|JOHNSTON, JOHN - Food Safety Inspection Service (FSIS)|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/24/2017
Publication Date: 11/7/2017
Citation: Lupton, S.J., Johnston, J.J. 2017. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) risk to beef consumers Part II: Adsorption, distribution, metabolism, and excretion studies for improving risk evaluations [abstract]. 8th International Symposium on Recent Advances in Food Analysis. Nov. 7-10, 2017. Prague, Czech Republic. Paper No. L106.
Interpretive Summary: .
Technical Abstract: Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are industrially produced chemicals used as surfactants and coatings in many industrial, commercial and consumer products. These compounds are ubiquitous in humans and the environment. PFOA and PFOS have been observed in biosolids from wastewater, suggesting exposure of agricultural animals to these chemicals may occur through application of biosolids to cattle pastures and animal food crops. Possible accumulation of PFOA and PFOS in edible tissues of agricultural animals could be a risk to consumers. As such, the United States Department of Agriculture (USDA) determined the absorption, distribution, metabolism, and excretion (ADME) of PFOA and PFOS in beef cattle following an oral dose. These studies determined the magnitude and distribution of these chemicals in beef cattle and data were used to improve risk evaluations conducted by the USDA. Initially, 4 Lowline Angus steers were provided single bolus doses of 14C-PFOA at 1 mg/kg body weight (bw) and 3 of the 4 steers also received a simultaneous unlabeled PFOS dose at 10 mg/kg bw and were held for 28 d. The one steer not receiving PFOS was used for control purposes. The second study consisted of 2 Angus steers and 4 Angus heifers given single bolus doses of PFOS at 0.098 mg/kg bw and 9.1 mg/kg bw, respectively, and maintained during the course of the 343 d study. Plasma was collected at various time intervals during the studies from all animals. Urine and feces were quantitatively collected each day during the 28 d study. After 28 days, 105, and 343 days, animals were sacrificed and tissues collected. 14C-PFOA analysis was completed by liquid scintillation counting (LSC) for liquid samples and sample oxidation with LSC for solid samples. PFOS was analyzed by an ion pairing extraction method with quantification using liquid chromatography mass spectrometry (LC-MS). From the 28 d study, peak concentrations of 14C-PFOA in plasma occurred between 24 and 36 h post-dose with the elimination half-life in plasma being 19.2 ± 3.3 h. However, plasma PFOS elimination half-life could not be determined from the 28 d study, but 30-40% of the dose was still circulating in the plasma on day 28. From the 343 d study, PFOS plasma half-lives were 120 d and 106 d for steers and heifers, respectively. Quantitative elimination of 14C-PFOA in urine was observed for the 28 d study at 100.8 ± 3.3% of dose, while elimination via feces was <5%. PFOS excretion via urine was minimal, <1% over 28 d, but feces contained 11% of the PFOS dose. As for tissue distribution, 14C-PFOA was not detected in any tissues at the conclusion of the 28 d study. PFOS concentrations in tissues (excluding plasma) were found to be highest in liver, kidney, and muscle for both studies and tissue half-lives were 116 d, 385 d, and 165 d, respectively. No metabolism was observed for either compound.