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PFAS — Per- and Polyfluoroalkyl Substances

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PFAS HOME
Navigating This Website
About ITRC
Fact Sheets
1 Introduction
2 Naming Conventions and Use
2 PFAS Chemistry and Naming Conventions, History and Use of PFAS, and Sources of PFAS Releases to the Environment overview
2.1 Environmental Significance
2.2 Chemistry, Terminology, and Acronyms
2.3 Emerging Health and Environmental Concerns
2.4 PFAS Reductions and Alternative PFAS Formulations
2.5 PFAS Uses
2.6 PFAS Releases to the Environment
3 Firefighting Foams
3 Firefighting Foams Overview
3.1 Foam Formulations
3.2 AFFF Characteristics
3.3 Mechanisms for Release to the Environment
3.4 AFFF Fate and Transport
3.5 Forensic Analysis of AFFF
3.6 AFFF Procurement and Inventory
3.7 Foam Systems and Operations
3.8 Emergency Firefighting Operations
3.9 Immediate Investigative and Cleanup Actions
3.10 AFFF Disposal
3.11 Firefighting Foam System Replacement
3.12 Federal, State and International Regulations and Guidance
3.13 Foam Research and Development
4 Physical and Chemical Properties
4 Physical and Chemical Properties Overview
4.1 Challenges and Limitations Related to PFAS Physical and Chemical Properties
4.2 Physical Properties
4.3 Chemical Properties
5 Fate and Transport
5 Environmental Fate and Transport Processes Overview
5.1 Fate and Transport Introduction
5.2 Phase Partitioning
5.3 Media-Specific Migration Processes
5.4 Transformations
5.5 PFAS Uptake into Aquatic Organisms
5.6 PFAS Uptake into Plants
6 Occurrence
6 Media-Specific Occurrence Overview
6.1 Air
6.2 Soil and Sediment
6.3 Groundwater
6.4 Surface Water
6.5 Biota
7 Health Effects
7 Human and Ecological Health Effects of select PFAS Overview
7.1 Human Health Effects
7.2 Ecological Toxicology
8 Basis of Regulations
8 Basis of Regulations Overview
8.1 Introduction
8.2 Regulatory Programs
8.3 Differences in the Available Regulations, Advisories, and Guidance Regulatory
9 Site Risk Assessment
9 Site Risk Assessment Overview
9.1 Human Health
9.2 Ecological Risk Assessment
9.3 Uncertainty
10 Site Characterization
10 Site Characterization Overview
10.1 Site Characterization Issues Relevant to PFAS
10.2 Initial Steps
10.3 Site Investigation
10.4 Data Analysis and Interpretation
10.5 Source Identification
11 Sampling and Analysis
11 Sampling and Analytical Methods Overview
11.1 Sampling
11.2 Analytical Methods/Techniques
11.3 Data Evaluation
11.4 Source Identification
12 Treatment Technologies
12 Treatment Technologies Overview
12.1 Overview
12.2 Field-Implemented Liquids Treatment Technologies
12.3 Field-Implemented Solids Treatment Technologies
12.4 Incineration
12.5 Limited Application and Developing Liquids Treatment Technologies
12.6 Limited Application and Developing Solids Treatment Technologies
12.7 Integrated Remedial Solutions
12.8 Sustainability of PFAS Treatment
12.9 Improving Evaluation of PFAS Treatment Technologies
13 Stakeholder Perspectives
13 Stakeholder Perspectives Overview
13.1 Stakeholder Concerns
13.2 Specific Tribal Stakeholder Concerns
13.3 Stakeholder Resources
14 Risk Communication
14 Risk Communication Overview
14.1 Role of Risk Perception: Public Stakeholders and Decision Makers
14.2 Risk Communication Challenges
14.3 Risk Communication Planning and Engagement Tools
15 Case Studies
15 Case Studies Overview
15.1 Site Characterization Case Studies
15.2 Treatment Case Studies
15.3 Risk Assessment Case Study
15.4 Risk Communication Case Studies
16 Surface Water Quality
16 Surface Water Quality
16.1    Introduction
16.2 Protection of Human Health
16.3 Protection of Biota
16.4 Sampling and Analysis
16.5 Surface Water Foam
Additional Information
References
17 Additional Information
17 Additional Information Overview
17.1 Additional Information for Media-Specific Occurrence
17.2 Additional Information for Human Health Effects
17.3 Additional Information for Risk Assessment
Acronyms
Glossary
Acknowledgments
Team Contacts
Document Feedback
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PFAS — Per- and Polyfluoroalkyl Substances
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Glossary

