PFAS Terminology and Nomenclature

Common PFAS terms
A word cloud containing some common PFAS terms. Made using Wordit.

Per- and polyfluoroalkyl substances (PFAS) are a ubiquitous emerging public health threat. PFAS terminology can be extremely confusing because it looks like an alphabet soup of similar acronyms. This article is the second of two on PFAS terminology. The first intended to provide an overview of PFAS structure (including what counts as PFAS), this one intends to help demystify PFAS terminology and nomenclature. These are part of a broader series on PFAS including their serendipitous discovery.


PFAS are a large chemical class generally produced in industrial processes which do not produce pure substances; often impurities are introduced to the end product. An isomer is a compound with the same chemical composition as another compound but a different chemical structure.  In the PFAS world the terms “branched” and “linear” refer to differing isomers. As a short hand, people often mean all isomers of a particular compound when they name it. PFAS can also be cyclic in which case the linear/branched nomenclature breaks down.

Linear and branched non-polymeric PFAS are typically composed of two parts: a hydrophobic as well as lipophobic fluorinated carbon backbone and a typically polar hydrophilic functional group.  The suffix philic means an affinity for and phobic means fear or aversion, the prefix hydro means water and lipo is for lipid or fat. 

Structural analogues are compounds similar to other compounds but differing in one aspect. Structural analogues are also known as congeners. An example could be homologues. PFAS with the same functional groups differing in the number of carbons and fluorine atoms in the backbone are known as homologue series. For example, perfluoroalkyl carboxylic acids with 4 fully saturated carbons in the backbone to 12 fully saturated carbons in the backbone would form a homologue series.  A homologue group includes all linear and branched carboxylic acids with the same number of carbons in the backbone. For example, the C8 carboxylic homologue group includes linear perfluoroalkyloctanoic acid (PFOA), isopropyl-PFOA, and 3-methyl-PFOA; there are 89 total theoretically possible C8 carboxylic homologue congeners although in addition to the linear form. The picture below shows some C8 carboxylic homologue congeners, while technically separate compounds for ease they are often referred to as a singular entity.

Examples of branched PFOA
Image courtesy of Battelle Memorial Institute particularly Craig Hutchings and Steve Helgen. While technically different compounds these are often considered together.

Naming Systems

There are 5 main systematic methods currently in use to name fluorinated compounds: the International Union for Pure and Applied Chemistry (IUPAC) nomenclature, the perfluoro nomenclature, code numbers, Chemical Abstract Service (CAS) nomenclature, and F-nomenclature systems. Due to strong similarities, fluorinated organic compounds tend to follow hydrocarbon naming conventions.

Basic Conventions

Many PFAS are acids and may exist as a protonated or anionic form as well as a mixture of both depending on the pH. The pKa values tend to be quite small and scientists generally refer to PFAS with acid functionalities as “acids” rather than carboxylates, sulfonates, or the correct terms even though the dissociated forms may be the only relevant forms. Scientists refer to both the protonated and ionized forms by the same acronyms.  Most perfluorinated acids are environmentally anions.  Some labs report results in the acidic form, some report anions, and some a mixture.  Many times, perfluorinated carboxylic acids are reported as acids (for example perfluorooctanoic acid instead of perfluorooctanoate) and perfluoroalkyl sulfonic acids as anions (for example perfluorooctane sulfonate instead of perfluorooctane sulfonic acid).  This has caused confusion.  The labs are really measuring the concentration of perfluorinated acid anions present; when the lab reports an acid the lab adjusts for the cation. Most sulfonate standards are prepared from salts and the mass adjusted which is why they are often reported that way.  This is especially true for PFHxS, PFOS, ADONA, 9Cl-PF3ONS and 11Cl-PF3OUdS. Section 7.2.3 of EPA Method 537.1 details how to convert to adjust for this.

