Assessing the Potential of Cell lines as Tools for the Cytotoxicity Testing of Acid Mine Drainage Effluent Impacting a Natural Water Resource

In vitro cytotoxicity was assessed using mammalian (Vero) and fish (RTgill-W1) cell lines in a water compartment impacted by acid mine effluent from a coalmine. Physico-chemical characterisation of the stream showed that Al, Mn, Fe and sulphates were much higher than the maximum recommended values established by South African legislation regarding effluent in receiving streams. Water collection points selected was immediately following a wetland (U) and another downstream (T) of the mixing zone where alkali is used to increase water pH to reduce acidity and precipitate metals. Another unaffected site served as the reference site (Ref). Cell viability assays were employed to detect effects of water samples on cells following exposure for 24h, 48h and 72h, namely the neutral red (NR), tetrazolium-based (MTT) colorimetric assays and the lactate dehydrogenase assay (LDH) which assess lysosomal, mitochondrial functions and cellular necrosis respectively. Toxicity was detected in U and T water samples against both cell lines using the NR and MTT techniques, being maximal at 72h with IC values 50 of 23.9% and 20.5% (MTT), and 32.2% and 49.4% (NR) for Vero cell lines (U vs. T). IC values for the RTgill-W1 cell lines were 8.4% and 7.19% 50 (MTT), and 10.5% and 35.3% (NR) for U and T respectively, but no cytotoxicity was recorded for Ref. The loss of cell viability resulting in damage to cellular functions gives rise to concerns regarding the potential risks for aquatic animals and downstream end users