Submitted to: Society of Toxicology
Publication Type: Abstract Only
Publication Acceptance Date: 12/6/2010
Publication Date: 1/3/2011
Citation: Huwe, J.K., Lupton, S.J., Smith, D.J., Dearfield, K., Johnston, J.J. 2011. Absorption and excretion of 14C- perfluorooctanoic acid (PFOA) in beef cattle. Society of Toxicology Annual Meeting, March 6-10, 2011, Washington, DC. Poster #2273. Interpretive Summary:
Technical Abstract: Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are industrial chemicals that are environmentally persistent. PFOS has recently been classified as a persistent organic pollutant under the Stockholm Convention. Both PFOS and PFOA can be found in biosolids, and the application of contaminated biosolids to pastures used for beef cattle production has raised concerns about the possible accumulation of PFOA and PFOS in the edible tissues of these animals. As such, the United States Department of Agriculture (USDA) has undertaken a study to determine the absorption, distribution, metabolism, and excretion of PFOA and PFOS in beef cattle following an oral dose. The animal protocol was approved by the local Institutional Animal Care and Use Committee and USDA Radiation Safety Committee. Four Lowline Angus steers (281–366 kg) were given single oral bolus doses containing 14C-PFOA (1 mg/kg) and unlabeled PFOS (10 mg/kg). Serum, plasma, urine, and feces were collected prior to and after dosing at various intervals from each steer for 28 days. Radioactivity in the serum, plasma, and urine was determined by liquid scintillation counting (LSC) and in the feces by combustion analysis followed by LSC. Radioactivity derived from 14C-PFOA was completely absorbed and excreted via the urine within 8 days of dosing (100.6 ± 3.3%). Blood and urine levels peaked between 24 and 36 hrs post-dose, and the serum elimination half life was 24 hrs. Minimal amounts of radioactivity were excreted in the feces (2–3%). Studies in rodents and non-human primates have calculated PFOA serum half lives of 10–30 d. One exception is female rats which have markedly increased urinary excretion rates and half lives of 3–5 hr. This study shows that PFOA is rapidly excreted by steers and indicates that it would be unlikely to accumulate in the edible tissues. Samples from this study have not yet been analyzed for PFOS.