PFAS Glossary
Comprehensive PFAS glossary with plain-language definitions for key terms, regulations, and treatment technologies.
A
AFFF
Aqueous Film Forming Foam, a firefighting foam containing PFAS compounds. Widely used at military bases, airports, and industrial facilities, AFFF is a major source of environmental PFAS contamination.
B
Bioaccumulation
The process by which PFAS and other chemicals build up in living organisms over time. PFAS bioaccumulate in blood, liver, and other tissues because the body cannot easily eliminate them.
Biomagnification
The increase in PFAS concentration as they move up the food chain. Predators at higher trophic levels, including humans, can have much higher PFAS concentrations than organisms lower in the food web.
Biosolids
Treated sewage sludge applied to agricultural land as fertilizer. Biosolids can contain PFAS from household and industrial sources, leading to contamination of soil, crops, and groundwater when applied to farmland.
C
Contamination Plume
A zone of contaminated groundwater that spreads from a pollution source. PFAS plumes can extend for miles underground, following groundwater flow patterns and affecting wells and surface water.
E
Electrochemical Oxidation
A treatment technology that uses electrical current to generate reactive species that can break down PFAS. Being researched as a potential method for destroying PFAS in water treatment systems.
Environmental Mobility
The tendency of PFAS to move through soil and water systems. PFAS are highly mobile, traveling long distances in groundwater and accumulating in surface water bodies far from original sources.
Environmental Persistence
The ability of PFAS to remain unchanged in the environment for extremely long periods. The carbon-fluorine bond in PFAS is one of the strongest chemical bonds, making these compounds virtually indestructible under normal environmental conditions.
EOF
Extractable Organofluorine, a measurement of total fluorinated organic compounds in a sample. EOF testing can detect PFAS precursors and unknown PFAS compounds not captured by targeted analysis.
G
GAC
Granular Activated Carbon, a common treatment technology for removing PFAS from water. GAC adsorbs PFAS onto its surface but requires regular replacement as it becomes saturated with contaminants.
H
HAL
Health Advisory Level, non-enforceable guidance from EPA about contaminant levels in drinking water that may cause health effects. EPA has established HALs for PFOA and PFOS at 70 parts per trillion combined.
I
Interim Remedial Measures
Temporary actions taken to reduce PFAS exposure while long-term cleanup solutions are developed. May include alternative water supplies, well closures, or containment systems to prevent contamination spread.
Ion Exchange
A water treatment technology that removes PFAS by exchanging them with other ions. Effective for many PFAS compounds but requires specialized resins and generates concentrated waste streams requiring disposal.
L
Landfill Leachate
Liquid that drains from landfills, often containing PFAS from disposed consumer products and industrial waste. Leachate can contaminate groundwater and requires treatment before discharge to water systems.
M
MCL
Maximum Contaminant Level, the highest amount of a contaminant allowed in drinking water under federal Safe Drinking Water Act regulations. EPA has proposed MCLs for PFOA and PFOS.
N
Natural Attenuation
Relying on natural processes to reduce contaminant concentrations over time. Not effective for PFAS due to their environmental persistence, making active remediation necessary for most contamination scenarios.
P
PFAS
Per- and polyfluoroalkyl substances, a class of synthetic chemicals that includes thousands of compounds. PFAS are called 'forever chemicals' because they persist in the environment and human body, breaking down very slowly or not at all.
PFAS Forensics
Scientific methods used to trace PFAS contamination back to specific sources using chemical fingerprinting, isomer ratios, and other analytical techniques. Critical for legal proceedings and cleanup responsibility.
PFAS Precursors
Chemical compounds that can transform into PFAS in the environment through various processes. Precursors may not be detected by standard PFAS testing but contribute to total PFAS contamination over time.
PFBS
Perfluorobutane sulfonic acid, a four-carbon PFAS compound used as a replacement for PFOS in some applications. While shorter-chain, it remains persistent and highly mobile in water systems.
PFHxA
Perfluorohexanoic acid, a shorter-chain PFAS compound increasingly found in environmental samples. Often considered a replacement for longer-chain PFAS but still persistent and mobile in the environment.
PFHxS
Perfluorohexane sulfonic acid, a six-carbon PFAS compound found in firefighting foams, textiles, and other applications. Highly persistent and commonly detected in water supplies near contamination sources.
PFNA
Perfluorononanoic acid, a nine-carbon PFAS compound found in environmental samples and human blood. Used in industrial applications and found as a contaminant in consumer products.
PFOA
Perfluorooctanoic acid, one of the most studied PFAS compounds. Used in manufacturing Teflon and other products, PFOA has been linked to various health effects including cancer, liver damage, and immune system impacts.
PFOS
Perfluorooctane sulfonic acid, a PFAS compound formerly used in stain-resistant fabrics, firefighting foams, and industrial applications. Phased out in many countries due to health and environmental concerns.
Plasma Treatment
An emerging technology that uses ionized gas to break down PFAS compounds. Shows promise for destroying concentrated PFAS waste streams but is still being developed for commercial applications.
ppt
Parts per trillion, a unit of measurement for very small concentrations. Equivalent to one drop of water in 20 Olympic-sized swimming pools. PFAS are often measured in ppt due to their potency at low levels.
R
Remediation
The process of cleaning up PFAS contamination in soil, groundwater, or surface water. Common methods include pump-and-treat systems, soil excavation, and advanced treatment technologies like granular activated carbon.
Reverse Osmosis
A membrane filtration technology that can remove PFAS from water by forcing water through a semi-permeable membrane. Highly effective but expensive and generates concentrated waste requiring management.
S
Source Apportionment
The process of identifying and quantifying different sources contributing to PFAS contamination at a site. Important for determining responsible parties and developing targeted cleanup strategies.
Supercritical Water Oxidation
An advanced treatment process using water at extremely high temperature and pressure to break down PFAS. Promising for concentrated waste streams but requires specialized equipment and high energy input.
Surfactant
A substance that reduces surface tension between two liquids. Many PFAS are surfactants, which explains their use in firefighting foams, cleaning products, and industrial applications.
T
Thermal Treatment
High-temperature processes like incineration used to destroy PFAS. Requires extremely high temperatures (>1000°C) and proper emissions controls to completely break down PFAS compounds.
TOF
Total Organofluorine, the total amount of fluorinated organic compounds in a sample. TOF measurements help identify the complete extent of PFAS contamination including unknown compounds.
U
UCMR5
Unregulated Contaminant Monitoring Rule 5, an EPA program requiring public water systems to monitor for 29 PFAS compounds to gather data for potential future regulation.
V
Vapor Intrusion
The movement of volatile PFAS compounds from contaminated soil or groundwater into buildings through cracks and openings. Can create indoor air quality concerns in buildings near contamination sources.