Toxicity of tri‐n‐butyltin to sea urchin eggs and larvae: Relation to bioaccumulation at the nanomolar level

Nnomolar concentrations of tri- n-butyltin (TBT) from 5 × 10−10 M to 5 × 10−9 M, were assayed on sea urchin (Paracentrotus lividus) egg cleavage and on larval development. Preincubation enhanced TBT toxicity to first cleavage DNA and protein syntheses but not to intracellular calcium sequestration. Exposure to nanomolar TBT affected the larval development up to the ninth day by reducing arm length and increasing the diameter of the rudiment. Chromatographic analysis of TBT in eggs shows a dose-dependent biomagnification with a half-time of 5 min, which is much shorter than the length of preincubation necessary to provoke cytotoxicity at the same concentration (5 × 10−9 or 5 × 10−10 M). Our data suggest that nanomolar concentrations of TBT similar to those encountered in polluted waters could directly affect sea urchin egg development after fertilization and the larval cycle, these effects being independent of bioaccumulation.