Per- and Polyfluoroalkyl Substances (PFAS)
A compilation of Frequently Asked Questions can be found Here
PFAS General
Per- and polyfluoroalkyl substances (PFAS) are a large group of human-made substances that do not occur naturally in the environment and are resistant to heat, water, and oil. PFAS have been used extensively in surface coating and protectant formulations due to their unique ability to reduce the surface tension of liquids [1]. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are two types of PFAS that are no longer manufactured or imported into the United States [2]; however, there could be some imported goods containing trace amounts of these substances[3].
Other PFAS goods and materials are still produced and used in the United States [4]. PFAS are persistent in the environment, can accumulate within the human body over time, and are toxic at relatively low concentrations [5]. Exposure to unsafe levels of PFOA/PFOS may result in adverse health effects including developmental effects to fetuses during pregnancy, cancer, liver effects, immune effects, thyroid effects, and other effects (such as cholesterol changes)[6]. PFOA and PFOS were found in the blood of nearly all people tested in several national surveys[7], [8]. According to the Center for Disease Control (CDC), blood levels of both PFOS and PFOA have steadily decreased in U.S. residents since 1999-2000[9].
PFAS can be introduced into the body by eating or drinking contaminated food or liquid (including water), breathing in or touching products treated with PFAS, such as carpets or clothing [10]. Exposure to PFOA and PFOS is generally dominated by the ingestion of food [11]. Food can be contaminated by the migration of PFAS from packaging [12], and some foods such as fish, meat, eggs and leafy vegetables may contain PFAS due to bioaccumulation and crop uptake [13].Contaminated drinking water has led to high levels of exposure to PFOA, PFOS, and other PFAS for some populations residing
near manufacturing facilities[14]. Workers in facilities that make or use PFAS can be exposed to higher amounts of these chemicals and have higher levels in their blood [15].
Infants may be exposed to PFAS through breastfeeding [16]. However, the benefits of breastfeeding are well known and generally outweigh potential risks from transfer of chemicals [17], but you can talk with your doctor if you have concerns.
PFAS, especially PFOS and PFOA, have been detected in air, water, and soil in and around manufacturing facilities; however, these releases have been declining since companies began phasing out the production and use of several PFAS in the early 2000s[18].Due to their chemical structure, PFAS are very stable in the environment and are resistant to breaking down.
Some PFAS are volatile and can be carried long distances through the air, which may lead to contamination of soils and groundwater far from the source of the PFAS emission [19]. PFAS have been detected in many parts of the world, including oceans and the Arctic, indicating that long-range transport is possible[20].
The four major sources of PFAS are: fire training/fire response sites, industrial sites, landfills, and wastewater treatment plants/biosolids[10]. PFAS can get into drinking water when products containing them are used or spilled onto the ground or into lakes and rivers[21]. Once in groundwater, PFAS are easily transported large distances and can contaminate drinking wells [10]. PFAS in the air can also end up in rivers and lakes used for drinking water[10]. Additional information regarding the fate and transport of PFAS in the environment may be found on the Interstate Technology Regulatory Council.
Potential Mechanisms of transport of PFAS from firefighting foam application to environmental media.
PFAS have been used extensively in surface coating and protectant formulations due to their unique ability to repel oil, grease and water. Major applications have included protectants for paper and cardboard packaging products, carpets, leather products, and textiles that enhance water, grease, and soil repellency, and in firefighting foams[22]. PFAS have also been used as processing aids in the manufacture of nonstick coatings on cookware[22].
Under the PFOA Stewardship Program with the U.S. Environmental Protection Agency (US EPA), eight major PFAS producers have phased out PFOA and other PFAS substances from emissions and products[2]. However, manufacturers are developing replacement technologies in the PFAS family by substituting longer-chain substances with shorter-chain substances such as GenX and ADONA [23]. While less information is available for these shorter-chain substances, studies have shown that they behave in a similar toxicological manner as their longer-chain counterparts [24], [25]. Due to the wide range of chemicals within the PFAS family and the observed similarities in their toxic mode-of-action, efforts are underway to calculate relative potency estimates for chemicals within the PFAS class in order to better inform regulation [26].
