Overview of PFOS and Related Compounds
Introduction
Potential Product and Process Sources of PFOS
Health Concern
Exposure Pathways
MPCA, MDH and MDNR Response
Excerpts from MPCA Website
Future Activities (from MPCA Website)
Web Links for More Information
As part of an ongoing effort to sample for perfluoro-chemicals (PFCs) in different settings in Minnesota, the Minnesota Pollution Control Agency recently discovered Perfluorooctane Sulfonate (PFOS) in fish tissue in Lake Calhoun. Low levels of PFOS were found in Lake Calhoun water in 2005.
PFOS is one of a class of hundreds of fluorinated compounds (based on an underlying 8 carbon molecule) that are extremely stable in the environment and were used in consumer and industrial manufacture until phasing out of production. The products derived from PFOS were used world-wide by a variety of industries beginning in the 1950s. PFOS was manufactured in the United States solely by 3M until it was phased out of production beginning in 2000.
Detection of PFOS in Lake Calhoun represents the first finding of PFCs above health-based levels from a location that is not associated with several east metro waste-disposal areas. These sources have apparently led to a wide area of groundwater impact and some surface water impact in Washington County. There are no currently known sources areas of PFCs in the area of the Minneapolis Chain of Lakes.
Potential Product and Process Sources of PFOS
PFOS and related perfluoro-chemicals (PFCs) were used in the following products/processes:
- Surface treatments for fabric, carpet, upholstery, and paper products
- Fire fighting foams
- Semi-conductor manufacture
- Chromium Plating (a mist suppressant)
- Non-stick coatings
- Photographic and lithographic processes
The stability of these compounds in the environment both contributed to their utility as surface treatments (they are durable) and to their persistence in the natural environment (they don’t degrade under normal environmental conditions). PFCs have been detected at parts-per-billion levels (ppb) in animal tissue and environmental media world-wide. Research has also shown them to bio-accumulate in the tissues of fish and mammals. That is, they tend to persist in the tissues of animals at higher levels than found in the environment. The bio-accumulation has triggered much of the recent health concern regarding PFCs. The recognition of the wide distribution and bio-accumulative nature of these compounds led, in part, to 3M ceasing production of PFOS and its voluntary withdrawal of related products (like Scotchgard ™ ) from the marketplace. Environmental stability and bioaccumulation, alone, do not indicate a health risk but they do indicate that a concern for long-term exposure exists.
Research by 3M and others has not shown significant risk from the concentrations found in the natural environment, animal tissues, or in exposed workers at 3M. Research on much higher exposures has shown that accumulation poses cancer risks in laboratory animals.
The USEPA began researching PFCs in 1999. The USEPA developed “Significant New Use Rules” (SNUR) in 2000 and 2002 to prevent the manufacture or import of PFOS in the future. There are exceptions for certain specialized uses (e.g., semi-conductors, aviation fluids). However, the widespread use in most consumer products (fabrics) has been discontinued. The USEPA is in the process of developing a comprehensive risk assessment of PFOS.
The Minnesota Department of Health has developed drinking water guidelines of 0.3 ppb for PFOS in drinking water. This standard is considered “cautious” by the MPCA and represents a conservative approach while definitive toxicology data are being developed. This standard applies to direct human consumption of water and not to ecological receptors (fish and wildlife or human consumption of fish).
The pathways for PFCs to enter the environment are not completely understood. The pathways are probably complex, as is the variety of industry and services that used the products. Industrial waste water discharge, urban runoff and solid waste disposal practices are among the likely pathways for release of PFCs to the environment. Since these chemicals are present in so many products the MPCA and EPA are likely to be looking closely at PFCs at a variety of types of facilities and sites in the near future.
Expanded fish sampling is planned and may include Lake Minnetonka. MPCA plans to sample inflow and outflow at 31 wastewater treatment plants. Groundwater and leachate will be tested at numerous active landfills.
