NORTH EAST, Pa. — The newest environmental threat to the Great Lakes is very, very small.
Tiny plastic beads used in hundreds of toiletries like facial scrubs and toothpastes are slipping through water treatment plants and turning up by the tens of millions in the Great Lakes. There, fish and other aquatic life eat them along with the pollutants they carry — which scientists fear could be working their way back up the food chain to humans.
Scientists have worried about plastic debris in the oceans for decades, but focused on enormous accumulations of floating junk. More recently, the question of smaller bits has gained attention, because plastics degrade so slowly and become coated with poisons in the water like the cancer-causing chemicals known as PCBs.
"Unfortunately, they look like fish food," said Marcus Eriksen, executive director of the 5 Gyres organization, speaking of the beads found in the oceans and, now, the lakes. His group works to eliminate plastic pollution.
Studies published in recent months have drawn attention to the Great Lakes, where there may be even greater concentrations of plastic particles than are found in oceans. The National Oceanic and Atmospheric Administration has also been looking at the impact of microplastics on marine life.
In recent months, major cosmetics companies including Johnson & Johnson, Unilever, and Procter & Gamble have pledged to phase out the use of the beads in favor of natural alternatives, though they say the shift could take two years or more. The Johnson & Johnson statement says, in part, "Our goal is to give consumers peace of mind that our products are gentle on people and gentle on the environment."
Johnson & Johnson, along with others, has questioned whether the spheres are actually getting through wastewater treatment plants. So Sherri A. Mason, an environmental chemist at the State University of New York in Fredonia, has spent the past two summers trolling the Great Lakes with a fine-mesh net that has a broad mouth for skimming surface waters.
Working with students aboard the historic brig Niagara, Dr. Mason has collected more than 100 samples, which her students examine minutely for beads and other debris. They sort out the plastics from bits of fly ash and other products from power plant smokestacks and, using electron microscopes to compare the spheres with those from commercial products, have found them to be similar in shape, size and composition. (Sandblasting uses small beads as well, but they tend to be more dense than the beads in consumer products, and sink.)
In a recent paper, Dr. Mason and colleagues took samples that suggested concentrations of as much as 1.1 million bits of microplastics per square mile in some parts of the lakes' surfaces, with beads making up more than 60 percent of the samples. She has found beads in all five of the lakes, with the greatest concentrations in Lakes Erie and Ontario, which take the water flows from the other lakes and which are ringed with cities and towns.
While many of the beads appear to enter the environment when storms cause many wastewater treatment plants to release raw sewage, it is increasingly clear that the beads slip through the processing plants as well, Dr. Mason said at a sewage treatment plant in North East, a town near Erie.
She visited the plant to see if she could find beads in the clean water flowing from the plant at the end of the treatment process, after the removal of the organic solids that sat ripely in large containers bound for a landfill.
Mike McCumber, a supervisor at the plant, challenged her: "You ain't going to find nothing!" But he helped her set up a pump to flush the water through fine screens, and after less than a minute, she had scraped a pearlescent sphere off the mesh.
"Hey, Mike! I think I got a bead," she told him.
"Oh, boy," he responded in defeat.
She was quick to point out that the sewage treatment plant is not designed to capture the tiny beads, which vary in size but are about as big as a period on a newspaper page. "It's not a design problem with the system," she said. "It's a design problem with the product."
Scientists are still working through the links of the chain leading back to humans; about 65 million pounds of fish are caught in the Great Lakes each year. Worldwide, the beads have been found in some marine organisms and not in others, and the transfer of poisons from the beads into the bodies of the creatures that eat them is still being established.
It has been shown to happen in lugworms, which live in the North Atlantic, and Dr. Mason said, "If it happens in lugworms, there's a pretty good chance that it's happening in other species."
Lorena Rios Mendoza, an assistant professor of chemistry at the University of Wisconsin-Superior, said that the bits of plastic have a great capacity to attract persistent pollutants to their surface, and that the Environmental Protection Agency has classified some of those compounds as priority pollutants that can interfere with human physiology.
"Plastics are not just acting as mimic food, but they can also cause physical damage to the organism," she said. She has examined fish guts and found plastic fibers — possibly from the breakdown of synthetic fabrics through clothes washing — that are laden with the chemicals, and said she expected to find beads as well.
Some producers of natural facial products have found alternatives to the inexpensive plastics — some of which can sound less like a cleanser than a variety of Whole Foods granola. St. Ives, a Unilever brand, uses natural exfoliants like ground walnut shells. A spokeswoman for Burt's Bees said the company had never used the plastic; its acne scrubs use jojoba beads, and its citrus facial scrub is made with "oat kernel flour, almond meal and pecan shell powder."
Dr. Mason applauded the use of alternatives, because there is no getting rid of the beads that are already in the water. Any attempt to skim the waters of the lakes to try to filter them out would scoop up plankton and other essential parts of the food chain, Dr. Mason said: "You'd be killing all the living necessary aspects of the ecosystem at the same time you're trying to extract the plastic."
So the answer to the problem of the tiny beads is to limit their use, she said. "We need to stop putting it out there."
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