Registration Dossier
Registration Dossier
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EC number: 215-960-8 | CAS number: 1461-25-2
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Three supporting studies are available for this endpoint.
In the first study, the intestinal uptake site, enterohepatic circulation, and excretion into bile, feces and urine of tetrabutyltin was investigated after oral, subcutaneous, or intestinal administration of the compounds to rats and rabbits. Tetrabutyltin is transported in the body through enterohepatic circulation.
Based on review information presented in the ATSDR document on health effects due to exposure of tin and tin compounds, only small pieces of information on toxicokinetics of tetrabutyltin were reported. In rats, absorbed tetrabutyltin appears to be excreted as the trialkyltin metabolite. No tetrabutyltin was detected in excreta of rats.
In the third supporting study, the metabolic fate of tetrabutyltin was examined in monooxygenase systems. Radiolabeled Bu4Sn yields 8 identified NADPH-dependent metabolites.
Key value for chemical safety assessment
Additional information
The intestinal uptake site, enterohepatic circulation, and excretion into bile, feces and urine of tetrabutyltin was investigated after oral, subcutaneous, or intestinal administration of the compounds to rats and rabbits. The main uptake sites in the small intestine were the jejunum and duodenum for tetrabutyltin. Tetrabutyltin was detected in the small intestine and contents of the intestinal lumen after subcutaneous injection of these compounds in rats. Tetrabutyltin is transported in the body through enterohepatic circulation. The route, rate and amount of excretion of tetrabutyltin depends on the velocity of dealkylation, doses, physical and chemical properties, and route of administration of the compound.
Based on review information presented in the ATSDR document on health effects due to exposure of tin and tin compounds, only small pieces of information on toxicokinetics of tetrabutyltin were reported. Ingested butyltin compounds and their dealkylation products distribute to soft tissues, including brain, kidney and liver. In rats, following five oral doses of 10 mg/kg tetrabutyltin, tissue:blood concentration ratios were: brain <1; kidney 10-12; and liver 20. The fraction of an ingested dose of butyltin compounds excreted in the urine increases with increasing number of butyl moieties, such that more highly butylated tin compounds may be absorbed to a greater extent. In rats, absorbed tetrabutyltin appears to be excreted as the trialkyltin metabolite. No tetrabutyltin was detected in excreta of rats.
Metabolic fate of tetrabutyltin was examined in monooxygenase systems. Radiolabeled Bu4Sn yields 8 identified NADPH-dependent metabolites. There were 2 unusual features of the results: A large loss of radiocarbon, possibly attributable to volatilization of Bu4Sn during incubation, extraction, workup , and TLC analysis; extensive formation of polar metabolites which chromatograph in positions appropriate for Bu3SnX derivatives with two sites of carbon hydroxylation or for Bu2SnX2 derivatives with one site of carbon hydroxylation. Bu4Sn is hydroxylated in the MO system to yield (beta HOBu)Bu3Sn and (gamma-HOBu)Bu3Sn. Although not detected in these studies, trace levels of (delta-HOBu)Bu3Sn and (gamma-C==O-Bu)Bu3Sn might also form. Bu3SnX undergoes a destannylation reaction in the buffer system to Bu3SnX and 1-butanol. Bu3SnX may also be formed by destannylation of (beta-HOBu)Bu3Sn, with the liberation of 1-butene.
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