Perfluorinated chemicals linked to military bases, airports
New analysis finds association between drinking water contamination and non-industrial sources
By Jessica Morrison
A new study links drinking water contamination from perfluorinated chemicals to airports and military bases.
Credit: U.S. Air Force/Greg L. Davis
Drinking water contamination from perfluorinated chemicals is a known concern for communities near industrial sites in the U.S. where the chemicals were once produced. Contamination that extends beyond the reach of production facilities is coming from other sources, experts say.
Researchers are now pointing to military bases, civilian airports, and wastewater treatment facilities as sources of poly- and perfluoroalkyl substances (PFASs) in ground and surface waters.
Xindi C. Hu of Harvard T.H. Chan School of Public Health and colleagues report drinking water supplies of some 6 million U.S. residents exceed the lifetime health advisory levels for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) set by the Environmental Protection Agency in May (Environ. Sci. Technol. Lett. 2016, DOI: 10.1021/acs.estlett.6b00260).
Hu and her colleagues examined EPA’s national drinking water contaminant data for a suite of PFASs and analyzed 16 industrial sites, 664 military fire training sites, 533 civilian airports, and 8,572 wastewater treatment plants. They show a statistical association between the number of these facilities in an area and the concentration of PFASs in its drinking water.
“This study gives weight to what many of us had suspected for many years, which is that there is a very significant contribution of non-industrial sources of these chemicals to contaminated water supplies,” says Christopher P. Higgins, an environmental chemist and professor at Colorado School of Mines and co-author of the study.
The Department of Defense late last year began investigating contamination at military training sites where aqueous film-forming foams containing PFOS and related fluorochemicals that can degrade to PFOA or PFOS had been used for fire training exercises. In addition, the authors note that wastewater treatment plants are unlikely to remove PFASs through standard treatment methods.
“The authors are to be commended for taking EPA data and interpreting it for the public and decision makers,” says Jennifer A. Field, an environmental chemist at Oregon State University who was not involved in the work.
Military bases and airports are more abundant than manufacturing sites, Field adds. “This issue has the potential to touch every state.”
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PFCs Quick Facts1
What are PFCs?
PFCs are very stable, man-made chemicals (always blame the men). The
chemical structure of PFCs is a chain of carbon atoms
(4 to 16) surrounded by fluorine atoms and often
with a charged functional group at the end (typically
acarboxylate or sulfonate salt or acid). PFCs with 8 or
greater Carbon atoms, including PFOA and PFOS, are
long-chain PFCs. They are unique substances that
repel oil, grease and water.
How have PFCs been used?
PFCs have been used to make fluoropolymer
coatings and products that are oil and water
repellent such as Teflon®, StainMaster® carpets,
Scotchgard®, and GoreTex®. They have also been
used to make surfactants that are used in firefighting
foams and mist suppressants for metal
plating operations.
Where are PFCs found in the environment?
PFCs are extremely stable and persistent in the
environment, and migrate easily. They have been
found globally (even in remote locations) in water,
soil, and air, as well as in food, breast milk, umbilical
cord blood, and human blood serum. They also
concentrate in the food chain.
How does exposure to PFCs affect human health?
Scientists are continuing to study PFCs. Studies show
that humans do not metabolize PFCs nor does the
human body excrete the longer chain compounds
very rapidly. In some cases it may take years for the
human body to rid itself of PFCs. This is in contrast to
animal (mice, rats) which rapidly excrete the
chemicals. Some studies suggest that these
substances may affect sex hormones and cholesterol
in humans. Animal studies indicate damage to the
liver and tumor development. The scientific evidence
is inconclusive on whether PFCs might cause cancer
in humans.
Source: ATSDR, 2009
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There are many chemicals that fall into the
generic family of PFCs. This paper will focus on the two most commonly researched PFCs and most prevalent in the environment:1
• perfluorooctanioc acid (PFOA)
• perfluorooctane sulfonate (PFOS)
The science surrounding PFCs is still evolving, especially in the fields of health and environmental effects and human toxicology. Much research has been and is being performed in the U.S. and internationally. PFCs are persistent, bio-accumulative, and toxic substances that have been detected all over the world, even in remote locations. They have been shown to be toxic to
laboratory animals, and there is inconclusive evidence that they might cause cancer in animals.
