A chemical contaminant considered a potential health risk has been detected in some private wells in two Twin Cities communities. The contaminant 1,4-dioxane was found in wells in Andover's Red Oaks neighborhood and in Gem Lake north of St. Paul, officials from the Minnesota Pollution Control Agency (MPCA) and state health department said Thursday.
The city of Andover’s municipal water system is safe and not affected, officials said. Gem Lake does not have a municipal water supply.
A man-made chemical, 1,4-dioxane is often used in manufacturing to stabilize industrial solvents. Consumer products like cosmetics, detergents and automotive fluids also contain the chemical. It's been found in groundwater around closed, unlined landfills and at industrial sites, including the Twin Cities Army Ammunition Plant in New Brighton, assistant MPCA commissioner Kirk Koudelka said.
“Its use is decreasing over time, but we still need to deal with these legacy issues and uses,” he said.
The chemical is considered a possible carcinogen, meaning exposure over a person’s lifetime can increase their risk of cancer and other health problems.
Like many other so-called “emerging” contaminants, there is no federal drinking water standard for 1,4-dioxane, so the state health department has established a health risk limit of one part per billion.
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At that concentration, based on current science, it’s considered likely to pose little or no risk to humans.
“We set very protective health guidelines for exposure to this chemical in drinking water that will protect the health of even our most vulnerable citizens here in Minnesota,” said Jim Kelly, who manages the environmental surveillance and assessment program at the state health department.
Levels of 1,4-dioxane at or above the health risk limit were detected in about 40 wells in Andover and 15 in Gem Lake, according to the MPCA. Those residents are now receiving bottled water.
The discoveries were made as part of expanded well sampling that the MPCA has been doing around the closed Waste Disposal Engineering (WDE) landfill in Andover and the Water Gremlin industrial site in White Bear Township, Koudelka said.
He said the MPCA is still investigating the source of the contaminants — and a long-term solution.
“If a responsible party is found during that source identification process and we can link it back up to a facility, we will go after those responsible parties to seek cost recovery,” he said. “But in the meantime, our efforts are making sure that we're checking folks’ wells [and] they have safe drinking water."
The MPCA will be doing more sampling to try to figure out where the chemicals are coming from, Koudelka said. He said the Andover wells are not in a path where chemicals would be expected to travel from the landfill, so it’s possible they are coming from another source.
Community meetings on the findings and next steps will be held Sept. 30 in Andover and Oct. 14 in Gem Lake.
“We understand this is an uneasy time for them to be told that there's contamination that's impacting their drinking water, and we're switching them to a new source,” Koudelka said. “So we understand that they have a lot of questions.
The MPCA is working with the city of Andover on long-term solutions, such as connecting the affected residents to its municipal water system, he said.
In Gem Lake, possible solutions could include digging deeper wells, hooking up to a neighboring municipal system or installing home treatment systems, Koudelka said.