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Use and Potential Impacts of AFFF Containing PFASs at Airports (2017)

Chapter: Chapter 2 - Primer Background on PFASs

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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
×
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Suggested Citation:"Chapter 2 - Primer Background on PFASs." National Academies of Sciences, Engineering, and Medicine. 2017. Use and Potential Impacts of AFFF Containing PFASs at Airports. Washington, DC: The National Academies Press. doi: 10.17226/24800.
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10 PFASs belong to a family of chemicals that are in a variety of products found at airports. The predominant “source” of these compounds at an airport is AFFF, used in firefighting, but these compounds can also be associated with commercial, industrial, or manufacturing applications of airport tenants. The impact of PFASs on environmental media (i.e., soil, groundwater, sediment, surface water) may be the result of historical activities at airports and the surrounding vicinity because PFASs do not break down easily in the environment. Elevated concentrations of PFASs found in the environment and human populations have led to increased investigation and regulation of these compounds. This chapter provides background information on PFASs, answering the following fundamental questions: • What are PFASs? • Where did/do PFASs come from? • Why and how do PFASs pose a concern? • What are the regulatory requirements regarding PFASs? • How might PFASs affect an airport? 2.1 What Are PFASs? PFASs are a large group of related, human-made, fluorinated organic chemicals (i.e., chemicals that contain fluorine and carbon atoms bonded together) that have unique properties due to their chemical structure and composition. As described in subsequent sections, many PFASs exhibit high degrees of chemical and thermal stability that make them useful in industrial and manu- facturing applications. The chemical and thermal stability of many PFASs is what enables AFFF to have better firefighting performance; however, these same properties also contribute to why some PFASs have negative impacts to human health and the environment. 2.1.1 Chemical Composition PFASs are organic chemicals that contain fluorine atoms bonded to a chain of carbon atoms. The carbon-fluorine bond is one of the strongest organic bonds in nature, and this strong bond contributes to the stability and persistence of some PFASs. Of particular interest and concern are perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). 2.1.2 Chemical Structure PFASs are generally composed of a perfluorinated carbon “tail” (i.e., carbon and fluorine) and a functional group “head.” The compounds tend to be dual-natured, as the “head” and the C h a p t e r 2 Primer—Background on PFASs

primer—Background on pFaSs 11 “tail” prefer different interactions (see Figure 2-1). The perfluorinated carbon tail tends to be both hydrophobic (water insoluble) and oleophobic (oil insoluble); the functional group head is more hydrophilic (water soluble). The solution chemistry (pH and ionic strength) affects the ability of PFASs to interact or bind with a surface by changing the electrostatic interactions between the head and the surface. Larger compounds can degrade or transform to smaller compounds that are more stable in the environment. Both PFOS and PFOA, for example, can be found in the environment as stable compounds resulting from the degradation of “parent” compounds, as well as being manufactured for a particular industrial application. PFASs found in AFFF can be cationic, zwitterionic, and anionic, resulting in very different fate and transport behaviors in the environment (1). In the past, PFASs were often inappropriately referred to as “PFCs” (perfluorinated compounds), but this term can also be understood as perfluorocarbons, which do not contain functional groups (i.e., the “head” shown in Figure 2-1) and consist solely of the carbon-fluorine “tail,” and therefore have properties and behaviors that are different from other types of PFASs. For the purpose of this report, PFASs can be referred to as “long-chain” and “short-chain.” Long-chain refers to • Perfluoroalkyl carboxylic acids (PFCAs) with eight or more perfluorinated carbons. • Perfluoroalkyl sulfonic acids (PFSAs) with six or more perfluorinated carbons. The definition of long-chain is different for PFCAs and PFSAs because a PFSA with a given number of carbons has a greater tendency to bioconcentrate and/or bioaccumulate than a PFCA with the same number of carbon atoms. Short-chain PFASs are PFCA compounds that have fewer than eight carbons and PFSAs that have fewer than six carbon molecules. Please note that in much of this report, short-chain PFASs are referred to as C6 or less because more recent AFFF formulations do not contain PFSAs. These more recent formulations include • Perfluorobutanoic acid (PFBA), with four carbons. • Perfluorohexanoic acid (PFHxA) with six carbons. Table 2-1 provides the standard adopted nomenclature and hierarchy for PFASs. Given the confusion and varying acronyms (e.g., PFCs), this table has been provided to improve dialogue and understanding of terms among researchers, regulators, consultants, and stakeholders. Acronyms for subgroups of PFASs that are referred to in this document, and are more commonly known, are provided. It should be noted that the conjugate base forms (e.g., carboxylates and sulfonates) of the compounds are the forms typically found in the environment, even though in Table 2.1, these forms are referred to as acids. Figure 2-1. Structure of a perfluoroalkyl compound: the PFOS anion.

