Microplastics in our Nation's waterways

Microplastics are the miniscule plastic fragments (smaller than 0.04 inch) that fall off of decomposing plastic bottles and bags, and are intentionally manufactured into some toothpastes and lotions. Scientists have found microplastics nearly everywhere, particularly in lakes, rivers, and aquatic animals.

Where in our waterways are microplastics found?

Studies have found particles in

12%

of freshwater fish1

Fish Picture

50

particles per serving of commercially-cultured oysters

90

particles per serving of commercially-cultured mussels2

Oyster Picture

1 particle for every

8

gallons of Great Lakes tributary water3

On average

1,285

particles per square foot of river sediment4

Stream Picture

and

112,000

particles per square mile of Great Lakes water5

Great Lakes Picture

What are the known risks of microplastic pollution?

Microplastics can be harmful to humans, as well as wildlife through:

  • The physical hazards of ingesting plastic particles (fish, birds, and other animals can experience digestive obstruction, impaired reproduction, other adverse biological effects, and even death)
  • The unhealthy additives found in plastic particles (some additives have been associated with cancer and endocrine disruption)
  • The contaminants that accumulate on plastic particles (polychlorinated biphenyls (PCB's), polycyclic aromatic hydrocarbons (PAH's), organochlorine pesticides, trace metals, and even pathogens have been found at high concentrations on microplastics)
Male coaster brook trout.

Can we kick the microplastics habit?

We’re trying. In 2015, the U.S. Congress passed Public Law 114-114 to ban the sale of cosmetics containing plastic microbeads. The ban takes effect in 2018.

The ban addresses microbeads alone, in part because early studies indicated that microbeads were the most common type of microplastic found in aquatic ecosystems. However, those early studies all took place in lakes. Is the same true in rivers?

Microplastics in rivers

U.S. Geological Survey and State University of New York Fredonia scientists sampled rivers flowing into the Great Lakes3 to find out which kinds of microplastics are most commonly found in rivers, and which rivers contain the most microplastics particles.

These scientists found that rivers carry many different kinds of microplastics, and were surprised to learn that plastic microbeads make up only a small fraction of all microplastics.

The USGS scientists found that fibers composed an average of 71% of the total number of microplastics particles found in samples of river water.

Microplastic sample

Hover over the following graph for more information.

How are plastics getting into our rivers?

That turns out to be a tricky question. USGS scientists plotted the microplastics data for the river water samples collected at various locations. Then they compared those data to land-use types found at those same sampling locations to determine if there seemed to be any patterns in the data.

Hover over the data on the graph below for more information.

Though the relationship is modest, it appears that urban watersheds tend to be associated with rivers that have high concentrations of microplastics in the water, which is especially true for plastic fragments, films, and foams. However, scientists were surprised to find no apparent pattern between land use and the most commonly observed microplastic type - fibers.

What's next?

While the ban on plastic microbeads has raised public awareness, the microplastics story is large and complex. Studies like this one conducted by USGS and SUNY Fredonia scientists and funded by the Great Lakes Restoration Initiative are bringing us toward a better understanding of the many forms and fates of microplastics in our Nation's waterways.

Piping Plover