Elevated levels of a chemical once manufactured by 3M have been detected in nine Minneapolis-area lakes, according to a recently released study. Storm water runoff is likely moving the chemical into the waters.

In spring and summer 2007, the Minnesota Pollution Control Agency (MPCA) collected and analyzed 381 fish from 20 lakes and two rivers. The fish were checked for perfluorooctane sulfonate (PFOS) and related compounds; 3M manufactured PFOS for decades for use in Scotchguard, firefighting foams and other various products before ceasing production in 2002.

The unanticipated discovery of high PFOS levels in Lake Calhoun bluegills is what initiated the metro lakes study. Scientists could not explain the contamination source, as the lake is not near any areas in which 3M was known to manufacture or dispose the chemical.

The study showed that three Minneapolis lakes and six in surrounding counties contained fish with PFOS levels "high enough to possibly be of concern," while 11 other lakes showed little or no chemical content, according to Paul Hoff, MPCA supervisor of environmental reporting and special studies.

"We're pretty certain that the higher levels are attributable to something specific in the watershed of those lakes that came in via storm water runoff," Hoff said. The PFOS may have entered the system long ago or in recent months, he added, via firefighting foam residue, the chrome-plating industry or various consumer products such as lubricants and hydraulic fluids.

The next step in studying the lakes' PFOS content is determining how it moves through the food chain, Hoff said. State health officials stated they will evaluate MPCA's new fish data and determine whether consumption advisories need to be issued.

Source: Star Tribune