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==Munitions Constituents – Sample Extraction and Analytical Techniques==  
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==Remediation of Stormwater Runoff Contaminated by Munition Constituents==  
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Munitions Constituents, including [[Wikipedia: Insensitive munition | insensitive munitions]] IM), are a broad category of compounds and, in areas where manufactured or used, can be found in a variety of environmental matrices (waters, soil, and tissues). This presents an analytical challenge when a variety of these munitions are to be quantified. This article discusses sample extraction methods for each typical sample matrix (high level water, low level water, soil and tissue) as well as the accompanying [[Wikipedia: High-performance liquid chromatography | HPLC]]-UV analytical method for 27 compounds of interest (legacy munitions, insensitive munitions, and surrogates).  
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Past and ongoing military operations have resulted in contamination of surface soil with [[Munitions Constituents | munition constituents (MC)]], which have human and environmental health impacts.  These compounds can be transported off site via stormwater runoff during precipitation events.  Technologies to “trap and treat” surface runoff before it enters downstream receiving bodies (e.g., streams, rivers, ponds) (see Figure 1), and which are compatible with ongoing range activities are needed. This article describes a passive and sustainable approach for effective management of munition constituents in stormwater runoff.
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<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
 
<div style="float:right;margin:0 0 2em 2em;">__TOC__</div>
  
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*[[Munitions Constituents]]
 
*[[Munitions Constituents]]
  
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'''Contributor(s):'''
 
  
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*Dr. Austin Scircle
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'''Contributor:''' Mark E. Fuller
  
 
'''Key Resource(s):'''
 
'''Key Resource(s):'''
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*SERDP Project ER19-1106: Development of Innovative Passive and Sustainable Treatment Technologies for Energetic Compounds in Surface Runoff on Active Ranges
  
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*[https://www.epa.gov/sites/default/files/2015-07/documents/epa-8330b.pdf USEPA Method 8330B]<ref name= "8330B">United States Environmental Protection Agency (USEPA), 2006. EPA Method 8330B (SW-846) Nitroaromatics, Nitramines, and Nitrate Esters by High Performance Liquid Chromatography (HPLC), Revision 2. [https://www.epa.gov/esam/epa-method-8330b-sw-846-nitroaromatics-nitramines-and-nitrate-esters-high-performance-liquid USEPA Website]&nbsp; &nbsp;[[Media: epa-8330b.pdf | Method 8330B.pdf]]</ref>
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==Background==
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===Surface Runoff Characteristics and Treatment Approaches===
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*Methods for simultaneous quantification of legacy and insensitive munition (IM) constituents in aqueous, soil/sediment, and tissue matrices<ref name="CrouchEtAl2020">Crouch, R.A., Smith, J.C., Stromer, B.S., Hubley, C.T., Beal, S., Lotufo, G.R., Butler, A.D., Wynter, M.T., Russell, A.L., Coleman, J.G., Wayne, K.M., Clausen, J.L., Bednar, A.J., 2020. Methods for simultaneous determination of legacy and insensitive munition (IM) constituents in aqueous, soil/sediment, and tissue matrices. Talanta, 217, Article 121008. [https://doi.org/10.1016/j.talanta.2020.121008 doi: 10.1016/j.talanta.2020.121008]&nbsp; &nbsp;[[Media: CrouchEtAl2020.pdf | Open Access Manuscript.pdf]]</ref>
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[[File: FullerFig1.png | thumb | 300 px | Figure 1. Conceptual model of passive trap and treat approach for MC removal from stormwater runoff]]
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During large precipitation events the rate of water deposition exceeds the rate of water infiltration, resulting in surface runoff (also called stormwater runoff). Surface characteristics including soil texture, presence of impermeable surfaces (natural and artificial), slope, and density and type of vegetation all influence the amount of surface runoff from a given land area. The use of passive systems such as retention ponds and biofiltration cells for treatment of surface runoff is well established for urban and roadway runoff. Treatment in those cases is typically achieved by directing runoff into and through a small constructed wetland, often at the outlet of a retention basin, or via filtration by directing runoff through a more highly engineered channel or vault containing the treatment materials. Filtration based technologies have proven to be effective for the removal of metals, organics, and suspended solids<ref>Sansalone, J.J., 1999. In-situ performance of a passive treatment system for metal source control. Water Science and Technology, 39(2), pp. 193-200. [https://doi.org/10.1016/S0273-1223(99)00023-2 doi: 10.1016/S0273-1223(99)00023-2]</ref><ref>Deletic, A., Fletcher, T.D., 2006. Performance of grass filters used for stormwater treatment—A field and modelling study. Journal of Hydrology, 317(3-4), pp. 261-275. [http://dx.doi.org/10.1016/j.jhydrol.2005.05.021 doi: 10.1016/j.jhydrol.2005.05.021]</ref><ref>Grebel, J.E., Charbonnet, J.A., Sedlak, D.L., 2016. Oxidation of organic contaminants by manganese oxide geomedia for passive urban stormwater treatment systems. Water Research, 88, pp. 481-491. [http://dx.doi.org/10.1016/j.watres.2015.10.019 doi: 10.1016/j.watres.2015.10.019]</ref><ref>Seelsaen, N., McLaughlan, R., Moore, S., Ball, J.E., Stuetz, R.M., 2006. Pollutant removal efficiency of alternative filtration media in stormwater treatment. Water Science and Technology, 54(6-7), pp. 299-305. [https://doi.org/10.2166/wst.2006.617 doi: 10.2166/wst.2006.617]</ref>.
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==Introduction==
 
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The primary intention of the analytical methods presented here is to support the monitoring of legacy and insensitive munitions contamination on test and training ranges, however legacy and insensitive munitions often accompany each other at demilitarization facilities, manufacturing facilities, and other environmental sites. Energetic materials typically appear on ranges as small, solid particulates and due to their varying functional groups and polarities, can partition in various environmental compartments<ref>Walsh, M.R., Temple, T., Bigl, M.F., Tshabalala, S.F., Mai, N. and Ladyman, M., 2017. Investigation of Energetic Particle Distribution from High‐Order Detonations of Munitions. Propellants, Explosives, Pyrotechnics, 42(8), pp. 932-941. [https://doi.org/10.1002/prep.201700089 doi: 10.1002/prep.201700089]</ref>. To ensure that contaminants are monitored and controlled at these sites and to sustainably manage them a variety of sample matrices (surface or groundwater, process waters, soil, and tissues) must be considered. (Process water refers to water used during industrial manufacturing or processing of legacy and insensitive munitions.) Furthermore, additional analytes must be added to existing methodologies as the usage of IM compounds changes and as new degradation compounds are identified.  Of note, relatively new IM formulations containing NTO, DNAN, and NQ are seeing use in [[Wikipedia: IMX-101 | IMX-101]], IMX-104, Pax-21 and Pax-41 (Table 1)<ref>Mainiero, C. 2015. Picatinny Employees Recognized for Insensitive Munitions. U.S. Army, Picatinny Arsenal Public Affairs.  [https://www.army.mil/article/148873/picatinny_employees_recognized_for_insensitive_munitions Open Access Press Release]</ref><ref>Frem, D., 2022. A Review on IMX-101 and IMX-104 Melt-Cast Explosives: Insensitive Formulations for the Next-Generation Munition Systems. Propellants, Explosives, Pyrotechnics, 48(1), e202100312. [https://doi.org/10.1002/prep.202100312 doi: 10.1002/prep.202100312]</ref>.
 
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Sampling procedures for legacy and insensitive munitions are identical and utilize multi-increment sampling procedures found in USEPA Method 8330B Appendix A<ref name= "8330B"/>. Sample hold times, subsampling and quality control requirements are also unchanged. The key differences lie in the extraction methods and instrumental methods. Briefly, legacy munitions analysis of low concentration waters uses a single cartridge reverse phase [[Wikipedia: Solid-phase extraction | SPE]] procedure, and [[Wikipedia: Acetonitrile | acetonitrile]] (ACN) is used for both extraction and [[Wikipedia: Elution | elution]] for aqueous and solid samples<ref name= "8330B"/><ref>United States Environmental Protection Agency (USEPA), 2007. EPA Method 3535A (SW-846) Solid-Phase Extraction (SPE), Revision 1. [https://www.epa.gov/esam/epa-method-3535a-sw-846-solid-phase-extraction-spe USEPA Website]&nbsp; &nbsp;[[Media: epa-3535a.pdf | Method 3535A.pdf]]</ref>. An [[Wikipedia: High-performance_liquid_chromatography#Isocratic_and_gradient_elution | isocratic]] separation via reversed-phase C-18 column with 50:50 methanol:water mobile phase or a C-8 column with 15:85 isopropanol:water mobile phase is used to separate legacy munitions<ref name= "8330B"/>. While these procedures are sufficient for analysis of legacy munitions, alternative solvents, additional SPE cartridges, and a gradient elution are all required for the combined analysis of legacy and insensitive munitions.   
 
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Previously, analysis of legacy and insensitive munitions required multiple analytical techniques, however the methods presented here combine the two munitions categories resulting in an HPLC-UV method and accompanying extraction methods for a variety of common sample matrices. A secondary HPLC-UV method and a HPLC-MS method were also developed as confirmatory methods. The methods discussed in this article were validated extensively by single-blind round robin testing and subsequent statistical treatment as part of ESTCP [https://serdp-estcp.mil/projects/details/d05c1982-bbfa-42f8-811d-51b540d7ebda ER19-5078]. Wherever possible, the quality control criteria in the Department of Defense Quality Systems Manual for Environmental Laboratories were adhered to<ref>US Department of Defense and US Department of Energy, 2021. Consolidated Quality Systems Manual (QSM) for Environmental Laboratories, Version 5.4. 387 pages. [https://www.denix.osd.mil/edqw/denix-files/sites/43/2021/10/QSM-Version-5.4-FINAL.pdf Free Download]&nbsp; &nbsp;[[Media: QSM-Version-5.4.pdf | QSM Version 5.4.pdf]]</ref>. Analytes included in these methods are found in Table 1.
 
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The chromatograms produced by the primary and secondary HPLC-UV methods are shown in Figure 1 and Figure 2, respectively. Chromatograms for each detector wavelength used are shown (315, 254, and 210 nm).
 
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==Extraction Methods==
 
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===High Concentration Waters (> 1 ppm)===
 
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Aqueous samples suspected to contain the compounds of interest at concentrations detectable without any extraction or pre-concentration are suitable for analysis by direct injection. The method deviates from USEPA Method 8330B by adding a pH adjustment and use of MeOH rather than ACN for dilution<ref name= "8330B"/>. The pH adjustment is needed to ensure method accuracy for ionic compounds (like NTO or PA) in basic samples. A solution of 1% HCl/MeOH is added to both acidify and dilute the samples to a final acid concentration of 0.5% (vol/vol) and a final solvent ratio of 1:1 MeOH/H<sub>2</sub>O. The direct injection samples are then ready for analysis.
 
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===Low Concentration Waters (< 1 ppm)===
 
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Aqueous samples suspected to contain the compounds of interest at low concentrations require extraction and pre-concentration using solid phase extraction (SPE). The SPE setup described here uses a triple cartridge setup shown in '''Figure 3'''. Briefly, the extraction procedure loads analytes of interest onto the cartridges in this order: Strata<sup><small>TM</small></sup> X, Strata<sup><small>TM</small></sup> X-A, and Envi-Carb<sup><small>TM</small></sup>. Then the cartridge order is reversed, and analytes are eluted via a two-step elution, resulting in 2 extracts (which are combined prior to analysis). Five milliliters of MeOH is used for the first elution, while 5 mL of acidified MeOH (2% HCl) is used for the second elution. The particular SPE cartridges used are noncritical so long as cartridge chemistries are comparable to those above.
 
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===Soils=== 
 
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Soil collection, storage, drying and grinding procedures are identical to the USEPA Method 8330B procedures<ref name= "8330B"/>; however, the solvent extraction procedure differs in the number of sonication steps, sample mass and solvent used. A flow chart of the soil extraction procedure is shown in '''Figure 4'''. Soil masses of approximately 2 g and a sample to solvent ratio of 1:5 (g/mL) are used for soil extraction. The extraction is carried out in a sonication bath chilled below 20 ⁰C and is a two-part extraction, first extracting in MeOH (6 hours) followed by a second sonication in 1:1 MeOH:H<sub>2</sub>O solution (14 hours). The extracts are centrifuged, and the supernatant is filtered through a 0.45 μm PTFE disk filter.  
 
