Per- and Polyfluoroalkyl Substances (PFAS)
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Environmental Health Division
History of MDH Activities - Per- and Polyfluoroalkyl Substances (PFAS)
Since 2002, the MDH has partnered with the Minnesota Pollution Control Agency (MPCA) to investigate PFAS in Minnesota. This work began with drinking water investigations near the 3M Cottage Grove plant and related legacy waste disposal sites in Washington County (east of St. Paul).
Health Based Values for PFAS: In 2002, MDH first developed Health Based Values for PFOS and PFOA. Since then, MDH continues to review available toxicological and more recently epidemiological information for many PFAS and develop new or revised values when needed. Currently, MDH has health-based guidance values for PFOS, PFOA, PFBS, PFBA, PFHxS, and PFHxA.
MDH Public Health Laboratory: In 2003, the MDH Public Health Laboratory developed an analytical method tailored to the PFAS found in the 3M waste disposal sites. Since then, they have also developed two other methods with longer analyte lists to evaluate AFFF and other PFAS sites. In 2009, the lab also developed methods to test for PFAS in blood serum, garden produce, and other media.
- The East Metro investigations have identified an area of groundwater contamination covering over 150 square miles, affecting the drinking water supplies of over 140,000 Minnesotans. By the end of 2021, a total of more than 3,800 private wells had been sampled and 1,451 private well advisories issued to East Metro homeowners with elevated PFAS in their well water. Homes where wells are issued drinking water advisories are either connected to city water or provided with whole-house GAC filters, which are maintained by the state. Biomonitoring of exposed residents demonstrated significant and steady reductions in blood serum levels of PFOS, PFOA, and PFHxS after installation of treatment systems to reduce or eliminate exposures.
- Fire-fighting training areas, including two sites in Duluth and one in Bemidji where city and/or private drinking water wells have detectable levels of PFAS;
- Fish monitoring in 93 lakes and rivers and issuance of fish consumption advisories where needed;
- Chrome-plating facilities, often identified by high levels of PFOS in either fish or surface waters; and
- Garden produce and house dust studies in the East Metro.
Biomonitoring: Biomonitoring of exposed residents in the East Metro demonstrated significant and steady reductions in blood serum levels of PFOS, PFOA, and PFHxS after installation of treatment systems to reduce or eliminate drinking water exposures.
Water Treatment Options: MDH also has undertaken testing of point-of-use water treatment devices, to provide residents of affected communities with information regarding options available to them for PFAS removal from their water. Currently, no certification exists for such home treatment systems. Testing included larger, “under the sink” type activated carbon and reverse osmosis systems as well as small, faucet-mounted activated carbon filters. While not exhaustive, these evaluations provided this provided much needed information for anyone seeking to further reduce their exposure to PFAS.
Communications and Outreach: Community engagement activities have been integral to PFAS activities in Minnesota. MDH staff have been in affected communities in a variety of settings since 2002. MDH has continuously provided outreach and education to community members as the science has changed and our understanding of PFAS exposure and health impacts has evolved. The result is a robust network of relationships in affected communities that increase the effectiveness of all aspects of the MDH PFAS work.
Community engagement activities have included but are not limited to:
- Materials, information sheets, websites and other information development which is continuously updated as information evolves
- Public meetings with presentations and time for one on one questions with staff
- County and local government updates and partnerships
- Technical assistance for local governments and support for their staff charged with protecting public drinking water
- One on one education with private well owners
- Providing office hours for concerned community members
- Email and phone line 24/7 for people to access with concerns or for information about site activities
Minnesota Pollution Control Agency: PFAS pollution webpage for information about their work to address PFAS contamination releases in Minnesota.
Stress at Contaminated Sites: Coping with the stress that environmental contamination can cause (PDF)
Timeline of PFAS Activities in Minnesota
- The Minnesota Pollution Control Agency (MPCA) requests that MDH develop Health Based Values (HBVs) for PFOA and PFOS after they were detected by 3M during investigations at the 3M Cottage Grove manufacturing facility. An HBV is a guidance value that has not been promulgated that represents the amount of a chemical in water that is considered to be safe for people to drink daily for a lifetime. MDH’s 2002 HBV for PFOA was 7 μg/L, and the HBV for PFOS was 1 μg/L.
- 3M discloses to MPCA locations where PFAS-containing wastes may have been disposed of, including the former Washington county Landfill, the 3M-Woodbury Disposal Site, and the 3M-Oakdale Disposal Site.
- The MDH Public Health Lab (PHL) develops the method to analyze water samples for PFOA and PFOS.
- Water sampling conducted by MDH finds no PFOS or PFOA in private wells immediately east of the 3M Cottage Grove plant.
