DULUTH, Minn. (AP) - Scientists have found tiny plastic particles in all of the Great Lakes.
They had previously discovered them in lakes Superior, Huron and Erie and new summer research uncovered small concentrations also in Lake Michigan and Lake Ontario.
Mary Balcer, director of the Lake Superior Research Institute at UW-Superior, who has studied more traditional Great Lakes threats such as zebra mussels, said plastics are a new culprit on the list of Great Lakes ecological troubles.
"The accumulation of plastic particles is a great threat to our natural ecosystem and to the humans who use Lake Superior for our drinking water supply," Balcer said Thursday.
Fresh off the research boat, Lorena Rios-Mendoza, assistant professor of chemistry at the University of Wisconsin-Superior, presented her preliminary findings to reporters Thursday.
She said Lake Erie seems to hold the highest concentrations of plastics, probably because the particles float downstream from the upper lakes, according to the Duluth News Tribune (http://bit.ly/1cnm6BS ).
The plastic has also been found in Lake Superior sediment, meaning it's not just floating on the surface, Rios-Mendoza said.
"It was very shallow where they were found, but they were in the sediment," Rios-Mendoza said.
The researchers dragged fine-mesh nets across the surface of lakes. Some of the plastic can be seen only under a microscope.
So far, Rios-Mendoza's hypothesis is that the plastic in the Great Lakes starts small, possibly as scrubbing beads in household or beauty products, facial scrubs and even some toothpaste.
The particles are tiny enough to slip through the screens at wastewater treatment plants and then start their journey across the Great Lakes.
Not only is the plastic itself an issue, she noted, but research has found that plastic can absorb persistent toxic chemicals, some of them known endocrine disrupters. So the floating plastic beads act like tiny, toxic sponges.
That's bad because the articles are just the size to be confused as food for small fish, she said.