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Microplastics In The Oceans And Our Food Are A Big Problem Says MC Chemistry Professor

Editor’s note: This story is part of our MC faculty series, in which professors discuss relevant topics within their areas of expertise. Craig Benson, PhD, is a chemistry professor at Montgomery College.

By Craig Benson

You’ve certainly noticed, and perhaps complained about, the bag tax in Montgomery County. Any time you make a purchase and need a disposable bag, you’ll be charged an extra five cents in an effort to decrease single-use plastic consumption in the county. Beyond the bag tax, Montgomery County banned polystyrene take-out containers in 2016, a law that will go statewide in July 2020. Moreover, the City of Rockville has opened a discussion on an ordinance to ban plastic straws, similar to the ban that was approved last spring in the European Union. Why are single-use plastics being banned? What are the problems with using them? And has the bag tax been effective?

Plastic bags end up polluting the oceans. Photo: Wikimedia Commons

The plastic bags you can find at the grocery store are most commonly high-density polyethelene, or HDPE. Despite the three-arrow recycling symbol you can likely find printed at the bottom, these bags are not recyclable in your county-provided blue bin because the thin bag gets caught in the machinery. While it can be returned to the grocery store for recycling, many people don’t do so because of the extra steps involved. Rather, most of these bags are destined for the garbage.

As garbage, those HDPE bags do not decompose the way organic matter does. HDPE is a polymer, a molecule that can be tens of thousands of atoms long. The feedstock for most polymers, including HDPE, is crude oil. This, unfortunately, means that plastic persists in the environment.

Fewer bags used means less litter, which ultimately means fewer microplastics in our ocean.

Prof. Craig Benson

So, what is the fate of plastic litter in Montgomery County? Typically, rains come and wash the plastics into storm drains or a local creek. These feed into rivers such as Paint Branch, then to the Potomac. Eventually, the plastic will be washed out into the Chesapeake Bay and, then, the Atlantic Ocean. As this process is taking place, the plastic will absorb ultraviolet light. This UV light weakens the chemical structure, breaking the plastics into smaller and smaller pieces, eventually becoming microplastics (defined as any plastic less than 5 mm in length). All the while, the plastic attracts and absorbs hydrophobic organic compounds (HOCs), such as certain pesticides and solvents. When plastics and microplastics enter the ocean, they may be consumed by sea creatures and work their way up the food chain. One study found that European consumers of seafood may eat up to 11,000 particles of microplastics each year! At present, microplastics have been found even in remote regions of Antarctica.

The effectiveness of the bag tax is difficult to quantify. By one measure, it takes more resources to make a single reusable grocery bag than producing many disposable bags. More importantly, however, the bag tax helps to reduce use of disposable bags. Henry Coppola, the volunteer services and community partnerships coordinator of the Montgomery County Department of Parks, has noticed a “marked decrease” in the number of disposable plastic bags found during park and stream cleanups.

Fewer bags used means less litter, which ultimately means fewer microplastics in our ocean. A plastic straw ban, if it comes, will have a similar effect. After all, the petroleum used to make the plastic has been around for millions of years, and the plastics that the petroleum are turned into could be around for tens of thousands of years or more. This is a very long timeframe for a bag that will be used just once. Our memories are short, but the environment, under our improved stewardship, will last for generations and beyond.


Banner photo: NOAA (National Oceanic and Atmospheric Administration) scientists collect microplastics samples. Source: National Park Service.

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