12 Use and potential Impacts of aFFF Containing pFaSs at airports 2.2 Where Did/Do PFASs Come From? PFASs were developed in the 1960s and adopted in AFFF formulations in the 1970s. In the airport industry, PFASs are known to have been used in AFFF for firefighting and associated training, industrial components related to aviation and aerospace, metal plating operations, biocides, and construction products. In addition, PFASs have been used in textiles, leather goods, and cooking utensils. Brief descriptions of product formulation and use are provided in the subsections below, with an emphasis on aviation-related sources. Perfluoroalkyl acids (PFAAs) Perfluoroalkyl carboxylic acids (PFCAs) Perfluorobutanoic acid—PFBA Perfluoropentanoic acid—PFPeA Perfluorohexanoic acid—PFHxA Perfluoroheptanoic acid—PFHpA Perfluorooctanoic acid—PFOA Perfluorononanoic acid—PFNA Perfluorodecanoic acid—PFDA Perfluoroundecanoic acid—PFUnA Perfluorododecanoic acid—PFDoA Perfluorotridecanoic acid—PFTrDA Perfluorohexadecanoic acid—PFHxDA Perfluorooctadecanoic acid—PFOcDA Perfluoroalkyl sulfonic acids (PFSAs) Perfluorobutane sulfonic acid—PFBS Perfluoropentane sulfonic acid—PFPeS Perfluorohexane sulfonic acid—PFHxS Perfluoroheptane sulfonic acid—PFHpS Perfluorooctane sulfonic acid—PFOS Perfluorononane sulfonic acid—PFNS Perfluoroalkyl sulfamido substances (FASAs) Precursor to PFSAs Perfluoroalkyl sulfamido substances (FASAs) Precursor to PFSAs N-Ethyl-perfluorooctane sulfonamido ethanol—N-EtFOSE N-Methyl-perfluorooctane sulfonamido ethanol—N-MeFOSE N-Ethyl-perfluorooctane sulfonamido acetic acid—N-Et-PFOSA-AcOH N-Methyl-perfluorooctane sulfonamido acetic acid—N-Me-PFOSA-AcOH Perfluorooctane sulfonamide—PFOSA Fluorotelomer alcohols (FTOHs) Precursor to PFCAs Fluorotelomer alcohols (FTOHs) Precursor to PFCAs 6:2 Fluorotelomer alcohol—6:2 FTOH 8:2 Fluorotelomer alcohol—8:2 FTOH Fluorotelomer sulfonic acids (FTSs) Precursor to PFCAs and PFSAs Fluorotelomer sulfonic acids (FTSs) Precursor to PFCAs and PFSAs 6:2 Fluorotelomer sulfonic acid—6:2 FTS 8:2 Fluorotelomer sulfonic acid—8:2 FTS Type Sub-Type Individual Chemical Name and Acronym Table 2-1. Example PFASs.

primer—Background on pFaSs 13 2.2.1 Firefighting In accordance with federal regulations (as detailed in Section 4.2), AFFF is used in airport operations as a fire-extinguishing agent to prevent, extinguish, or control Class B fires (i.e., fires of flammable and combustible liquids such as crude oil, gasoline, and fuel oils). The presence of PFASs in AFFF generates foam that retains water and separates fuel from flame, ultimately resulting in dramatic, fast knockdown of Class B fires. Historical AFFF formulations were made with fluorocarbon surfactants containing PFOS as the predominant active ingredient. Increasing concern regarding the effects of PFOS-based AFFF on human health and the environment led users to alternatives that contained long-chain, telomer-based fluorochemicals containing eight carbons or more. Subsequently, in some cases, it was found that the breakdown of these long-chain fluorochemicals in the environment could produce PFOA and other PFASs of concern. Since 2006, both the United States and Canada have taken steps to phase out the production and use of C8-based fluorotelomers. Consequently, AFFF manufacturers have shifted toward using shorter chain (i.e., ≤ C6, having six or fewer carbon molecules) C6 and C4 perfluoroalkylated chemicals. C6-based fluorotelomers are most commonly and widely used. Limited data are available on how these compounds behave in the environment and the potential risks they pose to both the environment and human health. PFASs at an airport may be related to the following firefighting equipment and materials: • Past and ongoing firefighting, training, and maintenance activities. These can lead to ground- water and soil contamination by PFASs due to uncontained release of firefighting foam. • Firefighting equipment, including protective clothing for firefighters. These can be surface treated with side-chain fluorinated polymers or made from fluoropolymers such as woven, porous polytetrafluoroethylene (PTFE) and its copolymers. • Testing firefighting systems (e.g., deluge system, roof turrets). This activity is often an over- looked source of PFASs. 2.2.2 Industrial Components in Aviation and Aerospace Fluoropolymers such as PTFE (e.g., Teflon™) are used extensively in various equipment components (e.g., semiconductors, wiring, tubing, piping, seals, gaskets, and cables). In addition, the salts of sulfonated PFASs (primarily PFOS) have been used as additives with a content of about or less than 0.1 percent in hydraulic fluids/lubricants to prevent evaporation, fires, and corrosion (2). 2.2.3 Metal Plating Operations Although metal plating operations may not be directly associated with the aviation industry, they are one of the most important ongoing users of products containing PFASs and are typically situated within industrial zones located near larger airport facilities. Fluorinated surfactants (i.e., PFOS and derivatives) are used in metal plating, and are considered to be essential for use as mist suppressants in the metal plating industry (3, 4). The use of PFOS in the European Union (EU) for chromium plating was estimated as 10,000 kg/year (5). There is potential for residual concentrations of other PFASs in the surfactants used for metal plating. 2.2.4 Biocides Non-polymeric PFASs have been used as active ingredients in some plant growth regula- tors and herbicides (6) and as inert ingredients in pesticide formulations in the United States (e.g., ant baits) (7).

