Uptake of Perfluorinated Alkyl Acids by Hydroponically Grown Lettuce (Lactuca sativa)

Abstract

An uptake study was carried out to assess the potential human exposure to perfluorinated alkyl acids (PFAAs) through the ingestion of vegetables. Lettuce (Lactuca sativa) was grown in PFAA-spiked nutrient solutions at four different concentrations, ranging from 10 ng/L to 10 μg/L. Eleven perfluorinated carboxylic acids (PFCAs) and three perfluorinated sulfonic acids (PFSAs) were analyzed by HPLC-MS/MS. At the end of the experiment, the major part of the total mass of each of the PFAAs (except the short-chain, C4-C7, PFCAs) taken up by plants appeared to be retained in the nonedible part, viz. the roots. Root concentration factors (RCF), foliage/root concentration factors (FRCF), and transpiration stream concentration factors (TSCF) were calculated. For the long chained PFAAs, RCF values were highest, whereas FRCF were lowest. This indicates that uptake by roots is likely governed by sorption of PFAAs to lipid-rich root solids. Translocation from roots to shoots is restricted and highly depending on the hydrophobicity of the compounds. Although the TSCF show that longer-chain PFCAs (e.g., perfluorododecanoic acid) get better transferred from the nutrient solution to the foliage than shorter-chain PFCAs (e.g., perfluoroheptanoic acid), the major fraction of longer-chain PFCAs is found in roots due to additional adsorption from the spiked solution. Due to the strong electron-withdrawing effect of the fluorine atoms the role of the negative charge of the dissociated PFAAs is likely insignificant.

Field study on the uptake and translocation of perfluoroalkyl acids (PFAAs) by wheat (Triticum aestivum L.) grown in biosolids-amended soils

“…1b). Similar results of foliage/root concentration factors decrease with increasing carbon chain length for both PFCAs and PFSAs were reported by Felizeter et al (2012). The inverse relationship indicated that the acropetal transfer potential from roots to straws for short-chain PFAAs was higher than that for long-chain PFAAs, which may be due to the relatively large molecule and/or high lipophilicity of long-chain PFAAs when compared with short-chain PFAAs.…”

“…The only exception is PFBA, in which recoveries were much lower (38e47%) than other PFAAs. Similar relatively low recoveries of PFBA were reported by Felizeter et al (2012). Thus, it is assumed that the concentrations of PFBA may be underestimated when only two isotope-labeled internal standards were used.…”

“…Studies have shown MTBE-NaOH (Felizeter et al, 2012) and MeOH-DCM to be efficient for the extraction of PFAAs from plant tissues. To evaluate the capability of different solvents, PFCAs and PFSAs in soils and wheat roots and straws collected from Plot 4 were extracted with MTBE-NaOH and MeOH-DCM according to the methods reported with some modifications, and cleaned up according to the method of Shi et al (2012).…”

“…So far very few studies have dealt with this issue in the soil-plant system. Pot studies by Zhao et al (2013), Felizeter et al (2012, Lechner and Knapp (2011) and Stahl et al (2009) showed that PFAAs could be taken up, for example, by maize, oats, wheat, potatoes, lettuce, cucumbers and carrots. Plant accumulation of PFAAs was dosedependent and varied with plant species.…”

The roles of protein and lipid in the accumulation and distribution of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) in plants grown in biosolids-amended soils

“…Wen et al (2013) found that the kinetics of PFOS and PFOA uptake by plant fitted Mechaelis-Menten equation well, suggesting their transport protein-mediated influx processes. In contrast, Felizeter et al (2012) suggested that uptake of PFASs by lettuce root was mainly governed by sorption to lipidrich root solids. Though species-dependent uptake and tissue distribution of PFASs in plants have been reported, there is still limited mechanistic understanding of the biotic parameters on PFASs accumulation in plants.…”