Toxicity of TBT-based paint leachates on the embryonic development of the sea urchin Paracentrotus lividus Lam

The toxicity of TBT was evaluated using sea urchin (Paracentrotus lividus Lam) sperm and eggs as well as early developmental stages as recommended model organism for toxicity testing. Various concentrations of TBT were obtained by leakage from painted plates or by addition of pure TBTO in sea water. The toxicity was estimated measuring the percentage of unfertilized eggs, the decreased cleavage rate, DNA and echinochrome production rate which provided the most accurate quantitative results. Following short exposure of unfertilized eggs, the EC50 values related to cleavage rate delay, DNA and echinochrome inhibition were in the range of 3.5–37 μg/L TBT leachate. The exposure of eggs to TBTO resulted with similar EC50 values: 9.7 and 12.0 μg/L TBTO for DNA and echinochrome production, respectively. Due to continuous exposure of fertilized eggs and developing embryos the EC50 values were 4.7 regarding DNA and 3.4 μg/L TBTO for echinochrome synthesis. The most vulnerable stages were swimming blastulae immediately following hatching. Toxic effects can be measured few hours later and the EC50 values were the lowest: 0.6–4.0 μg TBT leachate and 2.0 μ TBTO/L. The lowest concentration of TBTO that did not produce harmful effects on P. lividus development was calculated to be 0.8 μ/L.