Microplastics found throughout Great Lakes rivers: study

Harmful microplastics are prevalent in many rivers that flow into the Great Lakes, according to a new study published in the journal Environmental Science & Technology.

Microplastics fall off decomposing bottles and bags, wear off of synthetic clothing, and are manufactured into some toothpastes and lotions. Scientists with the U.S. Geological Survey and State University of New York at Fredonia studied 107 water samples collected from 29 Great Lakes tributaries in Minnesota, Wisconsin, Indiana, Michigan, Ohio, and New York, and found microplastics in all samples. Together, these 29 tributaries account for approximately 22 per cent of the total river water that flows into the Great Lakes.

“These microplastics, which are harmful to animal and possibly human health, will continue to accumulate in the Great Lakes well into the future,” said Austin Baldwin, a USGS scientist and the lead author of the report. “Our findings can help water managers better understand the types and sources of microplastics in rivers, and which rivers are the most polluted with microplastics.”

Baldwin noted that the study underestimates the actual microplastic concentrations in the rivers because the scientists sampled large microplastics greater than 0.33 millimeters (mm). The majority of microplastics are smaller than 0.1 mm.

The study also found that the highest concentration of microplastics was detected in the Huron River at Ann Arbor, Michigan, at 32 particles per cubic meter; and that high levels of microplastics were also detected in the Buffalo River at Buffalo, New York, the Ashtabula River near Ashtabula, Ohio, and the Clinton River near Mt. Clemens, Michigan.

“We were surprised by the small amount of plastic beads and high amount of fibers found in the samples,” Baldwin said. “These unexpected findings demonstrate how studies like ours are critical to better understanding the many forms and fates of microplastics in the environment.”

Ingested microplastics can cause digestive and reproductive problems, as well as death, in fish, birds and other animals. Unhealthy additives in the plastic, including flame retardants and antimicrobials, have been associated with cancer in humans. Also, pollutants such as pesticides, trace metals and even pathogens can accumulate at high concentrations on microplastic particles.