To complement the PFOA Stewardship Program, US EPA has issued regulations, known as Significant New Use Rules (SNURs), requiring manufacturers and processors of these chemicals to notify US EPA of new uses of these chemicals before they are commercialized[27]. Specifically, the regulations require that anyone who intends to manufacture (including import) or process any chemicals for uses contained in the SNUR must submit a notification to US EPA at least 90 days before beginning the activity[27]. This provides US EPA with an opportunity to review and, if necessary, place limits on manufacturers or processors who intend to reintroduce or import products with these chemicals.
Learn more about EPA’s actions on PFASs and other perfluorinated chemicals.
[1] T. H. Begley, K. White, P. Honigfort, M. L. Twaroski, R. Neches, and R. A. Walker, “Perfluorochemicals: Potential sources of and migration from food packaging,” Food Addit. Contam., vol. 22, no. 10, pp. 1023–1031, Oct. 2005.
[2] US EPA, “PFOA Stewardship Program Docket ID Number EPA-HQ-OPPT-2006- 0621. US Environmental Protection Agency, Washington, DC.,” 2006.
[3] 3M Company, “Fluorochemical use, distribution and release overview.,” AR226-0550, 1999.
[4] H. Lee, J. D’eon, and S. A. Mabury, “Biodegradation of Polyfluoroalkyl Phosphates as a Source of Perfluorinated Acids to the Environment,” Environ. Sci. Technol., vol. 44, no. 9, pp. 3305–3310, May 2010.
[5] Z. Wang, J. C. DeWitt, C. P. Higgins, and I. T. Cousins, “A Never-Ending Story of Per- and Polyfluoroalkyl Substances (PFASs)?,” Environ. Sci. Technol., vol. 51, no. 5, pp. 2508–2518, Mar. 2017.
[6] ATSDR, “Toxicological Profile for Perfluoroalkyls, Draft for Public Comment,” 2018.
[7] A. M. Calafat, L.-Y. Wong, Z. Kuklenyik, J. A. Reidy, and L. L. Needham, “Polyfluoroalkyl Chemicals in the U.S. Population: Data from the National Health and Nutrition Examination Survey (NHANES) 2003–2004 and Comparisons with NHANES 1999–2000,” Environ. Health Perspect., vol. 115, no. 11, pp. 1596–1602, Nov. 2007.
[8] J. M. Graber et al., “Per and polyfluoroalkyl substances (PFAS) blood levels after contamination of a community water supply and comparison with 2013–2014 NHANES,” J. Expo. Sci. Environ. Epidemiol., vol. 29, no. 2, pp. 172–182, Mar. 2019.
[9] CDC, “National Report on Human Exposure to Environmental Chemicals,” 2019.
[10] E. M. Sunderland, X. C. Hu, C. Dassuncao, A. K. Tokranov, C. C. Wagner, and J. G. Allen, “A review of the pathways of human exposure to poly- and perfluoroalkyl substances (PFASs) and present understanding of health effects,” J. Expo. Sci. Environ. Epidemiol., vol. 29, no. 2, pp. 131–147, Mar. 2019.
[11] L. S. Haug, S. Huber, G. Becher, and C. Thomsen, “Characterisation of human exposure pathways to perfluorinated compounds — Comparing exposure estimates with biomarkers of exposure,” Environ. Int., vol. 37, no. 4, pp. 687–693, May 2011.
[12] L. A. Schaider et al., “Fluorinated compounds in US fast food packaging,” Environ. Sci. Technol. Lett., vol. 4, no. 3, pp. 105–111, 2017.
[13] H. Zhang, R. Vestergren, T. Wang, J. Yu, G. Jiang, and D. Herzke, “Geographical Differences in Dietary Exposure to Perfluoroalkyl Acids between Manufacturing and Application Regions in China,” Environ. Sci. Technol., vol. 51, no. 10, pp. 5747–5755, 2017.
[14] X. C. Hu et al., “Detection of poly-and perfluoroalkyl substances (PFASs) in US drinking water linked to industrial sites, military fire training areas, and wastewater treatment plants,” Environ. Sci. Technol. Lett., vol. 3, no. 10, pp. 344–350, 2016.
