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Perfluorononanoic acid, or PFNA, is a synthetic
perfluorinated carboxylic acid Perfluoroalkyl carboxylic acids (PFCAs), or perfluorocarboxylic acids are compounds of the formula CnF(2n+1)CO2H that belong to the class of per- and polyfluoroalkyl substances. The simplest example is trifluoroacetic acid. These compounds are o ...
and
fluorosurfactant 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 ...
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 and
PFOA Perfluorooctanoic acid (PFOA; conjugate base perfluorooctanoate; also known colloquially as C8, for its 8 carbon chain structure) is a perfluorinated carboxylic acid produced and used worldwide as an industrial surfactant in chemical processes a ...
.


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 A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a ...
form as a salt it is stable and commonly ion paired with ammonium. 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 for the production of the fluoropolymer polyvinylidene fluoride.Supporting Information
(PDF).
It is produced mainly in Japan by the oxidation of a linear
fluorotelomer Fluorotelomers are fluorocarbon-based oligomers, or telomers, synthesized by telomerization. Some fluorotelomers and fluorotelomer-based compounds are a source of environmentally persistent perfluorinated carboxylic acids such as PFOA and PFNA, ...
olefin mixture containing F(CF2)8CH=CH2. It can also be synthesized by the
carboxylation Carboxylation is a chemical reaction in which a carboxylic acid is produced by treating a substrate with carbon dioxide. The opposite reaction is decarboxylation. In chemistry, the term carbonation is sometimes used synonymously with carboxylation ...
of F(CF2)8I. PFNA can form from the
biodegradation Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegradat ...
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 al ...
. Additionally, it is considered a probable degradation product of many other compounds. PFNA is the largest perfluorinated carboxylic acid surfactant. Fluorocarbon derivatives with terminal
carboxylate In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,...; ''carboxylat ...
s 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 ...
of water down to half of what hydrocarbon surfactants can by concentrating at the liquid-air interface due to the
lipophobicity Lipophobicity, also sometimes called lipophobia (from the Greek λιποφοβία from λίπος ''lipos'' "fat" and φόβος ''phobos'' "fear"), is a chemical property of chemical compounds which means " fat rejection", literally "fear of fat". ...
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 The carbon–fluorine bond is a polar covalent bond between carbon and fluorine that is a component of all organofluorine compounds. It is one of the strongest single bonds in chemistry (after the B–F single bond, Si–F single bond, and H–F s ...
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 reactiv ...
.


Environmental and health concerns

Like the eight-carbon
PFOA Perfluorooctanoic acid (PFOA; conjugate base perfluorooctanoate; also known colloquially as C8, for its 8 carbon chain structure) is a perfluorinated carboxylic acid produced and used worldwide as an industrial surfactant in chemical processes a ...
, the nine-carbon PFNA is a developmental toxicant and an immune system toxicant. However, longer chain
perfluorinated carboxylic acid Perfluoroalkyl carboxylic acids (PFCAs), or perfluorocarboxylic acids are compounds of the formula CnF(2n+1)CO2H that belong to the class of per- and polyfluoroalkyl substances. The simplest example is trifluoroacetic acid. These compounds are o ...
s (PFCAs) are considered more
bioaccumulative Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance at a rate faster than that at which the substance is lost or eliminated ...
and
toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
. 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 In the field of molecular biology, nuclear receptors are a class of proteins responsible for sensing steroids, thyroid hormones, vitamins, and certain other molecules. These receptors work with other proteins to regulate the expression of specif ...
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 ...
. 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 was compared to the lowest. Non-
HDL cholesterol High-density lipoprotein (HDL) is one of the five major groups of lipoproteins. Lipoproteins are complex particles composed of multiple proteins which transport all fat molecules (lipids) around the body within the water outside cells. They are ty ...
(or " bad cholesterol") levels were also higher in samples with more PFNA. In
bottlenose dolphins Bottlenose dolphins are aquatic mammals in the genus ''Tursiops.'' They are common, cosmopolitan members of the family Delphinidae, the family of oceanic dolphins. Molecular studies show the genus definitively contains two species: the comm ...
from
Delaware Bay Delaware Bay is the estuary outlet of the Delaware River on the northeast seaboard of the United States. It is approximately in area, the bay's freshwater mixes for many miles with the saltwater of the Atlantic Ocean. The bay is bordered inland ...
, PFNA was the perfluorinated carboxylic acid measured in the highest concentration in
blood plasma Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intr ...
; 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, PFOS is the perfluorinated compound that dominates in most wildlife
biomonitoring In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. Biomonitoring is performed ...
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 (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 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 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 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.


See also

*
Organofluorine compounds Organofluorine chemistry describes the chemistry of the organofluorines, organic compounds that contain the carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refr ...


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