  
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The solvent volume should generally be 10 mL but if different soil masses are required, solvent volume should be 5 mL/g. The extraction results in 2 separate extracts (MeOH and MeOH:H2O) that are combined prior to analysis.  
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===Surface Runoff on Ranges===
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Surface runoff represents a major potential mechanism through which energetics residues and related materials are transported off site from range soils to groundwater and surface water receptors (Figure 2). This process is particularly important for energetics that are water soluble (e.g., [[Wikipedia: Nitrotriazolone | NTO]] and [[Wikipedia: Nitroguanidine | NQ]]) or generate soluble daughter products (e.g., [[Wikipedia: 2,4-Dinitroanisole | DNAN]] and [[Wikipedia: TNT | TNT]]). While traditional MC such as [[Wikipedia: RDX | RDX]] and [[Wikipedia: HMX | HMX]] have limited aqueous solubility, they also exhibit recalcitrance to degrade under most natural conditions. RDX and [[Wikipedia: Perchlorate | perchlorate]] are frequent groundwater contaminants on military training ranges. While actual field measurements of energetics in surface runoff are limited, laboratory experiments have been performed to predict mobile energetics contamination levels based on soil mass loadings<ref>Cubello, F., Polyakov, V., Meding, S.M., Kadoya, W., Beal, S., Dontsova, K., 2024. Movement of TNT and RDX from composition B detonation residues in solution and sediment during runoff. Chemosphere, 350, Article 141023. [https://doi.org/10.1016/j.chemosphere.2023.141023 doi: 10.1016/j.chemosphere.2023.141023]</ref><ref>Karls, B., Meding, S.M., Li, L., Polyakov, V., Kadoya, W., Beal, S., Dontsova, K., 2023. A laboratory rill study of IMX-104 transport in overland flow. Chemosphere, 310, Article 136866. [https://doi.org/10.1016/j.chemosphere.2022.136866 doi: 10.1016/j.chemosphere.2022.136866]&nbsp; [[Media: KarlsEtAl2023.pdf | Open Access Article]]</ref>.
  
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===Tissues===  
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==Toxicological Effects of PFAS==
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The characterization of toxicological effects in human health risk assessments is based on toxicological studies of mammalian exposures to per- and polyfluoroalkyl substances (PFAS), primarily studies involving [[Wikipedia:Perfluorooctanesulfonic acid | perfluorooctanesulfonic acid (PFOS)]] and [[Wikipedia:Perfluorooctanoic acid|perfluorooctanoic acid (PFOA)]]. The most sensitive noncancer adverse effects involve the liver and kidney, immune system, and various developmental and reproductive endpoints<ref name="USEPA2024b">United States Environmental Protection Agency (USEPA), 2024. Per- and Polyfluoroalkyl Substances (PFAS) Final PFAS National Primary Drinking Water Regulation. [https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas Website]</ref>. A select number of PFAS have been evaluated for carcinogenicity, primarily using epidemiological data. Only PFOS and PFOA (and their derivatives) have sufficient data for USEPA to characterize as ''Likely to Be Carcinogenic to Humans'' via the oral route of exposure. Epidemiological studies provided evidence of bladder, prostate, liver, kidney, and breast cancers in humans related to PFOS exposure, as well as kidney and testicular cancer in humans and limited evidence of breast cancer related to PFOA exposure<ref name="USEPA2024b"/><ref name="USEPA2016a">United States Environmental Protection Agency (USEPA), 2016. Drinking Water Health Advisory for Perfluorooctane Sulfonate (PFOS). Office of Water, EPA 822-R-16-004. [https://www.epa.gov/sites/production/files/2016-05/documents/pfos_health_advisory_final-plain.pdf  Free Download]&nbsp; [[Media: USEPA-2016-pfos_health_advisory_final-plain.pdf | Report.pdf]]</ref><ref name="USEPA2016b">United States Environmental Protection Agency (USEPA), 2016b. Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA). Office of Water, EPA 822-R-16-005. [https://www.epa.gov/sites/production/files/2016-05/documents/pfoa_health_advisory_final_508.pdf Free Download]&nbsp; [[Media: pfoa_EPA 822-R-16-005.pdf | Report.pdf]]</ref>.
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USEPA’s Integrated Risk Management System (IRIS) Program is developing Toxicological Reviews to improve understanding of the toxicity of several additional PFAS (i.e., not solely PFOA and PFOS). Toxicological Reviews provide an overview of cancer and noncancer health effects based on current literature and, where data are sufficient, derive human health toxicity criteria (i.e., human health oral reference doses and cancer slope factors) that form the basis for risk-based decision making. For risk assessors, these documents provide USEPA reference doses and cancer slope factors that can be used with exposure information and other considerations to assess human health risk. Final Toxicological Reviews have been completed for the following PFAS:
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*Perfluorooctanesulfonic acid (PFOS)
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*Perfluorooctanoic acid (PFOA)
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*Perfluorobutanoic acid (PFBA)
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*Perfluorohexanoic acid (PFHxA)
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*Perfluorobutane sulfonic acid (PFBS)
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*Perfluoropropionic acid (PFPrA)
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*Perfluorohexane sulfonic acid (PFHxS)
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*Lithium bis[(trifluoromethyl)sulfonyl]azanide (HQ-115)
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*Hexafluoropropylene oxide dimer acid (HFPO DA) and its Ammonium Salt
  
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Tissue matrices are extracted by 18-hour sonication using a ratio of 1 gram of wet tissue per 5 mL of MeOH. This extraction is performed in a sonication bath chilled below 20 ⁰C and the supernatant (MeOH) is filtered through a 0.45 μm PTFE disk filter.
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Toxicity assessments are ongoing for the following PFAS:
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*Perfluorononanoic acid (PFNA)
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*Perfluorodecanoic acid (PFDA)  
  
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Due to the complexity of tissue matrices, an additional tissue cleanup step, adapted from prior research, can be used to reduce interferences<ref name="RussellEtAl2014">Russell, A.L., Seiter, J.M., Coleman, J.G., Winstead, B., Bednar, A.J., 2014. Analysis of munitions constituents in IMX formulations by HPLC and HPLC-MS. Talanta, 128, pp. 524–530. [https://doi.org/10.1016/j.talanta.2014.02.013 doi: 10.1016/j.talanta.2014.02.013]</ref><ref name="CrouchEtAl2020"/>. The cleanup procedure uses small scale chromatography columns prepared by loading 5 ¾” borosilicate pipettes with 0.2 g activated silica gel (100–200 mesh). The columns are wetted with 1 mL MeOH, which is allowed to fully elute and then discarded prior to loading with 1 mL of extract and collecting in a new amber vial. After the extract is loaded, a 1 mL aliquot of MeOH followed by a 1 mL aliquot of 2% HCL/MeOH is added. This results in a 3 mL silica treated tissue extract. This extract is vortexed and diluted to a final solvent ratio of 1:1 MeOH/H<sub>2</sub>O before analysis.
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It is important to note human health toxicity criteria for inhalation of PFAS are not included in the Final Toxicological Reviews and are not currently available.  
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In addition to IRIS, state agencies have developed peer-reviewed provisional toxicity values that have been incorporated into USEPA’s RSLs, which are updated biannually. These values have not been reviewed by or incorporated into IRIS.  
  
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With respect to ecological toxicity, effects on reproduction, growth, and development of avian and mammalian wildlife have been documented in controlled laboratory studies of exposures of standard toxicological test species (e.g., mice, quail) to PFAS. Many of these studies have been reviewed<ref name="ConderEtAl2020"> Conder, J., Arblaster, J., Larson, E., Brown, J., Higgins, C., 2020. Guidance for Assessing the Ecological Risks of PFAS to Threatened and Endangered Species at Aqueous Film Forming Foam-Impacted Sites. Strategic Environmental Research and Development Program (SERDP) Project ER 18-1614. [https://serdp-estcp.mil/projects/details/3f890c9b-7f72-4303-8d2e-52a89613b5f6 Project Website]&nbsp; [[Media: ER18-1614_Guidance.pdf | Guidance Document]]</ref><ref name="GobasEtAl2020">Gobas, F.A.P.C., Kelly, B.C., Kim, J.J., 2020. Final Report: A Framework for Assessing Bioaccumulation and Exposure Risks of PFAS in Threatened and Endangered Species on AFFF-Impacted Sites. SERDP Project ER18-1502. [https://serdp-estcp.mil/projects/details/09c93894-bc73-404a-8282-51196c4be163 Project Website]&nbsp; [[Media: ER18-1502_Final.pdf | Final Report]]</ref><ref name="Suski2020">Suski, J.G., 2020. Investigating Potential Risk to Threatened and Endangered Species from Per- and Polyfluoroalkyl Substances (PFAS) on Department of Defense (DoD) Sites. SERDP Project ER18-1626. [https://serdp-estcp.mil/projects/details/c328f8e3-95a4-4820-a0d4-ef5835134636 Project Website]&nbsp; [[Media: ER18-1626_Final.pdf | Report.pdf]]</ref><ref name="ZodrowEtAl2021a">Zodrow, J.M., Frenchmeyer, M., Dally, K., Osborn, E., Anderson, P. and Divine, C., 2021. Development of Per and Polyfluoroalkyl Substances Ecological Risk-Based Screening Levels. Environmental Toxicology and Chemistry, 40(3), pp. 921-936. [https://doi.org/10.1002/etc.4975 doi: 10.1002/etc.4975]&nbsp;&nbsp; [[Media: ZodrowEtAl2021a.pdf | Open Access Article]]</ref> to derive ecological Toxicity Reference Values (TRVs). TRVs can be used alongside exposure information and other considerations to assess ecological risk. Avian and mammalian wildlife receptors are generally expected to have the highest risks due to PFAS exposure. Direct toxicity to aquatic life, such as fish and invertebrates, from exposure to sediment and surface water also occurs, though concentrations in water associated with adverse effects to aquatic life are generally higher than those that could result in adverse effects to aquatic-dependent wildlife. Soil invertebrates and plants are less sensitive to PFAS when compared to terrestrial wildlife, with risk-based PFAS concentrations in soil being much higher than those associated with potential effects to terrestrial wildlife<ref name="ZodrowEtAl2021a"/>.
  
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==PFAS Screening Levels for Human Health and Ecological Risk Assessments==
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===Human Health Screening Levels===
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Human health screening levels for PFAS have been modified multiple times over the last decade and, in the United States, are currently available for drinking water and soil exposures as Maximum Contaminant Levels (MCLs) and USEPA Regional Screening Levels (RSLs). USEPA finalized a National Primary Drinking Water Regulation (NPDWR) for six PFAS<ref name="USEPA2024b"/>:
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*Perfluorooctanoic acid (PFOA)
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*Perfluorooctane sulfonic acid (PFOS)
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*Perfluorohexane sulfonic acid (PFHxS)
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*Perfluorononanoic acid (PFNA)
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*Hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX chemicals)
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*Perfluorobutane sulfonic acid (PFBS)
  
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Most federal, state, and local regulatory guidance for assessing and mitigating the [[Vapor Intrusion (VI) | vapor intrusion]] pathway reflects USEPA’s ''Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air''<ref name="USEPA2015">USEPA, 2015. OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air. U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, OSWER Publication No. 9200.2-154, 267 pages. [https://www.epa.gov/vaporintrusion/technical-guide-assessing-and-mitigating-vapor-intrusion-pathway-subsurface-vapor USEPA Website]&nbsp;&nbsp; [//www.enviro.wiki/images/0/06/USEPA2015.pdf  Report.pdf]</ref>. The paradigm outlined by that guidance includes: 1) a preliminary and mostly qualitative analysis that looks for site conditions that suggest vapor intrusion might occur (e.g., the presence of vapor-forming chemicals in close proximity to buildings); 2) a multi-step and more detailed quantitative screening analysis that involves site-specific data collection and their comparison to screening levels to identify buildings of potential VI concern; and 3) selection and design of mitigation systems or continued monitoring, as needed. With respect to (2), regulatory guidance typically recommends consideration of “multiple lines of evidence” in decision-making<ref name="USEPA2015" /><ref>NJDEP, 2021. Vapor Intrusion Technical Guidance, Version 5.0. New Jersey Department of Environmental Protection, Trenton, NJ. [https://dep.nj.gov/srp/guidance/vapor-intrusion/vig/ Website]&nbsp;&nbsp; [//www.enviro.wiki/images/e/ee/NJDEP2021.pdf  Guidance Document.pdf]</ref>, with typical lines-of-evidence being groundwater, soil gas, sub-slab soil gas, and/or indoor air concentrations.  Of those, soil gas measurements and/or measured short-term indoor air concentrations can be weighted heavily, and therefore decision making might not be completed without them. Effective evaluation of VI risk from sub-slab and/or soil gas measurements would require an unknown building-specific attenuation factor, but there is also uncertainty as to whether or not indoor air data is representative of maximum and/or long-term average indoor concentrations. Indoor air data can be confounded by indoor contaminant sources because the number of samples is typically small, indoor concentrations can vary with time, and because a number of household products can emit the chemicals being measured. When conducting VI pathway assessments in neighborhoods where it is impractical to assess all buildings, the EPA recommends following a “worst first” investigational approach.  
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MCLs are enforceable drinking water standards based on the most recently available toxicity information that consider available treatment technologies and costs. The MCLs for PFAS include a Hazard Index of 1 for combined exposures to four PFAS. RSLs are developed for use in risk assessments and include soil and tap water screening levels for multiple PFAS. Soil RSLs are based on residential/unrestricted and commercial/industrial land uses, and calculations of site-specific RSLs are available.
  