- Water sampling conducted by MPCA and MDH finds that seven private wells in Lake Elmo, near the former Washington County Landfill, are contaminated with PFOA. The 2002 HBVs are used by MDH to determine if a drinking water well advisory is warranted for an individual well. MPCA then uses the MDH advisories to determine if any mitigation measures are needed, such as providing bottled water or individual water treatment to impacted residents.
- MPCA and MDH begin testing drinking water from the eight wells that serve the Oakdale public water supply. PFOA and PFOS are detected in measurable amounts in four of the wells. In response, the City of Oakdale limits the use of the two most impacted wells and increases pumping from the least impacted wells.
- Construction begins on a water treatment plant to remove PFAS from two of Oakdale’s most affected wells.
- Private well sampling effort expands. By the end of 2005, nineteen residences in Lake Elmo receive well advisories for drinking water that exceeds the 2002 HBVs. Bottled water is provided by the MPCA as a temporary response followed later that year by GAC filter installation in most houses.
- New lab methods became available, expanding the list of chemicals to include five more PFAS: PFBA, PFBS, PFHxA, PFHxS, and PFPeA. Water sampling using the expanded list finds that all are present at low levels in the Oakdale public water supply except PFBS. Three of the chemicals (PFHxA, PFHxS, and PFPeA) were only found in wells that had previous detections of PFOA and PFOS. However, PFBA was detected at low levels in wells (both public and private wells) that previously had no detections of PFOA and PFOS. Since the PFBA contamination extends beyond the areas where PFOA and PFOS are detected, the size of the investigation area greatly increases, including Woodbury city wells.
- MDH begins using well advisory guidelines of 1 μg/L for PFOA and 0.6 μg/L for PFOS as interim measures while actively reviewing the growing amount of toxicological information available on these chemicals. These guidelines are also applied (as surrogates) to the additional five PFAS that the MDH PHL begins analyzing for in water.
- The Oakdale water treatment plant goes into operation in October 2006. The goal of the treatment plant is to treat the city drinking water so that the levels of PFAS are consistently below state and federal guidelines.
- MDH and MPCA staff initiate additional private well sampling further south and west in Lake Elmo. PFOA and PFOS are detected in over 300 private wells, 132 drinking water advisories issued.
- 3M provides the city of Lake Elmo with a grant to extend the municipal water supply to approximately 200 homes in two Lake Elmo neighborhoods with contaminated drinking water (Tablyn Park and Lake Elmo Heights). 3M also donates land for new Lake Elmo water tower.
- Based on PFBA detections in city of Woodbury wells, the city of Cottage Grove requests that their municipal wells be re-tested for PFAS using the expanded PFAS list. PFBA is detected in all of the Cottage Grove municipal wells at concentrations ranging from 0.3 to 1.5 μg/L. PFAS in Cottage Grove city wells are likely from another source, such as the 3M-Woodbury Disposal Site located northeast of the city’s main well field, rather than the 3M-Oakdale Disposal Site and Washington County Landfill.
- MDH and MPCA collected surface water samples from Raleigh Creek in Oakdale and Lake Elmo. Results suggest creek is transporting PFAS, including PFOS, from the 3M-Oakdale Disposal Site into the Lake Elmo area, where it re-enters the groundwater.
- By the end of 2006, a total of 159 well advisories in Lake Elmo and one in Oakdale have been issued.
- PFAS detected in Lake Elmo Municipal Well #3. A permanent pump was never installed in the well and it was never placed into service due to the presence of PFAS.
- Private well sampling near the 3M-Woodbury Disposal Site, on the border of Woodbury and Cottage Grove, detects PFBA in most wells sampled.
- PFBA is detected in city wells in Newport, St. Paul Park, Hastings, and South St. Paul.
- On March 15, 2007, MDH Well Management Section establishes the Lake Elmo-Oakdale Special Well and Boring Construction Area (SWBCA) in response to the discovery of PFAS chemicals in the groundwater and water-supply wells in the area. It established special requirements for the construction, repair, modification, and permanent sealing of wells and borings within the boundaries of the SWBCA. This has resulted in the need to require property owners building new homes in the area, or replacing existing wells, to have their new domestic water-supply wells drilled to deeper aquifers unaffected by PFAS. Some domestic wells have been drilled to depths over 500 feet. Owners of new wells must also pay for PFAS analysis of water samples before their wells may be placed in service.
- MDH and MPCA expand private well sampling in the East Metro to include all of Washington County south of Highway 5 and selected wells in Dakota County on the south bank of the Mississippi River. No PFAS detected in private wells south of the river.
- MDH issues revised HBVs for PFOA and PFOS of 0.5 μg/L and 0.3 μg/L, respectively and continues to use 1 μg/L as a surrogate for PFBA. The HBVs for PFOA and PFOS are promulgated as expedited Health Risk Limits (HRLs) when they are published in the State Register (August 27, 2007, Volume 32, Number 9, page 373).
