April 3, 2019
Health department issues new guidance values for two perfluoroalkyl substances (PFAS)
New health-based values incorporate more recent scientific data
Minnesota Department of Health (MDH) officials today issued new health-based advisory values for two chemicals associated with groundwater contamination in the eastern Twin Cities. MDH set the new values after reviewing the latest scientific data on the two chemicals.
The two chemicals – perfluorooctane sulfonate, or PFOS, and perfluorohexane sulfonic acid, or PFHxS – are in the family of chemicals known as perfluoroalkyl substances, or perfluorochemicals. The new PFOS value of 15 parts per trillion (ppt) replaces the previous value of 27 ppt. The new health-based value for PFHxS is 47 ppt. Until now, the state had used the 27 ppt PFOS health-based value as a “surrogate” for PFHxS due to a lack of available data specific to PFHxS.
Health-based values are among a number of different protective values Minnesota health officials use to help communities and individuals determine how to address low levels of water contamination. According to James Kelly, manager of Environmental Surveillance and Assessment at MDH, the new values reflect a small adjustment but provide additional protection for human health.
“These changes may seem minor but they are part of our ongoing commitment to protect the affected communities,” Kelly said. “As new scientific information becomes available, we use it to evaluate potential risks and provide updated guidance so people can have confidence that their drinking water is safe.”
Since 2002, MDH and the Minnesota Pollution Control Agency (MPCA) have been helping communities in the East Metro address groundwater contamination linked to the use and disposal of PFAS by 3M. During that time, MDH and MPCA have sampled almost 3,000 private wells in the affected communities and issued nearly 1,100 private well advisories. The new health-based values do not change any advice MDH has previously given to any community water supply systems. However, six private wells in south Washington County that had not previously exceeded the health-based values have groundwater that exceeds the new values. MDH is notifying those well owners, and MPCA will be providing them with an alternate water supply.
MDH first developed health-based values for PFOS and PFOA in 2002 after investigations found the chemicals in groundwater used as a source of drinking water at the 3M Cottage Grove plant, where the company produced PFCs. They were also found in several disposal sites in Washington County where 3M disposed of PFC-containing wastes. These chemicals were produced by 3M and other manufacturers and were used for decades in stain repellants, non-stick cookware, food packaging, fire-fighting foam and other consumer and industrial products.
“Minnesota has long been a leader in protecting its citizens and the environment with a rigorous process for determining health based values for PFAS,” said MPCA Assistant Commissioner Kirk Koudelka. “We will be using these new values to guide decision-making as we work alongside other agencies and local communities to address drinking water quality and sustainability issues in the east metro.”
For more information about PFAS and human health, please visit Perfluoroalkyl Substances (PFAS). For more information on the health-based guidance, please refer to the Human Health-Based Water Guidance Table.