14 Use and potential Impacts of aFFF Containing pFaSs at airports 2.2.5 Construction Products Fluoropolymers, such as PTFE and polyvinyl fluoride (PVDF), are commonly used in paints, acting as dispersion agents and leveling agents, as well as improving gloss and antistatic properties. Fluoropolymers and fluorotelomers have also been used as fire- or weather-resistant coating in various construction-related applications (8). 2.3 Why and How Do PFASs Pose a Concern? Some PFASs present potential risks to human health and the environment. Many PFASs are very persistent (i.e., do not break down readily).They bioaccumulate (i.e., accumulate in living tissue) and/or biomagnify (i.e., increase in concentration as they move up the food chain) in the environment. The following paragraphs provide an overview of PFASs, detailing environmental and toxicological concerns associated with PFASs, their fate and transport properties, and envi- ronmental factors that affect transport. 2.3.1 Environmental and Toxicological Concerns PFASs have been widely used throughout the world, and some types of PFASs (including PFOS and PFOA) are persistent in the environment. In the late 1990s, the U.S. EPA received information from 3M that PFOS was widespread in the blood of the general population, which raised concerns regarding persistence, bioaccumulation, and toxicity (9, 10). The results provided by 3M on PFOS impacts to human health and ecology suggested that the prevalence of these compounds, combined with their increasing ubiquity in the global environment, presented potential human health and ecological risks. In July 2006, a preliminary ecological screening assessment report by Environment Canada concluded that PFOS, its salts, and its precursors are entering the environment at concentra- tions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity (11). Studies evaluating the relative toxicity of the complex mixture of PFASs typically in the AFFF used at airports (a mixture consisting not just of PFOA and PFOS, but including other PFASs as well) are ongoing. Since multiple PFASs are typically found together in both human and wildlife environments, their cumulative risks and potential interactions are also being considered in ongoing research. Specific documented environmental and toxicological concerns are the following: • Per- and polyfluorinated compounds have the potential to bioaccumulate and biomagnify in wildlife. • Per- and polyfluorinated compounds are readily absorbed after oral exposure and accumulate primarily in the serum, kidney, and liver. • Toxicological studies on animals indicate potential developmental, reproductive, and systemic effects. PFOS, its salts, and its precursors meet the criteria for persistence under the Stockholm Convention, the Canadian Environmental Protection Act (CEPA) and the U.S. EPA. 2.3.2 Fate and Transport in the Environment The movement of PFASs and their persistence in the environment is a function of their structure (12). Part of the molecule prefers to associate with water and part of the molecule does not; thus these compounds travel along interfaces (e.g., water-air, water-soil, and water- lipid interfaces), smearing themselves along soil particles at the water table interface. In natural

primer—Background on pFaSs 15 waters, the predominant forms of PFCAs and PFSAs will be their anionic forms; the predominance of these forms is due to the low dissociation constants of these compounds. However, at low pH, both PFCAs and PFSAs can exist in water in their fully protonated (acid) forms. Depending on compound properties, manufacturing procedures, and use and disposal patterns, PFASs and their precursors may enter the environment by various pathways, such as direct dis- charge to waste (4, 13–16) and air particulate matter (17–20), as well as wash-off or direct use in the environment (2, 21–24) and inappropriate disposal of wastes containing PFASs (25–31). Emissions into the environment can be from both direct and indirect sources (13, 32–34). Direct sources include emissions during the manufacture, use, and disposal of products that contain PFASs or their derivatives as ingredients, unreacted raw materials (residuals), or unintended by-products (impurities). Indirect sources refer to the formation of PFCAs and PFSAs from degradation of precursors (i.e., parent compounds). PFCAs and PFSAs are among the more stable compound groups categorized as PFASs and include PFOA and PFOS. PFOA has been in manufactured AFFF and is also formed as a recalcitrant degradation by-product in AFFF. The perfluorinated carbon tail of these compounds is known to be very resistant to degradation, a property attributed to the carbon-fluorine bond. PFOS is considered to be persistent—the environmental half-life for PFOS (greater than 41 years) (35) exceeds the half-life criteria for persistence as defined by the Persistence and Bioaccumulation Regulations of the United Nations (UN) Stockholm Convention on Persistent Organic Pollutants (POPs) in 2001 (36), and the Canadian Environmental Protection Act, CEPA 1999 (37, 38). Under typical groundwater conditions (i.e., pH 6-8.5), PFOA and PFOS are water soluble and can migrate readily from soil to groundwater, where they can be transported long distances (39, 40). Different PFASs, many with different chemical structures, are often used and present in a mixture (e.g., AFFF). As a result of these chemical structure differences, release of these mixtures may result in distribution patterns of PFASs in the environment that are both source- and site-specific: • PFASs with longer perfluorinated carbon tails have a greater tendency to bioaccumulate than short-chain PFASs. There are limited studies available that have evaluated the behavior of short-chain PFASs in the environment and/or the potential risks they pose to human health or the environment (71). • Short-chain PFASs are more likely to be found in aqueous phases (i.e., water), whereas long-chain PFASs are more likely to be sorbed to solid matrices. • Larger and more hydrophobic molecules such as PFHxA or perfluorohexane sulfonic acid (PFHxS) can displace shorter PFASs (e.g., PFBA) from sorption sites. • Short-chain PFASs may be displaced by increased flow. Short-chain PFASs have been shown to wash out in flow-through adsorption column experiments (41). Specific fate and transport considerations include the following: • PFASs (particularly PFOS and PFOA) do not readily degrade in the environment to constituents that are not PFASs. • Although limited studies have been conducted, the scientific literature suggests that sulfonated compounds bind more with soil than do carboxylated compounds. • Perfluoroalkyl acids (PFAAs) (a subgroup of PFASs that includes PFOS and PFOA) precursors account for 41 to 100 percent of the total concentration of PFASs in archived AFFF formulations (on a molar basis) (12). • Precursors degrade and/or transform to intermediate compounds and PFAAs in the environment.

