3M Cottage Grove Facility
The 3M Company produced perfluorochemicals (PFCs) at its Cottage Grove facility from the late 1940's until 2002. Perfluorooctanoic acid (PFOA) was the main type of PFC made at this site. PFOA is used in the making of products that resist heat, oil, stains, grease and water. Common uses include nonstick cookware, stain-resistant carpets and fabrics, and other industrial applications.
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How were PFCs released on site?
For a time, wastes from the production process were disposed on site in a specially prepared pit; there may be other disposal sites as well. The water treatment plant on site that processed water from production activities did not remove PFCs, so PFCs were in the waste water that went into the Mississippi River. Some sludge left over from the water treatment process also contained PFCs and was disposed on site. On the west side of the site, firefighting foams containing PFCs were used in training exercises. PFCs may also have been released into the air.
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Where is the PFC contamination now?
Environmental testing shows that the groundwater beneath the 3M Cottage Grove site is contaminated with PFOA, and other PFCs including perfluorooctane sulfonate (PFOS) and perfluorobutanoic acid (PFBA). In some areas, the levels of PFCs exceed the Minnesota Department of Health (MDH) drinking water criteria. Groundwater beneath the site flows south and discharges to the Mississippi River. Sampling of river sediments near the site and the water within those sediments detects PFCs at levels of concern for humans and wildlife, but concentrations in the river water are much lower due to dilution.
An extensive system of wells contains and collects much of the contaminated groundwater from under the site so that the wastewater treatment plant can process it. This system was expanded in 2010 and a large granular activated carbon (GAC) filter system was added to the plant to remove PFCs from the water before it goes into the river. Further upgrades to this groundwater pump-out system are planned to try to stop all PFCs from leaving the site.
In 2009-2011, 3M excavated the former waste disposal areas and the sediments in a cove next to the river through which PFC-contaminated wastewater flowed in the past. The soil and sediments were disposed of off-site in lined containment facilities. More information about the site and 3M cleanup actions can be found on the MPCA webpage Perfluorochemical (PFCs) waste sites.
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Have people been exposed in the past?
Workers at the facility were exposed to PFCs in the course of their work and also through the facility's water supply. 3M now treats their drinking water with a GAC filter system. 3M has been monitoring PFCs in the workers' blood since the 1970's. Epidemiological studies of these workers show no impact of PFCs on worker mortality.
PFCs have been detected at concentrations below levels of health concern in the Cottage Grove municipal wells and private drinking water wells near the 3M-Cottage Grove facility. However, groundwater in this area flows south toward the Mississippi River. The sources of the PFCs in the city and private wells are believed to be the 3M-Woodbury Disposal Site and possibly also the 3M-Oakdale Disposal Site and Washington County Landfill in Lake Elmo. MDH and MPCA continue to monitor city and private wells throughout south Washington County and provide treatment systems for wells that exceed MDH drinking water criteria.
In 2008, 2010, and 2014, MDH completed biomonitoring studies of selected residents in Cottage Grove, Lake Elmo, and Oakdale who were known to have been exposed to PFOA and/or PFOS in their drinking water. The average concentration of PFCs in the participants' samples were higher than the averages for the general U.S. population. The studies also showed that over time, as the participants drink treated water, the PFC concentrations in their bodies decreased. More information about the biomonitoring studies can be found at PFC Biomonitoring: East Metro.
Studies do show that everyone has some PFCs in their blood, regardless of age. The way PFCs get into human blood is not known at this time. People could be exposed through food, water, use of commercial products or from the environment. PFCs stay in the human body for many years.
PFCs have also been found in the blood of several species of wildlife around the world; the highest concentrations are in bald eagles and mink in the midwestern U.S. Studies also show that PFOS bioconcentrates: large fish have more PFOS in their bodies than small fish. Fish sampling in the Mississippi River near the 3M-Cottage Grove facility and in other water bodies in Washington County and elsewhere in Minnesota have lead to fish consumption advisories being issued (See Minnesota Fish: Benefits and Risks).
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Additional information on the Web:
- Health Consultation: 3M Chemolite: Perfluorochemical Releases at the 3M Cottage Grove Facility, February 18, 2005 (PDF)
- MDH Perfluorochemicals and Health webpage
- Minnesota Pollution Control Agency: Perfluorochemicals
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