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Studies on tributyltin uptake and depuration from food or water by rats, <br />crabs, oysters, and fish showed that in all species it was accumulated and <br />metabolized, at least partly, within 48 hours to dibutyltins, monobutyltins, <br />and more polar metabolites; however, oysters (Crassostrea virginica) <br />metabolized significantly less tributlytin than did other species tested (Lee <br />1985). The accumulation of tributyltin compounds in different tissues <br />correlated well with lipid content and supports a partitioning mode of uptake <br />(Laughlin et al. 1986a). The mixed function oxygenase system from hepatic <br />tissues was able to metabolize tributyltins by forming hydroxylated <br />metabolites (Lee 1985). Tributyltins are also potent cytotoxicants in rabbit <br />erythrocyte and skin cultures (Gray et al. 1985). <br />The potential of tricyclohexyltins to modify the inducibility of <br />cytochrome P-450 by various substances, such as 3-methylcholanthrene, is of <br />considerable toxicological importance (Rosenberg et al. 1985). Significant <br />metabolic interactions can result from a combination of environmental <br />chemicals and drugs that produce alterations in heme and mixed function <br />oxygenise activity (Rosenberg et al. 1985), suggesting that more research is <br />needed on interaction effects of organotins with other environmental <br />substances or contaminants. <br />The biological effects of the tetraorganotin compounds, R Sn, seem to be <br />caused entirely by the R SnX derivative that is produced 0 their rapid in <br />vivo dealkylation (Duncan 1990; Davies and Smith 1982; Blunden and Chapman <br />1986). Increasing toxicity of tetra- and triorganotins in mammals has been <br />shown to be associated with decreasing length of their ligands, as reflected <br />by solubility in biological fluids (Arakawa et al. 1981). It is not known if <br />damage is produced by the metal or by its alkyl derivative, but the presence <br />of trialkyl groups seems to enhance the toxicity of tin--probably by <br />increasing its partition into lipids, thus aiding the absorption of the metal <br />and speeding its distribution to the site of action (Arakawa et al. 1981). <br />11