16 Use and potential Impacts of aFFF Containing pFaSs at airports 2.3.3 Environmental Factors That Affect Transport Groundwater geochemistry and soil properties can affect the ability of PFASs to attach to surfaces. Sorption of these compounds can be influenced by different soil types that contain reactive mineral surfaces and organic carbon (e.g., peaty soils or organic-rich fragments in sand). An increase of sorption of PFASs, such as PFOS to sediment, has been noted with increasing organic matter, decreasing pH, and increasing calcium ions (Ca2+) (42). However, in soils that have negatively charged surfaces (e.g., most clays), it has been found that pH, ionic strength, and/or calcium concentrations have minimal effect on sorption of PFOS to the mineral surface (43). Precursors are likely to have different physical and chemical properties to their degradatory products. Cationic or zwitterionic precursors may bind to clay minerals through ion exchange. The fate and transport of PFASs in the environment is very complex and influenced by many factors. The following box identifies factors that affect the mobility of PFASs in the environment, generally, in order of increasing mobility. The complexity of these compounds and their mobilization in the environment may be confounded by other, unidentified factors (e.g., co-contaminants, synergistic effects). Research into the fate and transport of PFASs is ongoing. Concentrations observed in bedrock (fractured) Elevated concentrations at surface (potential for human health risks, leaching) Elevated concentrations at greater depths (indicates pathway to groundwater) Ongoing source (e.g., unlined lagoon) Petroleum hydrocarbon (PHC) co-contaminants present Large water table fluctuation (larger “smear” zone) Greater groundwater flow Greater infiltration Large particle size (if high concentrations—leaching) Small particle size (silt—increased sorption—diffusive release)‡ Small particle size (clay—increased sorption)‡ High foc (increased sorption)‡ Particle reactivity (negatively charged, mineral surfaces increased sorption)‡ Increased salinity (increases sorption/decreases PFOS solubility)‡ Increased pH (decreases sorption/increases PFOS solubility)‡ ‡Increased sorption leads to decreased mobility, decreased leaching, “mass storage.” Lighter shading indicates system chemical factors that affect the mobility of PFASs. Darker shading indicates system physical factors that affect the mobility of PFASs. In cr ea se d M o b ili ty o f PF A Ss