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The limitations of this approach, as practiced, are the following:
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Internationally, Canada and the European Union have also promulgated drinking water standards for select PFAS. However, large discrepancies exist among the various regulatory organizations, largely due to the different effect endpoints and exposure doses being used to calculate risk-based levels. The PFAS guidance from the Interstate Technology and Regulatory Council (ITRC) in the US includes a regularly updated compilation of screening values for PFAS and is available on their PFAS website<ref name="ITRC2023">Interstate Technology and Regulatory Council (ITRC) 2023. PFAS Technical and Regulatory Guidance Document. [https://pfas-1.itrcweb.org/ ITRC PFAS Website]</ref>: https://pfas-1.itrcweb.org.
  
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*Decisions are rarely made without indoor air data and generally, seasonal sampling is required, delaying decision making.
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===Ecological Screening Levels===
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*The collection of a robust indoor air data set that adequately characterizes long term indoor air concentrations could take years given the typical frequency of data collection and the most common methods of sample collection (e.g., 24-hour samples).  Therefore, indoor air sampling might continue indefinitely at some sites.
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Most peer-reviewed literature and regulatory-based environmental quality benchmarks have been developed using data for PFOS and PFOA; however, other select PFAAs have been evaluated for potential effects to aquatic receptors<ref name="ITRC2023"/><ref name="ZodrowEtAl2021a"/><ref name="ConderEtAl2020"/>. USEPA has developed water quality criteria for aquatic life<ref name="USEPA2022"> United States Environmental Protection Agency (USEPA), 2022. Fact Sheet: Draft 2022 Aquatic Life Ambient Water Quality Criteria for Perfluorooctanoic acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS)). Office of Water, EPA 842-D-22-005. [[Media: USEPA2022.pdf | Fact Sheet]]</ref><ref name="USEPA2024c">United States Environmental Protection Agency (USEPA), 2024. Final Freshwater Aquatic Life Ambient Water Quality Criteria and Acute Saltwater Aquatic Life Benchmark for Perfluorooctanoic Acid (PFOA). Office of Water, EPA-842-R-24-002. [[Media: USEPA2024c.pdf | Report.pdf]]</ref><ref name="USEPA2024d">United States Environmental Protection Agency (USEPA), 2024. Final Freshwater Aquatic Life Ambient Water Quality Criteria and Acute Saltwater Aquatic Life Benchmark for Perfluorooctane Sulfonate (PFOS). Office of Water, EPA-842-R-24-003. [[Media: USEPA2024d.pdf | Report.pdf]]</ref> for PFOA and PFOS. Following extensive reviews of the peer-reviewed literature, Zodrow ''et al.''<ref name="ZodrowEtAl2021a"/> used the USEPA Great Lakes Initiative methodology<ref>United States Environmental Protection Agency (USEPA), 2012. Water Quality Guidance for the Great Lakes System. Part 132. [https://www.govinfo.gov/app/details/CFR-2013-title40-vol23/CFR-2013-title40-vol23-part132 Government Website]&nbsp; [[Media: CFR-2013-title40-vol23-part132.pdf | Part132.pdf]]</ref> to calculate acute and chronic screening levels for aquatic life for 23 PFAS. The Argonne National Laboratory has also developed Ecological Screening Levels for multiple PFAS<ref name="GrippoEtAl2024">Grippo, M., Hayse, J., Hlohowskyj, I., Picel, K., 2024. Derivation of PFAS Ecological Screening Values - Update. Argonne National Laboratory Environmental Science Division. [[Media: GrippoEtAl2024.pdf | Report.pdf]]</ref>. In contrast to surface water aquatic life benchmarks, sediment benchmark values are limited. For terrestrial systems, screening levels for direct exposure of soil plants and invertebrates to PFAS in soils have been developed for multiple AFFF-related PFAS<ref name="ConderEtAl2020"/><ref name="ZodrowEtAl2021a"/>, and the Canadian Council of Ministers of Environment developed several draft thresholds protective of direct toxicity of PFOS in soil<ref>Canadian Council of Ministers of the Environment (CCME), 2021. Canadian Soil and Groundwater Quality Guidelines for the Protection of Environmental and Human Health, Perfluorooctane Sulfonate (PFOS). [[Media: CCME2018.pdf | Open Access Government Document]]</ref>.  
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*The “worst first” buildings might not be identified correctly by the logic outlined in USEPA’s 2015 guidance and the most impacted buildings might not even be located over a groundwater plume.  Recent studies have shown [[Vapor Intrusion – Sewers and Utility Tunnels as Preferential Pathways |VI impacts in homes as a result of sewer and other subsurface piping connections]], which are not explicitly considered nor easily characterized through conventional VI pathway assessment<ref> Beckley, L, McHugh, T., 2020. A Conceptual Model for Vapor Intrusion from Groundwater Through Sewer Lines. Science of the Total Environment, 698, Article 134283. [https://doi.org/10.1016/j.scitotenv.2019.134283 doi: 10.1016/j.scitotenv.2019.134283]&nbsp;&nbsp; [//www.enviro.wiki/images/4/4e/BeckleyMcHugh2020.pdf  Open Access Article]</ref><ref name="GuoEtAl2015">Guo, Y., Holton, C., Luo, H., Dahlen, P., Gorder, K., Dettenmaier, E., Johnson, P.C., 2015. Identification of Alternative Vapor Intrusion Pathways Using Controlled Pressure Testing, Soil Gas Monitoring, and Screening Model Calculations. Environmental Science and Technology, 49(22), pp. 13472–13482. [https://doi.org/10.1021/acs.est.5b03564 doi: 10.1021/acs.est.5b03564]</ref><ref name="McHughEtAl2017">McHugh, T., Beckley, L., Sullivan, T., Lutes, C., Truesdale, R., Uppencamp, R., Cosky, B., Zimmerman, J., Schumacher, B., 2017.  Evidence of a Sewer Vapor Transport Pathway at the USEPA Vapor Intrusion Research Duplex.  Science of the Total Environment, pp. 598, 772-779. [https://doi.org/10.1016/j.scitotenv.2017.04.135 doi: 10.1016/j.scitotenv.2017.04.135]&nbsp;&nbsp; [//www.enviro.wiki/images/6/63/McHughEtAl2017.pdf  Open Access Manuscipt]</ref><ref name="McHughBeckley2018">McHugh, T., Beckley, L., 2018. Sewers and Utility Tunnels as Preferential Pathways for Volatile Organic Compound Migration into Buildings: Risk Factors and Investigation Protocol. ESTCP ER-201505, Final Report. [https://serdp-estcp.mil/projects/details/f12abf80-5273-4220-b09a-e239d0188421 Project Website]&nbsp;&nbsp; [//www.enviro.wiki/images/5/55/2018b-McHugh-ER-201505_Conceptual_Model.pdf Final Report.pdf]</ref><ref name="RiisEtAl2010">Riis, C., Hansen, M.H., Nielsen, H.H., Christensen, A.G., Terkelsen, M., 2010. Vapor Intrusion through Sewer Systems: Migration Pathways of Chlorinated Solvents from Groundwater to Indoor Air. Seventh International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May, Monterey, CA. Battelle Memorial Institute. ISBN 978-0-9819730-2-9. [https://www.battelle.org/conferences/battelle-conference-proceedings Website]&nbsp;&nbsp; [//www.enviro.wiki/images/9/95/2010-Riis-Migratioin_pathways_of_Chlorinated_Solvents.pdf Report.pdf]</ref>.
 
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*The presumptive remedy for VI mitigation (sub-slab depressurization) may not be effective for all VI scenarios (e.g., those involving vapor migration to indoor spaces via sewer connections).
 
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The '''VI Diagnosis Toolkit''' components were developed considering these limitations as well as more recent knowledge gained through research, development, and validation projects funded by SERDP and ESTCP.
 
  
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==The VI Diagnosis Toolkit Components==
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Wildlife screening levels for abiotic media are back-calculated from food web models developed for representative receptors. Both Zodrow ''et al.''<ref name="ZodrowEtAl2021a"/> and Grippo ''et al.''<ref name="GrippoEtAl2024"/> include the development of risk-based screening levels for wildlife. The Michigan Department of Community Health<ref>Dykema, L.D., 2015. Michigan Department of Community Health Final Report, USEPA Great Lakes Restoration Initiative (GLRI) Project, Measuring Perfluorinated Compounds in Michigan Surface Waters and Fish. Grant GL-00E01122. [https://www.michigan.gov/documents/mdch/MDCH_GL-00E01122-0_Final_Report_493494_7.pdf Free Download]&nbsp; [[Media: MDCH_Geart_Lakes_PFAS.pdf | Report.pdf]]</ref> derived a provisional PFOS surface water value for avian and mammalian wildlife. In California, the San Francisco Bay Regional Water Quality Control Board developed terrestrial habitat soil ecological screening levels based on values developed in Zodrow ''et al.''<ref name="ZodrowEtAl2021a"/>. For PFOS only, a dietary screening level (i.e. applicable to the concentration of PFAS measured in dietary items) has been developed for mammals at 4.6 micrograms per kilogram (μg/kg) wet weight (ww), and for avians at 8.2 μg/kg ww<ref>Environment and Climate Change Canada, 2018. Federal Environmental Quality Guidelines, Perfluorooctane Sulfonate (PFOS). [[Media: ECCC2018.pdf | Repoprt.pdf]]</ref>.
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[[File:DahlenFig1.png|thumb|450px|Figure 1. Vapor intrusion pathway conceptualization considering “alternate VI pathways”, including “pipe flow
 
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VI” and “sewer VI” pathways<ref name="JohnsonEtAl2020" />.]]
 
