|WAGNER, SARAH - North Dakota State University|
|DEARFIELD, KERRY - Food Safety Inspection Service (FSIS)|
|JOHNSTON, JOHN - Food Safety Inspection Service (FSIS)|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/22/2015
Publication Date: 11/3/2015
Citation: Lupton, S.J., Wagner, S., Dearfield, K.L., Johnston, J.J. 2015. Perfluorooctane sulfonate (PFOS) depletion in beef cattle [abstract]. Recent Advances in Food Analysis. p. 98.
Interpretive Summary: Perfluorooctane sulfonate (PFOS) is an industrial chemicals used in a wide range of products as surfactants and coatings, such as Teflon® and Scotchgard™. PFOS is widely spread in the environment and is found in humans and wildlife. Because this chemical appears to accumulate in the body it is important to understand routes of exposure for humans. Due to the fact that biosolids containing PFOS from wastewater treatment plants are spread on cattle pastures and animal food crops it is important to know to what extent agricultural animals such as cattle absorb and accumulate PFOS. For these reasons we have conducted a study to look at the absorption, distribution and depletion of PFOS in beef cattle. After a single oral dose of PFOS to Angus steers and heifers, we determined that PFOS remained at elevated levels in the blood and tissues throughout the 343 day study. PFOS was readily absorbed and distributed into the tissues of the cattle. The results from this study show that accumulation of PFOS in beef cattle is possible and the food supply could be a possible route of exposure for humans.
Technical Abstract: Perfluorooctane sulfonate (PFOS) is an industrial chemical that is used as a surfactant in several manufactured consumer products but is also a breakdown product from other chemical surfactants. As a result of its extensive use, PFOS is ubiquitous in the environment and is often detected in biosolids from waste water treatment plants. A common practice is the application of biosolids to pastures or croplands used for beef cattle feed production. The exposure of food animals to persistent organic chemicals has raised concerns about human exposure through the accumulation of PFOS in edible tissues. For these reasons, the United States Department of Agriculture (USDA) has undertaken a study to determine the absorption, distribution, and depletion of PFOS in beef cattle during a yearlong study period. Two Angus steers were given single oral bolus doses containing PFOS at 0.098 mg/kg body weight (bw) and four Angus heifers were given single bolus doses containing PFOS at 9.1 mg/kg bw. Two Angus steers served as undosed controls. Plasma was collected from each animal prior to, and at various intervals after dosing through 343 days. The high dose heifers were slaughtered at 105 days (n=2, ~1 PFOS half-life) and at 343 days (n=2, >2 PFOS half-lives), while all steers (2 dosed and 2 controls) were slaughtered at 343 days. Tissues collected included liver, kidney, backfat, intraperitoneal fat, muscle (ribeye, tenderloin, rump, and shoulder), bone, and skin (only from animals at 343 days). PFOS residues were extracted by liquid-liquid or liquid-solid ion pairing extraction methods and quantified by liquid chromatography-quadrupole time of flight mass spectrometry. The average maximum concentrations of PFOS in plasma for the steers and heifers were 0.61 µg/mL (n=2) and 65±12 µg/mL (n=4), respectively. Average plasma elimination half-lives for steers and heifers were estimated to be 115 days and 119 days, respectively. Apart from plasma, liver contained the highest tissue concentrations for steers at 149.0 ng/g wet weight (ww). Liver concentrations from the heifers at 105 days and 343 days were 8,765.3 ng/g ww and 4,744.1 ng/g ww, respectively. The second highest PFOS tissue concentrations were in the kidney for steers at 81.9 ng/g ww and for heifers at 3,964.3 ng/g ww (105 days) and 2,356.6 ng/g ww (343 days). For edible tissues such as muscle (tenderloin, shoulder, ribeye, and rump), the range of PFOS concentrations for steers was 4.1-7.2 ng/g and for heifers were 364.1-1,196.8 ng/g ww (105 days) and 168.7-394.0 ng/g ww (343 days). At 343 days PFOS residues were still detectable (limit of detection was ~2 ng/g in tissue) in all tissues tested including fat and muscle indicating there is potential for human exposure to PFOS even after an extended withdrawal period.