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  • Adsorption
    The mechanism whereby ions or compounds within a liquid or gas adhere to a solid surface upon contact. The term also refers to a method of treating wastes in which activated carbon is used to remove organic compounds from wastewater.
  • AFCEE
    Air Force Center for Engineering and the Environment AMA American Management Association
  • Anion
    A negatively charged ion.
  • Arithmetic mean
    The sum of a collection of numbers divided by the number of numbers in the collection, commonly referred to as the “average”.
  • Biochar
    A carbon-rich, porous solid synthesized by heating biomass, such as wood or manure, in a low-oxygen environment (pyrolysis).
  • Biomaterials
    Materials derived from plants or animals created for use as sorption materials.
  • Cation
    A positively charged ion.
  • Coagulation
    The process of destabilizing a colloid or suspension that unbalances the forces that separate the particles, often by neutralizing the charges on the particles and allowing the particles to clump or settle.
  • EBCT
    A measure of the time during which water to be treated is in contact with the treatment medium in a contact vessel, assuming that all liquid passes through the vessel at the same velocity. EBCT is equal to the volume of the empty bed divided by the flow rate (Sacramento State University 2019).
  • Electro precipitation/electrocoagulation
    The use of an electrical current to enhance the coagulation and precipitation of ionic compounds. The electrical current may attract the compounds to an anode or cathode, or create coagulating ions from a sacrificial anode, or both.
  • empty bed contact time
    A measure of the time during which water to be treated is in contact with the treatment medium in a contact vessel, assuming that all liquid passes through the vessel at the same velocity. EBCT is equal to the volume of the empty bed divided by the flow rate (Sacramento State University 2019).
  • Empty bed contact time (EBCT)
    A measure of the time during which water to be treated is in contact with the treatment medium in a contact vessel, assuming that all liquid passes through the vessel at the same velocity. EBCT is equal to the volume of the empty bed divided by the flow rate (Sacramento State University 2019).
  • Flocculation
    A process in which the suspended particles of a destabilized colloid or suspension form groups or clumps (known as a “floc”). Coagulation and flocculation work together to separate solids and liquids containing colloids and suspensions.
  • Fluorotelomer substance
    A polyfluoroalkyl substance produced by the telomerization process.
  • Geometric mean
    The central tendency or typical value of a set of numbers, derived by multiplying the numbers in a set then finding the nth root of the product, where “n” is the number of values in the set.
  • Head
    The part of a molecule that is a charged functional group attached at one end of the carbon chain tail.
  • Incineration
    Thermal destruction process typically characterized by oxidation at temperatures in excess of 1,000°C.
  • Isomers
    Chemicals with the same chemical formula, but different molecular structures.
  • Membrane fouling
     
  • Micelles
    Particles in which long hydrocarbon tails, repelled by the water molecules and attracted to each other, make up the interior, whereas the negatively charged heads coat the surface and interact with the surrounding water molecules and positive ions (Ege 1999).
  • Mineralization/decomposition/destruction
    The breakdown of a chemical compound into its constituent elements and carbon dioxide and water.
  • Moiety
    A specific group of atoms within a molecule that is responsible for characteristic chemical reactions of that molecule (Helmenstine 2019).
  • Organoclays
    A naturally occurring clay mineral that is organically modified to incorporate cations and enhance the sorption capability.
  • Perfluorinated chemical
    Subset of PFAS. Have carbon chain atoms that are totally fluorinated. Examples are perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) (Buck et al. 2011).
  • Perfluoroalkyl substance
    Fully fluorinated alkane (carbon chain) molecule. They have a chain (tail) of two or more carbons atoms with a charged functional group (head) attached at one end.
  • Permeate
    The water treated by a membrane filtration technology, which has passed through the membrane, and from which PFAS have been removed. The contaminants not passing the membrane accumulate in the filtrate, which also does not pass through the membrane.
  • Polyfluorinated chemical
    Subset of PFAS. Have at least one carbon chain atom that is not totally fluorinated (Buck et al. 2011).
  • Polyfluoroalkyl substance
    The molecule has a nonfluorine atom (typically hydrogen or oxygen) attached to at least one, but not all, carbon atoms, while at least two or more of the remaining carbon atoms in the carbon chain tail are fully fluorinated.
  • Polymer
    Large molecules formed by combining many identical smaller molecules.
  • Reactivation
    The process of treating regenerated GAC to restore treatment properties.
  • Redox
    Chemical reduction-oxidation processes and conditions that can result in the alteration of a chemical compound.
  • Regeneration
    The act of restoring some of the sorption capacity of a sorptive media (that is, activated carbon or ion exchange) by removing the adsorbed matter. For carbon, regeneration is a thermal oxidation process.
  • Stabilization
    A process to reduce mobility of compounds in the environment through physical or chemical means.
  • Surfactant
    A surface-active agent that lowers the surface tension of a liquid.
  • Tail
    The part of a molecule that is a chain of two or more carbon atoms.
  • Thermal desorption
    Thermal treatment process intended to remove the contaminants from a solid medium (such as soil, sediment, carbon) and drive them into the vapor phase.
  • Zwitterion
    An ionic compound containing both positively and negatively charged groups with a net charge of zero.
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