Urban-scale Measurements and Modeling Fate & Transport of PFAS Across Media

Abstract:

Per- and Polyfluoroalkyl Substances (PFAS) have gained attention due to their adverse health effects as well as unknown exposures to legacy and novel compounds. As many of these compounds are stable and persistent, many PFAS compounds have been detected worldwide across different media in the total environment. Thus, comprehensive multi-media PFAS chemical concentration data are needed to study PFAS human exposure and health impacts. While some PFAS measurements and exposure studies are available, no comprehensive PFAS measurement data exist at continental scale. Also, it is not clear to the local and federal government agencies as to how to account for the spatiotemporal distributions of PFAS contaminations and associated long-term health impacts. Such issues are acute at local to urban scales. Thus, the in-depth understanding of fate and transport of PFAS across media is much needed and may provide critical information for stakeholders.

The Washington Works plant in Parkersburg, West Virginia has emitted long-chain perfluorooctanoic acid (PFOA) into the environment for decades and at present it continues to emit hexafluoropropylene oxide dimer acid [(HFPO-DA), GenX]. A database for PFOA at Parkersburg was developed and these PFOA measurements in air, water, and soil provide a good opportunity to validate the multi-media modeling system. We are tailoring a robust and efficient suite of modeling tools to simulate PFAS fate and transport in air, water, and soil at urban scales. For air, a state-of-the-art dispersion model (QUIC) is being tested for PFAS air modeling. For other media, we are testing two state-of-the-art USGS models (MODFLOW and MT3D) for groundwater, the BreZo model for surface water, and EPA’s model PRZM-5 for vadose zone. These modeling tools can be used at seasonal to decadal timescales, and their PFOA estimations can be provided as input data to a high-throughput physiologically based pharmacokinetic (PBPK) model to estimate human exposure to PFAS. The combination of multi-media modeling system and PBPK model bridges the gaps between PFAS emissions and human exposure estimates, and thus can provide the basis for epidemiological studies. This research opens doors to study the association between human exposure to PFAS and specific human diseases.