Blood-Based Ante-Mortem Method for Estimating PFOS in Beef from Contaminated Dairy Cattle

A blood-based screening method was developed to facilitate ante-mortem screening of dairy cattle suspected of containing elevated concentrations of perfluorooctanesulfonic acid (PFOS) in their muscle tissue. The collection and subsequent laboratory analyses of 28 paired blood plasma and muscle samples from PFOS-exposed dairy cattle provided the PFOS plasma and muscle data to develop a model to estimate muscle PFOS concentrations based on plasma PFOS concentrations. The blood-based ante-mortem screening approach could be applied to predict whether beef (skeletal bovine muscle) from suspect cattle populations (or subpopulations) exceeds a particular level of concern. The data analyses indicated that the relationship between muscle and plasma PFOS concentrations differed by the class of dairy cattle (heifer, lactating, and dry) and the duration of removal (withdrawal time) from exposure to PFOS. A plasma depletion model was also developed to evaluate the estimated withdrawal time required to reduce PFOS in dairy cattle muscle to below an identified level of concern. The model indicated complex PFOS plasma depletion dynamics with a nonconstant rate of depletion. The required withdrawal time also depends on the initial concentration distribution (which differed between heifers and lactating/dry cows) and the identified level of concern.