primer—Background on pFaSs 17 2.4 What Are the Regulatory Requirements Regarding PFASs? The regulatory environment related to PFASs is rapidly changing. Improved analytical testing technologies and methodologies have resulted in the ability to detect these substances at low concentrations that new research suggests may have human health or environmental significance. The development of regulations and guidelines for the protection of human health and the environment has followed and continues to evolve. Between the years 2000 and 2015, countries including the United States, Canada, the United Kingdom (UK), Australia, Norway, the Netherlands, Germany, and Sweden introduced regulations and guidelines to phase out and limit the use of PFOS, PFOA, and their precursors. In 2004, the UN Stockholm Convention on POPs listed the first 12 POPs and added PFOS, one of the most common compounds of PFASs, and its 96 precursors to Annex A (Elimination). Chemicals in Annex A are destined for elimination with specific, time-limited exemptions. In 2009, PFOS was added to Annex B (Restriction) of the Stockholm Convention. PFOS was banned in countries in the EU on 27 June 2008 (noting, however, that this prohibition is subject to some time-unlimited exceptions relating to certain applications in the photolithographic and photographic industries and chromium plating and hydraulic fluids in the aviation industry). In the EU, firefighting foam containing PFOS and sold on the market prior to 27 December 2006 could have been used until 27 June 2011. The regulatory frameworks for PFASs of the United States, Canada, EU countries, and Australia are summarized in the sections that follow. Please note that the regulatory requirements for each country are subject to change, especially in the rapidly evolving regulatory environment relating to PFASs. Please refer to the regulatory authority having jurisdiction for the most up-to-date requirements. 2.4.1 United States of America The U.S. EPA issued the “Long-Chain Perfluorinated Chemicals (PFCs) Action Plan” in 2009 for perfluoroalkyl sulfonates (long-chain PFASs containing sulfonated functional groups, e.g., PFHxS, PFOS, their salts and precursors) and long-chain perfluoroalkyl carboxylates (long-chain PFASs containing carboxylic acid functional groups, e.g., PFOA, other higher homologues, and their salts and precursors). Since 2009, the U.S. EPA has conducted two screening reviews (in 2013 and 2015). In September 2013, U.S. EPA published a Significant New Use Rule (SNUR) that focused on the use of long- chain perfluoroalkyl carboxylates in carpets. U.S. EPA amended the SNUR (40 CFR 721.9582) on PFASs (1) to add PFASs for which the Toxic Substances Control Act (TSCA) new chemical review process had been completed, but which were not yet being produced or imported and (2) to designate (for all listed PFASs) processing as a significant new use. In January 2015, U.S. EPA proposed a SNUR under TSCA that requires manufacturers (including importers) of long-chain perfluoroalkyl carboxylates to notify the U.S. EPA at least 90 days prior to starting or resuming use of these chemicals in any products. The notification timeframe would allow U.S. EPA to evaluate the new use and, if necessary, take action to prohibit or limit the activity. In 2009, the U.S. EPA’s Office of Water established a provisional health advisory of 0.2 µg/L for PFOS and 0.4 µg/L for PFOA while assessing the potential risk from short-term exposure of these chemicals through drinking water. These values were revised in 2016 to 0.07 µg/L for both compounds, respectively, for chronic exposure (protective over a lifetime) (44). The new 2016 health advisory values supersede the 2009 provisional health advisory values. The health

18 Use and potential Impacts of aFFF Containing pFaSs at airports advisories are based on the U.S. EPA’s assessment of the latest peer-reviewed scientific literature and provide non-enforceable and non-regulatory guidance to state agencies and other public health officials so that they can take appropriate actions. The U.S. EPA’s Office of Water derived reference doses (RfDs) of 2 × 10–5 mg/kg/day in its Health Effects Support Documents for PFOA and PFOS to support the health advisories. Using these RfDs and the standard regional screening level equations (https://www.epa.gov/ risk/regional-screening-levels-rsls), risk-based residential soil-screening levels of 1.3 mg/kg can be calculated for PFOA and PFOS. Risk-based industrial soil-screening levels for a generic composite worker of 16.4 mg/kg can also be calculated. Site-specific soil-screening levels for other exposure scenarios and receptors (e.g., recreator, worker) can also be calculated. Risk-based screening levels for perfluorobutane sulfonic acid (PFBS) can also be calculated based on a pub- lished RfD by EPA on the same website. At the time of this writing, several states have established drinking water and groundwater guidelines, as follows: • Maine developed a maximum exposure guideline for PFOA in drinking water of 0.1 µg/L. • Michigan has established human noncancer values for drinking and non-drinking water uses for both PFOS (0.011 µg/L and 0.012 µg/L, respectively) and PFOA (0.042 µg/L and 12 µg/L, respectively) (45). • Minnesota has also established a chronic health risk limit of 0.3 µg/L for both PFOS and PFOA, and 7 µg/L for both PFBS and PFBA in drinking water (46). Minnesota has established well advisory guidelines of 1.0 µg/L for PFBA, perfluoropentanoic acid (PFPeA), and PFHxA, and 0.6 µg/L for PFBS and PFHxS. • New Jersey has established a preliminary health-based guidance value of 0.04 µg/L for PFOA in drinking water. The guidance level is the first phase of an ongoing process to establish a drinking water standard for this contaminant and will be adjusted as the science regarding PFOA is developed (47). • New Jersey has established a human-health-based interim specific groundwater quality criterion for PFOS and perfluorononanoic acid (PFNA) of 0.040 µg/L and 0.010 µg/L in groundwater, respectively (48, 49). • In 2006, North Carolina established an interim maximum allowable concentration (IMAC) of 2 µg/L for PFOA in groundwater (50). • In 2010, the North Carolina Secretary’s Science Advisory Board (NCSAB) on Toxic Air Pollutants recommended that the IMAC for PFOA in groundwater be reduced to 1 µg/L based on a review of the toxicological literature and discussions with scientists conducting research on the health effects associated with exposure to PFOA. At the time of this writing, the NCSAB’s recommendation was still pending review by the North Carolina Division of Water Quality (51). • In 2016, the Vermont Department of Health derived a drinking water health advisory of 0.02 µg/L applicable to the sum of PFOA and PFOS. • In September 2016, California EPA’s Office of Environmental Health Hazard Assessment issued a Notice of Intent to List PFOA and PFOS as known to the state to cause reproductive toxicity under the Safe Drinking Water and Toxic Enforcement Act of 1986 (52). If listed, warning requirements under the new regulatory scheme would be triggered within 1 year from the date of the Office of Environmental Health Hazard Assessment’s (OEHHA’s) listing. The guideline values are summarized in Table 2-2. Additionally, six PFASs are considered under the U.S. EPA’s Third Unregulated Contaminant Monitoring Rule (UCMR 3) (see Table 2-3). While it is not necessarily applicable to airport managers, the 1996 Safe Drinking Water Act (SDWA) amendments require that once every 5 years U.S. EPA issue a new list of no more than 30 unregulated contaminants to be monitored by public water systems. U.S. EPA uses the UCMR to collect data on contaminants that are

