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United States Department of Agriculture

Agricultural Research Service

Research Project: METABOLIC VARIABLES AFFECTING THE EFFICACY, SAFETY, AND FATE OF AGRICULTURAL CHEMICALS
2008 Annual Report


1a.Objectives (from AD-416)
Objective 1: Determine metabolic variables (rates of absorption, tissue and microbial biotransformation, excretion) that positively or negatively influence the practical use of novel pre-harvest food safety chemicals in food animals. Objective 2: Determine the fate of endogenous animal hormones, novel pre-harvest food safety compounds, and antibiotics in animal wastes, including their transport through soil and water, and develop intervention strategies that reduce their environmental impact. Objective 3: Develop sensitive and accurate analytical tools to rapidly detect and quantify agriculturally important chemicals studied under objectives 1 and 2.


1b.Approach (from AD-416)
The broad objective of this proposal is to determine the fate of chemicals in food animals and in the environment (excreta, soil, water) after elimination from food animals. We will study endogenously produced steroid hormones, novel developmental oxyanions, novel developmental nitro-compounds, and antibiotics. Endogenous steroid hormones (estrogens) are highly potent endocrine-disrupting compounds that may concentrate in intensive food-animal production settings. Novel developmental compounds show promise for food-safety applications in ruminant, non-ruminant, and avian food animals. Specifically we plan to.
1)determine the metabolic variables (i.e., absorption, tissue and microbial biotransformation, rates of excretion) that positively or negatively influence the food safety (i.e., tissue residues) of developmental oxyanions such as chlorate salts and novel nitro-compounds such as 2-nitropropanol in food animals;.
2)determine the fate of steroid hormones, antibiotics, and developmental compounds in manure management systems of animals and in soils with the goal of gaining an understanding of the impact that residues of such chemicals may have in intensive food animal production settings; and.
3)we will develop analytical tools for the accurate measurement and(or) identification of these analytes or their metabolites.


3.Progress Report
This report serves to document progress conducted for CRIS project 5442-32000-012 entitled “Metabolic variables affecting the efficacy, safety, and fate of agricultural chemicals”. A series of experiments was performed to determine the effects of chlorate salts on pure cultures of E. coli O157:H7 and to determine the metabolic fate of chlorate within these cultures. The formation of the putative toxic intermediate, chlorite, was directly measured using ion chromatography with radiochemical detection. Studies were also initiated to develop a mass-spectral based analytical method sufficient to measure chlorate concentrations in the gastrointestinal contents and feces of swine. The general method should be applicable to a variety of matrices. A series of experiments was initiated to determine the metabolic fate of a nitro substituted amino acid within ruminal cultures. This amino acid analog has been shown to be a potent inhibitor of ruminal methane production and understanding its ruminal fate will provide an indication of whether it might be safe for use in commercial livestock systems. An experiment was conducted with laboratory scale lagoons to measure the fate of steroid hormones under anaerobic conditions similar to those found in swine waste lagoons. Parent steroids were degraded to methane gas, two water-soluble metabolites, and to intermediates that bind tightly to lagoon solids. Anaerobic digestion of lagoon waste provided an effective tool to reduce the introduction of steroid hormones into the environment from commercial livestock systems. Estrogenic activity was measured in a variety of aqueous samples provided by the Environment Agency (UK) using an E-Screen assay. Cooperating research groups independently measured estrogens in the same samples using ELISA and an in vivo bioassay using fish. Results from all three methods were reproducible at higher estrogen concentrations (>1 ng/L), but at the lowest concentrations (0.5ng/L) results were more variable (>20%). This research will help to establish uniform testing methods for estrogens and help to establish the relative usefulness of each analytical method. All of the accomplishments relate to National Program 108, "Food Safety" component 1.1, "Pre-harvest food Safety", 1.1.1, "Methodology"; 1.1.3 "Ecology, Host Pathogen and Chemical Residue Relationships"; and 1.1.4 "Intervention Strategies".


4.Accomplishments
1. Destruction of Estrogens. Worldwide, surface waters are being made more estrogenic because of the excretion of natural estrogens by food animals in concentrated confinement and especially by synthetic estrogens excreted by humans. Synthetic estrogens are incompletely removed by municipal sewage treatment plants and natural estrogens may be incompletely removed by agricultural waste handling systems. In this study, we demonstrated that trace levels of Fe-TAML (a commercially available chemical) makes hydrogen peroxide more efficient at degrading natural and synthetic reproductive hormones present in water. The study demonstrated that Fe-TAML and hydrogen peroxide may be useful in removing natural and synthetic estrogens from agricultural and municipal waste streams. Program 108, “Food Safety”, Component 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”.

2. Estrogen Distribution in Water and Soil. Once estrogens are released into the environment from human or animal sources, their environmental fate and transport is controlled by factors such as sorption to soil particles and transformation to inactive products. Both processes must be understood to fully assess potential environmental exposure. Studies were conducted to discern the simultaneous transformation of 17ß-estradiol, a potent female hormone, and its distribution between water and soil. The resulting mathematical model provided a good description of the data and the estimates of the model parameters were reliable. The strong consistency of the model indicated that it could be used to describe estradiol behavior in soil systems. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”.