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The primary components of the VI Diagnosis Toolkit and their uses include:
 
  
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*'''External VI source strength screening''' to identify buildings most likely to be impacted by VI at levels warranting building-specific testing.
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==Approaches for Evaluating Exposures and Effects in AFFF Site Environmental Risk Assessment: Human Health==
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*'''Indoor air source screening''' to locate and remove indoor air sources that might confound building specific VI pathway assessment.
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Exposure pathways and effects for select PFAS are well understood, such that standard human health risk assessment approaches can be used to quantify risks for populations relevant to a site. Human health exposures via drinking water have been the focus in risk assessments and investigations at PFAS sites<ref>Post, G.B., Cohn, P.D., Cooper, K.R., 2012. Perfluorooctanoic acid (PFOA), an emerging drinking water contaminant: A critical review of recent literature. Environmental Research, 116, pp. 93-117. [https://doi.org/10.1016/j.envres.2012.03.007 doi: 10.1016/j.envres.2012.03.007]</ref><ref>Guelfo, J.L., Marlow, T., Klein, D.M., Savitz, D.A., Frickel, S., Crimi, M., Suuberg, E.M., 2018. Evaluation and Management Strategies for Per- and Polyfluoroalkyl Substances (PFASs) in Drinking Water Aquifers: Perspectives from Impacted U.S. Northeast Communities. Environmental Health Perspectives,126(6), 13 pages. [https://doi.org/10.1289/EHP2727 doi: 10.1289/EHP2727]&nbsp; [[Media: GuelfoEtAl2018.pdf | Open Access Article]]</ref>. Risk assessment approaches for PFAS in drinking water follow typical, well-established drinking water risk assessment approaches for chemicals as detailed in regulatory guidance documents for various jurisdictions.  
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*'''Controlled pressurization method (CPM)''' testing to quickly (in a few days or less) measure the worst-case indoor air impact likely to be caused by VI under natural conditions in specific buildings. CPM tests can also be used to identify the presence of indoor air sources and diagnose active VI pathways.
 
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*'''Passive indoor sampling''' for determining long-term average indoor air concentrations under natural VI conditions and/or for verifying mitigation system effectiveness in buildings that warrant VI mitigation.
 
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*'''Comprehensive VI conceptual model development and refinement''' to ensure that appropriate monitoring, investigation, and mitigation strategies are being selected (Figure 1).
 
  
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Expanded discussions for each of these are given below.
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Incidental exposures to soil and dusts for PFAS can occur during a variety of soil disturbance activities, such as gardening and digging, hand-to-mouth activities, and intrusive groundwork by industrial or construction workers. As detailed by the ITRC<ref name="ITRC2023"/>, many US states and USEPA have calculated risk-based screening levels for these soil and drinking water pathways (and many also include dermal exposures to soils) using well-established risk assessment guidance.  
  
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'''External VI source strength screening''' identifies those buildings that warrant more intrusive building-specific assessments, using data collected exterior to the buildings. The use of groundwater and/or soil gas concentration data for building screening has been part of VI pathway assessments for some time and their use is discussed in many regulatory guidance documents. Typically, the measured concentrations are compared to relevant screening levels derived via modeling or empirical analyses from indoor air concentrations of concern.
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Field and laboratory studies have shown that some PFCAs and PFSAs bioaccumulate in fish and other aquatic life at rates that could result in relevant dietary PFAS exposures for consumers of fish and other seafood<ref>Martin, J.W., Mabury, S.A., Solomon, K.R., Muir, D.C., 2003. Dietary accumulation of perfluorinated acids in juvenile rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry, 22(1), pp.189-195. [https://doi.org/10.1002/etc.5620220125 doi: 10.1002/etc.5620220125]</ref><ref>Martin, J.W., Mabury, S.A., Solomon, K.R., Muir, D.C., 2003. Bioconcentration and tissue distribution of perfluorinated acids in rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry, 22(1), pp.196-204. [https://doi.org/10.1002/etc.5620220126 doi: 10.1002/etc.5620220126]</ref><ref>Chen, F., Gong, Z., Kelly, B.C., 2016. Bioavailability and bioconcentration potential of perfluoroalkyl-phosphinic and -phosphonic acids in zebrafish (Danio rerio): Comparison to perfluorocarboxylates and perfluorosulfonates. Science of The Total Environment, 568, pp. 33-41. [https://doi.org/10.1016/j.scitotenv.2016.05.215 doi: 10.1016/j.scitotenv.2016.05.215]</ref><ref>Fang, S., Zhang, Y., Zhao, S., Qiang, L., Chen, M., Zhu, L., 2016. Bioaccumulation of per fluoroalkyl acids including the isomers of perfluorooctane sulfonate in carp (Cyprinus carpio) in a sediment/water microcosm. Environmental Toxicology and Chemistry, 35(12), pp. 3005-3013. [https://doi.org/10.1002/etc.3483 doi: 10.1002/etc.3483]</ref><ref>Bertin, D., Ferrari, B.J.D. Labadie, P., Sapin, A., Garric, J., Budzinski, H., Houde, M., Babut, M., 2014. Bioaccumulation of perfluoroalkyl compounds in midge (Chironomus riparius) larvae exposed to sediment. Environmental Pollution, 189, pp. 27-34. [https://doi.org/10.1016/j.envpol.2014.02.018  doi: 10.1016/j.envpol.2014.02.018]</ref><ref>Bertin, D., Labadie, P., Ferrari, B.J.D., Sapin, A., Garric, J., Geffard, O., Budzinski, H., Babut. M., 2016. Potential exposure routes and accumulation kinetics for poly- and perfluorinated alkyl compounds for a freshwater amphipod: Gammarus spp. (Crustacea). Chemosphere, 155, pp. 380-387. [https://doi.org/10.1016/j.chemosphere.2016.04.006 doi: 10.1016/j.chemosphere.2016.04.006]</ref><ref>Dai, Z., Xia, X., Guo, J., Jiang, X., 2013. Bioaccumulation and uptake routes of perfluoroalkyl acids in Daphnia magna. Chemosphere, 90(5), pp.1589-1596. [https://doi.org/10.1016/j.chemosphere.2012.08.026 doi: 10.1016/j.chemosphere.2012.08.026]</ref><ref>Prosser, R.S., Mahon, K., Sibley, P.K., Poirier, D., Watson-Leung, T. 2016. Bioaccumulation of perfluorinated carboxylates and sulfonates and polychlorinated biphenyls in laboratory-cultured Hexagenia spp., Lumbriculus variegatus and Pimephales promelas from field-collected sediments. Science of The Total Environment, 543(A), pp. 715-726. [https://doi.org/10.1016/j.scitotenv.2015.11.062 doi: 10.1016/j.scitotenv.2015.11.062]</ref><ref>Rich, C.D., Blaine, A.C., Hundal, L., Higgins, C., 2015. Bioaccumulation of Perfluoroalkyl Acids by Earthworms (Eisenia fetida) Exposed to Contaminated Soils. Environmental Science and Technology, 49(2) pp. 881-888. [https://doi.org/10.1021/es504152d doi: 10.1021/es504152d]</ref><ref>Muller, C.E., De Silva, A.O., Small, J., Williamson, M., Wang, X., Morris, A., Katz, S., Gamberg, M., Muir, D.C.G., 2011. Biomagnification of Perfluorinated Compounds in a Remote Terrestrial Food Chain: Lichen–Caribou–Wolf. Environmental Science and Technology, 45(20), pp. 8665-8673. [https://doi.org/10.1021/es201353v doi: 10.1021/es201353v]</ref>. In addition to fish, terrestrial wildlife can accumulate contaminants from impacted sites, resulting in potential exposures to consumers of wild game<ref name="ConderEtAl2021"/>. Additionally, exposures can occur though consumption of homegrown produce or agricultural products that originate from areas irrigated with PFAS-impacted groundwater, or that are amended with biosolids that contain PFAS, or that contain soils that were directly affected by PFAS releases<ref>Brown, J.B, Conder, J.M., Arblaster, J.A., Higgins, C.P.,  2020. Assessing Human Health Risks from Per- and Polyfluoroalkyl Substance (PFAS)-Impacted Vegetable Consumption: A Tiered Modeling Approach. Environmental Science and Technology, 54(23), pp. 15202-15214. [https://doi.org/10.1021/acs.est.0c03411 doi: 10.1021/acs.est.0c03411]&nbsp; [[Media: BrownEtAl2020.pdf | Open Access Article]]</ref>. Multiple studies have found PFAS can be taken up by plants from soil porewater<ref>Blaine, A.C., Rich, C.D., Hundal, L.S., Lau, C., Mills, M.A., Harris, K.M., Higgins, C.P., 2013. Uptake of Perfluoroalkyl Acids into Edible Crops via Land Applied Biosolids: Field and Greenhouse Studies. Environmental Science and Technology, 47(24), pp. 14062-14069. [https://doi.org/10.1021/es403094q doi: 10.1021/es403094q]&nbsp; [https://www.epa.gov/sites/production/files/2019-11/documents/508_pfascropuptake.pdf Free Download from epa.gov]</ref><ref>Blaine, A.C., Rich, C.D., Sedlacko, E.M., Hyland, K.C., Stushnoff, C., Dickenson, E.R.V., Higgins, C.P., 2014. Perfluoroalkyl Acid Uptake in Lettuce (Lactuca sativa) and Strawberry (Fragaria ananassa) Irrigated with Reclaimed Water. Environmental Science and Technology, 48(24), pp. 14361-14368. [https://doi.org/10.1021/es504150h doi: 10.1021/es504150h]</ref><ref>Ghisi, R., Vamerali, T., Manzetti, S., 2019. Accumulation of perfluorinated alkyl substances (PFAS) in agricultural plants: A review. Environmental Research, 169, pp. 326-341. [https://doi.org/10.1016/j.envres.2018.10.023 doi: 10.1016/j.envres.2018.10.023]</ref>, and livestock can accumulate PFAS from drinking water and/or feed<ref>van Asselt, E.D., Kowalczyk, J., van Eijkeren, J.C.H., Zeilmaker, M.J., Ehlers, S., Furst, P., Lahrssen-Wiederhold, M., van der Fels-Klerx, H.J., 2013. Transfer of perfluorooctane sulfonic acid (PFOS) from contaminated feed to dairy milk. Food Chemistry, 141(2), pp.1489-1495. [https://doi.org/10.1016/j.foodchem.2013.04.035 doi: 10.1016/j.foodchem.2013.04.035]</ref>. Thus, when PFAS are present in surface water bodies where fishing or shellfish harvesting occurs or terrestrial areas where produce is grown or game is hunted, the bioaccumulation of PFAS into dietary items can be an important pathway for human exposure.  
  
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More recently it has been discovered that VI impacts can occur via sewer and other subsurface piping connections in areas where vapor migration through the soil would not be expected to be significant, and this could also occur in buildings that do not sit over contaminated groundwater<ref name="RiisEtAl2010" /><ref name="GuoEtAl2015" /><ref name="McHughEtAl2017" /><ref name="McHughBeckley2018" />.  
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PFAAs such as PFOA and PFOS are not expected to volatilize from PFAS-impacted environmental media<ref name="USEPA2016a"/><ref name="USEPA2016b"/> such as soil and groundwater, which are the primary focus of most site-specific risk assessments. In contrast to non-volatile PFAAs, fluorotelomer alcohols (FTOHs) are among the more widely studied of the volatile PFAS. FTOHs are transient in the atmosphere with a lifetime of 20 days<ref>Ellis, D.A., Martin, J.W., De Silva, A.O., Mabury, S.A., Hurley, M.D., Sulbaek Andersen, M.P., Wallington, T.J., 2004. Degradation of Fluorotelomer Alcohols:  A Likely Atmospheric Source of Perfluorinated Carboxylic Acids. Environmental Science and Technology, 38(12), pp. 3316-3321. [https://doi.org/10.1021/es049860w doi: 10.1021/es049860w]</ref>. At most AFFF sites under evaluation, AFFF releases have occurred many years before such that FTOH may no longer be present. As such, the current assumption is that volatile PFAS, such as FTOHs historically released at the site, will have transformed to stable, low-volatility PFAS, such as PFAAs in soil or groundwater, or will they have diffused to the outdoor atmosphere. There is no evidence that FTOHs or other volatile PFAS are persistent in groundwater or soils such that they present an indoor vapor intrusion pathway risk concern as observed for chlorinated solvents. Ongoing research continues for the vapor pathway<ref name="ITRC2023"/>.
  
