Perfluorononanoic acid, or PFNA, is a synthetic perfluorinated carboxylic acid and fluorosurfactant that is also an

environmental contaminant Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

found in people and wildlife along with

PFOS Perfluorooctanesulfonic acid (PFOS) (conjugate base perfluorooctanesulfonate) is a chemical compound having an eight-carbon fluorocarbon chain and a sulfonic acid functional group and thus a perfluorosulfonic acid. It is an anthropogenic (man ...

and PFOA.

Chemistry and properties

In acidic form it is a highly reactive strong

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

. In its conjugate base form as a salt it is stable and commonly ion paired with

ammonium The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...

. In the commercial product

Surflon S-111 Surflon S-111 (CAS 72968-3-88) is a commercial product consisting of perfluorinated carboxylic acids (PFCAs) in ammonium salt form. It is commonly used as a polymerization aid in the production of fluoropolymers. The dominant chemical compound is ...

(CAS 72968-3-88) it is the primary compound present by weight. PFNA is used as

surfactant Surfactants are chemical compounds that decrease the surface tension between two liquids, between a gas and a liquid, or interfacial tension between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming ...

for the production of the

fluoropolymer A fluoropolymer is a fluorocarbon-based polymer with multiple carbon–fluorine bonds. It is characterized by a high resistance to solvents, acids, and bases. The best known fluoropolymer is polytetrafluoroethylene under the brand name "Teflon ...

polyvinylidene fluoride.Supporting Information
(PDF). It is produced mainly in Japan by the oxidation of a linear fluorotelomer

olefin In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

mixture containing F(CF₂)₈CH=CH₂. It can also be synthesized by the carboxylation of F(CF₂)₈I. PFNA can form from the biodegradation of 8:2

fluorotelomer alcohol Fluorotelomer alcohols, or FTOHs, are fluorotelomers with an alcohol functional group. They are volatile precursors to perfluorinated carboxylic acids, such as PFOA and PFNA, and other compounds. Naming Commonly, an individual fluorotelomer alco ...

. Additionally, it is considered a probable degradation product of many other compounds. PFNA is the largest perfluorinated carboxylic acid surfactant. Fluorocarbon derivatives with terminal carboxylates are only surfactants when they possess five to nine carbons. Fluorosurfactants reduce the

surface tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to f ...

of water down to half of what hydrocarbon surfactants can by concentrating at the liquid-air interface due to the lipophobicity of fluorocarbons. PFNA is very stable and is not known to degrade in the environment by oxidative processes because of the strength of the carbon–fluorine bond and the electronegativity of

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

Environmental and health concerns

Like the eight-carbon PFOA, the nine-carbon PFNA is a developmental toxicant and an immune system toxicant. However, longer chain perfluorinated carboxylic acids (PFCAs) are considered more bioaccumulative and toxic. PFNA is an

agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...

of the nuclear receptors PPARα and PPARγ. In the years between 1999–2000 and 2003–2004, the

geometric mean In mathematics, the geometric mean is a mean or average which indicates a central tendency of a set of numbers by using the product of their values (as opposed to the arithmetic mean which uses their sum). The geometric mean is defined as the ...

of PFNA increased from 0.5 parts per billion to 1.0 parts per billion in the US population's

blood serum Serum () is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not u ...

. and has also been found in human follicular fluid In a cross-sectional study of 2003–2004 US samples, a higher (13.9 milligram per deciliter) total cholesterol level was observed in when the highest

quartile In statistics, a quartile is a type of quantile which divides the number of data points into four parts, or ''quarters'', of more-or-less equal size. The data must be ordered from smallest to largest to compute quartiles; as such, quartiles are a ...

was compared to the lowest. Non- HDL cholesterol (or " bad cholesterol") levels were also higher in samples with more PFNA. In bottlenose dolphins from Delaware Bay, PFNA was the perfluorinated carboxylic acid measured in the highest concentration in blood plasma; it was found in concentrations well over 100 parts per billion. PFNA has been detected in polar bears in concentrations over 400 parts per billion. PFNA was the perfluorinated chemical measured in the highest concentration in Russian Baikal seals. However,

is the perfluorinated compound that dominates in most wildlife biomonitoring samples.Supporting Information
(PDF).

Drinking water regulations

In the United States there are no federal drinking water standards for any of the

perfluorinated alkylated substances Per- and polyfluoroalkyl substances (PFASs) are synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. An early definition, from 2011, required that they contain at least one perfluoroalkyl ...

as of late 2020. The

U.S. Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it be ...

(EPA) published a non-enforceable health advisory for PFOA in 2016. The agency's health advisory level for the combined concentrations of PFOA and PFOS is 70 parts per trillion (ppt). In June 2020 the

State of New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

published a drinking water standard for PFOA, the first state to do so.

Public water system Public water system is a regulatory term used in the United States and Canada, referring to certain utilities and organizations providing drinking water. United States The US Safe Drinking Water Act and derivative legislation define "public water ...

s in New Jersey are required to meet a maximum contaminant level (MCL) standard of 14 ppt. The state also set a PFOS standard at 13 ppt. The state had set a standard for PFNA in September 2018, with an MCL of 13 ppt. In August 2020 the

State of Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the l ...

adopted drinking water standards for 5 previously unregulated PFAS compounds and lowered acceptable levels for 2 previously regulated compounds PFOS and PFOA to 16 ppt and 8 ppt respectively. PFNA has a MCL of 6 ppt.

Food Regulation

In 2020, the

European Food Safety Authority The European Food Safety Authority (EFSA) is the agency of the European Union (EU) that provides independent scientific advice and communicates on existing and emerging risks associated with the food chain. EFSA was established in February 2002 ...

added PFNA in its revised safety threshold for PFAS that accumulate in the body. They set the threshold for a group of four PFAS of a

tolerable weekly intake Tolerable weekly intake (TWI) estimates the amount per unit body weight of a potentially harmful substance or contaminant in food or water that can be ingested over a lifetime without risk of adverse health effects. TWI is generally preceded by "pr ...

of 4.4 nanograms per kilogram of body weight per week.

Product Restrictions

In 2020, a California bill was passed banning PFNA as an intentionally added ingredient from cosmetics.

References

External links

Perfluorocarboxylic Acid Content in 116 Articles of CommercePDFCenters for Disease Control and Prevention, Polyfluorochemicals fact sheetPerfluorinated substances and their uses in SwedenPerfluoroalkylated substances, Aquatic environmental assessmentChain of Contamination: The Food Link, Perfluorinated Chemicals (PFCs) Incl. PFOS & PFOA
{{PPAR modulators Perfluorocarboxylic acids PBT substances Anionic surfactants