[15] F. A. Ubel, S. D. Sorenson, and D. E. Roach, “Health status of plant workers exposed to fluorochemicals - a preliminary report,” Am. Ind. Hyg. Assoc. J., vol. 41, no. 8, pp. 584–589, Aug. 1980.
[16] P. Grandjean et al., “Estimated exposures to perfluorinated compounds in infancy predict attenuated vaccine antibody concentrations at age 5-years,” J. Immunotoxicol., vol. 14, no. 1, pp. 188–195, Jan. 2017.
[17] M. N. Mead, “Contaminants in Human Milk: Weighing the Risks against the Benefits of Breastfeeding,” Environ. Health Perspect., vol. 116, no. 10, Oct. 2008.
[18] J. M. Armitage, M. MacLeod, and I. T. Cousins, “Modeling the Global Fate and Transport of Perfluorooctanoic Acid (PFOA) and Perfluorooctanoate (PFO) Emitted from Direct Sources Using a Multispecies Mass Balance Model,” Environ. Sci. Technol., vol. 43, no. 4, pp. 1134–1140, Feb. 2009.
[19] M. F. Rahman, S. Peldszus, and W. B. Anderson, “Behaviour and fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in drinking water treatment: A review,” Water Res., vol. 50, pp. 318–340, Mar. 2014.
[20] F. Wong et al., “Assessing temporal trends and source regions of per- and polyfluoroalkyl substances (PFASs) in air under the Arctic Monitoring and Assessment Programme (AMAP),” Atmos. Environ., vol. 172, pp. 65–73, Jan. 2018.
[21] E. Hepburn, C. Madden, D. Szabo, T. L. Coggan, B. Clarke, and M. Currell, “Contamination of groundwater with per- and polyfluoroalkyl substances (PFAS) from legacy landfills in an urban re-development precinct,” Environ. Pollut., vol. 248, pp. 101–113, May 2019.
[22] E. Kissa, Fluorinated surfactants and repellents, vol. 97. CRC Press, 2001.
[23] R. Renner, “The long and the short of perfluorinated replacements,” Environ. Sci. Technol., vol. 40, no. 1, pp. 12–13, Jan. 2006.
[24] S. C. Gordon, “Toxicological evaluation of ammonium 4,8-dioxa-3H-perfluorononanoate, a new emulsifier to replace ammonium perfluorooctanoate in fluoropolymer manufacturing,” Regul. Toxicol. Pharmacol., vol. 59, no. 1, pp. 64–80, 2011.
[25] Z. Wang, I. T. Cousins, M. Scheringer, and K. Hungerbuehler, “Hazard assessment of fluorinated alternatives to long-chain perfluoroalkyl acids (PFAAs) and their precursors: Status quo, ongoing challenges and possible solutions,” Environ. Int., vol. 75, pp. 172–179, Feb. 2015.
[26] J. Lijzen, “Mixture exposure to PFAS: A Relative Potency Factor approach,” National Institute for Public Health and the Environment, RIVM Report 2018-0070.
[27] USEPA, “Perfluoroalkyl Sulfonates; Significant New Use Rule,” Fed. Regist., vol. 67, no. 236, pp. 72854–72867, 2002.
Additional efforts in California by other CalEPA agencies are included below:
Laboratory studies in animals who were exposed to per- and polyfluoroalkyl substances (PFAS) found links between the chemicals and increased cholesterol, changes in the body’s hormones, alterations of the immunologic system, decreased fertility, increased risk of cancer (especially kidney and testicular), low birth weight, delayed puberty onset, and birth defects[1].