IUPAC Nomenclature

IUPAC Nomenclature systematically establishes unambiguous, unique, uniform, and consistent compound names based on their chemical structure.  IUPAC Nomenclature can be used for all organic compounds and is not specific to PFAS.  IUPAC Nomenclature is quite literally a book containing many precedents and steps however, the general simplified steps for IUPAC Nomenclature are:

  1. Identify the longest carbon chain.  The longest carbon chain is also known as the “parent chain.”
  2. Identify any groups off the parent chain.
  3. Number the carbons in the parent chain so that the groups off the parent chain have the lowest number.
  4. Number and name the groups just counted.
  5. Put all the name components together in alphabetical order; prefixes such as di- are not used for alphabetical order.

For example, C2F4 is tetrafluoroethene, shown below, is the simplest perfluorinated alkene (fully saturated carbon backbone with no functional groups).

Picture from Wikidata. There are two carbons and a double bond so it is named “ethene.” Tetrafluoro comes from the 4 fluorine atoms attached to the carbons.

Perfluoro Nomenclature

Perfluoro Nomenclature only applied to perfluoroalkyl substances.  It is commonly used to quickly identify fully fluorine saturated carbon compounds. For shorter substances using IUPAC naming conventions is still easy and understandable. Most chemists would immediately understand that hexafluorobenzene (C6F6 – shown below) has a cyclic fully saturated carbon backbone. However, for longer compounds such as pentadecafluorooctanoic acid it is difficult to readily tell which is the motivation for Perfluoro Nomenclature.  The proper IUPAC name for that compound is actually: 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctanoic acid which is fairly cumbersome to use further motivating Perfluoro Nomenclature.  The pentadecafluoro refers to the 15 fluorine atoms, octanoic acid refers to a carboxylic acid functional group that is off the 8th carbon in a chain.  This compound is pictured under hexafluorobenzene.

Picture from Wikimedia. Hexafluoro denotes the 6 fluorine atoms coming off the carbons in the benzine ring. By Buck et al’s or one of the OECD’s PFAS definitions this compound would not be included however, it would be under Glüge et al’s definition. The preferred IUPAC name for this compound is 1,2,3,4,5,6-hexafluorobenzene.
Pentadecafluorooctanoic acid
Pentadecafluorooctanoic acid courtesy of PubChem.

Perfluoro Nomenclature uses the prefix perfluoro along with standard hydrocarbon nomenclature. This simplified naming system has been in place since the 1950s and is the most common naming system among practitioners. The acronyms developed from this system follow a simple pattern; they all start with the prefix PF for perfluoro then have a root based on the carbon backbone, and a suffix denoting the functional group.  The table below gives the roots for C1-C14 and the two most common functional group abbreviations are A for carboxylic acids as well as S for sulfonic acids.

Carbon backbone length naming roots
Table of roots for specific carbon backbone lengths.
Carboxylic and sulfonic functional groups
The carboxylic acid (left) and sulfonic acid (right) functional groups. The R represents some organic chain.

The acronym itself provides a well-defined structure for the PFAS compound.  For instance perfluorobutanesulfonic acid or PFBS is shown below.  The front letters PF stand for per-fluoroalkyl, the B stands for but-, -ane shows there are only single bonds in the carbon backbone which is implied, and the S is for sulfonic acid.  PFBA, PFHpA, and PFDA are also shown.

Perfluorobutanesulfonic acid or PFBS
Perfluorobutanesulfonic acid or PFBS. The sulfonic acid functional group is circled in dashed yellow, the carbons are in red, numbered so that the first carbon is nearest the functional group. By convention, the unlabeled connectors are carbon atoms. Carbon always forms 4 total bonds, if 4 bonds are not shown the carbon by general agreement is bonded to a hydrogen.
Examples of PFAS acronyms
The table shows the appropriate root color coded, carboxylic acid groups are circled in dashed blue and sulfonic acid groups are circled in dashed yellow. PFBS is perfluorobutanesulfonic acid, PFHpA is perfluoroheptanoic acid, and PFDA is perfluorodecanoic acid. PFBA is perfluorobutanoic acid however, butanoic is sometimes replaced by butyric acid in older works.