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Therefore, in addition to groundwater and soil gas sampling, external data collection that includes and extends beyond the area of concern should include manhole vapor sampling (e.g., sanitary sewer, storm sewer, land-drain). Video surveys from sanitary sewers, storm sewers, and/or land-drains can also be used to identify areas of groundwater leakage into utility corridors and lateral connections to buildings that are conduits for vapor transport. During these investigations, it is important to recognize that utility corridors can transmit both impacted water and vapors beyond groundwater plume boundaries, so extending investigations into areas adjacent to groundwater plume boundaries is necessary.
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General and site-specific human health exposure pathways and risk assessment methods as outlined by USEPA<ref>United States Environmental Protection Agency (USEPA), 1989. Risk Assessment Guidance for Superfund: Volume I, Human Health Evaluation Manual (Part A). Office of Solid Waste and Emergency Response, EPA/540/1-89/002. [https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=10001FQY.txt Free Download]&nbsp; [[Media: USEPA1989.pdf | Report.pdf]]</ref><ref name="USEPA1997">United States Environmental Protection Agency (USEPA), 1997. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments, Interim Final. Office of Solid Waste and Emergency Response, EPA 540-R-97-006. [http://semspub.epa.gov/src/document/HQ/157941 Free Download]&nbsp; [[Media: EPA540-R-97-006.pdf | Report.pdf]]</ref> can be applied to PFAS risk assessments for which human health toxicity values have been developed. Additionally, for risk assessments with dietary exposures of PFAS, standard risk assessment food web modeling can be used to develop initial estimates of dietary concentrations which can be confirmed with site-specific tissue sampling programs.
  
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Using projected indoor air concentrations from modeling and empirical data analyses, and distance screening approaches, external source screening can identify areas and buildings that can be ruled out, or conversely, those that warrant building-specific testing.  
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==Approaches for Evaluating Exposures and Effects in AFFF Site Environmental Risk Assessment: Ecological==
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Information available currently on exposures and effects of PFAS in ecological receptors indicate that the PFAS ecological risk issues at most sites are primarily associated with risks to vertebrate wildlife.  Avian and mammalian wildlife are relatively sensitive to PFAS, and dietary intake via bioaccumulation in terrestrial and aquatic food webs can result in exposures that are dominated by the more accumulative PFAS<ref name="LarsonEtAl2018">Larson, E.S., Conder, J.M., Arblaster, J.A., 2018. Modeling avian exposures to perfluoroalkyl substances in aquatic habitats impacted by historical aqueous film forming foam releases. Chemosphere, 201, pp. 335-341. [https://doi.org/10.1016/j.chemosphere.2018.03.004 doi: 10.1016/j.chemosphere.2018.03.004]</ref><ref name="ConderEtAl2020"/><ref name="ZodrowEtAl2021a"/>. Direct toxicity to aquatic life (e.g., fish, pelagic life, benthic invertebrates, and aquatic plants) can occur from exposure to sediment and surface water at effected sites.  For larger areas, surface water concentrations associated with adverse effects to aquatic life are generally higher than those that could result in adverse effects to aquatic-dependent wildlife. Soil invertebrates and plants are generally less sensitive, with risk-based concentrations in soil being much higher than those associated with potential effects to terrestrial wildlife<ref name="ZodrowEtAl2021a"/>.
  
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Demonstration of neighborhood-scale external VI source screening using groundwater, depth, sewer, land drain, and video data is documented in the ER-201501 final report<ref name="JohnsonEtAl2020" />.  
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Aquatic life are exposed to PFAS through direct exposure in surface water and sediment. Ecological risk assessment approaches for PFAS for aquatic life follow standard risk assessment approaches. The evaluation of potential risks for aquatic life with direct exposure to PFAS in environmental media relies on comparing concentrations in external exposure media to protective, media-specific benchmarks, including the aquatic life risk-based screening levels discussed above<ref name="ZodrowEtAl2021a"/><ref name="USEPA2024a">United States Environmental Protection Agency (USEPA), 2024. National Recommended Water Quality Criteria - Aquatic Life Criteria Table. [https://www.epa.gov/wqc/national-recommended-water-quality-criteria-aquatic-life-criteria-table USEPA Website]</ref>.
  
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'''Indoor air source screening''' seeks to locate and remove indoor air sources<ref>Doucette, W.J., Hall, A.J., Gorder, K.A., 2010. Emissions of 1,2-Dichloroethane from Holiday Decorations as a Source of Indoor Air Contamination. Ground Water Monitoring and Remediation, 30(1), pp. 67-73. [https://doi.org/10.1111/j.1745-6592.2009.01267.x doi: 10.1111/j.1745-6592.2009.01267.x] </ref> that might confound building specific VI pathway assessment. Visual inspections and written surveys might or might not identify significant indoor air sources, so these should be complemented with use of portable analytical instruments<ref>McHugh, T., Kuder, T., Fiorenza, S., Gorder, K., Dettenmaier, E., Philp, P., 2011. Application of CSIA to Distinguish Between Vapor Intrusion and Indoor Sources of VOCs. Environmental Science and Technology, 45(14), pp. 5952-5958. [https://doi.org/10.1021/es200988d doi: 10.1021/es200988d]</ref><ref name="BeckleyEtAl2014">Beckley, L., Gorder, K., Dettenmaier, E., Rivera-Duarte, I., McHugh, T., 2014. On-Site Gas Chromatography/Mass Spectrometry (GC/MS) Analysis to Streamline Vapor Intrusion Investigations. Environmental Forensics, 15(3), pp. 234–243. [https://doi.org/10.1080/15275922.2014.930941 doi: 10.1080/15275922.2014.930941]</ref>.
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When an area at the point of PFAS release is an industrial setting which does not feature favorable habitats for terrestrial and aquatic-dependent wildlife, the transport mechanisms may allow PFAS to travel offsite. If offsite or downgradient areas contain ecological habitat, then PFAS transported to these areas are expected to pose the highest risk potential to wildlife, particularly those areas that feature aquatic habitat<ref>Ahrens, L., Bundschuh, M., 2014. Fate and effects of poly- and perfluoroalkyl substances in the aquatic environment: A review. Environmental Toxicology and Chemistry, 33(9), pp. 1921-1929. [https://doi.org/10.1002/etc.2663 doi: 10.1002/etc.2663]&nbsp; [[Media: AhrensBundschuh2014.pdf | Open Access Article]]</ref><ref name="LarsonEtAl2018"/>.
  
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The advantage of portable analytical tools is that they allow practitioners to expeditiously test indoor air concentrations under natural conditions in each room of the building. Concentrations in any room in excess of relevant screening levels trigger more sampling in that room to identify if an indoor source is present in that room. Removal of a suspected source and subsequent room testing can identify if that object or product was the source of the previously measured concentrations.  
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Wildlife receptors, specifically birds and mammals, are typically exposed to PFAS through uptake from dietary sources such as plants and invertebrates, along with direct soil ingestion during foraging activities. Dietary intake modeling typical for ecological risk assessments is the recommended approach for an evaluation of potential risks to wildlife species where PFAS exposure occurs primarily via dietary uptake from bioaccumulation pathways. Dietary intake modeling uses relevant exposure factors for each receptor group (terrestrial birds, terrestrial mammals, aquatic-dependent birds, and aquatic mammals) to determine a total daily intake (TDI) of PFAS via all potential exposure pathways. This approach requires determination of concentrations of PFAS in dietary items, which can be obtained by measuring PFAS in biota at sites or by using food web models to predict concentrations in biota using measured concentrations of PFAS in soil, sediment, or surface water. Food web models use bioaccumulation metrics such as bioaccumulation factors (BAFs) and biomagnification factors (BMFs) with measurements of PFAS in abiotic media to estimate concentrations in dietary items, including plants and benthic or pelagic invertebrates, to model wildlife exposure and calculate TDI. Once site-specific TDI values are calculated, they are compared to known TRVs identified from toxicity data with exposure doses associated with a lack of adverse effects (termed no observed adverse effect level [NOAEL]) or low adverse effects (termed lowest observed adverse effect level [LOAEL]), per standard risk assessment practice<ref name="USEPA1997"/>.
  
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'''Building-specific controlled pressurization method (CPM) testing''' directly measures the worst case indoor air impact, but it can also be used to determine contributing VI pathways and to identify indoor air sources<ref>McHugh, T.E., Beckley, L., Bailey, D., Gorder, K., Dettenmaier, E., Rivera-Duarte, I., Brock, S., MacGregor, I.C., 2012. Evaluation of Vapor Intrusion Using Controlled Building Pressure. Environmental Science and Technology, 46(9), pp. 4792–4799. [https://doi.org/10.1021/es204483g doi: 10.1021/es204483g]</ref><ref name="BeckleyEtAl2014" /><ref name="GuoEtAl2015" /><ref name="HoltonEtAl2015">Holton, C., Guo, Y., Luo, H., Dahlen, P., Gorder, K., Dettenmaier, E., Johnson, P.C., 2015. Long-Term Evaluation of the Controlled Pressure Method for Assessment of the Vapor Intrusion Pathway. Environmental Science and Technology, 49(4), pp. 2091–2098. [https://doi.org/10.1021/es5052342 doi: 10.1021/es5052342]</ref><ref name="JohnsonEtAl2020" /><ref name="GuoEtAl2020a">Guo, Y., Dahlen, P., Johnson, P.C., 2020a. Development and Validation of a Controlled Pressure Method Test Protocol for Vapor Intrusion Pathway Assessment.  Environmental Science and Technology, 54(12), pp. 7117-7125. [https://dx.doi.org/10.1021/acs.est.0c00811 doi: 10.1021/acs.est.0c00811]</ref>. In CPM testing, blowers/fans installed in a doorway(s) or window(s) are set-up to exhaust indoor air to outdoor, which causes the building to be under pressurized relative to the atmosphere. This induces air movement from the subsurface into the test building via openings in the foundation and/or subsurface piping networks with or without direct connections to indoor air. This is similar to what happens intermittently under natural conditions when wind, indoor-outdoor temperature differences, and/or use of appliances that exhaust air from the structure (e.g. dryer exhaust) create an under-pressurized building condition.  
+
Recently, Conder ''et al.''<ref name="ConderEtAl2020"/>, Gobas ''et al.''<ref name="GobasEtAl2020"/>, and Zodrow ''et al.''<ref name="ZodrowEtAl2021a"/> compiled bioaccumulation modeling parameters and approaches for terrestrial and aquatic food web modeling of a variety of commonly detected PFAS at AFFF sites. There are also several sources of TRVs which can be relied upon for estimating TDI values<ref name="ConderEtAl2020"/><ref name="GobasEtAl2020"/><ref name="ZodrowEtAl2021a"/><ref>Newsted, J.L., Jones, P.D., Coady, K., Giesy, J.P., 2005. Avian Toxicity Reference Values for Perfluorooctane Sulfonate. Environmental Science and Technology, 39(23), pp. 9357-9362. [https://doi.org/10.1021/es050989v doi: 10.1021/es050989v]</ref><ref name="Suski2020"/>. In general, the highest risk for PFAS is expected for smaller insectivore and omnivore receptors (e.g., shrews and other small rodents, small nonmigratory birds), which tend to be lower in trophic level and spend more time foraging in small areas similar to or smaller in size than the impacted area. Compared to smaller, lower-trophic level organisms, larger mammalian and avian carnivores are expected to have lower exposures from site-specific PFAS sources because they forage over larger areas that may include areas that are not impacted, as compared to small organisms with small home ranges<ref name="LarsonEtAl2018"/><ref name="ConderEtAl2020"/><ref name="GobasEtAl2020"/><ref name="Suski2020"/><ref name="ZodrowEtAl2021a"/>.
  
−
The blowers/fans can also be used to blow outdoor air into the building, thereby creating a building over-pressurization condition. A positive pressure difference CPM test suppresses VI pathways; therefore, chemicals detected in indoor air above outdoor air concentrations during this condition are attributed to indoor contaminant sources which facilitates the identification of any such indoor air sources.
+
Available information regarding PFAS exposure pathways and effects in aquatic life, terrestrial invertebrates and plants, as well as aquatic and terrestrial wildlife allow ecological risk assessment methods to be applied as outlined by USEPA<ref name="USEPA1997"/> to site-specific PFAS risk assessments. Additionally, food web modeling can be used in site-specific PFAS risk assessment to develop initial estimates of dietary concentrations for aquatic and terrestrial wildlife, which can be confirmed with tissue sampling programs at a site.
  
