Scientific Overview of PFAS and Drinking Water | AAAS EPI Center
Introduction to Per- and Polyfluoroalkyl Substances (PFAS) A class of thousands of synthetic organic chemicals, per- and polyfluoroalkyl substances (PFAS) are found in a variety of industrial and consumer applications, from clothing and food wrappers to firefighting foam. Designed for long-term stability, temperature resistance, friction reduction, and oil and water repellency, PFAS, often referred to as “forever chemicals,” do not easily break down in the environment. Not enough is known about the health impacts of most PFAS, but even small doses of several of the most-researched compounds can lead to health issues. Anyone can be exposed to these toxic substances 2 . These guides were developed to help local and state leaders understand the current scientific evidence as they begin to address potential PFAS contamination. The information in these guides can help people engage community members, drinking water providers, local and state regulatory agencies, and federal agencies to address PFAS in drinking water. This first guide provides an overview of the current scientific evidence of PFAS occurrence and toxicology, as well as what remains unknown and requires additional research. It explains the properties, history, toxicology, exposure routes, and the current status of federal and state regulations of PFAS. Detected in drinking water and drinking water sources throughout the United States, the chemical properties of PFAS, such as the strength of the carbon-fluorine bonds, make them difficult to treat and remove using conventional water treatment processes. In 2016, the U.S. Environmental Protection Agency (EPA) developed a lifetime health advisory level of 70 nanograms per liter (ng/L) or parts per trillion (ppt) for two PFAS: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), individually or combined. This health advisory, however, is not an enforceable standard. In the absence of enforceable federal regulations, several U.S. states adopted or PFAS include thousands of synthetic chemicals and are made up of carbon chains in which at least one carbon atom is “perfluorinated,” meaning that other than its carbon-atom neighbors, it is bonded only to fluorine atoms. Three primary characteristics, as described in Figure 1 , differentiate PFAS from other chemicals and add to their chemical stability 3 . First, PFAS have carbon chain backbones that can vary in chain length (number of carbon atoms) and impact their chemical stability, toxicity, and persistence in the environment. Their different chemical structures make for diverse chemical properties and unique chemical names such as PFOS and PFOA. proposed drinking water standards for specific PFAS. PFAS Have Unique Chemical Properties
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