PLANT UPTAKE OF SIX PER- AND POLYFLUOROALKYL SUBSTANCES UNDER MAXIMUM UPTAKE CONDITIONS

Perfluorinated compounds (PFCs) are incredibly stable environmental contaminants. In 2014, the United States Environmental Protection Agency labeled perfluorooctanoic acid and perfluorooctanesulfonic acid, the most persistent and toxic PFCs, as emerging contaminants due to their persistence in the environment. Data from animal studies on perfluorinated compounds indicate that they can cause several types of tumors, neonatal death, and may have toxic effects on the immune, liver, and endocrine systems.
While many studies have evaluated the fate of PFAS in aquatic environments, few have looked into the fate of PFAS in terrestrial environments. PFAS are environmentally stable and tend to sorb to soils they come in contact with. It has been proposed that the uptake of PFAS by crops could be a major exposure route for humans. The first two studies we conducted on PFAS plant uptake were used to gain scope on plant uptake of PFAS from soil, refine plant husbandry techniques, and create extraction techniques for PFAS in plant matrices.
In our third study, we evaluated the potential for multi-walled carbon nanotubes to act as a contaminant carrier for PFOA. We hypothesize that tomato plant uptake potential for PFOA from the soil would be increased when PFOA was sorbed to multi-walled carbon nanotubes in the soil. After conducting the study, we observed that multi-walled carbon nanotubes sorbed with PFOA potentially increased the plant uptake potential for PFOA.
The first objective of our fourth study was to determine the maximum PFAS bioconcentration factors for radish, carrot, and alfalfa. The hypothesis tied to this objective was that previously reported bioconcentration factors did not represent the maximum potential soil PFAS plant uptake for these species. Our results showed we were correct in this hypothesis. The second objective of this study was to use the bioconcentration factors we determined and assess current soil quality regulatory values of PFCs. We concluded that current soil PFAS regulatory values could be as much as 3 orders of magnitude higher than they should be based on exposure values we calculated using potential vegetable consumption.