PFAS Biomonitoring in Higher Exposed Populations

Abstract

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have a wide range of applications as a result of their chemical and thermal stability of the C-F bond and their hydrophobic and lipophobic characteristics. Because of these unique physical and chemical properties there have been numerous industrial and consumer applications. These characteristics have also resulted in the widespread presence and persistence of PFAS in the environment and detection in biological tissue in humans. In general, biomonitoring trend studies of the PFAS, in particular PFOS and PFOA, within the general population have shown marked declines in PFOS since a May 2000 phase-out announcement by a major manufacturer. The trends, however, for PFOA are more inconclusive as multiple manufacturers of PFOA and its various precursors (e.g., fluorotelomer alcohols) remain. Higher exposed populations can be defined by identifiable exposures (e.g., environmental, occupational) that have resulted in serum, plasma, or whole blood concentrations of PFASs that are substantively larger than those reported in the general population. Although some investigators refer to these populations as ‘highly exposed’, this description does not sufficiently describe the magnitude of exposure that occurs within these populations and/or individuals. Thus, the term ‘higher’ is preferred. For the purpose of this chapter, higher exposed populations and their serum concentrations are described into three categories: (1) PFAS manufacturing and ‘downstream’ production workers; (2) communities affected by specific identifiable sources of PFAS exposure (above background levels) through municipal and/or private water sources; and (3) medical, occupational, and consumer PFAS-related exposures that were targeted to a well-defined group of individuals. Each of these three higher exposure populations are reviewed separately for their biomonitoring data and then compared jointly. PFAS manufacturing workers had serum concentrations 2–3 orders of magnitude higher than those reported in the general population. Depending upon the communities whose drinking water sources were affected with PFAS, these populations tended to have average serum concentrations ranging between 2× and <1 order of magnitude higher than the general population. Individuals, however, within these communities may have had comparable concentrations to those at the higher levels within the manufacturing sector. Likewise, depending on the specific medical, occupational, and/or consumer exposures, there may have been substantively higher exposures to PFOS and PFOA than reported in the general population.