Cadmium-containing granules in kidney tissue of the Atlantic white-sided dolphin (Lagenorhyncus acutus) off the Faroe Islands

Top predators from the northern sub-polar and polar areas exhibit high cadm ium concentrations in their tissues. In the aim to reveal possible adverse effects, samples of five Atlantic white-sided dolphins Lagenorhyncus acutus have been collected on the occasion of the drive fishery in the Faroe Isla nds, for ultrastructural investigations and energy dispersive X-ray microan alyses. Cadmium concentrations were less than the limit of detection in bot h immature individuals and ranged from 22.7 to 31.1 mug g(-1) wet weight in the mature individuals. Two individuals with the highest cadmium concentra tions exhibited electron dense mineral concretions in the basal membranes o f the proximal tubules. They are spherocrystals made up of numerous strata mineral deposit of calcium and phosphorus together with cadmium. Cadmium ha s been detected with a molar ratio of Ca:Cd of 10:1 in the middle of these concretions. To our knowledge, this is the first report of such granules in a wild vertebrate. The role of these granules in the detoxification of the metal and the possible pathological effects are considered. (C) 2001 Elsev ier Science Inc. All rights reserved.