primer—Background on pFaSs 19 U.S. EPA 0.07* 0.07* NC NC NC NC NC NC Maine (maximum exposure in drinking water guideline) 0.1 NC NC NC NC NC NC NC Michigan (Health limits, drinking water) 0.42 0.011 NC NC NC NC NC NC Michigan (Health limits, non-drinking water use) 12 0.012 NC NC NC NC NC NC Minnesota (well advisory guidelines) NC NC 0.6 1.0 NC 1.0 1.0 0.6 Minnesota (chronic health risk limits, drinking water) 0.3 0.3 7.0 7.0 NC NC NC NC New Jersey (interim health-based values) 0.04 NC NC NC 0.010 NC NC NC North Carolina (IMAC) 2.0 NC NC NC NC NC NC NC Vermont (Health Department, drinking water) 0.02** 0.02** NC NC NC NC NC NC NC denotes “no criteria.” * Combined concentration of PFOA and PFOS are not to exceed 0.07 µg/L. **Combined concentration of PFOA and PFOS are not to exceed 0.02 µg/L. Agency PFOA (µg/L) PFOS (µg/L) PFBS (µg/L) PFBA (µg/L) PFNA (µg/L) PFPeA (µg/L) PFHxA (µg/L) PFHxS (µg/L) Table 2-2. Drinking water and well advisory guidelines in the United States. Perfluorooctanesulfonic acid (PFOS) 0.04 EPTDS EPA 537 Rev 1.1 Perfluorooctanoic acid (PFOA) 0.02 EPTDS EPA 537 Rev 1.1 Perfluorononanoic acid (PFNA) 0.02 EPTDS EPA 537 Rev 1.1 Perfluorohexane sulfonic acid (PFHxS) 0.03 EPTDS EPA 537 Rev 1.1 Perfluoroheptanoic acid (PFHpA) 0.01 EPTDS EPA 537 Rev 1.1 Perfluorobutanesulfonic acid (PFBS) 0.09 EPTDS EPA 537 Rev 1.1 EPTDS denotes “entry points to the distribution system.” Contaminant Minimum Reporting Level (µg/L) Sampling Points Analytical Methods Table 2-3. PFASs on UCMR 3 assessment monitoring (List 1 contaminants).

20 Use and potential Impacts of aFFF Containing pFaSs at airports suspected to be present in drinking water and do not have health-based standards set under the SDWA. U.S. EPA pays for the analysis of all samples from systems serving 10,000 or fewer people. If airport operators do not themselves participate in the program, they should be aware that nearby systems may be monitoring these compounds. 2.4.2 Canada The regulatory environment for PFASs (such as PFOS and PFOA) in Canada is in develop- ment. Canadian federal guidelines that protect the human health exposure pathways for potable groundwater use and direct soil contact have been developed for federal custodian sites (53). Environment Canada has developed proposed final federal environmental quality guidelines to help assess the significance of PFOS concentrations in the environment (54). These pro- posed final guideline values are based on studies that directly link laboratory exposure to adverse impacts in animals and have been developed for soil, groundwater, surface water, fish tissue, wildlife diet, and bird eggs. Concentrations above the draft guideline values indicate an increased likelihood that adverse effects in the environment may occur; however, PFOS concentrations above the guideline values do not necessarily indicate adverse effects. In August 2010, Health Canada issued provisional drinking water guidance values for PFOA and PFOS. Based on the available scientific literature and reviews conducted by other jurisdictions, Health Canada revised their 2011 values in 2016, establishing drinking water screening values of 0.0006 mg/L (0.6 µg/L) for PFOS; 0.2 µg/L for PFOA; 15 µg/L for PFBS; 30 µg/L for PFBA; 0.6 µg/L for PFHxS; and 0.2 µg/L for PFPeA, PFHxA, perfluoroheptanoic acid (PFHpA), and PFNA based on lifetime exposure. Environment Canada has developed Canadian Federal Environmental Quality Guidelines for PFOS in aquatic life (water), fish tissue, wildlife diets, and bird eggs (see Table 2-4). Proposed final guidelines have been developed for screening for soil exposure pathways (see Table 2-5) and groundwater exposure pathways (see Table 2-6) for PFOS and were most recently updated in February 2017. In 2016, British Columbia promulgated amendments to the BC Con- taminated Site Regulations, which will become effective November 1, 2017, that include regu- latory criteria for PFOS, PFOA, and PFBS based on toxicity, persistence in the environment, and relevance to contaminate sites in British Columbia. In addition, guidelines are currently in development in Ontario. 2.4.3 European Union Countries The directive on “Environmental Quality Standards” (EQSD) sets environmental quality stan- dards for certain priority hazardous substances for the EU. The EQSD presented in the document for PFOS were derived by the National Institute for Public Health and the Environment (RIVM) in the Netherlands. RIVM has derived scientific environmental risk limits for PFOS in fresh and marine sur- face waters. RIVM (55) provides maximum permissible concentration (MPC) values for both Water (µg/L) Fish Tissue (µg/g wet weight) Wildlife Diets (µg/g wet weight food) Bird Egg (µg/g wet weight) Mammalian Avian 6 8.3 4600 8200 1.9 Table 2-4. Federal Environmental Quality Guidelines for PFOS (Canada).

