A Problem You Can’t Scrub Away

Illinois recently became the first state to ban microbeads  those little plastic bits of grit found in some personal hygiene products. Katherine Martinko explains the environmental rationale:

Microbeads give facial and body scrubs a grainy texture for exfoliation, but they are an ecological nightmare. Because they range in size from 0.0004 to 1.24 millimeters, they are too small to be filtered out by water treatment plants. They get flushed into waterways, ending up in lakes where they float, absorb toxins, and get eaten by marine animals because they resemble fish eggs. It takes a freshwater mussel 47 days to flush out ingested microbeads.

Martinko shows how the decision has repercussions far beyond the Land of Lincoln:

Illinois’s ban is important, but one more statewide ban is desperately needed, since that would create a “distribution nightmare” for companies and force them to come up with alternatives. The CBC quoted 5 Gyres associate director Stiv Wilson: “Effectively by winning two states, you win the entire North American region.” New York, Ohio, and California all have anti-microbead legislation in the works.

Meanwhile, researchers are working to develop eco-friendly alternatives to the plastic beads. Alexa Kurzius considers the prospects of polyhydroxyalkanoate (PHA), a “bioplastic” made with fermented bacteria:

[T]he majority of microplastics tend to float, which means they move readily from your shower drain, through wastewater treatment plants, and into waterways. “It’s like the saying from Finding Nemo,” explains [researcher Kirk] Havens. “All drains lead to the ocean.”

PHA, on the other hand, is denser than water, and thus sinks to the bottom. When it sinks, it’s buried with other sediment or consumed by salt or freshwater bacteria. This is an improvement over synthetic microplastics, which are more likely to be eaten by microorganisms that mistake the tiny pellets for food. But if bacteria consume PHA, they break the substance down into water, carbon dioxide, biomass, and naturally occurring small molecules after a few months. These substances are relatively harmless compared to longer-living man-made plastics like polyethylene.

Update from a reader:

Just wanted make a slight correction to the quote you provide from Martinko. Microbeads can be removed by water treatment plants. Coagulation/flocculation removes particles down to 0.01 microns and granulation media filtration removes particles down to 0.5 um. So, microbeads wouldn’t end up in your drinking water.

Wastewater treatment plants, however, do not have the same emphasis on particle removal so, yes, microbeads do end up in receiving water ways.