Bioaccumulation of Tributyltin: The Link Between Environment and Organism

Several taxonomically distinct organisms have been shown to accumulate tributyltin (TBT). Accumulation from water, the most studied route, leads to tissue burdens greater than 3 ug/g, dependent upon external concentration, in fish, crabs and bivalves. Accumulation from tainted food appears to be important in crabs and bivalves (fish have yet to be tested). Humic acids weakly bind TBT but do not significantly reduce accumulation of TBT by marine mussels, Mytilus edulis. Kaolin, a representative clay mineral does not reduce TBT accumulation by mussels, presumably because it binds TBT poorly. Two processes appear to control TBT bioaccumulation. In most organisms, partitioning mediated by hydrophobic properties of TBT governs rates and steady-state levels. Binding may also be important in some organisms, particularly bacteria, which secrete polyionic extracellular products (slimes). Advancements in this field are dependent upon improvements in the analytical determination of organotin compounds to distinguish between the parent compound and metabolites/conjugates.