primer—Background on pFaSs 21 Final Soil Guideline 0.01 0.01 0.14 1 0.21 2 0.14 1 0.21 2 Soil Contact (SQGSC) 11 11 61 61 Soil Ingestion (SQG1C) 2.2 2.2 NR NR Soil Ingestion—secondary and tertiary consumers (SQG2C , SQG3C) 0.01 0.01 NR NR Agricultural (Livestock watering) 12 1 9 2 NR NR NR Protection of Freshwater Life (SQGFL) 0.14 1 0.21 2 Off-site migration (SQGOM-E) NR NR 0.14 0.14 NR denotes “not required.” *Federal Environmental Quality Guidelines for PFOS, Environment and Climate Change Canada, February 2017. 1 Coarse-grained soil 2 Fine-grained soil Land Use/Pathway Agricultural (mg/kg) Residential/ Parkland (mg/kg) Commercial (mg/kg) Industrial (mg/kg) Table 2-5. Federal soil quality guidelines for PFOS.* Final Groundwater Guideline (FGWQGFINAL) 1 0.068 0.068 Groundwater Contact (FGWQGGC) by Soil-Dependent Organisms 2 2 Protection of Freshwater Life (FGWQGFL) 2 0.068 0.068 Protection of Marine Life (FGWQGML) NC NC Protection of Livestock Watering (FGWQGLW) NC NC Protection of Irrigation Water (FGWQGIR) NC NC Management Considerations (FGWQGM)—Solubility 370 370 NC denotes “not calculated.” *Federal Environmental Quality Guidelines for PFOS, Environment and Climate Change Canada, February 2017. 1 The federal groundwater quality guideline-final (FGWQGFINAL) is the lowest of the pathway-specific guidelines while also taking the solubility into account. 2 FGWQGFL is the concentration in groundwater that is expected to protect against potential impacts on freshwater life from PFOS originating in soil that may enter groundwater and subsequently discharge to a surface water body. This pathway may be applicable under any land use category, where a surface water body sustaining aquatic life is present (i.e., within 10 kilometers of the site). Where the distance to the nearest surface water body is greater than 10 kilometers, application of the pathway should be evaluated on a case-by-case basis by considering the site-specific conditions. Exposure Pathway Coarse (mg/L) Fine (mg/L) Table 2-6. Federal groundwater quality guidelines for PFOS.*

22 Use and potential Impacts of aFFF Containing pFaSs at airports environmental and human health, with the value for human health based on consumption of fish and shellfish. The human health value represents the lowest MPC in freshwater at 0.65 ng/L. Table 2-7 presents maximum acceptable concentrations of PFOA and PFOS in drinking water as developed by the UK Health Protection Agency (HPA), the Danish Ministry of the Environment (DEPA) (56), and the Department of Environmental Protection in Germany. DEPA has also derived health-based soil quality criteria: • PFOS: 0.39 mg/kg • PFOSA: 0.39 mg/kg • PFOA (and salts, e.g., Ammonium pentadecafluorooctanoate [APFO]): 1.3 mg/kg In the case that PFOS, PFOA, and PFOSA occur in the soil together at the same time, the concentration/limit value must be < 1 mg/kg. 2.4.4 Australia In Australia, regulations on the use, release, and disposal of PFASs and any criteria for these chemicals is primarily a state and territory responsibility. However, interim national guidance on human health reference values for PFASs for use in site investigations has been derived by the Environmental Health Standing Committee (enHealth) of the Australian Health Protection Principal Committee and have been made available as of June 2016 (57). (See Table 2-8.) Additionally, the Government of Western Australia has produced a Contaminated Sites Guideline document containing interim screening levels for soil, sediment, surface water, and groundwater (58). (See Table 2-9.) The purpose of the Contaminated Sites Guideline document is to provide guidance on the assessment and management of PFASs within the applicable legislative framework. UK HPA 0.3 0.3 DEPA* 0.3 0.1 Germany Department of Environmental Protection 0.1 (sum of PFOA and PFOS) *Where PFOS, PFOA, and Perfluorooctane sulfonamide (PFOSA) occur in the drinking water at the same time, the total concentration/limit value must be < 1 ug/L. Agency PFOA (µg/L) PFOS (µg/L) Table 2-7. EU maximum allowable drinking water concentrations. Tolerable Daily Intake (µg/kg/d) 0.15 1.5 Drinking Water Quality Guideline (µg/L) 0.5 5 Recreational Water Quality Guideline (µg/L) 5 50 Toxicity Reference Value PFOS/PFHxS PFOA Table 2-8. Recommended enHealth interim values.

