Short-term toxicity of bis(tri-n-butyltin)oxide in flounder (Platichthys flesus): Pathology and immune function

The present study is part of a project that focuses on the relationship between environmental pollution and fish diseases. Field studies in various polluted coastal areas in Europe and the United States of America clearly indicate a relationship between pollution and the increase in prevalence of tumours and infectious diseases in fish. Research under controlled laboratory conditions is necessary to prove causal links between specific xenobiotics and disease prevalence. One of the chemicals of interest in the myriad of xenobiotics found in polluted waters and sediments is the organotin compound tributyltin (TBT), originating mainly from antifouling paints used on the hulls of ships. This report describes a study in which flounders (Platichthys flesus) were exposed to bis(tri-n-butyltin)oxide (TBTO) in the water under controlled laboratory conditions. The effects on several organs (gills, skin, eye, liver, mesonephros, ovary/testis, spleen, and gastrointestinal tract) were examined using histopathology, and morphometric analysis of the thymus was performed to assess the target organ(s) for TBTO in this fish species. Also the function of the non-specific and specific resistance was studied using ex vivo/in vitro immune function tests. Exposure of flounder to TBTO, in concentrations which were in the same order of magnitude as maximum TBT levels measured in the field (experiment: 17.3 mu g TBT/l; field: 7.2 mu g TBT/l), caused mortality after 7-12 days, resulted in gill lesions, and induced significant reduction of the non-specific resistance. A significant decrease of the relative thymus volume, but no marked effects on the specific immune system were noted after exposure to TBTO. (C) 1998 Published by Elsevier Science B.V. All rights reserved.