Perfluorooctanesulfonamide
Encyclopedia
Perfluorooctanesulfonamide (PFOSA) is a synthetic organofluorine compound. It is a fluorocarbon
derivative, or perfluorinated compound, with eight carbons and a terminal sulfonamide
functional group
. PFOSA was an ingredient in 3M
's former Scotchgard
formulation and the compound was used to repel grease and water in food packaging along with other consumer applications. It breaks down to form perfluorooctane sulfonate (PFOS). The perfluorooctanesulfonyl fluoride
-based chemistry that was used to make sulfonamides like PFOSA was phased out by 3M in the United States (US) during 2000–2002 but it has grown in China by other producers.
PFOSA can be synthesized from perfluorooctanesulfonyl halide
s by reaction with liquid ammonia
or by a two step reaction via an azide
followed by reduction with Zn
/HCl
. PFOSA is also a metabolic by-product of N-alkylated perfluorooctanesulfonamides. For example, N-ethyl perfluorooctanesulfonamidoethanol (N-EtFOSE), which was primarily used on paper,
and N-methyl perfluorooctanesulfonamidoethanol (N-MeFOSE), which was primarily used on carpets and textiles, both metabolize via acetate
s to PFOSA.
In addition, PFOSA is thought to be the biologically active form of the insecticide
Sulfluramid (N-ethyl perfluorooctanesulfomamide)
as it is an extremely potent uncoupler of oxidative phosphorylation
with an IC50
of about 1 micromolar (≈500 nanograms per milliliter or parts per billion). PFOSA was the most toxic perfluorinated compound in a study with PC12 cells
. Concentrations ranged from 10 to 250 micromolar in the study (or 5000 to 125,000 parts per billion).
Wildlife biomonitoring studies have found the highest level of PFOSA in the liver
of Common dolphin
(Mediterranean Sea
, Italy) with a concentration of 878 parts per billion; the liver of mink
from Illinois
, US contained 590 parts per billion. In fish, the highest levels detected were in the liver of Norway Pike
(91 parts per billion) and homogenate
s of slimy sculpin
(150 parts per billion) from Lake Ontario
. Differences in biotransformation across species could explain some of its presence. In humans, PFOSA has been detected in sub- to low-parts per billion levels; for example, in 1999–2000 US serum samples, the 95th percentile
(or value where only 5% of the population was higher) was 1.4 parts per billion while in 2003–2004 the 95th percentile fell to 0.2 parts per billion. However, whole blood concentrations are about five times higher than those in blood plasma/serum
.
Fluorocarbon
Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...
derivative, or perfluorinated compound, with eight carbons and a terminal sulfonamide
Sulfonamide (chemistry)
In chemistry, the sulfonamide functional group is -S2-NH2, a sulfonyl group connected to an amine group.A sulfonamide is a compound that contains this group. The general formula is RSO2NH2, where R is some organic group. For example, "methanesulfonamide" is CH3SO2NH2...
functional group
Functional group
In organic chemistry, functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. The same functional group will undergo the same or similar chemical reaction regardless of the size of the molecule it is a part of...
. PFOSA was an ingredient in 3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....
's former Scotchgard
Scotchgard
Scotchgard is a 3M brand of products used to protect fabric, furniture, and carpets from stains.The original formula for Scotchgard was discovered accidentally in 1952 by 3M chemists Patsy Sherman and Samuel Smith...
formulation and the compound was used to repel grease and water in food packaging along with other consumer applications. It breaks down to form perfluorooctane sulfonate (PFOS). The perfluorooctanesulfonyl fluoride
Perfluorooctanesulfonyl fluoride
Perfluorooctanesulfonyl fluoride is a synthetic perfluorinated compound with a sulfonyl fluoride functional group. It is used to make perfluorooctanesulfonic acid and PFOS-based compounds...
-based chemistry that was used to make sulfonamides like PFOSA was phased out by 3M in the United States (US) during 2000–2002 but it has grown in China by other producers.