The toxicity to humans is still being debated; although some studies suggest that these chemicals function as endocrine disruptors and mimic fatty acids in the body. The chemicals are not easily excreted and remain in the human body for years (estimated 4-8 years). In addition, PFCs do not degrade in the environment and are not removed by conventional water treatment methods, such as in-situ pump and treat, soil vapor
extraction and air sparing.
PFCs have been used to make fluoropolymer coatings and products that are widely used by consumers due to their oil and water repellent characteristics. They have also been used to make surfactants that are used in fire-fighting foams and mist suppressants for metal plating operations. Locations that may have been contaminated with PFCs include:
- firefighting training areas,
- aircraft crash sites,
- metal coating and plating facilities,
- water treatment systems and receiving water bodies, and
- airport hangars and other facilities storing fire-fighting foams
PFC contamination in the United States.
This document includes introductory information and resources specific to PFCs and their persistence in the environment, and summarizes policy decisions and programs being implemented at federal facilities and other cleanup sites within the United States. A case study provided by the Michigan Department of Environmental Quality is also presented.
MANUFACTURING AND USES OF PFCs
PFCs are a large class of synthetic fluorinated chemicals and have been used in many industries including aerospace, automotive, construction, manufacturing, electronics, and textiles. PFCs have been used since the 1940s as manufacturer-applied oil and water repellants on products such as clothing, upholstery, paper, and carpets, and are also used in making fluoropolymers for non-stick cookware.
PFCs surfactant qualities were also utilized in mist suppressants that can be
added to metal plating baths to prevent air releases and to fire-fighting foams for flammable liquids (ATSDR, 2009).
The two most commonly researched PFCs and most prevalent in the environment are PFOS and PFOA (ATSDR, 2009).
PFOS In 1966, aqueous film forming foam (AFFF) was patented as a method for extinguishing liquid hydrocarbon fires (Tuve & Jablonski, 1966). In 1969, the Department of Defense (DoD) issued military specification Mil-F-24385, which includes the requirements for AFFF liquid concentrate fire extinguishing agents consisting of PFOS.
AFFF meeting MIL-F-24385 specifications were developed by seven manufacturers since the 1960s – 3M, Ansul, National Foam, Angus,
Chemguard, Buckeye, and Fire Service Plus, Inc. – for the use in extinguishing fires at military bases, airports, oil refineries, and firefighting training facilities throughout the U.S. Between 2000 and 2002, the 3M Company, the largest manufacturer of AFFF in the world, voluntarily phased out its production. AFFF has not been manufactured in the United States since 2002 (Place &
Field, 2013; Houtz, Higgins, Field, & Sedlak, 2014).
AFFF products containing PFOS may still be in use. Although AFFF was reformulated in the early 2000s and no longer contains PFOS, civilian and military airports continue to maintain an inventory of PFOS-based AFFF. In recent years, the U.S. Environmental Protection Agency (EPA) issued Significant New Use Rules (SNURs) under its Toxic Substances Control Act (TSCA) authority
to restrict the production and use of products that contain PFOS and its precursors; however, the U.S. EPA, Federal Aviation Authority, and other regulatory agencies continue to allow its use (FAA, 2011). 67 FR 11008, 67 FR 72854, citing the TSCA Section 5(f)
In 2004 and 2011, Robert L. Darwin, P.E., prepared estimates on the quantities of AFFF in the U.S. for the Fire Fighting Foam Coalition. Estimates provided in 2011 are provided in Table 1 below.
