Study Provides a Data Resource for Per- and Polyfluoroalkyl Substances in Streams Within Iowa Agricultural Watersheds

Per- and polyfluoroalkyl substances (PFAS) make up a class of compounds that have been used in many household and industrial products globally for decades.  The properties that make them attractive for use also lead to public concern because many PFAS have been shown to persist in the environment or to degrade into less-understood PFAS byproducts.

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To date (2022), most environmental research has been conducted near potential PFAS sources such as wastewater treatment plants (WWTPs), airports, or military bases. Although research has documented multiple potential agriculture-related release pathways for PFAS (for example, biosolids and livestock manure), little environmental research exists on the prevalence of PFAS in small streams in agricultural regions of the United States.

To fill this gap, scientists conducted a statewide sampling of PFAS across a region of intense agricultural activity in Iowa. A set of 119 stream-water samples from 60 stream sites were collected across Iowa from June 2019 to January 2020 and analyzed for 34 PFAS.

The PFAS were detected in streams with and without documented sources of urban wastewater; however, sites with the greatest number of PFAS detected at the highest concentrations were small streams with identified WWTP discharges. The PFAS were detected in 19 of the 60 streams sampled (32 percent), with 10 different PFAS detected statewide.  Concentrations of detected PFAS ranged from 1 to 134 nanograms per liter in this study and were in a similar range as those reported from a separate study of large rivers throughout the United States with diverse upstream land use that ranged from less than 1 to 501 nanograms per liter.

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The data from this study of PFAS in Iowa streams provides a foundational resource to understand the extent of PFAS occurrence in water resources throughout the Nation. The information provides a resource for future research to address additional questions including: 1) what are the relative contributions of different PFAS sources in streams draining agricultural areas, 2) what is the degree to which instream attenuation (including dilution, volatilization, sorption to sediment, biodegradation via biofilms, and foam formation) is affecting instream PFAS concentrations, and 3) what, if any, are the adverse effects on exposed biota.

This study was supported by the USGS Ecosystems Mission Area’s, Environmental Health Program’s Food Resources Integrated Science Team and was conducted in collaboration with the University of Iowa Center for health Effects of Environmental Contamination. 

The Environmental Health Program scientists are developing innovative techniques to reliably detect PFAS in water and tissue. They use this information to determine where exposure occurs in the environment, and if there are any adverse health effects for fish and wildlife exposed to PFAS. They are also measuring PFAS in drinking water at the tap to provide a resource that can be used to understand  human exposure.