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Perfluoroalkyl acid distribution in various plant compartments of edible crops grown in biosolids-amended soils
Blaine, A., C. Rich, E. Sedlacko, L. Hundal, K. Kumar, C. Lau, Marc A. Mills, Kimberly M. Harris, AND C. Higgins. Perfluoroalkyl acid distribution in various plant compartments of edible crops grown in biosolids-amended soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 48(14):7858-65, (2014).
Because of the high-profile nature of findings reported in this manuscript, the Office of Science and Policy at ORD is taking the lead to coordinate with Region 5, OCSPP, OW and OSWER and develop a list of key public health messages and communication strategy for the media when the paper is accepted for publication. IMPACT STATEMENT -This paper represents the continuing efforts at ORE) to support the exposure and health risk assessment of perfluoroalkyl acids (PFAA5) presently conducted by OCSPP, OW and OSWER. The presence of PFAAs in generated waste sludge (biosolids) destined for use in agriculture, whether on farms or in home gardens, has raised concerns about their potential to enter the terrestrial food chain via bioaccumulation in edible plants. Through finding from the Regional Applied Research Effort (RARE) Program administered by ORO, scientists from Region 5, ORB, and the Colorado School of Mines jointly examined the potential for PFAA uptake and bioaccumulation into crops grown in biosolids-amended soils in Illinois farms, and compared to results derived from a greenhouse control study. In addition, the distribution profiles of PFAAs in various plant compartments of edible crops grown in green house with biosolids-amended soils were examined. Findings from this project indicate that uptake and bioaccumulation of PFAAs can occur, but results are strongly dependent on soil concentrations and properties, the type of crops, and specific PFAA analytes. Differential bloaccumulations of PFAAs are seen among roots, shoots and fruits of vegetable evaluated, which can be accounted for by plant anatomy and PFAA physic-chemical properties. In addition, results from this project suggest that edible crops grown in typical biosolids-amended soils are unlikely to be a significant source of long-chain PFAA exposure in humans.
Crop uptake of perfluoroalkyl acids (PFAAs) from biosolids-amended soil has been identified as a potential pathway for PFAA entry into the terrestrial food chain. This study compared the uptake of PFAAs in greenhouse-grown radish (Raphanus sativus), celery (Apium graveolens var.dulce), tomato (Lycopersicon lycopersicum), and sugar snap pea (Pisum sativum var. macrocarpon) from an industrially impacted biosolids-amended soil, a municipal biosolids amended soil, and a control soil. Individual concentrations of PFAAs, on a dry weight basis, in mature, edible portions of crops grown in soil amended with PFAA industrially impacted biosolids were highest for perfluorooctanoate (PFOA; 67 ng/g) in radish root, perfluorobutanoate (PFBA;232 ng/g) in celery shoot, and PFBA (150 ng/g) in pea fruit. Comparatively, PFAA concentrations in edible compartments of crops grown in the municipal biosolids-amended soil and in the control soil were less than 25 ng/g. Bioaccumulation factors (BAFs) were calculated for the root, shoot, and fruit compartments (as applicable) of all crops grown in the industrially impacted soil. BAFs were highest for PFBA in the shoots of all crops, as well as in the fruit compartment of pea. Root soil concentration factors (RCFs) for tomato and pea were independent of PFAA chain length, while radish and celery RCFs showed a slight decrease with increasing chain length. Shoot-soil concentration factors (SCFs) for all crops showed a decrease with increasing chain length (0.11 to 0.36 log decrease per CF2 group). The biggest decrease (0.54-0.58 log decrease per CF2 group) was seen in fruit-soil concentration factors (FCFs). Crop anatomy and PFAA properties were utilized to explain data trends. In general, fruit crops were found to accumulate fewer long chain PFAAs than shoot or root crops presumably due to an increasing number of biological barriers as the contaminant is transported throughout •the plant (roots to shoots to fruits). These data were incorporated into a preliminary conceptual framework for PFAA accumulation in edible crops. In addition, these data suggest that edible crops grown in soils conventionally amended for nutrients with biosolids (that are not impacted by PFAA industries) are unlikely a significant source of long-chain PFAA exposure to humans.