SPECIATION AND GENOTOXICITY OF BUTYLTIN COMPOUNDS

The northern part of the Elbe river in Germany is one of the most high ly polluted rivers in Europe, in particular with toxic organotin compo unds. Two major anthropogenic sources are the Hamburg harbour area wit h intensive docking activities and a chemical plant in Bitterfeld clos e to the Mulde river in eastern Germany. Tributyltin is leached from t he antifouling paints and enters the water phase. Thus, the Hamburg ha rbour area is highly contaminated with tributyltin and its degradation products, di- and mono-butyltin. Untreated run-off waters of an organ otin plant in Bitterfeld contaminate the Mulde, a tributary of the Elb e, extensively. The Mulde sediments contain butyltin compounds of the order of mg of Sn per kilogram of dry mass. In Raguhun sediments, conc entrations of tetrabutyltin and tributyltin were 1.8 +/- 0.4 mg of Sn per kilogram of dry mass and 1.1 +/- 0.2 mg of Sn per kilogram of dry mass, respectively. Remobilization of the sediments during high water periods transports the contaminants along the Mulde river into the Elb e river. Tetrabutyltin can be detected in the Elbe river as far as Cux haven and its estuary. To evaluate the ecological impact, fish tissues were analysed for their butyltin content and the data were correlated with the butyltin content in the surrounding water. The analysis of d ifferent fish tissues: liver, kidney, gills and the edible tissue, sho ws a clear enrichment of the tributyltin species. In the liver, tribut yltin concentrations of up to 200 ng of Sn per gram of wet tissue were found. Bioconcentration factors were calculated to be of the order of 4500-9000. Tetrabutyltin could not be found in all the tissues, where as it is present in water. The low bioavailability of tetrabutyltin is presumably caused by the low amount of tetrabutyltin in the dissolved constituents of water. Up to 99% of the tetrabutyltin content in wate r is bonded to particulate matter. The butyl groups influence the toxi c behaviour of the butyltins. Although the toxic effects of butyltins on different organisms are well investigated, the genotoxic potential of the butyltins has received much less attention. The SOS-Chromotest was used to evaluate their genotoxicity. All the butyltins were found to be genotoxic; dibutyltin was the most genotoxic (10-40 mu g of Sn p er litre) followed by tri-, tetra- and mono-butyltin. An enhancement o f the genotoxicity of all butyltins was observed using spiked lake wat er instead of distilled water. For the analysis of the butyltin compou nds sodium tetraethylborate was used as in situ ethylating agent in th e buffered samples. No pre-extraction steps with complexing agents are necessary. The extraction yields of all butyltin compounds are in the range of 82-94% for water; 76-88% for suspended particulate matter, s ediment and soil; 80-94% for organisms; and 76-97% for air samples. Th e limit of detection of GC-AAS is 25 +/- 5 pg of Sn per microlitre inj ected volume (3 sigma of the baseline noise).