PFOSA can be synthesized from perfluorooctanesulfonyl halide
Sulfonyl halide
Sulfonyl halide groups occur when a sulfonyl functional group is singly bonded to a halogen atom. They have the general formula R-SO2-X where X is a halogen.-Sulfonyl fluorides:...
s by reaction with liquid ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
or by a two step reaction via an azide
Azide
Azide is the anion with the formula N3−. It is the conjugate base of hydrazoic acid. N3− is a linear anion that is isoelectronic with CO2 and N2O. Per valence bond theory, azide can be described by several resonance structures, an important one being N−=N+=N−...
followed by reduction with Zn
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
/HCl
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
. PFOSA is also a metabolic by-product of N-alkylated perfluorooctanesulfonamides. For example, N-ethyl perfluorooctanesulfonamidoethanol (N-EtFOSE), which was primarily used on paper,
and N-methyl perfluorooctanesulfonamidoethanol (N-MeFOSE), which was primarily used on carpets and textiles, both metabolize via acetate
Acetate
An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...
s to PFOSA.
In addition, PFOSA is thought to be the biologically active form of the insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
Sulfluramid (N-ethyl perfluorooctanesulfomamide)
as it is an extremely potent uncoupler of oxidative phosphorylation
Oxidative phosphorylation
Oxidative phosphorylation is a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all aerobic organisms carry out oxidative phosphorylation to produce ATP,...
with an IC50
IC50
The half maximal inhibitory concentration is a measure of the effectiveness of a compound in inhibiting biological or biochemical function. This quantitative measure indicates how much of a particular drug or other substance is needed to inhibit a given biological process by half...
of about 1 micromolar (≈500 nanograms per milliliter or parts per billion). PFOSA was the most toxic perfluorinated compound in a study with PC12 cells
PC12 cells
PC12 is a cell line derived from a pheochromocytoma of the rat adrenal medulla. PC12 cells stop dividing and terminally differentiate when treated with nerve growth factor...
. Concentrations ranged from 10 to 250 micromolar in the study (or 5000 to 125,000 parts per billion).
Wildlife biomonitoring studies have found the highest level of PFOSA in the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
of Common dolphin
Common dolphin
The common dolphin is the name given to two species of dolphin making up the genus Delphinus.Prior to the mid-1990s, most taxonomists only recognised one species in this genus, the common dolphin Delphinus delphis...
(Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
, Italy) with a concentration of 878 parts per billion; the liver of mink
Mink
There are two living species referred to as "mink": the European Mink and the American Mink. The extinct Sea Mink is related to the American Mink, but was much larger. All three species are dark-colored, semi-aquatic, carnivorous mammals of the family Mustelidae, which also includes the weasels and...
from Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, US contained 590 parts per billion. In fish, the highest levels detected were in the liver of Norway Pike
Esox
Esox is a genus of freshwater fish, the only living genus in the family Esocidae — the esocids which were endemic to North America, Europe and Eurasia during the Paleogene through present.The type species is E. lucius, the northern pike...
(91 parts per billion) and homogenate
Homogenization (biology)
Homogenization is a process that involves breaking apart cells — releasing organelles and cytoplasm.When the purpose is to extract organelles, it is frequently done in two steps; first using a blender to break the tissue up, and then with an ultrasonic or mechanical tissue disruptor. The...
s of slimy sculpin
Slimy Sculpin
The slimy sculpin, Cottus cognatus, is a freshwater species of fish that inhabits cool, rocky streams, rivers and lakes throughout northern North America and eastern Siberia. The slimy sculpin is found in freshwater and sometimes brackish water in areas with rocky or gravel type bottoms...
(150 parts per billion) from Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
. Differences in biotransformation across species could explain some of its presence. In humans, PFOSA has been detected in sub- to low-parts per billion levels; for example, in 1999–2000 US serum samples, the 95th percentile
Percentile
In statistics, a percentile is the value of a variable below which a certain percent of observations fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found...
(or value where only 5% of the population was higher) was 1.4 parts per billion while in 2003–2004 the 95th percentile fell to 0.2 parts per billion. However, whole blood concentrations are about five times higher than those in blood plasma/serum
Blood plasma
Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...
.