Objective 1: Develop and (or) validate sensitive and accurate analytical tools to rapidly detect and quantify chemicals in food animals, food animal products, or other foods. Sub-objective 1.A: Validate the usefulness of rapid screening tests in ante-mortem matrices (urine, plasma, serum, saliva, milk, etc.) for predicting post-mortem tissue residues and(or) animal exposures to target compounds. Sub-objective 1.B: Develop and validate on-site detection methods for new and emerging xenobiotic residues. Objective 2: Investigate the kinetics of uptake, metabolism, distribution, and (or) the elimination of chemicals in and from food animals and (or) produce with the goal of reducing public exposure to chemical residues in foods. Sub-objective 2.A: Determine the effect of mediators of inflammation on drug metabolizing enzymes, drug clearance, and violative residues in food animals using flunixin meglumine as a model compound. Sub-objective 2.B: Determine the fate and distribution of chlorine dioxide gas in foods treated for pathogen or rot-organism remediation. Objective 3: Determine the fate of endogenous reproductive hormones, antibiotics, and or other chemicals, including biologically-active metabolites or degradation products in wastes of food animal or in food processing systems. Sub-objective 3A: Determine the partitioning of chemical residues into cream, curd, whey, and water fractions during milk processing. Sub-objective 3B: Determine the fate of estrogens in animal wastewater systems.
The broad objective of this project is to determine the fate of natural and manmade chemicals in food animals and in food animal systems (wastes, soil, water). Three broad classes of chemicals will be targeted for study: (1) veterinary drugs or feed additives administered to food animals under extra-label use conditions, (2) endogenous steroid hormones, and (3) novel developmental chemicals of potential utility to the livestock industry. Use of veterinary chemicals in an extra-label manner without knowledge of residue depletion kinetics has led to unsafe residues in meat products. Endogenous steroid hormones excreted by livestock are highly potent endocrine-disrupting compounds that are thought to disrupt the development of aquatic species after their entry into surface waters. Finally, chemical technologies developed by the ARS, e.g., chloroxyanions and nitro compounds, are active against Salmonella and E. coli pathogens in livestock immediately prior to slaughter, but the impacts of chemical residues in meat products have not been fully investigated for these compounds. Regardless of the chemical class being investigated, the development of sensitive and accurate analytical tools is critical completion of the objectives. Therefore, a significant portion of the project is devoted to developing the analytical tools required to ensure success of the project. The overall project goal is to understand the broad impact that chemical residues play in influencing food and environmental safety.
Objective 1. A study was conducted to determine the utility of using rapid (less than 10 min), cost-effective, lateral flow assays to determine the presence of penicillin residues in swine urine. Penicillin residues in urine correlates strongly with violative penicillin residues in kidneys of swine. A study was conducted to determine the utility of using a ractopamine lateral flow assay on incurred ractopamine residues in sheep fed trace quantities of ractopamine. Using highly sensitive LC-MS/MS quantitative assays, the rates of false-positives and false-negatives for the lateral flow assays were determined as were the presence of ractopamine residues in edible tissues. Urine samples (n > 300) from human cancer patients consuming high and low meat diets were screened for the presence of the approved beta-agonist leanness-enhancing agents ractopamine HCl and zilpaterol HCl. Objective 2. Studies on the stability of sodium chlorate residues in frozen tomato and cantaloupe homogenates during 120-day storage periods were conducted. Stability was assessed at high and low chlorate concentrations using UPLC with mass spectrometric detection. The analytical phase of a study investigating chlorate and perchlorate residues on ready-to-eat salami, subsequent to sanitization with chlorine dioxide gas, was completed. A commercial, chemically-based replacement for in vitro microsomal metabolism assays was tested for applicability towards the generation of dicoumarol and flunixin metabolites. In a collaborative study, the presence of dicoumarol was measured in feeds and blood samples of cattle exposed to silage containing sweet clover and experiencing slow clotting times. The chemical synthesis carbon-14 labeled dicoumarol (a mycotoxin) was accomplished for use in in vitro and in vivo studies. Preliminary work investigating the effects of chlorine dioxide gas on chemical residues, seed germination, and generic E. coli burden during alfalfa seed sanitation was started. Objective 3. A rainfall simulator was constructed and preliminary experiments investigating the fate of estrogenic activity in soils after the application of fresh layer-hen litter was conducted. The estrogenic activities of halogenated estradiol analogs were measured using an E-screen bioassay for estrogenic compounds. The partitioning of numerous xenobiotic compounds into milk fractions commonly used for processing (cream, whey, and protein) was measured and the data were used to construct partitioning prediction models.
1. Rapid and reliable detection of violative residues. Penicillin G is a valuable antibiotic for the treatment of infection in sows, however penicillin G residues deplete very slowly from some sows but rapidly in others. As a result, the marketing of groups of sows treated with penicillin G must be managed based on animals that clear penicillin G the slowest. ARS researchers in Fargo, North Dakota demonstrated that an inexpensive test strip could rapidly detect penicillin residues in urine of commercial sows, and that its presence in urine accurately predicts violative penicillin residues in edible tissues. The use of an inexpensive and easy to use test strip could allow the differential marketing of penicillin-free sows and sows retaining drug residues.