- MDH issues 28 drinking water advisories in Cottage Grove and 17 in Lake Elmo. MPCA issues Soil Reference Values (SRVs) of 2,000 μg/kg for PFOS and 4,000 μg/kg for PFOA based on a residential exposure scenario.
- The 2007 Legislature directs MDH to study the effectiveness of point-of-use treatment systems for individual households. A number of water-treatment systems are found to be effective at removing PFAS (Water Marketing & Science, 2008).
- The MPCA and 3M negotiates a Consent Order bringing investigation and cleanup of the Woodbury and Oakdale sites under the formal Superfund process. The Washington County Landfill is addressed under the state Closed Landfill Program.
- MDH tests small, inexpensive, commercially available activated carbon filters (faucet-mounted and pitcher style) for PFAS removal efficiency and published an information sheet.
- MDH issues first consumption advice based on levels of PFOS for fish from the Mississippi River and Minneapolis Chain of Lakes.
- 3M and the MPCA begin additional remedial actions to address PFAS at the Oakdale Disposal Site and the Washington County landfill.
- MDH establishes an HBV of 7 μg/L for PFBA.
- Connection of approximately 200 homes in the Tablyn Park and Lake Elmo Heights neighborhoods in Lake Elmo, to the Lake Elmo municipal water supply system is completed.
- Approximately 200 private water-supply wells that were impacted by PFAS chemicals are permanently sealed by licensed well contractors. MDH Well Management Section managed the well sealing project. Construction records did not exist for many of the wells. Consequently, MDH in collaboration with the Minnesota Geological Survey gamma-logged, video inspected, and flow-logged many wells to determine geologic formations penetrated by the wells, well construction details, and proper well sealing procedures.
- MDH conducts the “East Metro PFC Biomonitoring Pilot Project”. PFHxS, PFOA, and PFOS detected in 100% and PFBA in 28% of participants. Geometric mean concentrations of PFHxS, PFOA and PFOS are higher than in the general U.S. population.
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; two well advisories are issued in Cottage Grove.
- MDH and MPCA sample Eagle Point Lake, Sunfish Lake, and Lake Elmo; PFAS detected in all three lakes below health-based advisory values.
- MDH provides technical assistance to city of Woodbury in siting of new city well (#17).
- MDH Well Management section completes an evaluation of point-of-use water treatment devices (activated carbon and reverse osmosis); publishes results in July 2008.
- MDH reports on the Health Risk Limits for Perfluorochemicals to the Minnesota Legislature.
- The PFOA HRL is lowered to 0.3 μg/L (State Register, April 27, 2009, volume 33, number 43, page 1796). The PFOS HRL was also re-evaluated but did not result in a change to the HRL value.
- 3M begins additional remedial actions to address PFAS at the 3M-Woodbury Disposal Site and Cottage Grove facility.
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; one well advisory is issued in Lake Elmo and five in Cottage Grove.
- MDH and MPCA coordinate on statewide investigation of aqueous film forming foam (AFFF) use at fire-fighting training areas; MDH samples 17 municipal systems and 20 non-community public water supplies. PFAS detected in 7 municipal systems, all below health-based advisory values.
- “PFCs in Homes and Gardens Study” (PIHGS) recruitment and enrollment process begins in April 2010 to evaluate exposures to residents in the East Metro area who used contaminated water on lawns and in vegetable gardens.
- PIHGS sampling begins May 2010 and ends October 2010.
- MDH conducts the “East Metro PFC Biomonitoring Follow-up Project”. Although PFHxS, PFOA and PFOS still exceed levels in the general U.S. population, concentrations in East Metro participants’ blood serum decreases significantly (MDH 2013).
- Oakdale installs new city well (#10) outside PFAS-contaminated area; MDH provides technical assistance with well siting.
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; one well advisory is issued in Cottage Grove.
- HRLs of 7 μg/L for PFBA and PFBS go into effect when they are published in the State Register (March 14, 2011, volume 35 number 20, page 1395).
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; no new well advisories are issued.
- MDH assists MPCA with communicating PFAS sampling results to private well owners near Duluth Air National Guard Base; detected concentrations below health-based advisory values.
- MDH and MPCA continue to monitor ~400 private wells; no new well advisories issued.
- MDH begins using an action level of 0.3 μg/L for PFHxS to issue well advisories.
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; seven well advisories are issued in Cottage Grove and one in Lake Elmo based on PFHxS.
- MDH provides technical assistance to city of Woodbury in siting of new city well (#18).
- UCMR3 sampling detects PFAS in Bemidji city wells below health-based advisory values.
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; 1 well advisory is issued in Cottage Grove.
- MDH conducts the “East Metro PFC Biomonitoring Follow-up Project”. Although PFHxS, PFOA and PFOS still exceed levels in the general U.S. population, concentrations in East Metro participants’ blood serum continue to decrease significantly.
