Your Life with Microplastics
Yet another category of contaminants has emerged -- microplastics. Much of the press about these has focused on microplastics in cosmetics. It turns out that microplastics, typically in the form of small beads, are now found in many types of cosmetics including products to keep your hair in place and tangle free, products to make your eyes look glamorous (eye-liners and mascara) and your face wrinkle-free (fillers). Even if you are a manly man, you are not off the hook here. Microplastics are also found in shaving creams, toothpastes, deodorants and sunscreens. Even if you are in diapers, the pre-potty type, you are not off the hook. Microplastics are in kids’ bubble baths. As these materials are in the broad category of cosmetics, a consideration of their potential environment impact is not required for product testing or certification. In the U.S., only select components of cosmetics have to be evaluated. These include pigments and any potential medicinal compounds. The E.U. is more conservative, forcing a consideration of these materials in the product testing, but only for their intended use.
With increasing widespread use of these materials, surprise surprise, they’ve ended up in a range of environmental samples. In particular, studies have found them in aquatic environments. One of the prime sources of these materials is wastewater. And so, this month’s library is a primer on microplastics.
The first article is a general review on microplastics in cosmetics. Cosmetics are the most visible area of concern here. These particles are specially constructed, often in spheres, but also in random forms out of a range of different kinds of plastics. As product impact on the environment has not been a concern for the manufacturers, it has not been considered in their design and development. As a result, these are typically manufactured out of petroleum-based polymers and so have a very long lifespan. They are not expected to degrade in the environment for several human life spans. They potentially have a negative impact, although it is still not clear. Some filter feeders have shown impacts, others haven’t. They have shown up all over the place in all types of animals. The review notes wastewater treatment as a significant source of these compounds. It notes that treatment plants were not designed to remove these tiny balls and that it would cost a fortune to retrofit plants so that they could. It also mentions the biosolids as a source of these contaminants. Not so much for terrestrial organisms, but in the event that these beads roll down and out of the soil and into the sea.
The next article broadens the topic a little bit. It turns out that these microplastics don’t just come in beads, they come in threads. Literally and figuratively. Clothes made from synthetic fibers including polyesters, rayon and fleeces, shed tiny fibers each time you wash them. A load of wash can contain >1900 fibers. The authors looked at concentrations in different areas with matching urban sites where wastewater discharges would be expected to increase marine concentrations and more rural sites. Sure enough, they found increased concentrations in the urban areas.
If these microfibers are in wastewater, you can bet they are also in the biosolids. The third article in the library tested different land application sites in N.Y. State and different biosolids products from a single treatment plant to see if they could find these plastic fibers from clothes. Sure enough they did. The article includes really pretty images of the different types of fibers. As in marine systems, these fibers are not expected to go away anytime soon.
Then for article number 4 we go to the ‘this is a scary thing’ perspective. A short (2 page) article in Environmental Science & Technology, points out that if they are in the sea, these microplastics must also be on the land. They also note that these plastics may provide a sorptive surface for other organic contaminants, potentially increasing their availability and toxicity. The mechanisms that may make these compounds toxic in a marine environment may also be at play in a soil systems.
The final article in the series was written by students and I found it during my on line search on the topic. It is all about making biodegradable versions of these products. Whether or not they pose a real risk, and (right now we don’t know the answer to that) the thought of these tiny beads and threads in our soils and seas for thousands of years is not a pleasant one. In the same way we can now make biodegradable plastic bags, why can’t we make biodegradable plastics for cosmetics?
And as for the microplastics in clothes, I’m not clear about the right thing to do. Natural fibers are fabulous. I love silk, linen and cotton. But if you think about the environmental impact of growing cotton, maybe the right answer is to just wear the rayon shirt twice between washings. I’m not that clothes that naturally biodegrade will be so easy to market. Might make for some great YouTube videos though.
Sally Brown University of Washington