−
Data collected during CPM testing, when combined with screening level VI modeling, can be used to identify which VI chemical migration pathways are significant contributors to indoor air impacts<ref name="GuoEtAl2015" />. CPM testing guidelines were developed and validated under ESTCP Project ER-201501<ref name="GuoEtAl2020a" /><ref name="JohnsonEtAl2021" />.
+
==PFAS Risk Assessment Data Gaps==
 +
There are a number of data gaps currently associated with PFAS risk assessment including the following:
 +
*'''Unmeasured PFAS:''' There are a number of additional PFAS that we know little about and many PFAS that we are unable to quantify in the environment. The approach to dealing with the lack of information on the overwhelming number of PFAS is being debated; in the meantime, however, PFAS beyond PFOS and PFOA are being studied more, and this information will result in improved characterization of risks for other PFAS.  
  
−
'''Passive samplers''' can be used to measure long term average indoor air concentrations under natural conditions and during VI mitigation system operation. They will provide more confident assessment of long term average concentrations than an infrequent sequence of short term grab samples. Long term average concentrations can also be determined by long term active sampling (e.g., by slowly pulling air through a thermal desorption (TD) tube). However, passive sampling has the advantage that additional equipment and expertise is not required for sampler deployment and recovery.
+
*'''Mixtures:''' Another major challenge in effects assessment for PFAS, for both human health risk assessments and environmental risk assessments, is understanding the potential importance of mixtures of PFAS. Considering the limited human health and ecological toxicity data available for just a few PFAS, the understanding of the relative toxicity, additivity, or synergistic effects of PFAS in mixtures is just beginning.
  
−
Use of passive samplers in indoor air under time-varying concentration conditions was demonstrated and validated by comparing against intensive active sampling in ESTCP Project ER-201501<ref name="JohnsonEtAl2020" /><ref name="GuoEtAl2021">Guo, Y., O’Neill, H., Dahlen, P., and Johnson, P.C.  2021.  Evaluation of Passive Diffusive-Adsorptive Samplers for Use in Assessing Time-Varying Indoor Air Impacts Resulting from Vapor Intrusion.  Groundwater Monitoring and Remediation, 42(1), pp. 38-49.  [https://doi.org/10.1111/gwmr.12481 doi: 10.1111/12481]</ref>.
+
*'''Toxicity Data Gaps:''' For environmental risk assessments, some organisms such as reptiles and benthic invertebrates do not have toxicity data available. Benchmark or threshold concentrations of PFAS in environmental media intended to be protective of wildlife and aquatic organisms suffer from significant uncertainty in their derivation due to the limited number of species for which data are available. As species-specific data becomes available for more types of organisms, the accuracy of environmental risk assessments is likely to improve.  
−
 
 
−
The purpose of maintaining an evergreen '''comprehensive VI conceptual model''' is to ensure that the most complete and up-to-date understanding of the site is informing decisions related to future sampling, data interpretation, and the need for and design of mitigation systems. The VI conceptual model can also serve as an effective communication tool in stakeholder discussions.
 
−
 
 
−
Use of these tools for residential neighborhoods and in non-residential buildings overlying chlorinated solvent groundwater plumes is documented comprehensively in a series of peer reviewed articles<ref name="JohnsonEtAl2020" /><ref name="JohnsonEtAl2021" /><ref name="JohnsonEtAl2022" /><ref name="GuoEtAl2015" /><ref name="GuoEtAl2020a" /><ref name="GuoEtAl2020b">Guo, Y., Dahlen, P., Johnson, P.C. 2020b. Temporal variability of chlorinated volatile organic compound vapor concentrations in a residential sewer and land drain system overlying a dilute groundwater plume. Science of the Total Environment, 702, Article 134756.  [https://doi.org/10.1016/j.scitotenv.2019.134756 doi: 10.1016/j.scitotenv.2019.134756]&nbsp;&nbsp; [//www.enviro.wiki/images/e/e5/GuoEtAl2020b.pdf  Open Access Manuscript]</ref><ref name="GuoEtAl2021" /><ref name="HoltonEtAl2015" />.
 
−
 
 
−
==Summary==
 
−
In summary, the VI Diagnosis Toolkit provides a set of tools that can lead to quicker, more confident, and more cost effective neighborhood-scale VI pathway and impact assessments. Toolkit components and their use can complement conventional methods for assessing and mitigating the vapor intrusion pathway.
 
  
 
==References==
 
==References==
Line 108: Line 99:
  
 
==See Also==
 
==See Also==
−
 
+
[https://www.atsdr.cdc.gov/pfas/health-studies/index.html Agency for Toxic Substances and Disease Registry (ATSDR) PFAS Health Studies]
−
*[https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4000681 Evaluation of Radon and Building Pressure Differences as Environmental Indicators for Vapor Intrusion Assessment]
 
−
*[https://pubs.acs.org/doi/10.1021/es4024767 Temporal Variability of Indoor Air Concentrations under Natural Conditions in a House Overlying a Dilute Chlorinated Solvent Groundwater Plume]
 
−
*[https://serdp-estcp.mil/projects/details/e0d00662-c333-4560-8ae7-60f20b0e714b Integrated Field-Scale, Lab-Scale, and Modeling Studies for Improving Our Ability to Assess the Groundwater to Indoor Air Pathway at Chlorinated Solvent Impacted Sites]
 

Latest revision as of 18:26, 15 October 2025

Remediation of Stormwater Runoff Contaminated by Munition Constituents

Past and ongoing military operations have resulted in contamination of surface soil with munition constituents (MC), which have human and environmental health impacts. These compounds can be transported off site via stormwater runoff during precipitation events. Technologies to “trap and treat” surface runoff before it enters downstream receiving bodies (e.g., streams, rivers, ponds) (see Figure 1), and which are compatible with ongoing range activities are needed. This article describes a passive and sustainable approach for effective management of munition constituents in stormwater runoff.

Related Article(s):


Contributor: Mark E. Fuller

Key Resource(s):

  • SERDP Project ER19-1106: Development of Innovative Passive and Sustainable Treatment Technologies for Energetic Compounds in Surface Runoff on Active Ranges

Background

Surface Runoff Characteristics and Treatment Approaches

File:FullerFig1.png
Figure 1. Conceptual model of passive trap and treat approach for MC removal from stormwater runoff

During large precipitation events the rate of water deposition exceeds the rate of water infiltration, resulting in surface runoff (also called stormwater runoff). Surface characteristics including soil texture, presence of impermeable surfaces (natural and artificial), slope, and density and type of vegetation all influence the amount of surface runoff from a given land area. The use of passive systems such as retention ponds and biofiltration cells for treatment of surface runoff is well established for urban and roadway runoff. Treatment in those cases is typically achieved by directing runoff into and through a small constructed wetland, often at the outlet of a retention basin, or via filtration by directing runoff through a more highly engineered channel or vault containing the treatment materials. Filtration based technologies have proven to be effective for the removal of metals, organics, and suspended solids[1][2][3][4].

Surface Runoff on Ranges

Surface runoff represents a major potential mechanism through which energetics residues and related materials are transported off site from range soils to groundwater and surface water receptors (Figure 2). This process is particularly important for energetics that are water soluble (e.g., NTO and NQ) or generate soluble daughter products (e.g., DNAN and TNT). While traditional MC such as RDX and HMX have limited aqueous solubility, they also exhibit recalcitrance to degrade under most natural conditions. RDX and perchlorate are frequent groundwater contaminants on military training ranges. While actual field measurements of energetics in surface runoff are limited, laboratory experiments have been performed to predict mobile energetics contamination levels based on soil mass loadings[5][6].

Toxicological Effects of PFAS

The characterization of toxicological effects in human health risk assessments is based on toxicological studies of mammalian exposures to per- and polyfluoroalkyl substances (PFAS), primarily studies involving perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The most sensitive noncancer adverse effects involve the liver and kidney, immune system, and various developmental and reproductive endpoints[7]. A select number of PFAS have been evaluated for carcinogenicity, primarily using epidemiological data. Only PFOS and PFOA (and their derivatives) have sufficient data for USEPA to characterize as Likely to Be Carcinogenic to Humans via the oral route of exposure. Epidemiological studies provided evidence of bladder, prostate, liver, kidney, and breast cancers in humans related to PFOS exposure, as well as kidney and testicular cancer in humans and limited evidence of breast cancer related to PFOA exposure[7][8][9].

USEPA’s Integrated Risk Management System (IRIS) Program is developing Toxicological Reviews to improve understanding of the toxicity of several additional PFAS (i.e., not solely PFOA and PFOS). Toxicological Reviews provide an overview of cancer and noncancer health effects based on current literature and, where data are sufficient, derive human health toxicity criteria (i.e., human health oral reference doses and cancer slope factors) that form the basis for risk-based decision making. For risk assessors, these documents provide USEPA reference doses and cancer slope factors that can be used with exposure information and other considerations to assess human health risk. Final Toxicological Reviews have been completed for the following PFAS:

  • Perfluorooctanesulfonic acid (PFOS)
  • Perfluorooctanoic acid (PFOA)
  • Perfluorobutanoic acid (PFBA)
  • Perfluorohexanoic acid (PFHxA)
  • Perfluorobutane sulfonic acid (PFBS)
  • Perfluoropropionic acid (PFPrA)
  • Perfluorohexane sulfonic acid (PFHxS)
  • Lithium bis[(trifluoromethyl)sulfonyl]azanide (HQ-115)
  • Hexafluoropropylene oxide dimer acid (HFPO DA) and its Ammonium Salt

Toxicity assessments are ongoing for the following PFAS:

  • Perfluorononanoic acid (PFNA)
  • Perfluorodecanoic acid (PFDA)

It is important to note human health toxicity criteria for inhalation of PFAS are not included in the Final Toxicological Reviews and are not currently available. In addition to IRIS, state agencies have developed peer-reviewed provisional toxicity values that have been incorporated into USEPA’s RSLs, which are updated biannually. These values have not been reviewed by or incorporated into IRIS.

With respect to ecological toxicity, effects on reproduction, growth, and development of avian and mammalian wildlife have been documented in controlled laboratory studies of exposures of standard toxicological test species (e.g., mice, quail) to PFAS. Many of these studies have been reviewed[10][11][12][13] to derive ecological Toxicity Reference Values (TRVs). TRVs can be used alongside exposure information and other considerations to assess ecological risk. Avian and mammalian wildlife receptors are generally expected to have the highest risks due to PFAS exposure. Direct toxicity to aquatic life, such as fish and invertebrates, from exposure to sediment and surface water also occurs, though concentrations in water associated with adverse effects to aquatic life are generally higher than those that could result in adverse effects to aquatic-dependent wildlife. Soil invertebrates and plants are less sensitive to PFAS when compared to terrestrial wildlife, with risk-based PFAS concentrations in soil being much higher than those associated with potential effects to terrestrial wildlife[13].

PFAS Screening Levels for Human Health and Ecological Risk Assessments

Human Health Screening Levels

Human health screening levels for PFAS have been modified multiple times over the last decade and, in the United States, are currently available for drinking water and soil exposures as Maximum Contaminant Levels (MCLs) and USEPA Regional Screening Levels (RSLs). USEPA finalized a National Primary Drinking Water Regulation (NPDWR) for six PFAS[7]:

  • Perfluorooctanoic acid (PFOA)
  • Perfluorooctane sulfonic acid (PFOS)
  • Perfluorohexane sulfonic acid (PFHxS)
  • Perfluorononanoic acid (PFNA)
  • Hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX chemicals)
  • Perfluorobutane sulfonic acid (PFBS)

MCLs are enforceable drinking water standards based on the most recently available toxicity information that consider available treatment technologies and costs. The MCLs for PFAS include a Hazard Index of 1 for combined exposures to four PFAS. RSLs are developed for use in risk assessments and include soil and tap water screening levels for multiple PFAS. Soil RSLs are based on residential/unrestricted and commercial/industrial land uses, and calculations of site-specific RSLs are available.

Internationally, Canada and the European Union have also promulgated drinking water standards for select PFAS. However, large discrepancies exist among the various regulatory organizations, largely due to the different effect endpoints and exposure doses being used to calculate risk-based levels. The PFAS guidance from the Interstate Technology and Regulatory Council (ITRC) in the US includes a regularly updated compilation of screening values for PFAS and is available on their PFAS website[14]: https://pfas-1.itrcweb.org.

