Minnesota to Update Residents on PFCs
The Minnesota Department of Health scheduled a series of public meetings in six Washington County communities to update residents on perfluorochemicals (PFCs) in groundwater and discuss public health concerns.
About one year ago, department staff and the Minnesota Pollution Control Agency held meetings in the area after widespread perfluorobutanoic acid (PFBA) contamination was found in the groundwater underneath Woodbury, Cottage Grove, Newport. St. Paul Park, South St. Paul, and Hastings. In 2004 and 2005, two other perfluorooctane sulfate (PFOS) and perfluorooctanoic acid (PFOA) were found in private wells in Lake Elmo and several city wells in Oakdale.
The department has established a health-based value of 7 ppb for PFBA, which is higher than the drinking water guideline (1 ppb) that was used previously. That guideline was based on limited health information. The value is the calculated concentration of a groundwater contaminant, or a mixture of contaminants, that poses little or no risk to health, even if consumed daily over a lifetime.
The new health-based value for PFBA reflects a clearer understanding of its potential for health impacts during fetal and other developmental life stages and of how long it remains in the human body.
"Generally speaking, PFBA is less toxic than we previously thought, in part because it passes through the body even more quickly than was suspected earlier," said Helen Goeden, Ph.D., the department toxicologist who worked on the health-based value.
The new value takes into account the results of three major studies: a 28-day study of rats, a 90-day study of rats, and a developmental study of mice exposed before birth. The 28- and 90-day studies were commissioned by 3M but conducted by an independent testing laboratory. The developmental study was conducted by scientists at the U.S. Environmental Protection Agency's National Health and Environmental Effects Research Laboratory.
The revised value for PFBA means that a well advisory will no longer be needed for about 30 of the wells that currently have an advisory in Lake Elmo and Oakdale. The drinking water from 23 private wells still exceeds health-based exposure limits and continues to require water treatment to remove PFCs or alternate water. Early on, in 2007, the need to treat water in a much larger group of over 200 homes in Lake Elmo was eliminated when they were connected to the city water system.
In Cottage Grove, the new value means one well advisory will be issued in addition to nine private wells where water treatment systems have been installed and are still required. About 20 homes in Cottage Grove will no longer require a well advisory. All homes with an existing well advisory will be resampled to confirm the current levels of contamination before any well advisory is rescinded. No decisions have been made regarding the future of treatment systems installed in homes that no longer require treatment due to a well advisory. Well advisories are based on combined concentrations of PFOA, PFOS and PFBA.
Detections of PFBA in municipal water supplies in south Washington County are well below the new health-based value.
Over the last year, the Minnesota agencies sampled more than 1,000 private wells to determine the size of the underground plumes of contamination. Although PFCs are detected in the groundwater across a large portion of southern Washington County, the areas that pose a health concern are very limited in size. A full year of monthly sampling of city wells in the affected communities shows that the levels of PFCs in the groundwater are stable – neither increasing nor decreasing. Continued sampling of public and private wells will tell if the PFC plumes are changing over time.