Location: Food Animal Metabolism Research
2020 Annual Report
Objectives
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.
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.
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.
Objective 4: Develop and/or validate rapid screening assays for the detection of environmental chemicals relevant to U.S. food production.
Objective 5: Determine levels and sources of dioxins and related compounds in the domestic food supply. Provide food safety agencies with data to confirm or refute the wholesomeness and competitiveness of beef, pork, chickens, turkeys and/or catfish.
Objective 6: Determine the uptake, metabolism (in vitro or in vivo), distribution, excretion, and fate of environmental contaminants with the goal of developing pharmacokinetic rate and volume constants pertinent to residue depletion, selection of marker compounds, and calculation of withdrawal intervals.
Approach
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.
Progress Report
Objectives 1 and 4, which are similar due to a consolidation of two projects, focus on the development and (or) validation of analytical tools to rapidly detect and quantify chemicals -including environmental contaminants- in food animals, food animal products, or other foods. We have advanced the use of traditional liquid chromatograph mass spectrometers to conduct automated analyses in the absence of chromatographic separation. For example, traditional electrospray ionization was used to analyze beta-agonists, non-steroidal anti-inflammatory drugs, and antibiotics in urine and tissues of pigs, sheep, and cattle, but without chromatographic separation of analytes. Analyses were sensitive, quantitative, and well correlated with widely used quantitative analytical methods. Likewise, electrospray ionization inlet mass spectrometry was used without chromatographic separation to quantify veterinary drugs and perfluoroalkyl substances in ruminant tissue matrices. Saliva is an attractive matrix for ante-mortem monitoring and for this reason a rapid screening method for a battery of 9 veterinary compounds is being developed using columnless electrospray ionization. Using immunochemical techniques, the presence of 7 undeclared food allergens in 137 frozen and ready-to-eat meals were determined. Under Objectives 2 and 6 which focus on the uptake, metabolism, distribution, and (or) the elimination of environmental and veterinary chemicals in food animals and (or) produce, several studies have been completed or are being completed. First, laboratory work is being completed on a large residue depletion study from a perfluoroalkyl contaminated dairy herd. A battery of 11 separate perfluoro sulfonates and carboxylic acids were analyzed in blood, liver, kidney, lung, skin, muscle, milk, and other tissues. Data are being shared with regulatory partners to generate models useful for predicting the post-exposure withdrawal times necessary for perfluoroalkyl depletion from edible tissues. Laboratory work was also completed on a study which measured the distribution and elimination of 3 brominated diphenyl ether flame retardants in laying hens. The live phase of chlorite residue study was completed in broiler chickens; chlorate, the stable marker residue of chlorite exposure, is currently being measured in edible tissues. Preliminary in vitro work demonstrated the rapid degradation of chlorite, and relative stability of chlorate, in simulated poultry intestinal fluids. Further, the metabolism of the non-steroidal anti-inflammatory agent flunixin was studied in bovine microsomes and the metabolism by specific cytochrome P450 isozymes was probed. Studies investigating the fate of endogenous reproductive hormones and other chemicals in wastes of food animal or in food processing systems (Objective 3) have been completed. For example, field and analytical work was completed on a 3-year study investigating the fate of estrogens incurred into poultry and swine litter which had been tilled into test plots. Rainfall simulation experiments were used to measure the transfer of estrogens into simulator runoff after rain events. Under the auspices of Objective 5 over 500 beef, turkey, swine, and broiler samples were analyzed for 17 polychlorinated dioxins, dioxin-like furans, and phenols. Analysis of the same samples for brominated flame retardants is in progress.
Accomplishments
1. Rapid detection of chemical analytes. Liquid chromatography-mass spectrometry (LC-MS) is a very powerful analytical tool used to identify and/or quantify a host of chemicals in water, foods, and environmental samples. During a typical analysis, samples undergo a lengthy extraction process, are introduced onto a LC-MS, and analytes are separated chromatographically using a solvent system and an expensive column. ARS researchers in Fargo, North Dakota, eliminated column chromatography and utilized a new ionization technique (electrospray ionization inlet; ESII) to quantify a diverse set of chemicals in complex animal matrices including urine, blood, and tissues. The new technique was notable because sensitivity for most analytes was increased relative to conventional LC-MS. Additionally, the total analysis time was reduced, and less solvent was used relative to standard techniques. Thus, ESII analysis represents a potentially useful, environmentally friendly, and time saving analytical method for the analysis of chemical residues.
