PFOS and PFOA: What You Need to Know
Brief History of PFCs such as PFOS and PFOA
PFOA and PFOS are the two most widely discussed fluorinated organic chemicals that are part of a larger group of chemicals referred to as perfluoroalkyl substances (PFASs) or perfluoroalkyl compounds (PFCs). Beginning in the 1950s, PFCs were used to manufacture a variety of household products. PFCs are especially common in products that resist stains and oils (e.g. non-stick) or repel water
Common consumer products created using PFCs include:
- Carpet and furniture treatments
- Cleaning products
- Non-stick cookware
- Outdoor clothing (stain and water resistant clothing)
- Cosmetics (usually powder based, such as powder foundation, eyeshadow, blush and bronzer)
- Fire-retarding foams
- Food packaging
Between 2000 and 2002, PFOS was voluntarily phased out of production in the U.S. in response to a series of studies displaying significant evidence of accumulated environmental exposure. This exposure was mainly due to the dumping of PFOS and PFOA or chemicals that degrade to PFOS or PFOA into water, soil and air surrounding manufacturing facilities. In 2006, eight major companies voluntarily (through request of the U.S. EPA) agreed to phase out their global production of PFOA and PFOA-related chemicals by 2015, although there are still a limited number of ongoing uses.
Why are PFOS and PFOA so Widespread in the Environment?
One major concerns is that PFOS and PFOA, as complex synthetic substances, are not easily degraded by natural processes. Additionally, these compounds are water soluble, and thus can easily disperse from soil to groundwater. Exposure near manufacturing facilities (usually urban areas) is to be expected, however, studies also revealed the presence of PFOS and PFOA in remote regions of the word.
Two theories have been proposed to account for this widespread transport. The first theory is long range transport by oceanic currents (Yamashita N, Kannan K, Taniyasu S, Horii Y, Petrick G, Gamo T. A global survey of perfluorinated acids in oceans, Mar. Pollut. Bull. , 2005, vol. 51 (pg. 658-668)) which is supported by the finding of parts per quadrillion (pg/l) of PFAAs in the surface water of the Atlantic and Pacific Oceans, South China Sea, Sulu Sea, and the Labrador Sea, with PFOA being the major PFAA detected followed by PFOS. The second theory involves atmospheric transport and transformation of precursor chemicals. While the volatility of PFOA and PFOS is nominal, that of their precursors and derivatives is high at normal temperature and pressure. (A great summary found here)
The presence of PFOS and PFOA in water has also led to studies of its effects on marine life. Traces of PFOS and PFOA have been found in the blood and tissue of marine animals, thus rendering them, as well as their ecosystem (both environment and those that feed upon them) vulnerable.
PFOS and PFOA Health Concerns
The primary evidence cautioning against PFOS and PFOA contact comes from animal studies. Laboratory animals exposed to fluorochemicals experience a range of adverse health effects. Exposed rats have displayed concerning developmental, reproductive, and neuroendocrine issues, along with other physiological problems. Researchers have determined that PFOS and PFOA interfere with lipid metabolism and disrupt the breakdown and utilization of fatty acids in animals, which may cause severe multi-systemic issues.
Based on the current available peer-reviewed studies on laboratory animals and epidemiological evidence in human populations, the EPA released the following statement in Spring of 2016:
“These studies indicate that exposure to PFOA and PFOS over certain levels may result in adverse health effects, including developmental effects to fetuses during pregnancy or to breastfed infants (e.g., low birth weight, accelerated puberty, skeletal variations), cancer (e.g., testicular, kidney), liver effects (e.g., tissue damage), immune effects (e.g., antibody production and immunity), thyroid effects and other effects (e.g., cholesterol changes).”
PFOS/PFOA and Drinking Water
Drinking water supplies have become a central area of reform due to the tendency of fluorochemicals to accumulate in groundwater. In May of 2016 the EPA issued a health advisory for PFOS and PFOA in public water systems, warning municipalities that the presence of levels over 70 parts per trillion of either PFOS or PFOA in community water supplies is not safe. This can be equated to just one drop of the chemicals in 20 Olympic sized swimming pools. The EPA's prior health advisory was issued in 2009, warning municipalities that only above 40 parts per trillion for PFOA and above 20 parts per trillion for PFOS were cause for concern. Unfortunately, boiling water before use will not suffice to protect oneself from PFOS/PFOA exposure. If levels go above 70 parts per trillion, water systems should promptly notify their State drinking water safety agency (or with EPA in jurisdictions for which EPA is the primary drinking water safety agency) and consult with the relevant agency on the best approach to conduct additional sampling.
According to the EPA, in order to limit exposure, drinking water systems can reduce concentrations of perfluo- roalkyl substances, including PFOA and PFOS, by closing contaminated wells or changing rates of blending of water sources. Alternatively, public water systems can treat source water with activated carbon or high pressure membrane systems (e.g., reverse osmosis) to remove PFOA and PFOS from drinking water.
A strong fluorine-carbon bond and low vapor pressure can make PFOA and PFOS resistant to many municipal and home water treatment technologies, including direct oxidation, biodegradation, air stripping, vapor extraction and direct photolysis (ultraviolet light), making treatment difficult. However, several groundwater treatment options may be applicable:
Membrane Filtration: Membrane filtration, a technique that uses a porous membrane filter to separate particles in fluids, is an option. To be effective, this process may need the addition of other minerals, and waste/byproducts must be managed.
Anion Exchange: A process that separates a substance based on its charge using ion exchange resin, where the resin is coated with negatively charged counter-ions (anions) is a complex treatment option and competition with common ions for binding sites on resins can impact its effectiveness. Additionally, organics, total dissolved solids, and minerals can clog resins and reduce the efficiency of the treatment.
Granular Activated Carbon: Calgon Carbon has been investigating the application of granular activated carbon (GAC) as an effective way to remove PFCs from sources of drinking water. Recent testing has demonstrated GAC filters as effective technologies for reducing perfluorinated compounds from water. Accelerated Column Tests (ACTs) of virgin GAC show successful removal of harmful compounds in groundwater, including PFOA as well as perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPA), perfluorohexanoic acid (PFFHxA), and perfluorodecanoic acid (PFDA). The spent activated carbon, containing adsorbed PFCs, can be thermally reactivated, thereby destroying the contaminants and allowing the activated carbon to be recycled and reused in groundwater treatment applications. Lab testing and field trials have led to activated carbon systems being successfully employed to treat groundwater for PFC removal throughout North America.