Since humans and animals react differently to PFAS, not all effects observed in animals may occur in humans. Although many epidemiology studies have examined the potential of PFAS to result in adverse health effects, most of the studies are cross-sectional in design and do not establish causality. Based on several factors outlined in the report of PFAS by the Center for Disease Control (CDC) including the consistency of findings across studies, the available epidemiology studies suggest associations between PFAS exposure and several health outcomes in humans [1]:
- Pregnancy-induced hypertension/pre-eclampsia (PFOA, PFOS)
- Liver damage, as evidenced by increases in serum enzymes and decreases in serum bilirubin levels (PFOA, PFOS, PFHxS)
- Increases in serum lipids, particularly total cholesterol and low-density lipoprotein (LDL) cholesterol (PFOA, PFOS, PFNA, PFDeA)
- Increased risk of thyroid disease (PFOA, PFOS)
- Decreased antibody response to vaccines (PFOA, PFOS, PFHxS, PFDeA)
- Increased risk of asthma diagnosis (PFOA)
- Increased risk of decreased fertility (PFOA, PFOS)
- Small decreases in birth weight (PFOA, PFOS)
The International Agency for Research on Cancer has classified PFOA as possibly carcinogenic (causing cancer) to humans [2], but it has not evaluated whether other PFAS may also cause cancer. The Department of Health and Human Services has not yet evaluated whether PFOA and other PFAS can cause cancer.
In August 2019, the Office of Health Hazard and Assessment (OEHHA) developed PFOA reference levels in drinking water associated with pancreatic and liver tumors. The level of 0.1 ng/L (nanogram/liter) or parts per trillion (ppt) represents the concentration of PFOA in drinking water that would not pose more than a one in one million cancer risk. OEHHA developed PFOS reference levels in drinking water associated with liver tumors. The level of 0.4 ng/L (nanogram/liter) or parts per trillion (ppt) represents the concentration of PFOS in drinking water that would not pose more than a one in one million cancer risk.
CDC scientists measured PFAS in the blood serum (the clear portion of blood) of 98% of participants aged 12 years and older who took part in the National Health and Nutrition Examination Survey (NHANES) since 1999, indicating widespread exposure to PFAS in the U.S. population [3]. Median PFOA serum levels of 45,276 non-occupationally exposed individuals residing in southeastern Ohio and West Virginia who were exposed to PFOA via contaminated drinking water were approximately 6 times greater than the median concentration of the general population [3], [4].
Due in large part to the phasing out of certain PFAS compounds by the USEPA’s PFOA Stewardship Program [5], serum levels of PFOA and PFOS in the general population of the United States have decreased dramatically in recent years [3]. For example, the geometric mean concentrations of PFOA and PFOS in the general population were 5.2 and 30.4 micrograms per liter (or parts per billion, ppb), respectively, in 1999–2000, but have decreased to 1.56 ppb (PFOA) and 4.72 ppb (PFOS) in 2015–2016 [3]. Learn more about the US EPA’s actions on PFAS. Learn more about the California State Water Board’s actions on PFAS.
Learn more about the US EPA's actions on: PFAS at https://www.epa.gov/pfas. Learn more about the California State Water Board's actions on PFAS at: https://www.waterboards.ca.gov/pfas/.
[1] ATSDR, “Toxicological Profile for Perfluoroalkyls, Draft for Public Comment,” 2018.
[2] IARC (International Agency for Research on Cancer, “Perfluorooctanoic acid. Volume 110.,” Lyon, France: World Health Organization.
[3] CDC, “National Report on Human Exposure to Environmental Chemicals,” 2019.
[4] H.-M. Shin et al., “Environmental Fate and Transport Modeling for Perfluorooctanoic Acid Emitted from the Washington Works Facility in West Virginia,” Environ. Sci. Technol., vol. 45, no. 4, pp. 1435–1442, Feb. 2011.
[5] US EPA, “PFOA Stewardship Program Docket ID Number EPA-HQ-OPPT-2006- 0621. US Environmental Protection Agency, Washington, DC.,” 2006.
1 Out of 12 PFAS measured, four PFAS (PFOS or perfluorooctanesulfonate, PFOA or perfluorooctanoic acid, PFHxS or perfluorohexane sulfonic acid, and PFNA or perfluorononanoic acid) had detection frequencies in serum of greater than 98% of people tested.
In May 2016, the United States Environmental Protection Agency (U.S. EPA) issued a lifetime health advisory (LHA) for PFOA and PFOS in drinking water, advising municipalities that they should notify their customers of the presence of levels over 70 nanograms per liter (or parts per trillion) in community water supplies. The LHA is the level, or amount, calculated to offer a margin of protection against adverse health effects to the most sensitive populations. The LHA level is 70 (ppt) for PFOA and PFOS individually or combined. Currently, the US EPA has not set health advisory levels for the other PFAS chemicals.
