Retrospective monitoring of organotin compounds in biological samples from North Sea and Baltic Sea – are the use restrictions successful?
Rüdel, Heinz; Steinhanses, Jürgen; Müller, Josef; Schröter-Kermani, Christa
Umweltwiss. Schadst. Forsch. 21 (2009), 3, 282-291
Original titel: Retrospektives Monitoring von Organozinnverbindungen in biologischen Proben aus Nord- und Ostsee - Sind die Anwendungsbeschränkungen erfolgreich?
Background, aim, and scope
Organotin compounds are used as biocides, plastic additives and catalysts. With respect to environmental effects, tributyltin (TBT) and triphenyltin (TPT) compounds are the most relevant, because of their high aquatic toxicity and endocrine effects on mussels and snails. TBT was mainly used as antifouling agents in coatings of ships and boats. In 1989, Germany banned the application to ships < 25 m length. Finally, in 2003, the use of organotin-based antifoulants within the European Union was completely banned. To verify the effectiveness of the restrictions a retrospective monitoring study was initiated.
Material and methods
A set of appropriate archived samples was retrieved from the German environmental specimen bank (ESB) comprising standardized pooled samples of eelpout (Zoarces viviparus) muscle tissue and of soft bodies of common mussels (Mytilus edulis) sampled at two locations in the North Sea and one in the Baltic Sea. Analysis of organotin compounds included n-hexane extraction, derivatisation with sodium tetraethyl borate, capillary gas-chromatographic separation and atomic emission detection.
Results and Discussion
Altogether, time series cover the period 1985 to 2006, including data of an earlier study (Rüdel et al. 2003). Until the late 1990s, TBT remained more or less constant in all samples (e. g. 17 ± 3 ng/g wet weight, ww, in mussels from Jadebay/North Sea). The German ban of TBT-based antifoulings for small ships had no effects on environmental concentrations because large ships dominate in the investigated North Sea regions. After the EU-wide ban of TBT in 2003, however, significant decreases in mussel and fish contamination could be observed. In mussels from Jadebay, TBT concentrations were 14 and 6 ng/g ww in 2004 and 2005, respectively. TBT contamination in eelpout of the same region decreased to about 30 percent of the initial concentrations in 2006. Corresponding decreases were detected for TPT. Declining trends were also found in fish and mussels sampled from a Baltic Sea offshore site.
The results demonstrate the effectiveness of the legal measures undertaken to control organotin inputs into the aquatic environment. Nevertheless, organotin compounds are still relevant pollutants. Water concentrations calculated from the measured tissue concentrations by using the respective bioconcentration factors are still above the Environmental Quality Standards derived in the context of the Water Framework Directive (0.2 ng/l) and the OSPAR mussel EAC (Environmental Assessment Criteria; 2.4 ng/g ww). Thus adverse effects to marine organisms cannot be excluded.
Recommendations and perspectives
Further studies should be performed to verify the declining trends. More sensitive analytical methods, e. g. species-specific isotope dilution analysis, are recommended in order to detect lower environmental concentrations.