Advances in Water Treatment and Enviromental Management

48 WATER TREATMENTFigure 2 shows the wide range of concentrations of tributyltin (TBT) whichhave caused adverse effects in different species (Zabel et al 1988).Figure 2. Concentrations of TBT in ng/l reported to have caused adverse effects.TBT is designed as an anti-fouling treatment and is therefore targeted atmolluscs and algae, which are much more sensitive to TBT than the nontargetfish species. However, there is also a wide range of sensitivities fordifferent species of the same taxonomic group, and it is therefore importantto collect data for more than one species.Bioaccumulation is another important parameter for assessing ‘safeconcentrations’ in the environment since some compounds can be selectivelyretained in the living tissue of animals and plants. These compounds cancause direct effects on the target organism, or they may be transferred viathe food chain to other organisms. They can also lead to discoloration ortainting of the tissues, making them unacceptable for human consumptionor causing their rejection as food by higher organisms.Bioaccumulation was utilised in the derivation of the marine environmentEQS for TBT. The correlation between the incidence of imposex (caused bygrowth blocking the pallial oviduct of females, preventing the release ofeggs and causing premature death) in the dog whelk, Nucella lapillus, andthe corresponding TBT tissue concentrations was determined. Thebioaccumulation factor was used to determine the water concentration whichwould produce an insignificant increase in the occurrence of imposex. Thiswater concentration was similar to the tentative EQS derived by applying