Ref ID : 6670
Philipp Egeler, J. Rombke, M. Meller, Thomas Knacker, and R. Nagel; Bioaccumulation test with Tubificid Sludgeworms in artificial media - development of a standardisable method. Hydrobiologia 406:271-280, 1999
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Lipophilic chemicals entering aquatic ecosystems often tend to adsorb to sediment. Although often not bioavailable to pelagic organisms, these compounds can be subject to bioaccumulation and thus pose a potential threat for sediment-dwelling organisms. The assessment of bioaccumulation is currently based on the extrapolation of fish bioconcentration data. Thus, measuring the bioaccumulation in benthic organisms gives more detailed information on the hazard of chemicals for aquatic ecosystems. The freshwater tubificids Tubifex tubifex and Limnodrilus hoffmeisteri were chosen as test organisms. Breeding of the oligochaetes as well as bioaccumulation studies were carried out in a system consisting of artificial sediment and reconstituted water. [14C]-lindane (gamma-hexachlorocyclohexane, gamma-HCH) and [14C]-hexachlorobenzene (HCB) served as model substances. Additionally, [14C]-3,4-dichloroaniline (3,4-DCA) was tested. Uptake and elimination of lindane and HCB were examined. Bioaccumulation factors (BAF) were determined from the ratio of concentration in oligochaete tissue to concentration in sediment. The tubificids accumulated [14C]-lindane, [14C]-HCB, and [14C]-3,4-DCA by factors of 4.7 (mean value; n=4), 6.6 (mean value; n=4) and 13.2, respectively, based on wet weight and radioactive concentrations. No major metabolites were detected in worms, sediment and water. Elimination kinetics were examined for [14C]-lindane and [14C]-HCB. When transferred to clean sediment, the worms eliminated both test substances rapidly and nearly completely. The tubificid bioaccumulation factors are contrasted with corresponding fish bioconcentration factors from literature. The presented data indicate once more that the assessment of bioaccumulation based exclusively on lipophilicity and on the extrapolation of fish bioconcetration data to other organisms or environmental compartments is not appropriate.