Should it be necessary to refer to a specific salt for a perfluorinated compound it is customary to write the salt’s common abbreviation in front of the standard perfluorinated abbreviation then drop the acid from the name.  For instance, the ammonium salt of PFOA, ammonium perfluorooctanoate, is often abbreviated APFO. While not strictly included in the perfluorinated system, some polyfluoroalkyl compounds can degrade into perfluorinated compounds. A polyfluoroalkyl compound is one where the carbon backbone is not fully fluorinated. An important subset of polyfluoroalkyl substances are fluorotelomers. Fluorotelomers are substances made from the most common industrial process for perfluorinated compounds, telomerization. In telomerization a transfer agent, known as a telogen, reacts with a polymerizable taxogen (monomer) to produce a telomer.  Generally in commercial production, perfluoroethyl (pentafluoroethyl) iodide as a telogen reacts with tetrafluoroethylene oligomers as taxogens, most commonly tetrafluoroethylene, to produce telomer perfluoroalkyl iodide polymers.  The perfluoroalkyl iodide polymers are then converted into other substances.

Picture from the Big Chemical Encyclopedia showing pentafluoroethyl iodide reacting with tetrafluoroethylene oligomers to produce perfluoroalkyl iodide polymers.

Similar to perfluorinated acids, fluorotelomer substances are typically named for their functional group.  Fluorotelomers often are abbreviated FT followed by their functional group.  There are often numbers preceding the abbreviation such as 8:2. The first number represents the total perfluorinated carbon atoms and the second number the unsaturated carbons atoms.

8:2 FTOH
By convention the unlabeled connectors are carbon atoms. Carbon atoms always have 4 bounds and as this field was developed from hydrocarbon chemistry the hydrogens are typically not shown unless part of a functional group. The carbon atom labeled “2” in green for instance has two hydrogens attached to it. An alcohol group is a hydroxyl connected to an aliphatic carbon.

Code numbers

Systematic names are fantastic in precision but can be difficult to use.  Unless you work with compounds frequently, memorizing the prefix structures and extra rules, which were glossed over in this article can represent an annoying time commitment.  Additionally, it can be error prone especially to infrequent or new users.  Industrial PFAS manufacturers such as ICI Fluoropolymers, ISC, DuPont, and 3M developed inhouse shorthands for PFAS.  As the inhouse systems were not meant for the general public this initially caused confusion. In Organofluorine Chemistry dichlorodifluoromethane (CF2Cl2) is used as an example to illustrate this. Dichlorodifluoromethane was known as Freon-12 by DuPont, Arcton-6 by ICI, and Isceon-122 by ISC. By 1957 a standardized code number system based on DuPont’s system was adopted and formalized as The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 34 which was last updated in 2019. DuPont’s system was first developed by Albert Henne, Thomas Midgley, and Robert McNary in 1929.


Dichlorodifluoromethane (CF2Cl2), better known as Freon-12, was formerly a popular chlorofluorocarbon halomethane refrigerant now banned under the Montreal Protocol. It is now only allowed as a fire suppressant in submarines and aircraft. Picture from the Gas Encyclopedia by Air Liquide.

In the ASHRAE system for pure compounds, a letter designates the primary purpose of the compound, R for refrigerant, P for aerosol propellant, S for solvent, and the numbers are based on the chemical formula.  Sometimes the letter is replaced with a  trade name such as Freon.  For blends, numbers are assigned sequentially based on ASHRAE data review completion date. For an ASHRAE designation, the first digit from the right is the number of fluorine atoms.  The second digit from the right is the number of hydrogen atoms plus one.  The third digit is the number of carbon atoms minus one; if this is a zero then that number would be omitted. The fourth digit is the number of unsaturated carbon-carbon bonds, in saturated compounds this number is omitted. If an upper-case B or I appears the number immediately following it is the number of bromine or iodine atoms respectively. There are often lowercase letters following the numeric designations.  The first appended letter is for substitutions on the central carbon atom, an x represents a chlorine substitution, y for fluorine, and z for hydrogen. The second appended letter designates substitutions on the terminal methylene carbon, =CCl2 is -a, =CClF is -b, =CF2 is -c, =CHCl is -d, =CHF is -e, and =CH2 is -f. Isomers are also designated by a Z or an E appended to the name for “zusammen” or “entgegen” respectively. Zusammen is German for together and entgegen is opposite; they represent cis and trans isomers respectively. 

