MINNEAPOLIS -- Residents of the Como neighborhood are beginning to sign up for underground vapor tests, which will determine whether they need special ventilation systems installed in their homes.
The Minnesota Pollution Control Agency, or MPCA, is offering those tests to roughly 200 residents of an area in southeast Minneapolis, to determine which homes have hazardous levels of trichloroethylene fumes in the soil beneath them.
The chemical, also known as TCE, was part of a solvent General Mills used to clean heavy metal equipment at the company's research lab on Hennepin Avenue East. The company dumped the chemical in a soil pit from the mid 1940s to the early 1960s.
"Decades ago they didn't know this was wrong," General Mills spokesman Tom Forsythe told KARE.
"But we're going to stand behind it and make it as right, to the extent that we can, now that we know what we're dealing with there."
The company sold the property in 1977, but discovered the TCE dump on the site in 1981. By then a plume of contamination had spread through the groundwater for several blocks to the southeast of the lab, leading to the Mississippi River.
The EPA declared it a Superfund Site in 1984, putting the federal government in charge of the cleanup. Since then the groundwater has been cleaned and regularly retested for quality.
Historically, the fear was that people could suffer health effects by drinking water from wells tainted by TCE. But more recently regulators turned their attention to the risk of TCE vapors moving from the water table to the soil, and then seeping into basements of homes.
General Mills notified the EPA of the possibility of vapors in 2011, and began testing in April of 2012. The preliminary results of 40 soil tests in the area led the company and the MPCA to go public with their concerns Nov. 7.
Representatives of General Mills, the MPCA and the Minn. Dept. of Health met with residents at two public meetings Tuesday to explain the state's vapor intrusion investigation and what options homeowners and renters will have.
Birth defects worry
A health department toxicology expert said the most urgent concern is for pregnant women who live in basement apartments or have basement bedrooms in their homes.
That's because TCE has been linked to heart defects in newborns. In adults it can weaken immune systems and even cause cancer if there is prolonged exposure over many years.
"We definitely spend time in our basement and if there could be an effect on our baby, it would be good to know," Kristin Hamre, an expectant mother who came to the public meeting at Van Cleve Rec Center Tuesday night, told KARE.
Hamre's husband, Derek Nord, said he wished the people in the neighborhood would've been put on alert more than a year ago when General Mills and state agencies first started the soil sampling.
"It's troubling because we're just finding out about this in November that, in fact, it was a concern enough for the Department of Health to start testing," Nord remarked.
He said he's lived in the neighborhood since 2009 and had never heard about the Superfund groundwater cleanup project stemming from the TCE disposal site.
"How do we know this isn't going to change in the future?" he said.
"Nobody's assured me that there's going to be ongoing monitoring after this or said how they're going to respond to further shifts of the aquifer."
Technicians will test the air pockets underneath the basement floors, looking for buildup of TCE vapors. Those with a harmful concentration of fumes will be offered a ventilation system similar to those used to rid homes of radon gas.
General Mills is paying for the testing and the ventilation systems.
"Even 10 years ago we didn't know we were supposed to look for vapors," Forsythe explained.
"The way we're looking for it now is something we couldn't have done, because this is emerging science."
For indoor air, the Department of Health considers anything above two micrograms of TCE per cubic liter of air to be hazardous. But TCE levels inside homes can very greatly, depending on air circulation and whether that household is using other products that contain TCE.
The MPCA and General Mills are proposing to intervene if the soil vapors built up under the home are higher than 20 micrograms of TCE per cubic liter. That's based on the idea that the concentration will be much higher under the floor slab that it is inside the house.
The alternative is to only test the indoor air without drilling through the basement floor, but that would require a series of tests over an extended period of time.
General Mills prefers to see the ventilation systems installed as soon as an unsafe concentration of TCE is detected under those homes. Those systems collect the vapors under the basement and send them through a pipe that vents through the roof.
Once the vapors enter the atmosphere they disperse and are no longer of a high enough concentration to be harmful.
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