3. Transport of Steroid Hormones in Soil. Laboratory experiments have consistently indicated that steroid hormones such as estrogen (E2) and testosterone (T) are bound to soil and degraded rapidly. Nevertheless E2 and T are regularly detected in water samples from diverse environments. A field experiment was conducted to identify the major factors that control E2 and T movement through, and degradation in, soil. The major influences on hormone transport through the soil were the amount of water in soil pores and the amount of organic matter in the soil. These results indicate that colloids contribute to the transport of steroid hormones in soil. This study provides evidence for processes that explain the mobility and presence of steroid hormones in the environment. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”.

4. Degradation and Biological Activity of Sodium Chlorate in Cattle Wastes. Chlorate is being developed as a feed additive to reduce the numbers of harmful bacteria in live cattle. A series of studies was conducted to determine whether chlorate would also reduce the populations of harmful bacteria in cattle wastes (a mixture of urine and feces) and to determine the chemical fate of chlorate after excretion from cattle. Chlorate salts present in manure had no significant effects on two human pathogens, E. coli O157:H7 and Salmonella Typhimurium. Low activity against these bacteria was likely due to rapid chlorate degradation in manure and lagoons. Collectively our results suggest that the use of chlorate as a food safety tool would be environmentally friendly because of its rapid degradation to natural products. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships.”

5. Sulfonamides in Waste- and Surface Waters. Sulfonamide antibacterial agents have been found in modest concentrations in wastewater treatment plants and waterways worldwide. Sulfamethazine (used in veterinary medicine) and sulfamethoxazole (used in human medicine) are two sulfonamides of particular interest because of their extensive use. A new immunologically-based assay for sulfamethazine worked well in the analysis of wastewater from swine raising facilities. Similarly, an immunologically-based assay for sulfamethoxazole worked well to determine the amount of sulfamethoxazole in water from two wastewater treatment plants. The immuno-based results were confirmed by separate analyses using liquid chromatography-mass spectral-based assays. The immunologically-based assays could be used to assist in the monitoring of wastewater processing systems due to their sensitivity, selectivity, and relatively low cost. Program 108, “Food Safety”, Component 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”.

6. Metabolism of 2,4,6-Trinitrotoluene (TNT) by Sheep. Estimates suggest that over 1 million tons of soils in the United States are contaminated with residues of the explosive trinitrotoluene (TNT). Remediation efforts are currently underway at some of the most contaminated sites, but at great financial costs. Previous studies have shown that TNT is very rapidly metabolized by gastrointestinal fluids from grazing animals such as cattle. This study was conducted to determine the fate of TNT in live sheep. Sheep rapidly detoxified TNT to residues that were bound to organic molecules and most of the bound residues were excreted in feces. The use of grazing animals on ground with low levels of TNT contamination has the potential to speed the reclamation these lands at fairly low cost. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”.


6.Technology Transfer

Number of the New MTAs (providing only)1
Number of New Patent Applications Filed1
Number of Non-Peer Reviewed Presentations and Proceedings4
Number of Newspaper Articles and Other Presentations for Non-Science Audiences2

Review Publications
Wagner, S.A., Mostrum, M.S., Hammer, C.J., Thorson, J.S., Smith, D.J. 2008. Adverse effects of zilpaterol administration in horses: three cases. Journal of Equine Veterinary Science 28(4):238-243.

Smith, D.J., Craig, A.M., Duringer, J.M., Chaney, R.L. 2008. Absorption, tissue distribution, and elimination of residues after 2,4,6-trinitro[14C]toluene administration to sheep. Environmental Science and Technology 42(7):2563-2569.

Shappell, N.W., Vrabel, M.A., Madsen, P.J., Harrington, G.E., Billey, L.O., Hakk, H., Larsen, G.L., Beach, E.S., Horwitz, C.P., Ro, K.S., Hunt, P.G., Collins, T.J. 2008. Destruction of estrogens using Fe-TAML/peroxide catalysis. Environmental Science and Technology 42:1296-1300.

Casey, F.X., Oduor, P., Hakk, H., Larsen, G.L., Desutter, T.M. 2008. Transport of 17beta-estradiol and testosterone in a field lysimeter. Soil Science 173:456-467.

Shelver, W.L., Shappell, N.W., Franek, M., Rubio, F.R. 2008. ELISA for sulfonamides and its application for screening in water contamination. Journal of Agricultural and Food Chemistry 56:6609-6615.

Oliver, C.E., Magelky, B.K., Bauer, M., Cheng, F., Caton, J.S., Hakk, H., Larsen, G.L., Anderson, R.C., Smith, D.J. 2008. Fate of chlorate present in cattle wastes and its impact on Salmonella typhimurium and E. coli 0157:H7. Journal of Agricultural Chemistry 56:6573-6583.

Fan, Z., Casey, F.X., Hakk, H., Larsen, G.L. 2008. Modeling of Coupled Degradation, Sorption, and Transport of 17beta-Estradiol in Undisturbed Soil. Water Resources Research 173:456-467.

Last Modified: 12/18/2014
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