Learn more about US EPA’s actions on PFAS and other perfluorinated chemicals.
In June 2018, the California Office of Environmental Health Hazard Assessment (OEHHA) recommended interim notification levels for PFOA (based on liver toxicity, as well as cancer risks) and for PFOS (based on immunotoxicity). OEHHA made these recommendations following its review of currently available health-based advisories and standards and supporting documentation. After independent review of the available information on the risks, the California State Water Resources Control Board's Division of Drinking Water (DDW) established interim notification levels.
In August 2019, OEHHA provided updated information on health-impacts. Based on this updated information, DDW established notification levels at concentrations of 6.5 ppt for PFOS and 5.1 ppt for PFOA, consistent with OEHHA’s recommendations.
In August 2019, California’s Division of Drinking Water established notification levels for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) (6.5 parts per trillion for PFOS and 5.1 parts per trillion for PFOA), as well as a single health advisory response level which offers a margin of protection for all persons throughout their life from adverse health effects resulting from exposure to PFOA and PFOS in drinking water. Notification levels are a non-regulatory, precautionary health-based measure for concentrations in drinking water that warrant notification and further monitoring and assessment. Public water systems are encouraged to test their water for contaminants with notification levels, and in some circumstance may be ordered to test. If the systems do test, they are required to report exceedances to their governing boards and the State Water Board and are urged to report this information to customers.
In November 2017, OEHHA added PFOA and PFOS under Proposition 65, which requires manufacturers to disclose the presence of these chemicals as a potential carcinogenic compound in materials in which they are present. Documentation supporting OEHHA’s determination that the criteria for administrative listing have been satisfied for PFOA and PFOS is available on OEHHA’s website (https://oehha.ca.gov/).
The Department of Toxic Substances Control (DTSC) included food packaging as a product category in the Safer Consumer Products 2018-20 Work Plan due to concerns regarding exposure to PFAS and other chemicals included in food packaging, including the migration of PFAS from food packaging into packaged foods, becoming indirect food additives.
On February 15, 2018, DTSC released its Product-Chemical Profile on Carpets and Rugs with PFASs, documenting potential exposures and harm from these products. The Priority Product listing regulation triggers requirements that manufacturers look for safer alternatives. The process to make the requirements into regulations is likely to begin in the spring of 2019. The latest information about PFAS in the Safer Consumer Products program can be found on DTSC’s website at: https://dtsc.ca.gov/scp/carpets-and-rugs-with-perfluoroalkyl-and-polyfluoroalkyl-substances-pfass/
In June 2018, California Air Resources Board (CARB) began a rulemaking effort to amend the Hexavalent Chromium Airborne Toxic Control Measure for Chrome Plating and Chromic Acid Anodizing Operations (Chrome Plating ATCM).Throughout this process, CARB staff is collecting information and soliciting input on ways to further reduce emissions of hexavalent chromium from chrome plating and chromic acid anodizing operations, and to address concerns about potential health and environmental impacts of PFAS-containing chemical fume suppressants. More information about CARB is available at: https://ww2.arb.ca.gov/
Biomonitoring California’s Scientific Guidance Panel designated PFAS as a program priority. Its California Regional Exposure (CARE) study includes 12 PFAS chemicals and is analyzing sources of exposures in the Asian Pacific Islander Community Exposure projects. More information about Biomonitoring in California is provided at: https://biomonitoring.ca.gov/
In May 2016, the United States Environmental Protection Agency (US EPA) issued a lifetime health advisory for PFOS and PFOA for drinking water, advising municipalities that they should notify their customers of the presence of levels over 70 parts per trillion in community water supplies. US EPA recommended that customer notifications include information on the increased risk to health, especially for susceptible populations.
On July 13, 2018, DDW established an interim notification level of 14 parts per trillion (ppt) for PFOA and 13 ppt for PFOs and a single response level of 70 ppt for the combined concentrations of PFOA and PFOS.
In August 2019, DDW evaluated updated health-impact information provided by OEHHA. Based on this, DDW revised the notification levels to 6.5 parts per trillion for PFOS and 5.1 parts per trillion for PFOA. The single health advisory response level (for the combined values of PFOS and PFOA) remains at 70 ppt.