Cyclic compounds (R300 series), ethers, inorganic fluids (R700 series), and miscellaneous organic compounds (R600 series) have additional rules.  The series are specified so the 000 series are methane based compounds, 100 are ethane based, 200 are propane based, and 300 are cyclic. The 400 series are zeotropes and 500 are azeotropes. The 600 series are other organic compounds. The 700 series are inorganic refrigerants such as ammonia, also known as R-717. The 1000 series which are unsaturated organic compounds such as the new R-1234yf refrigerant. R-1234yf is used for about half of all automobiles built after 2018 and it breaks down into short chained perfluorinated carboxylic acids; specifically, trifluoroacetic acid.

2,3,3,3-Tetrafluoropropene also known as HFO-1234yf and R-1234yf.  It has a greenhouse gas (GHG) warming potential less than that of carbon dioxide. R-134a, which R-1234yf  helped replace, has a GHG warming potential of 1,430 as a comparison. Picture from Wikipedia.
The compound on the left is R-1234ye(E) and the compound on the right is R-1234ye(Z).
The compound on the left is R-1234ye(E) and the compound on the right is R-1234ye(Z).  The part which makes the compound an isomer is circled in dotted blue lines. R-1234 has other possibilities and chemical structures as well which can be further specified by the letters following the numbers. As an example R-1234yc is CH2FCF=CF2.

There are other code systems in use that are more field dependent as well.  For instance, chlorofluorocarbons have a numbering system as do halogenated fire extinguishers.  The Halon numbering system is in comparison very easy; there are always four numbers and left to right the digits represent carbon, fluorine, chlorine, and bromine atoms present in the molecule.  For instance, Halon-1211 (CF2ClBr also known as Freon-12B1) and Halon-1301 (CF3Br which would also be known as R-13B1).  On 1 January 1994 the United States banned the import and production of halons 1211 and 1301 under the Clean Air Act to comply with the Montreal Protocol. These halons are still allowed to be used and recycled halons may be purchased.  Both Halon 1211 and 1301 have Class A, B, and C ratings. Halon-1211 is a “streaming agent,” and more commonly used in hand-held extinguishers because it discharges mostly as a liquid stream.  Halon-1301 is a “flooding agent” and discharges mostly as a gas, allowing it to penetrate tight spaces and behind obstacles making it ideal for enclosed spaces commonly found in aircraft.  The United States owns about 40% of global halon-1301 supply and it will likely stay in use for many years worldwide.  Halon-1301 is critical as it was formerly the only material usable in enclosed spaces where humans were present. 

CAS nomenclature

CAS stands for Chemical Abstract Service (CAS) and it is a division of the American Chemical Society. A CAS number is a unique identifier assigned by CAS to every chemical substance. It includes isotopes, mixtures, alloys, and substances which have unknown or variable composition. CAS numbers do not contain information about the substance structure unlike all previously discussed naming systems, simplified molecular-input line-entry system (SMILES), or the IUPAC International Chemical Identifier (InChI) system.

The same PFAS chemical in different forms will have differing chemical properties because of structural differences.  For example, PFOS (perfluorooctanesulfonic acid) in its acid form (C8HF17O3S) has a CAS number of 1763-23-1, its potassium salt (C8F17KO3S) 2795-39-3, and its ammonium salt (C8H4F17NO3S) 29081-56-9.


F-nomenclature was accepted by the American Chemical Society as an alternative to perfluoro nomenclature because some early fluorochemistry pioneers disliked perfluoro nomenclature. JH Simons in particular disliked perfluoro nomenclature. Simons invented the electrochemical fluoridization processes which was the first industrial process for producing perfluorinated compounds.

In F-nomenclature perfluoropentanoic acid (PFPeA – a C5 fully saturated carboxylic acid) would be F-pentanoic acid. As an aside, C5H10O2 which is pentanoic acid, is also known as valeric acid because it is the cause of the unpleasant smell in valerian.

