Zeranol: a review of the metabolism, toxicology, and analytical methods for detection of tissue residues
Zeranol, an anabolic agent produced commercially for use in cattle and sheep intended for human consumption, is noncarcinogenic, nonteratogenic, and nonmutagenic. Toxicity testing (acute, subacute, and chronic) in several species by various routes of administration reveals an extremely low toxicity, the oral rat LD/sub 50/ exceeding 40 g/kg. Postmortem abnormalities of high-dose animals are attributed to the effects of the compound on the endocrine system. Both zeranol itself and zearalanone, the major Phase I metabolite in the seven species studied, are excreted in the feces and in the urine, either free or as sulfates/glucuronides. A minor urinary metabolite has been identified as taleranol, an epimer of zeranol. Both metabolites exhibit a very low order of toxicity (oral rat LD/sub 50/ exceeding 10 g/kg in both cases), and both exhibit less biological activity than the parent compound. The four types of analytical methods which have been employed for the specific detection and quantitation of residues of zeranol in edible tissues are: (1) gas chromatography (detection limit . 20 ppb), (2) high-performance liquid chromatography (detection limit . 5 ppb), (3) thin-layer chromatography (detection limit . 1-3 ppb), and (4) radioimmunoassay methods (detection limit to be published). The following residue levels were determined radiometrically in tissue samples taken 45 days after implantation of cattle with 36 mg tritiated zeranol: less than or equal to 2 ppb in liver, less than or equal to 1 ppb in kidney and fat, and less than or equal to 0.2 ppb in muscle and plasma. A no-effect level (NEL) of 0.225 mg/kg was determined as the highest oral dosage of zeranol which produced no estrogenic effects in female monkeys. Based on the NEL, a tolerance level for tissue residues of zeranol was calculated as 315 ppb.
- Research Organization:
- International Minerals and Chemical Corporation, Terre Haute, Indiana
- OSTI ID:
- 5272819
- Journal Information:
- Regul. Toxicol. Pharmacol.; (United States), Vol. 3:1
- Country of Publication:
- United States
- Language:
- English
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GAS CHROMATOGRAPHY
LIQUID COLUMN CHROMATOGRAPHY
METABOLISM
RADIOIMMUNOASSAY
THIN-LAYER CHROMATOGRAPHY
TISSUE DISTRIBUTION
TOXICITY
COWS
DOGS
DOSE-RESPONSE RELATIONSHIPS
FOOD CHAINS
MONKEYS
RABBITS
RATS
SHEEP
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMALS
CATTLE
CHROMATOGRAPHY
DISTRIBUTION
DOMESTIC ANIMALS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
PRIMATES
RADIOASSAY
RODENTS
RUMINANTS
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