Ecological Screening Levels

Most peer-reviewed literature and regulatory-based environmental quality benchmarks have been developed using data for PFOS and PFOA; however, other select PFAAs have been evaluated for potential effects to aquatic receptors[14][13][10]. USEPA has developed water quality criteria for aquatic life[15][16][17] for PFOA and PFOS. Following extensive reviews of the peer-reviewed literature, Zodrow et al.[13] used the USEPA Great Lakes Initiative methodology[18] to calculate acute and chronic screening levels for aquatic life for 23 PFAS. The Argonne National Laboratory has also developed Ecological Screening Levels for multiple PFAS[19]. In contrast to surface water aquatic life benchmarks, sediment benchmark values are limited. For terrestrial systems, screening levels for direct exposure of soil plants and invertebrates to PFAS in soils have been developed for multiple AFFF-related PFAS[10][13], and the Canadian Council of Ministers of Environment developed several draft thresholds protective of direct toxicity of PFOS in soil[20].

Wildlife screening levels for abiotic media are back-calculated from food web models developed for representative receptors. Both Zodrow et al.[13] and Grippo et al.[19] include the development of risk-based screening levels for wildlife. The Michigan Department of Community Health[21] derived a provisional PFOS surface water value for avian and mammalian wildlife. In California, the San Francisco Bay Regional Water Quality Control Board developed terrestrial habitat soil ecological screening levels based on values developed in Zodrow et al.[13]. For PFOS only, a dietary screening level (i.e. applicable to the concentration of PFAS measured in dietary items) has been developed for mammals at 4.6 micrograms per kilogram (μg/kg) wet weight (ww), and for avians at 8.2 μg/kg ww[22].

Approaches for Evaluating Exposures and Effects in AFFF Site Environmental Risk Assessment: Human Health

Exposure pathways and effects for select PFAS are well understood, such that standard human health risk assessment approaches can be used to quantify risks for populations relevant to a site. Human health exposures via drinking water have been the focus in risk assessments and investigations at PFAS sites[23][24]. Risk assessment approaches for PFAS in drinking water follow typical, well-established drinking water risk assessment approaches for chemicals as detailed in regulatory guidance documents for various jurisdictions.

Incidental exposures to soil and dusts for PFAS can occur during a variety of soil disturbance activities, such as gardening and digging, hand-to-mouth activities, and intrusive groundwork by industrial or construction workers. As detailed by the ITRC[14], many US states and USEPA have calculated risk-based screening levels for these soil and drinking water pathways (and many also include dermal exposures to soils) using well-established risk assessment guidance.

Field and laboratory studies have shown that some PFCAs and PFSAs bioaccumulate in fish and other aquatic life at rates that could result in relevant dietary PFAS exposures for consumers of fish and other seafood[25][26][27][28][29][30][31][32][33][34]. In addition to fish, terrestrial wildlife can accumulate contaminants from impacted sites, resulting in potential exposures to consumers of wild game[35]. Additionally, exposures can occur though consumption of homegrown produce or agricultural products that originate from areas irrigated with PFAS-impacted groundwater, or that are amended with biosolids that contain PFAS, or that contain soils that were directly affected by PFAS releases[36]. Multiple studies have found PFAS can be taken up by plants from soil porewater[37][38][39], and livestock can accumulate PFAS from drinking water and/or feed[40]. Thus, when PFAS are present in surface water bodies where fishing or shellfish harvesting occurs or terrestrial areas where produce is grown or game is hunted, the bioaccumulation of PFAS into dietary items can be an important pathway for human exposure.

PFAAs such as PFOA and PFOS are not expected to volatilize from PFAS-impacted environmental media[8][9] such as soil and groundwater, which are the primary focus of most site-specific risk assessments. In contrast to non-volatile PFAAs, fluorotelomer alcohols (FTOHs) are among the more widely studied of the volatile PFAS. FTOHs are transient in the atmosphere with a lifetime of 20 days[41]. At most AFFF sites under evaluation, AFFF releases have occurred many years before such that FTOH may no longer be present. As such, the current assumption is that volatile PFAS, such as FTOHs historically released at the site, will have transformed to stable, low-volatility PFAS, such as PFAAs in soil or groundwater, or will they have diffused to the outdoor atmosphere. There is no evidence that FTOHs or other volatile PFAS are persistent in groundwater or soils such that they present an indoor vapor intrusion pathway risk concern as observed for chlorinated solvents. Ongoing research continues for the vapor pathway[14].

General and site-specific human health exposure pathways and risk assessment methods as outlined by USEPA[42][43] can be applied to PFAS risk assessments for which human health toxicity values have been developed. Additionally, for risk assessments with dietary exposures of PFAS, standard risk assessment food web modeling can be used to develop initial estimates of dietary concentrations which can be confirmed with site-specific tissue sampling programs.

Approaches for Evaluating Exposures and Effects in AFFF Site Environmental Risk Assessment: Ecological

Information available currently on exposures and effects of PFAS in ecological receptors indicate that the PFAS ecological risk issues at most sites are primarily associated with risks to vertebrate wildlife. Avian and mammalian wildlife are relatively sensitive to PFAS, and dietary intake via bioaccumulation in terrestrial and aquatic food webs can result in exposures that are dominated by the more accumulative PFAS[44][10][13]. Direct toxicity to aquatic life (e.g., fish, pelagic life, benthic invertebrates, and aquatic plants) can occur from exposure to sediment and surface water at effected sites. For larger areas, surface water concentrations associated with adverse effects to aquatic life are generally higher than those that could result in adverse effects to aquatic-dependent wildlife. Soil invertebrates and plants are generally less sensitive, with risk-based concentrations in soil being much higher than those associated with potential effects to terrestrial wildlife[13].

Aquatic life are exposed to PFAS through direct exposure in surface water and sediment. Ecological risk assessment approaches for PFAS for aquatic life follow standard risk assessment approaches. The evaluation of potential risks for aquatic life with direct exposure to PFAS in environmental media relies on comparing concentrations in external exposure media to protective, media-specific benchmarks, including the aquatic life risk-based screening levels discussed above[13][45].

When an area at the point of PFAS release is an industrial setting which does not feature favorable habitats for terrestrial and aquatic-dependent wildlife, the transport mechanisms may allow PFAS to travel offsite. If offsite or downgradient areas contain ecological habitat, then PFAS transported to these areas are expected to pose the highest risk potential to wildlife, particularly those areas that feature aquatic habitat[46][44].

Wildlife receptors, specifically birds and mammals, are typically exposed to PFAS through uptake from dietary sources such as plants and invertebrates, along with direct soil ingestion during foraging activities. Dietary intake modeling typical for ecological risk assessments is the recommended approach for an evaluation of potential risks to wildlife species where PFAS exposure occurs primarily via dietary uptake from bioaccumulation pathways. Dietary intake modeling uses relevant exposure factors for each receptor group (terrestrial birds, terrestrial mammals, aquatic-dependent birds, and aquatic mammals) to determine a total daily intake (TDI) of PFAS via all potential exposure pathways. This approach requires determination of concentrations of PFAS in dietary items, which can be obtained by measuring PFAS in biota at sites or by using food web models to predict concentrations in biota using measured concentrations of PFAS in soil, sediment, or surface water. Food web models use bioaccumulation metrics such as bioaccumulation factors (BAFs) and biomagnification factors (BMFs) with measurements of PFAS in abiotic media to estimate concentrations in dietary items, including plants and benthic or pelagic invertebrates, to model wildlife exposure and calculate TDI. Once site-specific TDI values are calculated, they are compared to known TRVs identified from toxicity data with exposure doses associated with a lack of adverse effects (termed no observed adverse effect level [NOAEL]) or low adverse effects (termed lowest observed adverse effect level [LOAEL]), per standard risk assessment practice[43].

Recently, Conder et al.[10], Gobas et al.[11], and Zodrow et al.[13] compiled bioaccumulation modeling parameters and approaches for terrestrial and aquatic food web modeling of a variety of commonly detected PFAS at AFFF sites. There are also several sources of TRVs which can be relied upon for estimating TDI values[10][11][13][47][12]. In general, the highest risk for PFAS is expected for smaller insectivore and omnivore receptors (e.g., shrews and other small rodents, small nonmigratory birds), which tend to be lower in trophic level and spend more time foraging in small areas similar to or smaller in size than the impacted area. Compared to smaller, lower-trophic level organisms, larger mammalian and avian carnivores are expected to have lower exposures from site-specific PFAS sources because they forage over larger areas that may include areas that are not impacted, as compared to small organisms with small home ranges[44][10][11][12][13].

Available information regarding PFAS exposure pathways and effects in aquatic life, terrestrial invertebrates and plants, as well as aquatic and terrestrial wildlife allow ecological risk assessment methods to be applied as outlined by USEPA[43] to site-specific PFAS risk assessments. Additionally, food web modeling can be used in site-specific PFAS risk assessment to develop initial estimates of dietary concentrations for aquatic and terrestrial wildlife, which can be confirmed with tissue sampling programs at a site.

PFAS Risk Assessment Data Gaps

There are a number of data gaps currently associated with PFAS risk assessment including the following:

  • Unmeasured PFAS: There are a number of additional PFAS that we know little about and many PFAS that we are unable to quantify in the environment. The approach to dealing with the lack of information on the overwhelming number of PFAS is being debated; in the meantime, however, PFAS beyond PFOS and PFOA are being studied more, and this information will result in improved characterization of risks for other PFAS.
  • Mixtures: Another major challenge in effects assessment for PFAS, for both human health risk assessments and environmental risk assessments, is understanding the potential importance of mixtures of PFAS. Considering the limited human health and ecological toxicity data available for just a few PFAS, the understanding of the relative toxicity, additivity, or synergistic effects of PFAS in mixtures is just beginning.
  • Toxicity Data Gaps: For environmental risk assessments, some organisms such as reptiles and benthic invertebrates do not have toxicity data available. Benchmark or threshold concentrations of PFAS in environmental media intended to be protective of wildlife and aquatic organisms suffer from significant uncertainty in their derivation due to the limited number of species for which data are available. As species-specific data becomes available for more types of organisms, the accuracy of environmental risk assessments is likely to improve.