2. Safe use of chlorine dioxide to sanitize produce and eggs. Chlorine dioxide gas is very effective at eliminating microbiological contaminants from a variety of fruits, vegetables, melons, seeds, and even eggs. Although the gas has been proposed for sanitation of human foods to eliminate pathogens and/or rot organisms, the gas has not been approved by regulatory authorities for use on foods other than tomatoes or cantaloupe because chemical residues of chlorine dioxide have not been described. ARS researchers in Fargo, North Dakota, demonstrated that nearly all the residue deposited on the surfaces of eggs, avocados, onion, and sweet potato after the use of chlorine dioxide for sanitation is chloride ion, a nutrient required for life. The scientists also found that chlorate, a byproduct of chlorine dioxide, was present in low quantities and could serve as a useful marker of chlorine dioxide treated products. The study suggests that chemical residues are not a major obstacle for the commercial development of cost-effective chlorine dioxide gas technologies to safely eliminate pathogens and rot organisms from a variety of produce and eggs.
Review Publications
Casey, F.X., Hakk, H., Desutter, T.M. 2020. Free and conjugated estrogens detections in drainage tiles and wells beneath fields receiving swine manure slurry. Environmental Pollution. 256. https://doi.org/10.1016/j.envpol.2019.113384.
Vance, C.K., King, E., Bowers, S.D., Ryan, P.L., Walters, K., Shappell, N.W. 2019. Reproductive performance of mares fed dietary zearalenone. Frontiers in Veterinary Science. 6:423. https://doi.org/doi: 10.3389/fvets.2019.00423.
Chakrabarty, S., Shelver, W.L., Smith, D.J. 2021. Electrospray ionization inlet tandem mass spectrometry: A hyphenated method for the sensitive determination of chemicals in animal tissues and body fluids. Journal of American Society for Mass Spectrometry. 32:14-20. https://doi.org/10.1021/jasms.9b00114.
Shappell, N.W., Berg, E.P., Magolski, J.D., Billey, L.O. 2019. An in vitro comparison of estrogenic equivalents per serving size of some common foods. Journal of Food Science. https://doi.org/10.1111/1750-3841.14847.
Smith, D.J., Scapanski, A.R. 2020. Distribution and chemical fate of [36Cl]chlorine dioxide gas on avocados, eggs, onions, and sweet potatoes. Journal of Agricultural and Food Chemistry. 68:5000-5008. https://doi.org/10.1021/acs.jafc.0c01466.
Smith, J.S., Marmulak, T.L., Angelos, J.A., Lin, Z., Rowe, J.D., Carlson, J.L., Shelver, W.L., Lee, E.A., Tell, L.A. 2020. Pharmacokinetic parameters and estimated milk withdrawal intervals for domestic goats (Capra aegagrus hircus) after administration of single and multiple intravenous and subcutaneous doses of flunixin meglumine. Frontiers in Veterinary Science. 7:213. https://doi.org/10.3389/fvets.2020.00213.
Singh, A., Hakk, H., Lupton, S.J. 2019. Facile synthesis of bromo- and mixed bromo/chloro dibenzo-p-dioxins and [14C]-labeled 1,3,7,8-tetrabromodibenzo-p-dioxin. Chemosphere. 239. https://doi.org/10.1016/j.chemosphere.2019.124626.
Chakrabarty, S., Shelver, W.L., Smith, D.J. 2020. Electrospray ionization rapid screening (ESI-RS) sans LC column: A sensitive method for detection and quantification of chemicals in animal tissues and urine. Rapid Communications in Mass Spectrometry. 34:8876. https://doi.org/10.1002/rcm.8876.