Table 1: Estimates of AFFF Quantities by Sector, 2004 – 2011 (Darwin, 2011)
Sector PFOS-based AFFF (2004) PFOS-based AFFF(2011)
Military & Other Federal 2,100,000 1,094,700
Civil Aviation (Aircraft Rescue and Fire) 130,000 20,000
Oil Refineries 950,000 152,000
Other Petro-Chem 1,000,000 500,000
Civil Aviation (Hangars) 190,000 70,300
Fire Departments 120,000 60,000
Miscellaneous 150,000 75,000
TOTALS 4,600,000 gallons 1,972,000
PFOA
PFOA has been manufactured in industrial quantities since the 1940s, and unlike PFOS, PFOA continues to be manufactured in the United States although several companies are phasing out its use. PFOA has been used primarily as an aqueous dispersion agent (additive) in the manufacturing of fluoropolymers, which are substances with special properties that have thousands of manufacturing and industrial applications. Well-known fluoropolymers are Teflon®, which is used in non-stick cookware, Gore-Tex® textiles, Stainmaster® carpets, and Scotchgard®. These registered and trademarked products are still available; however their manufacturers have ceased purchasing materials containing PFOA or revised the chemical formulas to eliminate the use of PFOA.
PFOA can also be created by the degradation of some fluorinated telomers that are not manufactured using PFOA. Fluorinated telomers are used in fire-fighting foams and as surface protection to provide soil, stain, grease, and water resistance in products such as tile, stone, textiles, and paper packaging (U.S. EPA, 2014).
In 2006, U.S. EPA partnered with eight chemical companies to launch the 2010/2015 PFOA Stewardship Program to reduce emissions and product content of PFOA and long-chain PFCs that break down to PFOA by 95% in 2010, and to eliminate long-chain PFCs by 2015. As of January 2015, the program is on
track to meet its goal of phasing out the use of PFOA by 2015 (U.S. EPA, 2015).
ENVIRONMENTAL FATE AND TRANSPORT
PFOS and PFOA compounds are highly soluble in water and typically present as an anion (conjugate base) in solution and have very low volatility due to their ionic nature (ATSDR, 2009).
Long chain PFCs have low vapor pressure, and aquatic environments are expected to be their primary sink in the environment (Environment Canada, 2010). These compounds do not readily degrade by most natural processes. They are thermally, chemically, and biologically stable and are resistant to
biodegradation, atmospheric photooxidation, direct photolysis, and hydrolysis. The structure of PFCs increase their resistance to degradation: the carbon-fluorine bonds require a lot of energy to break, and the fluorine atoms shield the carbon backbone (OECD, 2002).
PFCs have been found worldwide in soil, groundwater, surface water, rain, ice caps, air, plants, animal tissue, and blood serum (Furl & Meredith, 2010). The highest concentrations found in the environment tend to be associated with direct discharge from industries where PFCs are in use.
Fresh waters in the vicinity of these industries have been documented to have concentrations of PFCs ranging from 1 – 1000s parts per trillion (ppt). Oceanic concentrations of PFCs are several orders of magnitude lower, ranging closer to 0.01 – 0.1 ppt (Lindstrom, Strynar, & Libelo, 2011).
U.S. EPA Region 5 (2009) has detected PFCs in municipal tap water in Chicago and Cleveland with PFOS concentrations ranging from 2.0ppt to 5.0 ppt. Interestingly, while not volatile, PFCs have been detected in air, sediments, and fauna in the Arctic, despite being geographically separated from any possible human sources (Lindstrom et al., 2011).
PFCs are mobile in soil and leach into groundwater (SERDP, 2012). It is not completely understood how the compounds are transported to areas far removed from industrial facilities or consumer products. Three hypotheses have been presented regarding the method of long-range transport of
PFCs. One possibility is direct ocean transport of PFCs (ATSDR, 2009).
The second is that PFCs are transported directly as marine aerosols, which is supported by evidence that surfactants accumulate at the surface of water bodies (ATSDR, 2009). In addition, a third hypothesis is that volatile
fluorotelomer alcohols travel great distances in the atmosphere and degrade into PFOSand PFOA (Wallington et al., 2006)