ReviewBioassays for toxicological risk assessment of landfill leachate: A review

•Application of bioassays for assessing leachate toxicity is critically reviewed.•119 research articles on evaluation of leachate toxicity by bioassays are studied.•In vivo and in vitro bioassays involving different trophic levels are included.•Studying the effects on a single species leads to under-/over-estimation of risk.•Multispecies approach is vital for minimizing uncertainties in evaluating toxicity.

Landfilling is the most common solid waste management practice. However, there exist a potential environmental risk to the surface and ground waters due to the possible leaching of contaminants from the landfill leachates. Current municipal solid waste landfill regulatory approaches consider physicochemical characterization of the leachate and do not assess their potential toxicity. However, assessment of toxic effects of the leachates using rapid, sensitive and cost-effective biological assays is more useful in assessing the risks as they measure the overall toxicity of the chemicals in the leachate. Nevertheless, more research is needed to develop an appropriate matrix of bioassays based on their sensitivity to various toxicants in order to evaluate leachate toxicity. There is a need for a multispecies approach using organisms representing different trophic levels so as to understand the potential impacts of leachate on different trophic organisms. The article reviews different bioassays available for assessing the hazard posed by landfill leachates. From the review it appears that there is a need for a multispecies approach to evaluate leachate toxicity.