References

  1. ^ Sansalone, J.J., 1999. In-situ performance of a passive treatment system for metal source control. Water Science and Technology, 39(2), pp. 193-200. doi: 10.1016/S0273-1223(99)00023-2
  2. ^ Deletic, A., Fletcher, T.D., 2006. Performance of grass filters used for stormwater treatment—A field and modelling study. Journal of Hydrology, 317(3-4), pp. 261-275. doi: 10.1016/j.jhydrol.2005.05.021
  3. ^ Grebel, J.E., Charbonnet, J.A., Sedlak, D.L., 2016. Oxidation of organic contaminants by manganese oxide geomedia for passive urban stormwater treatment systems. Water Research, 88, pp. 481-491. doi: 10.1016/j.watres.2015.10.019
  4. ^ Seelsaen, N., McLaughlan, R., Moore, S., Ball, J.E., Stuetz, R.M., 2006. Pollutant removal efficiency of alternative filtration media in stormwater treatment. Water Science and Technology, 54(6-7), pp. 299-305. doi: 10.2166/wst.2006.617
  5. ^ Cubello, F., Polyakov, V., Meding, S.M., Kadoya, W., Beal, S., Dontsova, K., 2024. Movement of TNT and RDX from composition B detonation residues in solution and sediment during runoff. Chemosphere, 350, Article 141023. doi: 10.1016/j.chemosphere.2023.141023
  6. ^ Karls, B., Meding, S.M., Li, L., Polyakov, V., Kadoya, W., Beal, S., Dontsova, K., 2023. A laboratory rill study of IMX-104 transport in overland flow. Chemosphere, 310, Article 136866. doi: 10.1016/j.chemosphere.2022.136866  Open Access Article
  7. ^ 7.0 7.1 7.2 United States Environmental Protection Agency (USEPA), 2024. Per- and Polyfluoroalkyl Substances (PFAS) Final PFAS National Primary Drinking Water Regulation. Website
  8. ^ 8.0 8.1 United States Environmental Protection Agency (USEPA), 2016. Drinking Water Health Advisory for Perfluorooctane Sulfonate (PFOS). Office of Water, EPA 822-R-16-004. Free Download  Report.pdf
  9. ^ 9.0 9.1 United States Environmental Protection Agency (USEPA), 2016b. Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA). Office of Water, EPA 822-R-16-005. Free Download  Report.pdf
  10. ^ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 Conder, J., Arblaster, J., Larson, E., Brown, J., Higgins, C., 2020. Guidance for Assessing the Ecological Risks of PFAS to Threatened and Endangered Species at Aqueous Film Forming Foam-Impacted Sites. Strategic Environmental Research and Development Program (SERDP) Project ER 18-1614. Project Website  Guidance Document
  11. ^ 11.0 11.1 11.2 11.3 Gobas, F.A.P.C., Kelly, B.C., Kim, J.J., 2020. Final Report: A Framework for Assessing Bioaccumulation and Exposure Risks of PFAS in Threatened and Endangered Species on AFFF-Impacted Sites. SERDP Project ER18-1502. Project Website  Final Report
  12. ^ 12.0 12.1 12.2 Suski, J.G., 2020. Investigating Potential Risk to Threatened and Endangered Species from Per- and Polyfluoroalkyl Substances (PFAS) on Department of Defense (DoD) Sites. SERDP Project ER18-1626. Project Website  Report.pdf
  13. ^ 13.00 13.01 13.02 13.03 13.04 13.05 13.06 13.07 13.08 13.09 13.10 13.11 13.12 Zodrow, J.M., Frenchmeyer, M., Dally, K., Osborn, E., Anderson, P. and Divine, C., 2021. Development of Per and Polyfluoroalkyl Substances Ecological Risk-Based Screening Levels. Environmental Toxicology and Chemistry, 40(3), pp. 921-936. doi: 10.1002/etc.4975   Open Access Article
  14. ^ 14.0 14.1 14.2 14.3 Interstate Technology and Regulatory Council (ITRC) 2023. PFAS Technical and Regulatory Guidance Document. ITRC PFAS Website
  15. ^ United States Environmental Protection Agency (USEPA), 2022. Fact Sheet: Draft 2022 Aquatic Life Ambient Water Quality Criteria for Perfluorooctanoic acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS)). Office of Water, EPA 842-D-22-005. Fact Sheet
  16. ^ United States Environmental Protection Agency (USEPA), 2024. Final Freshwater Aquatic Life Ambient Water Quality Criteria and Acute Saltwater Aquatic Life Benchmark for Perfluorooctanoic Acid (PFOA). Office of Water, EPA-842-R-24-002. Report.pdf
  17. ^ United States Environmental Protection Agency (USEPA), 2024. Final Freshwater Aquatic Life Ambient Water Quality Criteria and Acute Saltwater Aquatic Life Benchmark for Perfluorooctane Sulfonate (PFOS). Office of Water, EPA-842-R-24-003. Report.pdf
  18. ^ United States Environmental Protection Agency (USEPA), 2012. Water Quality Guidance for the Great Lakes System. Part 132. Government Website  Part132.pdf
  19. ^ 19.0 19.1 Grippo, M., Hayse, J., Hlohowskyj, I., Picel, K., 2024. Derivation of PFAS Ecological Screening Values - Update. Argonne National Laboratory Environmental Science Division. Report.pdf
  20. ^ Canadian Council of Ministers of the Environment (CCME), 2021. Canadian Soil and Groundwater Quality Guidelines for the Protection of Environmental and Human Health, Perfluorooctane Sulfonate (PFOS). Open Access Government Document
  21. ^ Dykema, L.D., 2015. Michigan Department of Community Health Final Report, USEPA Great Lakes Restoration Initiative (GLRI) Project, Measuring Perfluorinated Compounds in Michigan Surface Waters and Fish. Grant GL-00E01122. Free Download  Report.pdf
  22. ^ Environment and Climate Change Canada, 2018. Federal Environmental Quality Guidelines, Perfluorooctane Sulfonate (PFOS). Repoprt.pdf
  23. ^ Post, G.B., Cohn, P.D., Cooper, K.R., 2012. Perfluorooctanoic acid (PFOA), an emerging drinking water contaminant: A critical review of recent literature. Environmental Research, 116, pp. 93-117. doi: 10.1016/j.envres.2012.03.007
  24. ^ Guelfo, J.L., Marlow, T., Klein, D.M., Savitz, D.A., Frickel, S., Crimi, M., Suuberg, E.M., 2018. Evaluation and Management Strategies for Per- and Polyfluoroalkyl Substances (PFASs) in Drinking Water Aquifers: Perspectives from Impacted U.S. Northeast Communities. Environmental Health Perspectives,126(6), 13 pages. doi: 10.1289/EHP2727  Open Access Article
  25. ^ Martin, J.W., Mabury, S.A., Solomon, K.R., Muir, D.C., 2003. Dietary accumulation of perfluorinated acids in juvenile rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry, 22(1), pp.189-195. doi: 10.1002/etc.5620220125
  26. ^ Martin, J.W., Mabury, S.A., Solomon, K.R., Muir, D.C., 2003. Bioconcentration and tissue distribution of perfluorinated acids in rainbow trout (Oncorhynchus mykiss). Environmental Toxicology and Chemistry, 22(1), pp.196-204. doi: 10.1002/etc.5620220126
  27. ^ Chen, F., Gong, Z., Kelly, B.C., 2016. Bioavailability and bioconcentration potential of perfluoroalkyl-phosphinic and -phosphonic acids in zebrafish (Danio rerio): Comparison to perfluorocarboxylates and perfluorosulfonates. Science of The Total Environment, 568, pp. 33-41. doi: 10.1016/j.scitotenv.2016.05.215
  28. ^ Fang, S., Zhang, Y., Zhao, S., Qiang, L., Chen, M., Zhu, L., 2016. Bioaccumulation of per fluoroalkyl acids including the isomers of perfluorooctane sulfonate in carp (Cyprinus carpio) in a sediment/water microcosm. Environmental Toxicology and Chemistry, 35(12), pp. 3005-3013. doi: 10.1002/etc.3483
  29. ^ Bertin, D., Ferrari, B.J.D. Labadie, P., Sapin, A., Garric, J., Budzinski, H., Houde, M., Babut, M., 2014. Bioaccumulation of perfluoroalkyl compounds in midge (Chironomus riparius) larvae exposed to sediment. Environmental Pollution, 189, pp. 27-34. doi: 10.1016/j.envpol.2014.02.018
  30. ^ Bertin, D., Labadie, P., Ferrari, B.J.D., Sapin, A., Garric, J., Geffard, O., Budzinski, H., Babut. M., 2016. Potential exposure routes and accumulation kinetics for poly- and perfluorinated alkyl compounds for a freshwater amphipod: Gammarus spp. (Crustacea). Chemosphere, 155, pp. 380-387. doi: 10.1016/j.chemosphere.2016.04.006
  31. ^ Dai, Z., Xia, X., Guo, J., Jiang, X., 2013. Bioaccumulation and uptake routes of perfluoroalkyl acids in Daphnia magna. Chemosphere, 90(5), pp.1589-1596. doi: 10.1016/j.chemosphere.2012.08.026
  32. ^ Prosser, R.S., Mahon, K., Sibley, P.K., Poirier, D., Watson-Leung, T. 2016. Bioaccumulation of perfluorinated carboxylates and sulfonates and polychlorinated biphenyls in laboratory-cultured Hexagenia spp., Lumbriculus variegatus and Pimephales promelas from field-collected sediments. Science of The Total Environment, 543(A), pp. 715-726. doi: 10.1016/j.scitotenv.2015.11.062
  33. ^ Rich, C.D., Blaine, A.C., Hundal, L., Higgins, C., 2015. Bioaccumulation of Perfluoroalkyl Acids by Earthworms (Eisenia fetida) Exposed to Contaminated Soils. Environmental Science and Technology, 49(2) pp. 881-888. doi: 10.1021/es504152d
  34. ^ Muller, C.E., De Silva, A.O., Small, J., Williamson, M., Wang, X., Morris, A., Katz, S., Gamberg, M., Muir, D.C.G., 2011. Biomagnification of Perfluorinated Compounds in a Remote Terrestrial Food Chain: Lichen–Caribou–Wolf. Environmental Science and Technology, 45(20), pp. 8665-8673. doi: 10.1021/es201353v
  35. ^ Cite error: Invalid <ref> tag; no text was provided for refs named ConderEtAl2021
  36. ^ Brown, J.B, Conder, J.M., Arblaster, J.A., Higgins, C.P., 2020. Assessing Human Health Risks from Per- and Polyfluoroalkyl Substance (PFAS)-Impacted Vegetable Consumption: A Tiered Modeling Approach. Environmental Science and Technology, 54(23), pp. 15202-15214. doi: 10.1021/acs.est.0c03411  Open Access Article
  37. ^ Blaine, A.C., Rich, C.D., Hundal, L.S., Lau, C., Mills, M.A., Harris, K.M., Higgins, C.P., 2013. Uptake of Perfluoroalkyl Acids into Edible Crops via Land Applied Biosolids: Field and Greenhouse Studies. Environmental Science and Technology, 47(24), pp. 14062-14069. doi: 10.1021/es403094q  Free Download from epa.gov
  38. ^ Blaine, A.C., Rich, C.D., Sedlacko, E.M., Hyland, K.C., Stushnoff, C., Dickenson, E.R.V., Higgins, C.P., 2014. Perfluoroalkyl Acid Uptake in Lettuce (Lactuca sativa) and Strawberry (Fragaria ananassa) Irrigated with Reclaimed Water. Environmental Science and Technology, 48(24), pp. 14361-14368. doi: 10.1021/es504150h
  39. ^ Ghisi, R., Vamerali, T., Manzetti, S., 2019. Accumulation of perfluorinated alkyl substances (PFAS) in agricultural plants: A review. Environmental Research, 169, pp. 326-341. doi: 10.1016/j.envres.2018.10.023
  40. ^ van Asselt, E.D., Kowalczyk, J., van Eijkeren, J.C.H., Zeilmaker, M.J., Ehlers, S., Furst, P., Lahrssen-Wiederhold, M., van der Fels-Klerx, H.J., 2013. Transfer of perfluorooctane sulfonic acid (PFOS) from contaminated feed to dairy milk. Food Chemistry, 141(2), pp.1489-1495. doi: 10.1016/j.foodchem.2013.04.035
  41. ^ Ellis, D.A., Martin, J.W., De Silva, A.O., Mabury, S.A., Hurley, M.D., Sulbaek Andersen, M.P., Wallington, T.J., 2004. Degradation of Fluorotelomer Alcohols:  A Likely Atmospheric Source of Perfluorinated Carboxylic Acids. Environmental Science and Technology, 38(12), pp. 3316-3321. doi: 10.1021/es049860w
  42. ^ United States Environmental Protection Agency (USEPA), 1989. Risk Assessment Guidance for Superfund: Volume I, Human Health Evaluation Manual (Part A). Office of Solid Waste and Emergency Response, EPA/540/1-89/002. Free Download  Report.pdf
  43. ^ 43.0 43.1 43.2 United States Environmental Protection Agency (USEPA), 1997. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessments, Interim Final. Office of Solid Waste and Emergency Response, EPA 540-R-97-006. Free Download  Report.pdf
  44. ^ 44.0 44.1 44.2 Larson, E.S., Conder, J.M., Arblaster, J.A., 2018. Modeling avian exposures to perfluoroalkyl substances in aquatic habitats impacted by historical aqueous film forming foam releases. Chemosphere, 201, pp. 335-341. doi: 10.1016/j.chemosphere.2018.03.004
  45. ^ United States Environmental Protection Agency (USEPA), 2024. National Recommended Water Quality Criteria - Aquatic Life Criteria Table. USEPA Website
  46. ^ Ahrens, L., Bundschuh, M., 2014. Fate and effects of poly- and perfluoroalkyl substances in the aquatic environment: A review. Environmental Toxicology and Chemistry, 33(9), pp. 1921-1929. doi: 10.1002/etc.2663  Open Access Article
  47. ^ Newsted, J.L., Jones, P.D., Coady, K., Giesy, J.P., 2005. Avian Toxicity Reference Values for Perfluorooctane Sulfonate. Environmental Science and Technology, 39(23), pp. 9357-9362. doi: 10.1021/es050989v

See Also

Agency for Toxic Substances and Disease Registry (ATSDR) PFAS Health Studies

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