100 clothing items. I’d venture to guess that a majority of those are made with synthetic fibers or synthetic blends. These clothes have changed fashion for the better in many ways. They are cheaper, more stain resistant, don’t stretch or shrink easily, and tend to be more durable.
The problem? If it wasn’t micropolymer pollution, it wouldn’t fit in this essay very well, would it?
The European Environment Agency estimates that between 16 and 35 percent of all microplastic pollution globally comes from synthetic fibers. There are many routes for this escape to nature from the textile mills to the manufacturing facilities, wear and tear to landfills, and yes, even your own humble washing machine.
This is a systemic problem that individuals will not be able to solve on their own.
We can tackle much of this problem, though, through installation of filters on washing machines. Several are available on the market. We are also starting to see a bit of movement in Europe to require filters to be installed by manufacturers. For example, France is requiring all new washing machines sold in the country to contain filters starting in 2025. This is a good first step that hopefully spreads across the globe in the coming years.
What you can do
As I ponder a future where there are more plastics in the oceans than fish, where our seas are no longer able to effectively sequester carbon, and where we are all eating even more microplastic in our diets, it would seem that today is as good a day as any to take action to reduce the plastic, both macro and micro, that is making its way into our environment.
If you’re a user of products that may shed micropolymers, put in the work to find out how you can decrease your impact. Installing filters on washing machines, using microfiber filtering laundry bags, or even washing only full loads can help reduce your own impact. Another suggestion is to purchase a front-loader washing machine when it is time to replace; they tend to cause less microfiber shedding than their top-loading counterparts.
If you’re employed by a company that is contributing to micropolymer pollution in the environment, make sure you are doing all you can to push them toward innovation in this space. This is a systemic problem that individuals will not be able to solve on their own. You could encourage your company to do R&D to limit micropolymer pollution from products, support legislation that would limit pollution or start a collaborative effort with others in your sector to tackle the problem.