primer—Background on pFaSs 23 2.5 How Might PFASs Affect an Airport? Use of AFFF (containing PFASs) at airports has the potential to impact the environmental media on, or in, the vicinity of airports. PFASs may impact airport operations and environmental management. The primary impacts to operations would be related to firefighting activities— specifically, how airports procure, store, handle, apply, remove, and dispose of AFFF. With regard to environmental management, PFASs will have a potentially significant impact on how envi- ronmental media are investigated and remediated. Similarly, media impacted by PFASs that require special handling may be encountered as capital projects are undertaken. The following sections discuss these considerations. 2.5.1 Known Practices of AFFF Use AFFF is used for fire suppression. Its role is to cool the fire and coat the fuel, preventing fuel from contacting oxygen and suppressing further combustion. In the mid-1960s, the U.S. Navy developed AFFF, which was observed to have dramatic “fire knockdown” capabilities, an important factor in crash rescue firefighting. AFFF solutions are mixed with water at the point of use to cre- ate the desired mixture strength. The application mixture is typically shown on the container of AFFF concentrate or in the product manufacturer’s directions. The foam forms spontaneously upon ejection of the concentrate/water mixture from a nozzle. Environmental release of PFASs related to AFFF use has historically resulted from emergency response, testing, emergency activation of fire suppression systems in hangars, leaks from storage tanks and/or supply lines, and firefighter training exercises. Additionally, storage tanks or supply lines previously containing PFASs could still contribute residual amounts. Best practices for managing release of PFASs into the environment include the following: • Up-to-date document and inventory management and personnel training. • Spill containment during refilling of storage containers and foam tests. • Fire training activities with an environmentally benign type of foam (e.g., no PFASs). • Engineered containment systems in hangars, firefighter training areas (FFTAs), and tarmac (e.g., storm sewer) that capture and direct any discharged AFFF. Soil Human Health Residential (mg/kg) 4 − Human Health Industrial/Commercial (mg/kg) 100 − Surface Water and Groundwater Drinking Water (µg/L) 0.5 − Non-Potable and Recreational Uses (µg/L) 5 − Ecological—Freshwater (µg/L) 0.00023 19 0.13 220 2.0 31 632 (90% species protection) 1,824 (80% species protection) Exposure Scenario PFOS PFOA Table 2-9. Western Australia interim screening levels for PFOS and PFOA in environmental media.

24 Use and potential Impacts of aFFF Containing pFaSs at airports 2.5.2 Potential Sources of PFASs Potential sources for PFASs at an airport facility are mostly linked to past use of AFFF and could include the following: • Firefighting training areas where AFFFs were used. • Firefighting equipment maintenance areas (e.g., from foam tests). • Disposal areas. • Treatment lagoons. • Impacted soils. • Drainage and wastewater systems used to contain discharged fire-extinguishing materials. • Storage areas for AFFF. • Tanks, vehicles, equipment, and distribution systems that were used to store or apply AFFF, and then were not adequately rinsed and may have become a continuous source. 2.5.3 Environmental Considerations As discussed previously, releases to the environment of small amounts of AFFF containing PFASs could significantly impact environmental media, wildlife, and, potentially, human popu- lations. Responses to environmental impacts of PFASs that present unacceptable human health or ecological risks will be shaped by regulations. Capital projects may be affected by impacts of PFASs on soil and groundwater because if, in the course of a capital project, PFASs are found in these media, care may be required (potentially at significant cost) to handle and properly dispose of the soil and groundwater impacted by PFASs (e.g., dewatering). 2.5.4 Human Health Considerations Best management practices protect not only the environment from exposure, but also work to protect workers and individuals that may come into contact with AFFF containing PFASs at air- ports. Firefighters, in particular, are an occupationally exposed population. PFASs in firefighting products have been measured in the blood of firefighters at concentrations above those in the average population (59–62). Special consideration must be given to ensuring contaminated sites are cleaned up. Preventative measures should be put into place to limit occupational exposure to AFFF containing PFASs and to monitor worker’s health.

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TRB's Airport Cooperative Research Program (ACRP) Research Report 173: Use and Potential Impacts of AFFF Containing PFASs at Airports explores the potential environmental and health impacts of per- and polyfluoroalkyl substances (PFASs) typically found in aqueous film-forming foams (AFFFs). The report describes methods that can be used to identify areas of potential concern at an airport and ways to implement management and remediation practices.

To help airports identify areas of potential environmental concern, the research team developed the Managing AFFF and PFASs at Airports (MAPA) Screening Tool. The MAPA Screening Tool is available in two versions: one for running in Microsoft Excel 2010 and the other, a version called the compatibility version, that can be run in Microsoft Excel 97 to 2003, or 2007.

Disclaimer - This software is offered as is, without warranty or promise of support of any kind either expressed or implied. Under no circumstance will the National Academy of Sciences, Engineering, and Medicine or the Transportation Research Board (collectively "TRB") be liable for any loss or damage caused by the installation or operation of this product. TRB makes no representation or warranty of any kind, expressed or implied, in fact or in law, including without limitation, the warranty of merchantability or the warranty of fitness for a particular purpose, and shall not in any case be liable for any consequential or special damages.

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