Bioaccumulation of 14C-17α-ethinylestradiol by the aquatic oligochaete Lumbriculus variegatus in spiked artificial sediment

Abstract

A bioaccumulation study was performed with the endobenthic freshwater oligochaete Lumbriculus variegatus M u¨ ller exposed to the radiolabelled synthetic steroid 17α-ethinylestradiol ( 14C-EE 2) in a spiked artificial sediment. Concentration of total radioactivity increased constantly and almost linearly during 35 days of exposure. The accumulation factor normalised to worm lipid content and sediment TOC (AF lipid/OC) was 75 at the end of the uptake period, but a steady state was not reached. Uptake kinetics were calculated fitting the measured AFs to a kinetic rate equation for constant uptake from sediment using iterative non-linear regression analysis. After 10 days of elimination in contaminant-free sediment 50% of the accumulated total radioactivity was excreted by the worms. Extracts from L. variegatus sampled at the end of the uptake phase were analysed by thin layer chromatography (TLC). The results showed that 6% of the total radioactivity incorporated by the worms was 14C-EE 2. After treatment of extracts with β-glucuronidase the amount of 14C-EE 2 increased to 84%. These results suggest that L. variegatus has the potency to accumulate high amounts of conjugated EE 2. Hence, a transfer of EE 2 to benthivores and subsequent secondary poisoning of predators might be possible.