2007 Annual Report
Metabolism of Sodium Chlorate in Rats. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”. Studies published in the early 1980’s on the fate of the chloroxyanion, chlorate, used as a “bleaching” agent during municipal water treatment plants indicated that chlorate was metabolized to, and excreted as, the toxic agent chlorite in rats. Because chlorate is not metabolized to chlorite by cattle, swine, or poultry, a study was conducted to verify or refute earlier chlorate metabolism work with rats. Using modern analytical methods, it was proven in an unambiguous manner that chlorite is not excreted by rats and that chlorite is not present in rat tissues after chlorate administration. These results clearly demonstrated that chlorate is converted to a nutrient (chloride ion) in an important lab species and that food animals such as cattle, swine, and chickens are not different from lab species in this regard. Further, it was demonstrated that earlier reports of chlorite being excreted by rats were due to faulty analytical methods used by earlier investigators. Results of this study are consistent with the notion that chlorate salts could safely be used as a pre-harvest tool to safely eliminate pathogens from animal carcasses.
Fate of Sodium Chlorate in Gastrointestinal Fluids of Cattle. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”. Chlorate is converted to large amounts of chloride ion by cattle, exactly where this conversion took place was unknown. A study was conducted that clearly showed that substantial quantities of sodium chlorate may be converted to chloride ion in gastrointestinal fluids of cattle and that the diets of cattle did not greatly influence the conversion of chlorate to chloride ion. Conversion of chlorate to chloride ion within the digestive tract reduces the amount of chlorate available to kill pathogens, a factor that must be taken into account in the development of chlorate as a pre-harvest food safety tool.
Fate of Steroidal Hormones in Waste Systems. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”. Steroidal hormones are constantly released into the environment by man-made and natural sources. The goal of this study was to obtain experimental evidence for the persistence and fate of 17beta-estradiol and testosterone in soil under aerobic and anaerobic, as well as, native and sterile conditions. Testosterone was metabolized to carbon dioxide to a much greater extent (10-fold) than 17beta-estradiol in native soil under aerobic conditions. Methane production was very limited for testosterone under anaerobic conditions, while it was nonexistent for 17beta-estradiol. Metabolism of these hormones was determined to be microbially-mediated because no metabolites were produced under sterile conditions. A majority of each hormone dose was tightly bound to soil particles (humic substances), even under sterile conditions. These findings suggest that previous estimates of the persistence and risk of these hormones in the environment might be overestimated due to their high aerobic metabolism by soil biota and reduced bioavailability resulting from non-extractable sorption to soils.
Fate of Estrogenic Hormones in Lagoon Wetlands. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”. Hormonal activity in livestock waste and treated wastewater releases is of interest because of intense livestock production practices. A lagoon, constructed wetland system was evaluated for efficacy in removal of estrogenic activity from swine wastewater at a swine birthing facility. Wetlands reduced estrogenic activity 83-93%. Nutrient removals were typical for treatment wetlands; nitrogen 59-75%, and orthophosphate (a form of phosphorus) 0-18%. Expected seasonal differences were observed (limited data). Good agreement was found between the E-screen (a bioassay) values and the equivalent concentrations determined by chemical analyses. The most persistent estrogenic compound was identified as estrone, a breakdown product of estradiol. Constructed wetlands were effective in producing water with estrogenic activity below the lowest equivalent E2 concentration known to have an effect.
Validation and Harmonization of Analytical Methods for Estrogens. Program 108, “Food Safety”, Components 1.1 “Pre-harvest Food Safety” and 1.1.3 “Ecology, Host Pathogen and Chemical Residue Relationships”. Project NORMAN (Network of Reference Laboratories for Monitoring of Emerging Environmental Pollutants) was created by Environment Agency of UK in part to create a network of expert reference laboratories and to encourage the validation and harmonization of analytical methods. To this end, estrogenic activity was assessed using an E-Screen assay in a variety of aqueous samples provided by the Environment Agency. Cooperating research groups independently assessed estrogenic hormones in the same samples by ELISA, and in vivo estrogenic activity by vitellogenin induction in fish exposed to samples. Results from this cooperative effort will help to establish uniform testing methods for estrogenic compounds and to establish the relative usefulness of each method.
Oliver, C.E., Craigmill, A.L., Caton, J.S., Anderson, R.C., Smith, D.J. 2007. Pharmacokinetics of ruminally-dosed sodium chlorate in beef cattle. Journal of Veterinary Pharmacology and Therapeutics 30:358-365.
Fan, Z., Casey, F.X., Hakk, H., Larsen, G.L. 2007. Persistence and Fate of 17beta-estradiol and testosterone in agricultural soils. Chemosphere 67(5):886-895.
Horrocks, S.M., Jung, Y., Huwe, J.K., Harvey, R.B., Ricke, S.C., Carstens, G.E., Callaway, T.R., Anderson, R.C., Ramlachan, N., Nisbet, D.J. 2007. Effects of short-chain nitrocompounds against Campylobacter jejuni and Campylobacter coli in vitro. Journal of Food Science. 72:M50-M55.
Shappell, N.W., Billey, L.O., Forbes, D., Poach, M.E., Matheny, T.A., Reddy, G.B., Hunt, P.G. 2007. Estrogenic activity and steroid hormones in swine wastewater processed through a lagoon constructed-wetland system.. Environmental Science and Technology 41(2):444-450.
Smith, D.J., Anderson, R.C., Huwe, J.K. Effect of sodium [36cl]chlorate dose on total radioactive residues and residues of parent chlorate in growing swine. Journal of Agriculture and Food Chemistry 54:8648-8653.
Fan, Z., Casey, F.X., Hakk, H., Larsen, G.L. 2007. Discerning and Modeling the Fate and Transport of Testosterone in Undisturbed Soil. Journal of Environmental Quality 36:864-873.
Van Emon, J.M., Shelver, W.L. 2007. Journal of Agricultural and Food Chemistry 55:3749-3749.
Oliver, C.E., Bauer, M.L., Caton, J.S., Anderson, R.C., Smith, D.J. 2007. The in vitro reduction of sodium [36Cl]-chlorate in bovine ruminal fluid. Journal of Animal Science 85:2059-2068.
Smith, D.J., Byrd, J.A., Anderson, R.C. 2007. Total radioactive residues and residues of [36Cl]chlorate in market size broilers. Journal of Agricultural and Food Chemistry 55:5898-5903.
Hakk, H., Smith, D.J., Shappell, N.W. 2007. Tissue residues, metabolism, and excretion of Na[36Cl]O3 in rats. Journal of Agricultural and Food Chemistry 55:2034-2042.