Lysosomal response of earthworm coelomocytes induced by long-term experimental exposure to heavy metals

Microcosms were established in 1995 in which laboratory cultures of Eisenia fetida were exposed to Pb, Zn and Cd salts over a period of three years. T he lysosome response was used as biomarker to explore the cytotoxicity of t he various metals. A conventional as well as a cell-marking counting proced ure was followed to determine the neutral red retention times resulting fro m exposure to the different metal salts. Cd and Pb accumulated in the worms (369.7 +/- 31.0 mu g . g(-1) and 176.9 +/- 20.4 mu g . g(-1) respectively) while Zn-worms had a body load of 94.9 +/- 4.4 mu g . g(-1) at the time of sampling. The neutral red retention times (conventional method) of the exp osed worms were significantly shorter than those for control worms (93.5 +/ - 0.5 minutes) compared to 58.2 +/- 0.8 (Pb), 53.8 +/- 0.6 (Zn) and 35.4 +/ - 0.7 (Cd). The results showed that both methods yielded basically the same results and also indicated that the neutral red retention method has the p otential to detect the sublethal effects of different metals.