It is important to recognize that past environmental sampling generally did not look for PFCs. Thus, an historical database from which to infer trends over time is not available. The appearance of PFCs in the environment is probably not new, given the presence of PFCs in consumer products for over half a century. Rather, the appearance of these compounds reflects the emergence of the overall PFC concern, sampling procedures and availability new analytical methods for detection.
PFCs are a “hot topic” at the present time. Additional human risk assessment, environmental fate, and ecological risk assessment research is currently underway. Various “fact sheets” and other information are available from the USEPA, MPCA and 3M. We can expect to see rapid development of new guidelines and standards at the state and national levels in the near future.
“The MPCA is involved in a number of activities related to cleanup and research about perfluorinated chemicals, or PFCs. Some of the most notable of these include:
- Working with the Minnesota Department of Health to sample private and municipal drinking water supplies;
- Evaluating closed and active landfills that may have accepted waste containing perfluorooctane sulfate (PFOS) and perfluorooctanic acid (PFOA);
- Sampling Mississippi River sediment and discharge from outfalls at the 3M Cottage Grove facility;
- Sampling effluent from the metro wastewater plant;
- Fish tissue sampling;
- Review and oversight of 3M monitoring and work plans for sites in Superfund or the Voluntary Investigation and Cleanup Program;
- Coordination of information with the U.S. Environmental Protection Agency (EPA) about PFOA; and
- Developing water quality criteria for surface water discharge of PFOS and PFOA.
The Minnesota Department of Health is responsible for setting limits for contaminants in drinking water. Because PFCs are present in drinking water in some areas, the MDH has developed criteria, known as Health Based Values (HBVs), for PFOA and PFOS. HBVs are criteria that MDH considers safe for human consumption over a lifetime.
In early March 2007, MDH issued revised HBVs for PFOA and PFOS of 0.5 micrograms per liter (μg/L) and 0.3 µg/L, respectively.”
“Filters containing activated carbon have been shown to be effective at removing PFCs from water supplies where they have been used and tested. Other types of common water treatment systems, such as water softeners or reverse osmosis units, are not likely to remove PFCs. Boiling the water will not remove the PFCs.”
Future Activities (from MPCA Website)
“Since a number of household, commercial, and industrial products containing PFCs are ultimately disposed of in solid waste facilities and landfills throughout Minnesota, additional sampling is anticipated at solid waste facilities evaluated during the 2006 landfill screening effort. The upcoming effort will include ground-water sampling of downgradient monitoring wells. This effort will expand to include a subset of demolition landfills that don’t have synthetic liners. This sampling is expected to take place in 2007.
MPCA budgeted projects which include investigation for PFCs:
- $115,000 for additional fish tissue sampling in the Mississippi River and other locations;
- $20,000 for baseline sampling to determine if PFCs are present in ambient ground water (i.e. – not associated with disposal site)
- $200,000 for consultant contract to accelerate development of criteria for PFOS and PFOA that would apply to wastewater effluent discharge to surface waters of the state; and
- $154,500 for active landfill evaluation of PFCs.
- $150,000 for the evaluation of PFCs at wastewater treatment plants.”
As part of an ongoing effort to sample for perfluoro-chemicals (PFCs) in different settings in Minnesota, the Minnesota Pollution Control Agency recently discovered Perfluorooctane Sulfonate (PFOS) in fish tissue in Lake Calhoun. Low levels of PFOS were found in Lake Calhoun water in 2005.
PFOS is one of a class of hundreds of fluorinated compounds (based on an underlying 8 carbon molecule) that are extremely stable in the environment and were used in consumer and industrial manufacture until phasing out of production. The products derived from PFOS were used world-wide by a variety of industries beginning in the 1950s. PFOS was manufactured in the United States solely by 3M until it was phased out of production beginning in 2000.
Detection of PFOS in Lake Calhoun represents the first finding of PFCs above health-based levels from a location that is not associated with several east metro waste-disposal areas. These sources have apparently led to a wide area of groundwater impact and some surface water impact in Washington County. There are no currently known sources areas of PFCs in the area of the Minneapolis Chain of Lakes.