This article originally appeared in Storm Water Solutions March/April 2020 issue as "Into the Water"
Over the past twenty years or so (as evidenced by my gray hair) we have focused on storm water borne pollutants, such as oil and grease, trash, total dissolved solids (TSS), total phosphorus, heavy metals and, in some cases, total nitrogen. To address these issues, we have developed many effective regulations, design approaches and technologies.
However, as more research on water quality and receiving water impacts are done, other more insidious pollutants are emerging. Among these pollutants are per- and polyfluoroalkyl substances (PFAS) and micro-rubber compounds. Even though these compounds have been in use for decades, new research seeking to identify and characterize the impact on receiving waters and associated biota, including humans, has created the current buzz. What strikes me is that both pollutants are fully integrated into our modern lives and taking them out of the aquatic environment may not be possible given the practical realities of contemporary society.
There are nearly 5,000 PFAS compounds in products used in our everyday lives, including cookware, water-resistant fabrics, cleaning products, paints, fire retardants and more. These compounds are stable and persistent in the environment. In fact, they are ubiquitous in human blood and in our drinking water. Though sophisticated water treatment methods are available, such technology is usually not practical for storm water runoff. The jury is still out on the impacts on human health and the natural environment and how to regulate them, but I think I will start using my mom’s well-seasoned cast iron pan from here on out.
Micro-rubber is a subsect of microplastics, which include the use of persistent polymers used in a wide array of products, including personal care products, pharmaceuticals, etc. and includes hundreds of unidentified compounds. Micro-rubber, originating from tire wear, has been linked to aquatic toxicity for Coho Salmon in the Pacific Northwest. Research by Empa Material Science and Technology Labs indicates that micro-rubber accounts for more than 90% of microplastic particles found in the environment. Of that, they indicate that 20% end up in our receiving waters while the remainders end up in the soils nearby and are carried into the atmosphere. As a driver, I have always noted the rapid accumulation of black solids on the rear window of my car and, working in the treatment business, I have always noted the “black sticky” sediment from roadway runoff.
A paper by Masakazu Yamashita presented an estimation of the annual volume of tire wear dust created in Japan to be on the order of 1.7 million cubic meters.
I am not sure what to think about all of this as it is hard to imagine modern vehicles with environmentally benign or biodegradable tire compounds that give you at least 40,000 miles of use or maybe no tires at all. I figure, if that was easy, the tire companies would have figured that out by now. What would life look like without the use of PFAS? And even more concerning, what about the pollutants and compounds that are not even on the radar yet? How do we establish a balance between the benefits of what we produce versus the long term environmental impacts of those products?