Effluent from bauxite factory induces developmental and reproductive damage in sea urchins

The effluent from a bauxite plant was tested on sea urchin embryos and sperm for the induction of: a) developmental defects in effluent-exposed embryos; b) loss of fertilization success, and c) transmissible damage to the offspring of pretreated sperm. The chemical composition of the bauxite sludge was analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). Dose-related effects were observed at effluent dilutions ranging from 1:10⁵ to 1:10² [equal to 1.5 to 1,500 μg (dry weight)/ml]. The effects were exerted on developmental toxicity, spermiotoxicity, and offspring malformations/mortality. Toxicity was exerted by sludge concentrations in the order of 1:10³ (or 150 μg/ml). Chemical analysis of sludge pointed to the presence of several inorganics, with prevalence of aluminum, iron and chromium. In spite of the recognized difficulties in referring the effects of complex mixtures (bauxite sludge) to the toxicities of individual components, the results reported here are fairly consistent with those reported on the toxicities of the major sludge components. Based on the present data, uncontrolled disposal of bauxite sludge may be a major hazard(s) to the environment, involving early life stages and recruitment in aquatic biota.