Bioaccumulation and toxicity of oxaliplatin in fresh water: A study with Lemna minor

Abstract

Oxaliplatin is the newest platinum-based drug to be used widely in chemotherapy. However, very little is known about its behaviour and toxicity once discharged to the environment. In this study, the freshwater macrophyte, Lemna minor, has been exposed to three concentrations of the drug (low, medium and high; 0.4, 10 and 100 μg mL−1, respectively) for seven days according to OECD guidelines and the growth rate, biochemical changes and extent of membrane damage determined. The stability of oxaliplatin was also monitored during the exposures and the accumulation, as both adsorbed and internalised fractions, evaluated by chemical extraction and digestion at the end of the experiment. Oxaliplatin appeared to remain intact throughout, with no measurable metabolite formation in the growth medium, and bioconcentration factors were < 100 mL g−1. The majority of oxaliplatin taken up by L. minor (about 66 to 84%) was internalised, presumably through passive diffusion and, possibly, uptake through transporters. Among the end-points tested, only relative growth rate of frond area and ion leakage were adversely affected at the medium and/or high concentrations employed. These observations suggest that oxaliplatin is unlikely to be phytotoxic at concentrations typically encountered in the environment and that L. minor is not a suitable biomonitor or phytoremediator of contaminated waters.