Perfluorooctanoic acid (PFOA) uptake by alfalfa (Medicago sativa) and bioavailability in Sprague-Dawley rats
By Sara J Lupton and Heldur Hakk
J Food Prot
December 1, 2020
Perfluorooctanoic acid (PFOA) is a perfluorinated alkyl substance (PFAS) used as surfactant in a wide variety of industrial and consumer products. Over the past decade, concern has increased over the presence of PFOA in biosolids from wastewater treatment plants used as fertilizer on agricultural lands having the potential to enter the food chain. In this study, the uptake of 14C-PFOA from soil by alfalfa was determined, as was the bioavailability of 14C-PFOA-incurred into alfalfa in Sprague-Dawley rats. Alfalfa leaves accumulated PFOA to as high as 4-5 µg/g of dry leaf, approximately 10 times higher than accumulation in the stem. Alfalfa was ground for feeding to 15 female Sprague-Dawley rats (175-200 g). Animals within metabolism cages were fed 10 g of feed (6 g alfalfa + 4 g ground rat chow) twice a day for 14 days (equivalent to 50 ug-PFOA/kg/day). At the end of the feeding period, rats (n=3) were sacrificed at withdrawal days of 0, 3, 7, 11, and 14 days. During the feeding and withdrawal phases, urine and feces were collected daily. At sacrifice, blood, liver, kidney, adipose, muscle, skin, brain, heart, adrenals, spleen, lungs, and thymus were removed and assayed for 14C-PFOA by combustion and LSC analysis. Rats eliminated 72.8 ± 3.4% of the total dose via urine at 14-days, but urinary radioactivity fell below the LOD by day 3 of the withdrawal period. Fecal elimination was 6.5 ± 1.2 % of the dose and fell below the LOD by 2 days of withdrawal. The rapid and high elimination via urine indicates that a majority of the dose was absorbed. The uptake of PFOA into alfalfa was low from a high organic content soil, however, PFOA was highly bioavailable from the alfalfa when used as a feed component for rats. This study provides data for regulators investigating PFOA bioavailability and disposition in animals or animal products exposed to contaminated feed.