Thoughts From Engineers: Microplastics: An Unavoidable Reality of Modern Life?
There’s nothing like the widespread use of plastic by all—and for nearly all purposes—to thwart any ambitions we may have as a society to live more sustainably. Plastic is indisputably fundamental to the world’s economy. The material’s strength, flexibility and durability make it indispensable in virtually all fields, from the delivery of vaccines to the manufacture of auto parts and ordinary household gadgets.
But after the object’s useful life is over, the plastic invariably lives on, often in the most remote and unexpected locales. Plastic matter in Arctic ice is a prime example of the human race’s unmistakable thumbprint on all things and all places. It takes only one look at a Cambodian shoreline, heaped with imported plastic waste, or an urban beach along Lake Michigan, littered with the remnants of a bash from the night before, to know that managing plastic waste is a problem not easily resolved.
This is a complicated topic, which is why I’m characterizing this column as a “snapshot” written to provide a glimpse into an issue still largely under the radar. California is taking action, but it’s largely alone in its efforts. What’s there to know about this interesting topic?
Travel by Air, Water and Land
Plastics obviously don’t decompose; rather, they lose some of their original characteristics, become brittle and break apart. In a process described as “the plastic cycle” by several U.K. researchers, plastic exposed to a variety of environmental forces (e.g., wind, water, air, hard surfaces, etc.) degenerates into smaller fragments and parts, which makes them light enough to travel well beyond their point of origin. The most widely used definition of microplastics defines these particles as no larger than 5 millimeters in length—about the size of a grain of rice.
Depending on the characteristics of the original plastic, macroplastics or larger plastic items break down into fragments, foams, fibers and particles. Washing synthetic clothing and other textiles typically break into plastic fibers. Films often originate from plastic bags and a variety of wrappers, whereas fragments are typically broken bits from larger plastic objects.
There are multiple paths of transport, including stormwater runoff, movement by wind, wastewater effluent or even application of wastewater sludge on farm fields. All these vectors can transport and degrade plastics as well as move plastics from one ecological system to another and back again. Plastic originating on land can move to lakes, rivers and ultimately oceans. Plastics used at sea can wash up on shore, to be degraded further in coastal areas. The relentless breakdown of material by physical forces in the environment means microplastics are, with time, undetectable to the human eye—and impossible to recover—but found virtually everywhere.
A Meal with a Side of Plastic
Research has shown that microplastics are present in a variety of food and drink, from sea salt to beer to ordinary tap water. A 2018 study conducted by U.S. researchers analyzed 159 samples of tap water from around the world, 12 varieties of beer brewed with water from the Great Lakes and 12 different brands of sea salt. Sampling revealed that 81 percent of the tap water samples had some synthetic materials, with an average of 5 particles/liter. Plastic matter was found in each variety of sea salt, averaging 212 particles/kg, and the beer samples showed a range of 0 to 14.3 particles/liter. Plastics have been found in seafood—farmed and freshwater fish—but its presence in meat and grains remains unclear.
Keep in mind that plastics absorb toxins that tend to linger in the environment, which means microplastics can be vehicles for carrying PCBs as well as bisphenols, phthalates and other chemicals. Ingesting a significant amount of plastic material can’t be good for us—and animal studies confirm this—but data on what the risks actually are for people remain unanswered for the moment.
The bottom line is that we don’t yet realize the scale at which microplastics may be accumulating in our environment—or us, for that matter. By some estimates, we’re likely to have ingested a credit card’s worth of microplastic with our meals by the end of a week—enough to give pause to even the most intrepid among us.
Testing the Waters
The World Health Organization declared in 2019 that because the human health risks of plastic in drinking water are unclear, no action on drinking-water standards is warranted at this point. The State of California isn’t convinced. In September 2018, the California Legislature passed a bill requiring the State Water Resources Control Board define microplastics and develop a standardized testing methodology by July 2021, followed by a four-year program in which water quality is tested regularly and the results made available to the public. At this point, the California Water Board’s guidelines for microplastics in drinking water are expected in fall 2021.
Capturing and Containing Plastic
A large portion of plastic waste is destined for the landfill, and a much smaller fraction is recycled or, worse yet, exported to countries poorly equipped to handle it. This column’s focus has been on the plastic that has evaded standard waste-management channels and now is lost to the environment, where it begins the steady process of breaking down and infiltrating ecological systems.
California’s law tackles the problem of microplastics already present in drinking water, and the state is devoting resources to the development of guidelines and testing protocols. Studies also show the technology exists to significantly remove microplastics during wastewater processing. These are all encouraging developments, but solutions designed to get ahead of the problem should be our primary target.
A large proportion of plastic waste enters waterways through storm drains, which is why a few cities are experimenting with filter devices equipped with permeable fabric and overflow ports. San Francisco Bay is experimenting with a Trash Capture Demonstration project. Modifying existing infrastructure to more-effectively trap plastic waste, ramping up public education, eliminating single-use plastic bottles and providing incentives to switch to alternative forms of packaging are important measures. An argument could be made that we need more of them.
Our dependence on plastics, most of which are based on a formula developed from coal, natural gas and crude oil, is another aspect of our deep-rooted reliance on fossil fuels. The battle to move away from these fuels to support our way of life is best described as a slog: slow and riddled with potholes. We’re unlikely to significantly slow the production of plastic in the near future, so we must focus our efforts on capturing and containing plastic waste.
About Chris Maeder
Chris Maeder, P.E., M.S., CFM, is engineering director at CivilGEO Inc.; email: [email protected].