Picture of valerian by Ivar Leidus.  The unpleasant smell these flowers give off is caused by pentaonic acid.

Some elements of this naming system have survived.  For instance, the symbol -R which indicates an organic backbone sometimes is written -RF to indicate a perfluoro backbone. Also, placing an F internal to a benzene ring structure is a shorthand saying that all the bonds off the ring not otherwise indicated are fluorine instead of hydrogen.  A forerunner to F-nomenclature used a phi (φ) but was generally similar to F-nomenclature. 

Other less common nomenclature systems

In the 1970s, J.H. Simons, an early fluorochemistry pioneer, advocated for placing “for” before the final syllable in standard hydrocarbon nomenclature to convey it was perfluorinated. Organofluorine Chemistry gives the following examples: CF4 as methforane and the perfluorinated version of ethene, CF2=CF2 would be ethforene. 

Conclusion and Key Take Aways

Most PFAS naming systems are designed to reveal information about the basic chemical structure or function and to facilitate communication.  In industrial settings where not many PFAS are used simultaneously it can be easier to use codes to cut down on potential errors common in systematic names.  It is important to understand the basic names within your specific use.

This article is one of several on PFAS. You can read about PFAS discovery, structure, or all my articles on PFAS.


Wastewater and Covid-19 Surveillance

Screenshot of Biobot report
Report from Biobot on Livingston County, MI on Covid-19 from wastewater

Covid-19 is currently a hot topic, environmental health and engineering is no exception. Wastewater is now in international news because of it! This Reuters article from 19 June 2020 for example shows that researchers found RNA from Covid-19 in Milan and Turin’s wastewater in December 2019 before China reported the first cases on 31 December 2019! The Italian National Institutes of Health examined 40 sewage samples collected in northern Italy between October 2019 and February 2020 and found that samples in Milan and Turin from 18 December 2019 showed SARS-Cov-2. Monitoring sewage for health purposes is known as “wastewater-based epidemiology” (WBE).

Early WBE

Using wastewater to track populations is not a new idea. It was first proposed by Christian Daughton in 2001 to track illicit drug use. You can read his paper here. As a former wastewater teacher of mine, COL Timmes, liked to say: “everyone passes through us.” Generally, he meant that you can’t easily hide from the central sewage system. In more polite terms raw wastewater is a reservoir of excretion products such as: parent compounds, metabolites, and genetic material. The earliest widespread use of WBE (then called “sewage epidemiology”) was in 2005 to monitor for illicit drugs which you can find here. After this early case WBE gained traction. At least Australia, Belgium, Germany, Ireland, Italy, the Netherlands, Norway, Spain, South Korea, the United Kingdom, and the United States use WBE to monitor illicit drug use. After this initial use WBE started to take off in public health circles and WBE started to be used to track broader chemical public health indicators, for instance alcohol consumption in Norway, counterfeit medicine distribution in the Netherlands, and even tobacco use in Italy.

Environmental engineers and public health officials eventually realized that any excreted substance that has known kinetic pathways in wastewater could be used to reverse engineer the initial concentration. All these early methods focused on chemicals and were based around mass spectrometry. WBE was then and is still used to study exposure to chemicals or pollutants such as pesticides, herbicides, and flame retardants. After the sewer’s viability as a surveillance network was established, someone around 2008 realized with some work they could use quantitative polymerase chain reaction methods (qPCR) to amplify, detect, and quantify genetic material.

WBE basics

WBE’s popularity continues to increase because exclusive reliance on testing of individuals is slow, costly, and generally impractical. WBE also often serves as a disease early warning indicator because asymptomatic or prodromal individuals typically don’t get tested and there may be underdiagnosis. In cases like this WBE serves as an unbiased community prevalence estimator. This is especially true with Covid-19 whose asymptomatic period is about a fortnight. Ultimately, WBE allows near real-time cheap monitoring of health indicators such as obesity, diabetes, drug use, microbial antibiotic resistance, and disease outbreak. Its use in disease outbreaks offers particularly rich data on genetic diversity of outbreaks and phylogenic analysis can reveal viral ancestry.

