Effects of lipophilic complex formation on the uptake and distribution of some metals in fish

Dithiocarbamates, xanthates, dialkyldithiophosphates and pyridinethiones are groups of compounds which can form lipophilic complexes with heavy metals. These compounds are widely used in industry and in agriculture and forestry and may pollute the aquatic environment. We have exposed fish (brown trouts) to substances belonging to these groups of compounds together with heavy metals (Cd2+, Ni2+, Hg2+, CH3-Hg+ or Pb2+) and then examined the uptake of the metals in the tissues of the fishes. Some of the examined complexing substances were found to cause highly increased tissue levels of the metals in the trouts. However, the enhancing effects varied for different complexing substances and for different metals. A facilitated penetration of the lipophilic complexes over the gill membranes and cellular membranes in other tissues may underlie the increments in the tissue levels of the metals. The lipophilicity and the stability of the complexes may be of importance for the effects of the substances on the disposition of the metals. Studies by other authors, in fishes as well as in other aquatic organisms, have also shown enhanced metal accumulation by compounds forming lipophilic complexes. It is considered that this type of interaction may have important implications for the behaviour of metals in aquatic ecosystems.