Title: Tissue Residues, Metabolism, and Excretion of Na[36cl]o3 in Rats Authors
Submitted to: Journal of Agriculture and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 4, 2006
Publication Date: February 6, 2007
Citation: 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. Interpretive Summary: Administration of an experimental sodium chlorate-containing product (ECP) to food animals 24-72 h prior to slaughter has previously shown to reduce certain pathogenic bacteria in the gastrointestinal tracts. Application of this technology may have significant implications for food safety. However, the edible tissue concentrations of all possible chlorine species need to be first determined to satisfy food safety requirements prior to approval. Therefore, a metabolism and disposition experiment of the active ingredient in ECP was conducted in male rats, which received a single oral dose of [36Cl]-radiolabeled sodium chlorate. Urine, feces, and respired air were collected for 72 h. Radiochlorine absorption was >88% of the administered dose, and the major route of excretion was the urine. Parent chlorate was the major chlorine species present in urine initially, but its level declined sharply later in the study. Chloride was the only other species of chlorine detected in urine. Only the carcass remains, skin, and GI tract contained more than 1% of the dose. The vast majority of the chlorine (>98%) in the edible tissues of liver, kidney, and skeletal muscle was chloride. One of the possible chlorine intermediates, chlorite, was demonstrated to be unstable in urine and sera from both rats and cattle, therefore previous reports of its presence in chlorate-dosed rats was shown to be an artifact of the analytical methods employed. Results from this study indicate that chlorate is rapidly absorbed and reduced to non-toxic chloride in rats, and demonstrates that ECP may continue to be developed as a pre-harvest food safety tool.
Technical Abstract: A novel pre-harvest technology that reduces certain pathogenic bacteria in the gastrointestinal tracts of food animals involves feeding an experimental sodium chlorate-containing product (ECP) to animals 24-72 h prior to slaughter. In order to determine the metabolism and disposition of the active ingredient in ECP, four male Sprague-Dawley (~350 g) rats received a single oral dose of sodium [36Cl]chlorate (3.0 mg/kg body weight). Urine, feces, and respired air were collected for 72 h. Radiochlorine absorption was 88-95% of the administered dose, and the major excretory route was the urine. Parent chlorate was the major species of radiochlorine present in urine at 6h (~98%), but declined sharply by 48h (~10%); chloride was the only other species of radiochlorine detected. Except for carcass remains (4.6% of dose), skin (3.2%) and GI tract (1.3%), remaining tissues contained relatively low quantities of radioactivity; and >98% of radiochlorine remaining in the liver, kidney, and skeletal muscle was chloride. Chlorite instability was demonstrated in urine and sera from both rats and cattle. The previously reported presence of chlorite in excreta of chlorate-dose rats was shown to be an artifact of the analytical methods employed. Results from this study indicate that chlorate is rapidly absorbed and reduced to chloride, but not chlorite, in rats.