In Australia, the University of Queensland has been linking census data to wastewater samples across the country to see the interrelationship between wastewater chemicals and social and economic measures of a population. Doing that opened the study of socioeconomic influences on chemical consumption. This study showed that caffeine consumption is associated with aspects of financial capability and educational attainment in Australia for instance.

WBE success

WBE is successful in sentinel surveillance providing early outbreak warnings and in determining the efficacy of public health interventions. It is remarkably sensitive at picking up infections and viral load in wastewater. For polio for instance, WBE sensitivity is estimated at about 1 case per 10,000 uninfected people. WBE also allows spatial sensitivity by moving “upstream.” WBE can detect variations in circulating strains through phylogenic analysis allowing for comparisons between region and viral genomic evolution. Another important benefit of WBE is that it enables disease prevalence gauging by circumventing individual stigmatization which can arrive from clinical diagnosis (early AIDS research for instance).

SARS-Cov-2 Simplified WBE Procedure

In general all WBE follows the same process: pretreatment, concentration, recovery, secondary concentration, then detection. Detection normally means either molecular analysis or traditional culturing. In an International Water Association (IWA) webinar on 19 June 2020 Charles Gerba, an environmental microbiologist at the Water, Energy, and Sustainable Technology Center (WEST) in the University of Arizona provided an outline of how they were testing:

  • Gather a 500 mL to 1 L sample of wastewater (grab or composite was not specified)
  • Take a 100-250 mL aliquot to process
  • Spike some samples with 229E to test efficiency
  • Store at -80°C for future analysis
  • Centrifuge to remove solids because some virus are lost to solids – in general about 100 mL would spin down to 1-3 mL
  • RT-qPCR: biomarkers (gene targets) N1, N2, N3, E229. Normally N2 and E229 are used to ensure the signal is specific enough. N1 and N3 are typically dropped

Difficulties in WBE Interpretation

WBE sounds amazing and it truly is. It has already been used successfully to track public health threats from polio to alcohol and all these achievements for a field under 20 years old. Its full potential isn’t even near realized at this point. However, there are several issues in the field. The largest is the lack of standardization and inability to compare results between testing facilities. These two factors are intrinsically linked but one will not necessarily solve the other. Another set of issues revolve around tying total loads to population numbers.

Difficulties with standardization

WBE is still a new field. It has not decided upon standards for many common procedures yet. For instance, some areas preform pre-process techniques to lower the risk of catching Covid-19 from working with SARS-Cov-2. Different pre-processing techniques such as pasteurization or filtration, will produce different signal drops.

Even the sample collection is very different. In wastewater there are typically two kinds of sampling: grab and composite. Grab sampling reflects a discrete point in time and space; composite sampling essentially is several grab samples pooled together at regular time or spatial intervals. Composite sampling is the most common in wastewater because varying flow patterns cause hydraulic surges followed by intermittent periods of low to no flow. However, that does not necessarily make it the best method for WBE.

The solids amount in the wastewater can also reduce efficacy of RT-qPCR methods; what phase to analyze (particulate or liquid) can affect results. Likewise, different inhibitors used for sample shipment may reduce the signal strength. The specific method chosen as a standard unfortunately must consider cost as well as effectiveness and test time. Likewise decontamination procedures between tests must be considered.

Difficulties with linking viral loads to population cases

Sewers undergo infiltration and inflow (i/i). Infiltration is where groundwater enters the sewer system through joints or breaks, inflow is where water is channeled into a sewer from various sources into the sewer such as downspouts. Without getting too deep, there are combined, separate, and merged sewer systems referring to surface runoff or sewage removal. Most large cities have merged systems were sewers were initially built as combined but started providing separate runoff and sewage systems. In short, a remote lab won’t necessarily have the proper infrastructural or weather contextualization to interpret the RNA signal in testing.

