Performing Department
(N/A)
Non Technical Summary
Exposure to perfluorooctanesulfonic acid (PFOS) causes serious pathologies in humans. The US EPA current advisory level for PFOS in drinking water is 70 ppt. Based on this threshold, Maine was the first state to set the action level for milk PFOS at 210 ppt. Among the thousands of per- and polyfluoroalkyl substances (PFAS), PFOS contaminates milk and beef to a far greater extent than the other PFAS. This is in part because it easily bioaccumulates in cattle and is relatively abundant in contaminated sites. Because milk is a major excretion route of PFOS in animals, dairy products are especially vulnerable to contamination. Our preliminary data showed that a selected binder can effectively bind PFOS under ruminal conditions, while other binder types failed. We also know that PFOS is not immediately released from forages under ruminal conditions, and it is gradually released and then taken in part by rumen microbes from the liquid fraction.
Animal Health Component
(N/A)
Research Effort Categories
Basic
30%
Applied
(N/A)
Developmental
70%
Goals / Objectives
1) Evaluate the relative efficacy of binders to sequester PFOS across simulated ruminal, abomasal, and intestinal conditions;2) Evaluate the effects of application rate on the capacity of a selected binder to sequester PFOS across simulated ruminal, abomasal, and intestinal conditions; and3) Evaluate the PFOS release kinetics and partition between rumen fluid and microbial mass from a PFAS-contaminated grass under simulated ruminal conditions.
Project Methods
Objective 1: Evaluate the relative efficacy of a collection of binders to sequester PFOS across simulated ruminal, abomasal, and intestinal conditions.Substrate. A grass stand reporting 6 ± 1 ppb of PFOS (DM basis) will be mowed and wilted to 80-85% DM. Enough hay will be collected from 5 plots within the stand [plots= blocks], dried at 60°C for 48 h, and ground to pass a 1-mm screen. Ground hay from each of the five plots (plots= blocks) will be further divided into four piles, and treatments will be allocated randomly to each of those piles.Treatments. Three adsorbents plus a control. All adsorbents will be applied at 1.7% grass hay (w/w; DM basis) as outlined in the response to reviewers. Briefly, binders can be applied up to 2% without causing health issues (Harvey et al., 1991). We are aware that above 1% binders will dilute dietary nutrients, but the purpose of this experiment is not to recommend a dose for in vivo studies but to identify promising binder types that could be further optimized to bind PFOS in cattle.Measures. The filtrate from the ruminal, abomasal, and intestinal incubation steps will be submitted for the basic PFAS analysis package at Maine Laboratories (Norridgework, ME; see attached quote). The following 18 analytes will be included: PFOS and PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA, PFTrDA, PFTeDA, NMeFOSAA, NEtFOSAA, PFBS, PFHxS, HFPO-DA, ADONA, 9Cl-PF3ONS, 11Cl-PF3OUdS. Rumen pH, VFA profile, NH3N, and gas production data will be processed and analyzed as described by Killerby et al. (2022).Experimental design. The concentration of each unbound (soluble) PFAS will be analyzed using a randomized complete block design (RCBD, 5 blocks) with the effects of 4 treatments measured across three simulated gastrointestinal conditions, which will be considered a repeated measure (repeated in condition). Treatments will be in 5 blocks as suggested by a power analysis conducted using SAS GLMPOWER (α= 0.05 and a β= 0.85) and the data from our preliminary results. Rumen adsorption results for each of the adsorbents will also be analyzed relative to the untreated control filtrate values using the following formula:Ruminal soluble PFAS relative adsorption (%) = [(PFAScon-PFASads)/PFAScon]×100PFAScon= Given PFAS concentration in control rumen fluid; PFASads= Given PFAS concentration in adsorbent rumen fluid. The adsorption and desorption data will be analyzed using an RCBD (minus the control). Gas production and ruminal fermentation data will be analyzed using an RCBD (incl. the control). The PROC GLIMMIX of SAS 9.4 will be used to evaluate all data generated. Fisher's LSD will be used for mean separation. Significances will be declared at a P-value < 0.05.Objective 2: Evaluate the effects of application rate on the capacity of a selected binder to sequester PFOS across simulated ruminal, abomasal, and intestinal conditions.Substrate. Same as in Objective 1. Grass hay generated from 5 field blocks (blocks= plots).Treatments. Treatments will have a factorial arrangement of 4 doses (0, 0.5, 1, and 1.7%, w/w relative to grass; DM basis). The highest dose is based on our preliminary study.Experimental design. Same as in Objective 1. Each unbound (soluble) PFAS concentration will be analyzed using a randomized complete block design (RCBD, 5 blocks) with 4 doses across rumen, abomasal, intestinal simulated conditions. The dose effect will be modeled using polynomial contrasts to assess if the dose-response was linear, quadratic, or cubic. We do not see the benefit of assessing if the dose had a quartic response from 0 to 1.7% w/w. Power analysis approach and results were the same as Obj. 1.Objective 3 - Evaluate the PFOS kinetics release and partition between rumen fluid and microbial mass from a PFAS-contaminated grass under simulated ruminal conditionsSubstrate. Same as in Objective 1. Grass hay generated from 5 field blocks (blocks= plots).Treatments. A factorial arrangement of 6 ruminal incubation times (0, 2, 6, 12, 24, and 48 h) × 2 ruminal fractions (fluid and microbial mass)Measures. The filtrate from the ruminal incubation step and the microbial pellet will be analyzed for the same PFAS analysis package as Obj. 1. Same for fermentation analysis (Obj. 1).Experimental design. The ruminal fluid and microbial mass PFOS concentrations and the relative proportion to the initial grass PFOS will be analyzed using an RCBD (5 blocks). Since samples over time will not be obtained from the same unit, this will not be a repeated measures study. Treatments will be replicated in 5 blocks as suggested by a power analysis [SAS GLMPOWER (α= 0.05 and a β= 0.85)] and the data from Kowalczyk et al. (2015) and our preliminary results.