Joseph G. Allen, Harvard T.H. Chan School of Public Health
Maia Gokhale, Harvard T.H. Chan School of Public Health
Xindi Hu, Harvard T.H. Chan School of Public Health
Elsie Sunderland, Harvard John A. Paulson School of Engineering and Applied Sciences
First produced in 1949, poly- and perfluoroalkyl substances (PFASs), also sometimes referred to as polyfluorinated chemicals (PFCs), are a group of chemical compounds within a set of highly fluorinated substances called fluorochemicals.1 Fluorochemicals are characterized by their carbon-fluorine bonds, one of the strongest elemental bonds, making these compounds extremely persistent in the environment.2 While fluorochemicals can appear in a variety of different structures, PFASs contain unique properties including low surface tension, high durability against friction, and a resistance to biodegradation.3 As a result, PFASs are highly resistant to grease, water and oil, which has resulted in the chemicals widespread manufacture for a variety of industries.4 They are used in many common products, including non-stick cookware, fabrics, upholstery, food packaging, electronics, paints and carpeting. PFASs also serve an industrial purpose as surfactants for products such as firefighting foams that extinguish fuel-based fires in military bases and airports. Because PFASs do not occur in the natural world, their existence is due entirely to human activities.2
PFASs are highly resistant to grease, water and oil. As such, they are used in many common products, including non-stick cookware, fabrics, upholstery, food packaging, electronics, paints and carpeting.
Two of the most prevalent PFASs are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). PFOA and PFOS are released into their surroundings during the manufacture, use, and disposal of fluorochemical products. The hydrophobic and lipophobic properties of these chemicals allow them to bind to blood proteins and accumulate in the liver and gall bladder.5 Combined with their unusually long half-life, many PFASs are able to bioaccumulate in the body for several years at a time.1 In a 2011 study of 7,876 Americans over 12 years of age, researchers detected the presence of 4 PFASs (PFOS, PFOA, PFHxS, PFNA) in 95% of their participants.6 Given the widespread industrial use of these chemicals and their long-range transport abilities,8 traces of PFASs can be found in even the most remote regions of the world; one study conducted between 1981-2000 found traces of PFASs in polar bears and ringed seals in the rural Arctic, several thousand miles away from manufacturing facilities.9
Six million people in the U.S. have PFASs in their drinking water above the EPA health advisory limit.24
PFASs are persistent organic pollutants (POPs); once released they can stay in the environment without breaking down for millennia.5 Humans get exposed to PFASs through multiple pathways such as diet, drinking water, air, dust and usage of consumer products. The water-solubility of PFOA allows it to migrate easily from soil to groundwater, resulting in drinking water contamination.16 Industrial wastewater treatment facilities are not designed to remove PFASs from organic waste,2 making drinking water the primary exposure pathway to PFASs in some areas. Presently, the US EPA has issued a lifetime health advisory for PFOA and PFOS in drinking water at 70 parts per trillion, yet no PFASs have are regulated in the Safe Drinking Water Act (SDWA).22 High concentrations of PFASs in drinking water can be found near industrialized areas due to air and wastewater discharge, near military fire training areas and airports due to use of PFASs-containing fire fighting foam, and near wastewater treatment plants due to industrial and municipal wastewater discharge.23, 24 Six million people in the U.S. have PFASs in their drinking water above the EPA health advisory limit.24 Higher levels of PFASs in blood have also been linked to indoor exposures.25
In 1999, the United States Environmental Protection Agency (EPA) began investigating PFASs in earnest after receiving data suggesting the toxic effects of PFOS in Scotchgard, a popular water-repellant surfactant.10 In 2005, the US EPA identified its carcinogenic potential in a draft risk assessment,11 and the International Agency for Research on Cancer (a part of the World Health Organization) classified PFOA as “possibly carcinogenic” (group 2B) in 2015.12 Over the years, subsequent studies have determined positive associations between PFOA exposure and risk of liver, testicle, mammary gland, and pancreatic cancers,6,12,13 atherosclerosis,14 elevated cholesterol,15 diabetes,16 obesity,17 thyroid disease,18 and decreased antibody production,19 among others. Studies have also found traces of PFASs in cord blood and uterine tissue, identifying links between prenatal PFAS exposure and hormonal imbalances in newborns.15,17
Studies have determined positive associations between PFOA exposure and risk of liver, testicle, mammary gland, and pancreatic cancers,6,12,13 atherosclerosis,14 elevated cholesterol,15 diabetes,16 obesity,17 thyroid disease,18 and decreased antibody production,19
In 2000, in an agreement with the EPA, the major manufacturer discontinued its production of PFOS,20 and in 2002 shut down production of PFOA in partnership with eight other companies and the Center for Disease Control.13 In 2015, Daikin Industries, a global PFASs producer, also ceased its manufacture of PFOA and related substances.21 While major industries are taking significant strides to mitigate the effects of these two PFASs, the production of several other classes of fluorochemicals being used as substitutes has been increasing, whose long-term health effects have not been studied as extensively. Further, while PFOS and PFOA are phased out in the United States, the effort to reduce global emission has been offset by the geographical shift in production from developed countries to emerging Asian economies, especially China.13 PFASs have the potential to undertake long-range transport, so the increase of production overseas still represents a health concern globally.
Consumers and institutional purchasers can avoid purchasing products that use PFASs in order to limit introducing these chemicals into the indoor environment. Indications that a product may contain these chemicals are words on the label that may include: non-stick, stain repellent, water resistant, grease resistant. Many apparel, furnishing and consumer product companies have begun phasing out the use of these chemicals (many more have not). You can call the manufacturer to request information on the use of these chemicals in their products.