From 2013 to 2015, the US EPA, under the Unregulated Contaminant Monitoring Rule (UCMR 3), required all large water systems (i.e., water systems serving over 10,000 people) nationwide to collect and analyze more than 12,000 drinking water samples for PFOS and PFOA. In addition, some water systems serving less than 10,000 people reported approximately 400 drinking water results for PFOS and PFOA. This occurrence data identified 36 sources with PFOS detections and 32 sources with PFOA detections. A summary of the findings for California is available at: https://www.epa.gov/dwucmr/occurrence-data-unregulated-contaminant-monitoring-rule
In March 2019, the Division of Drinking Water issued Health and Safety Code 116400 Orders to 600 water system sites, and nearly 250 locations such as airports with fire training and response areas, and municipal solid waste landfills are being reported to the State Water Boards and will continue to be collected until into early 2020. More water system data will be requested in the area of other types of sources in 2019, including industrial sites. The assessment of this data will be used to determine data information gaps. Additional and more assessment will be required in the coming years.
Some analytical methods using liquid chromatography-mass spectrometry-electrospray ionization methods (LC/MS/ESI) can achieve reporting limits for PFOA and PFOS at the nanogram per liter (ng/L) level. For the UCMR 3 monitoring program, LC/MS/MS-EPA Method 537 (rev 1.1) was required with minimum reporting limits of 20 ng/L and 40 ng/L for PFOA and PFOS, respectively. In November 2018, revised US EPA Method 537.1 was published that can detect PFOA, PFOS, and 16 other per-and polyfluorinated alkyl substances. Compliance with the recently changed NLs to 5.1 ng/L (PFOA) and 6.5 ng/L (PFOS) will require reporting limits lower than what can be achieved with US EPA Method 537. US EPA Method 537.1 is reported to be able to achieve lowest concentration minimum reporting levels (LCMRL) of 0.82 ng/L (PFOA) and 2.7 ng/L (PFOS). An LCMRL is defined as the lowest true concentration for which the future recovery is predicted to fall, with 99% confidence, between 50 and 150% recovery of the matrix spike (US EPA, Method 537.1, 2018).
Further information regarding PFAS in drinking water may be found at the Division of Drinking Water PFOA/PFOS webpage. (https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/PFOA_PFOS.html).
- Example PFOA/PFOS Notification Letter: (PDF)
- PFAS Water Systems Orders - April 30, 2019
- Laboratories Accredited to Analyze for PFAs in Drinking Water by EPA Method 537 Revision 1.1 or EPA Method 537.1
- Drinking Water Sample Collection for PER and POLYFLUORINATED ALKYL SUBSTANCES (PFAS) Sampling Guidance
- April 5, 2019: Table 1 for the Landfill and Airport 13267 Investigative Orders
- March 20, 2019: FAQ for PFAS 13267 Investigatory Orders
- March 20, 2019: Landfill 13267 Investigative Order
- March 20, 2019: Airport 13267 Investigative Order
- March 20, 2019: PFAS General Sampling Guide
- GeoTracker PFAS Reference Table
- Analytical Reporting Limits for Leachate, Groundwater, and Soil for PFAS compliance with DoD Table B-15 of QSM, Version 5.1 or later
Frequently Asked Questions (FAQs)
PFAS Treatment and Remediation
What treatment techniques are used to reduce per- and polyfluoroalkyl (PFAS) levels in drinking water?
Most conventional water treatment techniques (i.e. coagulation/sedimentation/filtration, chlorination, ozonation, UV/H2O2) are ineffective for reducing PFAS levels in drinking water Several treatments have shown to be effective in the removal of PFAS from drinking water. Promising techniques include granular activated carbon (GAC), powdered activated carbon (PAC), high pressure membranes (reverse osmosis/nanofiltration) and ion exchange resin.
Activated carbon treatment is the most studied treatment for PFAS removal. Activated carbon is commonly used to adsorb natural organic compounds, taste and odor compounds, and synthetic organic chemicals in drinking water treatment systems. Adsorption is both the physical and chemical process of accumulating a substance, such as PFAS, at the interface between liquid and solids phases. Activated carbon is an effective adsorbent because it is a highly porous material and provides a large surface area to which contaminants may adsorb. Activated carbon (GAC) is made from organic materials with high carbon contents such as wood, lignite, and coal; and is often used in granular form called granular activated carbon (GAC).