- MDH provides technical assistance to city of Woodbury in siting of new city well (#19).
- MDH sampling of Bemidji city wells confirms PFAS contamination, below health-based advisory values, but sufficient to trigger quarterly monitoring. MDH also initiates annual private well sampling downgradient of city well field; only trace levels of PFBA detected.
- MDH and MPCA continue to monitor ~400 private wells in the East Metro; no well advisories are issued.
- USEPA issues Lifetime Health Advisory (LHA) values of 0.07 μg/L for PFOS and PFOA (individually or combined concentrations).
- MDH sampled private wells in Bemidji, no PFAS detected.
- In August, based on previous sample results, MDH issues80 well advisories using the new USEPA LHA values and expanded the private well sampling program, leading to 56 more well advisories by the end of the year.
- MDH samples private wells and surface water near Duluth Air National Guard Base, no PFAS detected in wells but PFAS in the surface waters exceed health-based advisory values.
- MDH conducted additional testing of a small, faucet-mounted activated carbon filter to ensure removal of PFAS to new, lower detection limits; published an information sheet with the findings.
- MDH issues revised HBVs for PFOA, PFOS, and PFBS of 0.035, 0.027, and 2 μg/L respectively. PFBA was also reviewed but no changes to the existing HBV of 7 μg/L were made. PFOS continues to be used as a surrogate for PFHxS.
- Based on existing sampling data, MDH issues 120 private well advisories and expands private well sampling program, leading to251 more well advisories by the end of the year.
- MDH provides technical assistance to city of Cottage Grove in siting of new city well (#12)
- MDH samples surface water system throughout Lake Elmo, Oakdale, and Afton to clarify extent of surface water transport to groundwater in these communities.
- MDH sampled private wells in Bemidji, no PFAS detected.
- MDH and MPCA sampled private wells near Duluth Air National Guard Base, issued one drinking water advisory.
- Published “Occurrence of PFAS in garden produce”. DP Scher et al. 2018. Chemosphere 196:548-555. https://doi.org/10.1016/j.chemosphere.2017.12.179
- MDH and MPCA continue to sample private wells in the East Metro. Over 650 private wells were sampled and 182 well advisories were issued.
- In April, MDH issues revised HBVs for PFOS and PFHxS of 0.015 and 0.047 μg/L, respectively.
- Published “Tracked in soil”. DP Scher et al. 2019. J Expo Sci Env Epi 29:218-226; https://www.nature.com/articles/s41370-018-0101-6
- Published “A transgenerational toxicokinetic model and its use in derivation of Minnesota PFOA water guidance”, Goeden et al 2019. J Expo Sci Env Epi 29:183-195; https://www.nature.com/articles/s41370-018-0110-5
- The MDH PHL lowers its laboratory detection limits in response to the new HBVs.
- By the end of 2019, over 1,200 private well advisories have been issued to East Metro homeowners with elevated PFAS in their well water.
- Work on the 3M natural resource damage settlement continues, with proposals for expedited drinking water projects requested by MPCA and DNR.
- The City of Lake Elmo reaches a legal settlement with 3M over past costs incurred by the city to address PFAS in their city wells.
- MDH and MPCA continued to sample private wells in the East Metro. Over 800 private wells were sampled and 106 well advisories were issued.
- By the end of 2020, a total of more than 3,600 private wells have been sampled and 1,378 private well advisories have been issued to East Metro homeowners with elevated PFAS in their well water
- In August, MDH revised the cancer classification for PFOA. The cancer classification was changed from “suggestive” to “likely to be carcinogenic at high doses”. MDH considered the noncancer Health Based Value (HBV) to be protective for cancer and a cancer HBV was not derived.
- MDH and MPCA continued to sample private wells in the East Metro. Over 541 private wells were sampled and 73 well advisories were issued. By the end of 2021, a total of more than 3,800 private wells have been sampled and 1,451 private well advisories have been issued to East Metro homeowners with elevated PFAS in their well water.
- In December, MDH issued a Health Based Value for PFHxA of 0.2 μg/L.
- A comprehensive drinking water plan for 14 East Metro communities impacted by PFAS was completed in August of 2021. This plan is part of the 3M settlement MDH staff participated in the workgroups responsible for the plan.
- Statewide PFAS Monitoring Project was initiated.
- In March, MDH issued a revised Health Based Value for PFBS, lowering the value from 2 to 0.1 μg/L.
- In March, MDH expanded the health endpoints for PFOA to include thyroid and pancreas in addition to developmental, liver, immune, and kidney.
- MDH and MPCA continue to sample private wells in the East Metro.
- Interactive Dashboard for PFAS Testing in Drinking Water dashboard was released in June 2022.