TRAVERSE CITY, Mich. (AP) - An organization representing more than 100 cities in the U.S. and Canada is calling for steps to deal with the recently discovered problem of "microplastic" pollution in the Great Lakes. Microplastics are tiny bits of plastic less than an inch in diameter. Many can be seen only through a microscope. Over the past two years, scientists have detected significant concentrations of the particles in the lakes, with Lake Erie having the highest amounts. Some of the particles are believed to come from consumer products such as body washes, toothpastes and deodorants. The Great Lakes and St. Lawrence Cities Initiative sent letters Tuesday to federal regulators in both nations asking them to look into the problem. The group also is asking manufacturers of the plastics to phase them out by 2015.