Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/18/2005
Publication Date: 8/13/2005
Citation: Smith, D.J., Oliver, C.E., Caton, J.S., Anderson, R.C. 2005. Effect of sodium [36Cl]chlorate dose on total radioactive residues and residues of parent chlorate in beef cattle. Journal of Agricultural and Food Chemistry 53:7352-7360. Interpretive Summary: Each year thousands of US consumers become ill because they have eaten food products that are contaminated with pathogenic bacteria. Intense efforts have been made during the last decade to eliminate pathogenic contamination from food animals. To date, no single strategy to eliminate pathogens from food animal products has been widely accepted. A new pre-harvest food safety strategy has been developed that has been shown to greatly reduce, or even eliminate gram-negative pathogens from cattle. Use of this new feed additive has not been approved by regulatory organizations because it is not known whether residues present in edible tissues of treated animals represent a health risk. The purpose of this study was to determine the effect that the dose of a new chlorate based feed additive has on residues of chlorate in edible tissues of beef animals. For all of the doses tested, chlorate residues in liver, kidney, muscle, and fat fell well below amounts that the FDA have estimated to be safe. Further research on the chlorate-based product is warranted because it could have a significant impact on lowering the incidence of harmful bacteria on meat products, and because residues of the product fall below levels that regulatory agencies have estimated to be safe.
Technical Abstract: The objective of this study was to determine total radioactive residues and chlorate residues in edible tissues of cattle administered three levels of sodium [36Cl]chlorate over a 24-hour period and slaughtered after a 24-hour withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intra-ruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate per kg body weight. In order to simulate a 24-hour exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 hours. Urine and feces were collected in 12-hour increments for the duration of the 48-hour study. Twenty-four hours after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from non-detectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue. Results of this study suggest that further development of chlorate as a pre-harvest food safety tool merits consideration.