Expanding the search for potentially hazardous vapors in homes and businesses in St. Louis Park, the Environmental Protection Agency said Wednesday that it will add about 50 properties to its study area on both sides of Hwy. 7 near Wooddale Avenue.

State and federal pollution officials grew concerned about risks to residents after an investigation found solvents and other fumes last year in the groundwater and shallow soils. The fear is that if those underground vapors are beneath basements, they may be seeping into homes or businesses through foundation cracks and accumulating indoors at unhealthy levels.

The main chemicals of concern, trichloroethylene and perchloroethylene, have been used for decades as industrial degreasers, metal cleaners and dry-cleaning fluids and seeped into the groundwater under St. Louis Park. Long-term exposure to them at certain levels has been linked to cancer, liver disease and other problems, according to state health officials.

Sonia Vega, the EPA's on-scene coordinator, said that the study area was expanded because testing along its eastern border and near Hwy. 7 showed fairly high concentrations of fumes beneath buildings.

"Every step we take has a dual purpose," Vega said. "We're not only determining the extent of the contamination and making sure that we're protecting the public, but it will also help determine the direction of the [pollution] plume and potential sources."

EPA officials will go door-to-door this Saturday to explain the situation to those living in the expanded study area, and to seek their permission to take air samples. The testing involves drilling a small hole in the basement and inserting a 2-foot probe about the width of a pencil.

The initial study area contained about 270 homes and businesses, and the EPA received permission from owners to test vapors beneath 214 of the buildings. Of that number, 32 homes and eight commercial buildings were found to have enough contamination to justify more testing to check air in different rooms and for longer periods of time.

Vega said that the results from those tests will not be available for another two to three weeks.

Contaminated groundwater in the area is not used for drinking, and continues to be monitored, according to St. Louis Park authorities. The EPA and the state are still searching for the sources of the contamination.

Tom Meersman • 612-673-7388