GAC has been shown to effectively remove PFAS from drinking water when it is used in a flow through filter mode after particulates have already been removed. GAC works well on longer-chain PFAS like PFOA and PFOS, but shorter chain PFAS like Perfluorobutanesulfonic acid (PFBS) and Perfluorobutyrate (PFBA) do not adsorb as well.
Another type of activated carbon treatment is powdered activated carbon (PAC) which is the same material as GAC, but it is smaller in size- powder like. Because of the small particle size, PAC cannot be used in a flow through bed, but can be added directly to the water and then removed with the other natural particulates in the clarification stage (conventional water treatment or low-pressure membranes - microfiltration or ultrafiltration). Used in this way, PAC is not as efficient or economical as GAC at removing PFAS.
Another treatment option is anion exchange treatment, or resins. Ion exchange resins are made up of highly porous, polymeric material that is acid, base, and water insoluble. The tiny beads that make up the resin are made from hydrocarbons. There are two broad categories of ion exchange resins: cationic and anionic. The negatively charged cationic exchange resins (CER) are effective for removing positively-charged contaminants and positively charged anion exchange resins (AER) are effective for removing negatively charged contaminants, like PFAS. Ion exchange resins are like tiny powerful magnets that attract and hold the contaminated materials from passing through the water system. Negatively charged ions of PFAS are attracted to the positively charged anion resins. AER has shown to have a high capacity for many PFAS; however, it is typically more expensive than GAC. Of the different types of AER resins, perhaps the most promising is an AER in a single use mode followed by incineration of the resin. One benefit of this treatment technology is that there is no need for resin regeneration so there is no contaminant waste stream to handle, treat, or dispose.
Like GAC, AER removes 100 percent of the PFAS for a time that is dictated by the choice of resin, bed depth, flow rate, which PFAS need to be removed, and the degree and type of background organic matter and other contaminants.
High-pressure membranes, such as nanofiltration or reverse osmosis (RO), are extremely effective at removing PFAS. RO membranes are tighter than nanofiltration membranes Research shows that these types of membranes are typically more than 90 percent effective at removing a wide range of PFAS, including shorter chain PFAS. With both high-pressure membrane types, approximately 80 percent of the feedwater, the water coming into the membrane, passes through the membrane to the effluent (treated water). Approximately 20 percent of the feedwater is retained as a high-strength concentrated waste. A high-strength waste stream at 20 percent of the feed flow can be difficult to treat or dispose, especially for a contaminant such as PFAS. High pressure membranes may be best suited as a point of use technology for a homeowner, since the volume of water being treated is much smaller and the waste stream could be disposed of more easily with less cause for concern.
| Granular Activated Carbon (GAC) |
Powdered Activated Carbon (PAC) | Anion Exchange Resin (PFAS Selective) | High Pressure Membranes (Reverse Osmosis or Nanofiltration) | Short-Chain PFAS (i.e. PFBA) Removal |
Moderately Effective |
Not Effective |
Moderately Effective |
Effective |
|---|---|---|---|---|
Long-Chain PFAS (i.e. PFOA, PFOS) Removal |
Very Effective |
Moderately Effective |
Very Effective |
Effective |
Co-contaminant Removal |
Very Effective |
Not Effective |
Moderately Effective |
Very Effective |
Relative Cost ($-$$$$) |
$-$$ |
$$ |
$$$ |
$$$$ |
Disposal Requirements |
