MEGAPROBLEM

America’s rivers and streams are overflowing with microplastic pollution

For years, cosmetic, toothpaste, and body care product manufacturers added “microbeads,” microscopic balls of plastic, to their merchandise, touting their skin-exfoliating effects. A Congressional ban that goes into effect beginning in 2017 will put an end to the environmentally toxic practice, at least in the US.

Researchers studying America’s waterways have now discovered microbeads may be the tip of the iceberg for plastic pollution.

A study published in Environmental Science & Technology on Sept. 14 found rivers and streams in the US are full of microplastic debris. Scientists studied 29 tributaries that flow into the Great Lakes across six states and floating microplastics were found in all 107 samples collected. The trash ranged from fragments, films, foams, and pellets (most prevalent in urban areas) to tiny fibers, potentially originating from fishing line, nets, and synthetic textiles.

Microscopic images of assorted microplastic particles (Austin Baldwin, Steven Corsi, Sherri Mason)

Concentrations peaked in Michigan’s Rouge River at 32 particles per cubic meter, but dropped as waterways passed through forested and undeveloped areas.

The most common debris throughout were the thin plastic fibers that come from textiles like clothing, carpet, and fishing gear, and which account for about 71% of the total plastic pollution in the samples. The researchers could not pin down a single source for the plastic fibers; in the study, they note they did not find higher concentrations near cities, wastewater treatment plants, and other likely contributing sites. That, in turn, suggests either multiple local sources or that the particles remain suspended in the water over long-distances.

Plastic objects (styrofoam, plastic bags, bottles, wrappers, cigarette butts, tires) degrade over time, breaking into microscope plastic debris that runs off into the waterstream. Wastewater treatment plants capture heavier polyester fibers before they enter waterways like rivers and lake (though these fibers may make their way back into the water once treated sewage sludge from plants is applied to fields and golf courses). But the plants do not eliminate most microplastics. This pollution presents a danger to marine life by obstructing an animal’s digestive system, interfering with reproduction, and carrying harmful chemicals that can stymie development or even kill water-dwelling creatures.

The problem is worsening. Microplastic concentrations in lakes and rivers now rival or exceed what’s been found in oceanic gyres, such as the infamous Great Pacific Garbage Patch, say the authors.

Microplastic debris in the Great Pacific Garbage Patch can turn seawater into cloudy soup. (NOAA)

Yet removing microplastics from the water is virtually impossible. “I think the best solution is to try and reduce the source,” said hydrologist Austin Baldwin of the U.S. Geological Survey, the study’s lead author in the publication Take Part. Banning microbeads was a start, but, Baldwin said, that was “easy.” Microbeads, after all, are a single component that can be taken out of the supply chain in one fell swoop. “Stopping litter from breaking down and washing into the stream is a lot harder,” he said. Other contributors to microplastic pollution—textiles, washing machines, fishing gear—are much more difficult to untangle from the products they come from, and there’s not yet easy way for treatment plants to filter out microplastics.

The human and ecological health implications of microplastics are still poorly understood, but scientists see a “plasticized” food chain as cause for concern. New Jersey’s science advisory board issued a 2015 study (pdf) that found the human impact of microplastics (and even smaller particles below 100 nanometers in size) couldn’t be fully assessed, but current science suggests “it is plausible that human exposures are occurring, and may lead to adverse health effects.” A 2015 study in Nature found that roughly a quarter of marine fish from markets in Indonesia and California had plastic debris and textile fibers in their guts.

A UN survey in 2015 (pdf) also identified microplastics as one of world’s most emerging environmental problems and a potential public health danger. “The presence of microplastic in foodstuffs could potentially increase direct exposure of plastic-associated chemicals to humans and may present an attributable risk to human health,” stated the report.

Feature image above by Oregon State University on Flickr, licensed under CC-BY-2.0.

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