The Great Lakes are being polluted by tiny beads of plastic like the ones found in exfoliating face wash, and the effects of the untold millions of "microplastics" in the lakes have yet to be fully understood.

Great Lakes researchers are worried that the microplastics could be harming the environment and entering the food chain. Some of the plastic beads are so tiny they can only be seen with a microscope.

By trawling the lake floor and sorting through the sediment, researchers have found microplastics in Lakes Superior, Huron and Erie, and this summer Lakes Michigan and Ontairo will be searched for microplastic contamination.

"If you're out boating in the Great Lakes, you're not going to see large islands of plastic," project leader Sherri Mason, a chemist with State University of New York at Fredonia, told the Associated Press. "But all these bits of plastic are out there."

Mason and her colleagues are currently studying whether fish are eating the microplastics, which can easily be mistake for a food source. It is unclear how long the tiny plastics have been entering the Great Lakes system, but it appears the plastics are small enough to bypass filters in regional wastewater processing facilities.

The exact source of the microplastics is undetermined, but the spherical shape and size of many of the pollutants are consistent with the abrasive "micro beads" found in skin care products and toothpaste, the AP reported.

"They matched the same size, color, texture and shape of the microbeads found in popular consumer products," Marcus Eriksen, executive director of 5 Gyres Institute, a non-profit California-based environmental activist group, told Reuters.

Lorena Rios-Mendoza, a chemist with the University of Wisconsin-Superior, told the AP that 1.7 million tiny plastic particles were collected last year in Lake Erie.

Under pressure from scientists and advocates, some large companies have agreed to phase out the use of the "microbeads." Procter & Gamble and Johnson & Johnson have announced phaseout plans. L'Oreal says it won't develop new products with microbeads, according to the AP.

Eriksen told Reuters there is no practical way to remove the microplastics from the water and that it's unknown how long it will take for the plastic to leave the lake completely, if ever.

"Plastic doesn't biodegrade so once it's in the water, it doesn't just disappear," Rios-Mendoza said