PFASs are a family of synthetic chemicals containing a fully (per-) or partly (poly-) fluorinated carbon chain connected to a carboxylate, sulfonate, or other functional group. Our scientists' experience includes modeling the movement of PFAS from the primary impacted source through the environment, evaluating both direct and indirect exposure pathways, and using biomonitoring data to understand human exposures. In addition, we have developed toxicity values, performed dose response assessments and hazard evaluations for a variety of PFASs, and conducted historical exposure reconstructions.

Project Example: Hazard Evaluation and Human Health Risk Assessment for a Farm After Land Application of Biosolids

Project Overview: Cardno ChemRisk was asked to perform a hazard evaluation and human health risk assessment for a farm in Southern California after twenty years of land application of biosolids as part of litigation. The purpose of these assessments was to determine whether there was a scientific basis for banning agricultural application of Class A-EQ biosolids, based on the allegations that trace chemicals, including perfluoroalkylated substances (PFASs), accumulate through repeated agricultural land application and may cause human and environmental health effects.

Our Approach: For this project, Cardno ChemRisk performed a hazard evaluation and human health risk assessment for a farm in Southern California after twenty years of land application of biosolids. As part of this project, Cardno ChemRisk also designed and conducted some of the sampling for soil, biosolids, groundwater, irrigation water, and plant silage to provide site-specific values for the partitioning of PFAS from biosolids and soil into plants and irrigation water. As consulting experts, Cardno ChemRisk provided technical review and strategic consulting on the potential for exposure and risk assessment issues associated with the litigation at this site.

Our Value: Cardno ChemRisk has extensive experience using applied risk science to help fill data gaps associated with the novel risk assessment scenarios. Because of this experience, we advised our client on the utility of collecting site-specific data on the partitioning of PFAS to plants as part of the risk assessment. At the time, published data on PFAS plant uptake was not readily available and the site-specific information on plant uptake allowed for a more refined risk assessment that demonstrated that there was no concern associated with using biosolids. This risk assessment was key in assisting the client with this litigation.