PFAS are a group of chemicals made for use in industrial and consumer products. They are also processing byproducts and breakdown products of other fluorinated chemicals. PFAS are found ubiquitously in human populations and other species, even in remote locations far from manufacturing or use of PFAS. This wide-spread detection has been attributed to their resistance to biodegradation and their bioaccumulative properties. Detectable concentrations have also been found in surface water, ground water and sediments.
PFAS have been manufactured since the 1950s. PFOS has been used in various capacities, including in stain and water repellants for apparel, carpets, fabrics, leather and upholstery. Additionally, it has been used in food containers, non-stick cookware, paints, paper coatings (approved for food contact), floor polishes, insect formulations, photographic film, cosmetics, shampoos, denture cleaners, fire-fighting foams and fire protection products, alkaline cleaners, coatings, surfactants, including mining and oil wells, and in metal plating and electronic etching baths. PFOA is used in breathable waterproof fabrics, biomaterials, insulations for electrical wiring, and foam fire extinguishers.
PFAS can be absorbed by oral, dermal, and inhaled routes. It is thought that most exposure occurs orally through food and drinking water. Crops grown in PFAS contaminated soil are able to take up and accumulate these compounds. Analysis of foods have revealed the detection of PFAS (specifically, PFOA/PFOS) in apples, bread, canned vegetables, eggs, fish, green beans, ground beef, milk, potatoes, seafood, and sugar. Furthermore, migration of residual PFOA into the diet can occur via PTFE-coated products like dental floss, cookware, and food contact items (e.g. microwave popcorn bags). Locally contaminated drinking water resources are also of concern particularly for those living in areas that are impacted by industrial emissions. Exposure to PFAS contaminated air, house dust, and/or direct contact with PFAS-containing consumer products are other potential sources of exposure.
PFAS accumulate in the liver and gall bladder. PFOA and PFOS have been found to have long half-lives in humans, ranging widely from 1.5-9.1 years for PFOA and 2.2-21.3 years for PFOS. They cross the placenta and have been measured in maternal and cord blood, and breast milk.