Minnesota health officials are launching a major investigation into whether drinking water in 15 Minnesota cities is contaminated with chemicals formerly manufactured by 3M Co. and used in municipal fire-fighting foam.

The tests, set to begin next month, will be important to residents and fire officials in communities across the country where a 3M firefighting foam has been used for years in training exercises, often on city-owned property adjacent to municipal wells. The foam is flushed into storm sewers or left to seep into the ground, raising the possibility that drinking water has been affected.

"This could have national significance," said Doug Wetzstein, supervisor in the superfund section at the Minnesota Pollution Control Agency. Firefighters virtually everywhere have used the foam for decades, he said, at city practice areas, community college training courses, and especially at military bases, airports and refineries where jet fuel and other petroleum-based fires are a major concern.

The cities are Apple Valley, Bemidji, Brooklyn Center, Burnsville, Cloquet, Goodview, Luverne, North Mankato, Perham, Pierz, Pine River, Randall, Richfield, Rochester and Winona.

The possible contaminants, a family of compounds known as perfluorochemicals, were found in drinking water in Oakdale and Lake Elmo in 2004 at levels that exceed state health guidelines. They do not break down in the environment, and accumulate in humans and wildlife. 3M stopped making two of the compounds, known as PFOS and PFOA, in 2002, but they remain in foam stockpiled by fire departments.

Stew Thornley, health educator for the Minnesota Department of Health, said the 15 cities were judged to have the highest potential risk for groundwater contamination based upon the depth of their wells, the proximity to fire training areas, the known and repeated use of certain foam products, and other factors.

"This is something we need to check as a precaution," Thornley said.

Don't stop drinking the water

The chemicals do not cause any acute health problems, he said, so authorities are not suggesting that citizens in the communities stop drinking the water. The test results will be shared with communities as soon as possible, he said, beginning this summer.

Concern about the chemicals came from an unlikely place: a former missile silo site near St. Bonifacius in western Hennepin County.

More than a dozen fire departments trained there with foam and other materials during the 1980s and 1990s. Wetzstein said the MPCA tested the property for a number of contaminants, including 3M chemicals in groundwater. They found PFOS and PFOA at concentrations more than 100 times higher than state health guidelines, but not in any nearby private wells. The MPCA then hired a consultant in 2008 to survey fire departments across the state, and learned that 106 of those that responded have used foams with 3M chemicals for training and 79 did so in the same location year after year.

In addition to the cities that health officials are studying, the MPCA sent letters to fire chiefs and city administrators on Jan. 28 asking permission to take soil and groundwater samples at fire-fighting training areas in Kenyon, Claremont, Alexandria, Myrtle, Harmony, Fridley and Preston. The MPCA is also working with oil refineries, and the Twin Cities and Duluth airports to see where tests may be necessary.

Apple Valley's sandy soils

Apple Valley City Administrator Tom Lawell said Friday that he met with public works staff recently to tell them about the upcoming water testing.

"We have no reason to think that there's a concern, but if the department of health asks for cooperation, we're going to cooperate with them," he said.

The investigators were drawn to Apple Valley because sandy soils in the area allow chemicals to migrate toward groundwater, he said, adding that he wasn't aware of a local source of the chemicals.

City officials in some of the affected cities, including Rochester, Richfield and Brooklyn Center, said late Friday that they had not been notified about the tests.

State fire marshal Jerry Rosendahl said he was briefed on the upcoming tests on Jan. 15, and will wait to see what health officials discover. "We're not throwing up the red flag at this point," he said. "We're not experts in this area [of chemistry]." Rosendahl said he'll communicate with all of the state's 788 fire departments about the state's findings and whether they should affect firefighting training programs.

Foam smothers fires

The MPCA survey showed that some fire departments use different foams for training, or practice in different areas each year, or no longer have stockpiles of 3M foams. Fire departments often have different foams for different types of fires. Foams that do not contain perfluorochemicals are typically used for "Class A" wildfires, structures and other fires. The 3M foam was developed with the U.S. Navy in the 1960s for "Class B" petroleum fires and spills. The foam quickly covers fuels with a thin film to block oxygen and smother fires and prevent flammable vapors from exploding.

3M stopped making PFOA and PFOS in 2002. State officials said it's unclear whether competing products from other companies also have perfluorochemicals in their foam formulations. 3M will pay for the tests and lab analyses as part of a broader agreement with the state signed in 2007.

Matt Simcik, associate professor of environmental chemistry at the University of Minnesota, is studying 3M chemicals in fish tissue. He said researchers in Oregon have studied firefighting foams and contamination at military installations, but Minnesota will lead the nation as it studies whether 3M chemicals from foam have contaminated city wells. "Just because 3M's not producing it anymore doesn't mean much," he said. "The stuff's still out there."

Staff writers Katie Humphrey and Allie Shah contributed to this report. Tom Meersman • 612-673-7388