Evaluation of oxidation treatment on algal toxins and cytotoxic effects of algal toxins post oxidation

2017 Fall.Includes bibliographical references.Algal blooms are a growing threat to the water industry, and one of the major reasons is that they are often accompanied by proliferation of the harmful species cyanobacteria. Cyanobacteria produce a variety of toxins that can cause serious adverse health effects. Microcystin-LR (MC-LR) and cylindrospermopsin (CYN) are known hepatotoxins, both named priority toxins by the EPA. Cyanotoxins are usually treated with oxidation in conventional drinking water treatment plants this approach has shown to successfully break down the toxin molecules. The goal of this project was to evaluate the effects of standard oxidation treatments on the concentration and cytotoxicity of MC-LR and CYN. Toxin solutions were prepared in water and treated with three oxidants – chlorine, potassium permanganate, and ozone. Once the toxin solutions were treated with oxidants, two assays were conducted in parallel: (1) the PrestoBlue cytotoxicity assay was conducted on HepG2 carcinoma cells following treatment, and (2) an LC-MS/MS analysis of the toxin solutions was used to quantify the toxins concentration post-treatment. The results of the LC-MS analysis suggested that neither chlorine, potassium permanganate or ozone treatment were effective at reducing the concentrations of MC-LR or CYN. These findings are consistent with the results of the cytotoxicity assay, which did not show a significant reduction of cell death after exposure to toxins treated with oxidation compared to untreated toxins. The oxidation of MC-LR and CYN likely failed due to a high starting concentration of the toxin, much higher than what occurs naturally. Future research should focus on a biological endpoint other than apoptosis to evaluate the potential health risks of the toxin metabolites at concentrations relevant to natural exposure