Another significant hurdle for disease monitoring is figuring out each disease’s excretion pattern. While it may seem reasonable that a greater number of sick people or sicker people excrete a higher viral load this is not always the case. Extrapolating the viral load to clinical cases becomes complicated. If the disease already has a well known viral shedding pattern and spread pattern with significant effort based, on where in the outbreak a disease is, you can get a correlation however it would be predicated upon many assumptions. For diseases with well defined correlations between degree of illness and viral shedding combined with disease transmission knowledge it is not possible to distinguish between one moderately sick person and two or more asymptomatic people with any degree of precision. With novel diseases only trend analysis is possible. Given the unknowns around viral shedding it becomes difficult to determine how the RNA signal drop corresponds with prevalence drops in the local community. It also becomes difficult to determine how strong the signal change needs to be to differentiate from statistical noise.

Correlating viral loads with clinically identified cases becomes even more challenging because of variable excretion rates during the infection, temporal delays, inconsistent spatial variability due to travel leading to use of multiple wastewater treatment systems, i/i, inactivation during transport, or infrequent, absent or inadequate clinical testing. Genomic instability in wastewater, sampling variability (grab/composite), and viral concentration efficiency differences compound these problems.

Where the sample was taken from, for instance from the sewage network or treatment plant, is also believed to effect viral recovery making comparisons difficult. The type of upstream user, for example domestic or industrial, will make a large difference as well. Areas with more septic systems then become harder to check. Likewise there is a divide between smaller more rural populations and larger cities; cities tend to create more normalization and may not necessarily be compared to their rural counterparts.

Practical difficulties with WBE

The best monitoring schedule at what frequency and spatial resolutions remain open questions which most likely vary across diseases. Likewise, who pays for the monitoring is an important consideration. Currently, WEST’s price list is between $350 and $1,250 per sample depending on how exactly they perform and analyze the sample. The quantification level can be tricky as well since most PCR techniques were developed for the clinical setting instead of an environmental one. There is also a privacy issue with this sort of monitoring.


WBE is an amazing tool for disease monitoring but is better suited to looking at trends because direct comparisons across catchments remains elusive. Since some aspects rely on data individual to specific catchments (recent precipitation, sewer condition, length of sewer and viral decay in sewer transport etc…) direct comparisons between viral loads may never really be achieved.

Further Resources

US EPA on Coronavirus in water and wastewater

Research Centers:


  • Kitajima, M., Ahmed, W., Bibby, K., Carducci, A., Gerba, C. P., Hamilton, K. A., … & Rose, J. B. (2020). SARS-CoV-2 in wastewater: State of the knowledge and research needs. Science of The Total Environment, 139076
  • Nemudryi, A., Nemudraia, A., Surya, K., Wiegand, T., Buyukyoruk, M., Wilkinson, R., & Wiedenheft, B. (2020). Temporal detection and phylogenetic assessment of SARS-CoV-2 in municipal wastewater. medRxiv : the preprint server for health sciences, 2020.04.15.20066746
  • Venugopal, Anila, Harsha Ganesan, Suresh Selvapuram Sudalaimuthu Raja, Vivekanandhan Govindasamy, Manimekalan Arunachalam, Arul Narayanasamy, Palanisamy Sivaprakash et al. “Novel Wastewater Surveillance Strategy for Early Detection of COVID–19 Hotspots.” Current Opinion in Environmental Science & Health (2020)
  • Ahmed, W., Angel, N., Edson, J., Bibby, K., Bivins, A., O’Brien, J. W., … & Tscharke, B. (2020). First confirmed detection of SARS-CoV-2 in untreated wastewater in Australia: A proof of concept for the wastewater surveillance of COVID-19 in the community. Science of The Total Environment, 138764
  • Gracia-Lor, E., Castiglioni, S., Bade, R., Been, F., Castrignanò, E., Covaci, A., … & Lai, F. Y. (2017). Measuring biomarkers in wastewater as a new source of epidemiological information: Current state and future perspectives. Environment international, 99, 131-150
  • Xagoraraki, I., & O’Brien, E. (2020). Wastewater-based epidemiology for early detection of viral outbreaks. In Women in Water Quality (pp. 75-97). Springer, Cham