Difficult |
Difficult |
Difficult |
Difficult |
Challenges |
desorption can diminish effectiveness when influent concentrations are variable; fate of PFASs during thermal regeneration not understood |
Performance dependent on activated carbon properties and background water matrix |
Performance dependent on resin properties; background water matrix effects unexplored |
High energy requirement; membrane fouling; concentrate needs to be managed |
PFCAs | PFSAs | FOSAA | FOSA | FTS | FTCA | FASE | FASA | PFECA
Perfluoroalkylcarboxylic acids (PFCAs)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| Perfluorohexanoic acid | PFHxA | 307-24-4 |
| Perfluorododecanoic acid | PFDoDA | 307-55-1 |
| Perfluorooctanoic acid | PFOA | 335-67-1 |
| Perfluorodecanoic acid | PFDA | 335-76-2 |
| Perfluorobutanoic acid | PFBA | 375-22-4 |
| Perfluoroheptanoic acid | PFHpA | 375-85-9 |
| Perfluorononanoic acid | PFNA | 375-95-1 |
| Perfluorotetradecanoic acid | PFTeDA | 376-06-7 |
| Perfluoroundecanoic acid | PFUnDA | 2058-94-8 |
| Perfluoropentanoic acid | PFPeA | 2706-90-3 |
| Perfluorotridecanoic acid | PFTrDA | 72629-94-8 |
| Perfluorohexadecanoic acid | PFHxDA | 67905-19-5 |
| Perfluorooctadecanoic acid | PFODA | 16517-11-6 |
Perfluorinated sulfonic acids (PFSAs)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| Perfluorodecane sulfonic acid | PFDS | 335-77-3 |
| Perfluorohexane sulfonic acid | PFHxS | 355-46-4 |
| Perfluorobutane sulfonic acid | PFBS | 375-73-5 |
| Perfluoroheptane sulfonic acid | PFHpS | 375-92-8 |
| Perfluorooctane sulfonic acid | PFOS | 1763-23-1 |
| Perfluoropentane sulfonic acid | PFPeS | 2706-91-4 |
| Perfluorononane sulfonic acid | PFNS | 474511-07-4 |
| 9-Chlorohexadecafluoro-3-oxanonane-1-sulfonic acid | 9-Cl-PF3ONS | 756426-58-1 |
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid | 11-Cl-PF3OUdS | 763051-92-9 |
Perfluorinated sulfonamidoacetic acids (FOSAA)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| N-Methyl perfluorooctane sulfonamidoacetic acid | NMeFOSAA | 2355-31-9 |
| N-Ethyl perfluorooctane sulfonamidoacetic acid | NEtFOSAA | 2991-50-6 |
Perfluorinated sulfonamides (FOSA)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| Perfluorooctanesulfonamide | PFOSAm | 754-91-6 |
Fluorotelomer sulfonates (FTS)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| 6:2 Fluorotelomer sulfonic acid | 6:2 FTS | 27619-97-2 |
| 8:2 Fluorotelomer sulfonic acid | 8:2 FTS | 39108-34-4 |
| 4:2 Fluorotelomer sulfonic acid | 4:2 FTS | 757124-72-4 |
| 10:2 Fluorotelomer sulfonic acid | 10:2 FTS | 120226-60-0 |
Fluorotelomer carboxylic acids (FTCA)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| 2H,2H,3H,3H-Perfluorohexanoic acid | 3:3 FTCA | 812-70-4 |
| 2H,2H,3H,3H-Perfluorodecanoic acid | 3:3 FTCA | 812-70-4 |
| 2H,2H,3H,3H-Perfluorohexanoic acid | 7:3 FTCA | 812-70-4 |
| 2H,2H,3H,3H-Perfluorooctanoic acid | 5:3 FTCA | 914637-49-3 |
Perfluoroalkane sulfonamido ethanols (FASE)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| N-Ethyl perfluorooctane sulfonamide ethanol | EtFOSE | 1691-99-2 |
| N-Methyl perfluorooctane sulfonamide ethanol | MeFOSE | 24448-09-7 |
Perfluoroalkane sulfonamides (FASA)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| N-Ethyl perfluorooctane sulfonamide | EtFOSA | 4151-50-2 |
| N-Methyl perfluorooctane sulfonamide | MeFOSA | 31506-32-8 |
Perfluoroether carboxylic acids (PFECA)
| Chemical Name | Abbreviation | Chemical Abstracts Service (CAS) No. |
|---|---|---|
| Hexafluoropropylene oxide dimer acid | HFPO-DA | 13252-13-6 |
| 4,8-Dioxa-3H-perfluorononanoic acid | ADONA | 919005-14-4 |
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Other PFAS Resources
- Feb 14, 2019: US EPA announcements PFAS action Plan
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