CyanoTOX: Tools for Managing Cyanotoxins in Drinking Water Treatment With Chemical Oxidants

Spies

et al. 2019

Journal of Toxicology

Permanganate pretreatment of drinking water is effective in transforming dissolved, noxious contaminants and in reducing halogenated by-products. Permanganate targets specific compounds such as taste and odor compounds, disinfection precursors, manganese, and natural organic contaminants that are not removed readily by conventional treatment alone. Cyanobacterial blooms (cHABs) can increase disinfection by-product precursors as well as the cyanotoxin, microcystin (MC), a potent liver toxin. MC toxicity is conferred by a unique, conserved amino acid, Adda, that inhibits protein phosphatase 1 and 2A. Although over 150 MC congeners have been reported, thousands of MCs are statistically possible. Over the last ten years, one congener, MC-LA, has been reported with increasing frequency, making it one of the most common cyanotoxins identified in North American freshwater systems; yet its oxidation has not been widely studied. Frequently, Adda specific enzyme-linked immunosorbent assay (ELISA) and protein phosphatase inhibition assay (PPIA) are used to quantitate total MCs to evaluate treatment efficiency and exposure. Anecdotal reports suggest that MC degradation products can cause interference with the Adda-ELISA. MC-LA was used as the model MC compound in this study. PPIA quantitation of MC-LA in water agreed with liquid chromatography high resolution mass spectrometry (LC/HRMS), whereas the ELISA quantitation did not agree with LC/HRMS quantitation. We determined the second order rate constant for MC-LA as 118 ± 9 M−1 s−1, the activation energy to be 21.2 kJ mol−1, and the rate to be independent of pH between pH 6 and 9. Ten oxidation products (OPs) were observed by LC/HRMS and three primary reaction pathways are proposed. The reaction pathways were used to explain differences in the quantification by Adda-ELISA, HRMS, and PPIA. The oxohydroxylation of MC-LA produced two major OPs, C46H67N7O14 [M+H] + = 942.4819 and C46H69N7O15 [M+H]+ =960.4925. Major OPs may contain an unmodified Adda and are the likely cause of interference with the Adda-ELISA. Several governmental agencies recommend the use of the Adda-ELISA to determine the MC quantitation for treatment efficiency and customer exposure; yet our results suggest that these or other OPs interfere with the Adda-ELISA causing artificially high values for total MCs.

Section: Resultsmentioning

confidence: 99%

Permanganate Oxidation of Microcystin-LA: Kinetics, Quantification, and Implications for Effective Drinking Water Treatment

Spies

et al. 2019

Journal of Toxicology

“…To evaluate the chlorination kinetics of CyanoTOX v.1.0 (Stanford et al ), the oxidant concentrations were determined at 0.5 min and 20 min. The C × T used in the effluent method was calculated directly using the oxidant dosage at 20 min multiplied by the reaction time.…”

Section: Resultsmentioning

confidence: 99%

“…Because of the timing of the US Environmental Protection Agency's (USEPA's) final health advisory levels, efforts focused on developing the model, along with protocols for oxidation testing and powdered activated carbon. CyanoTOX v.1.0 was based on the best available kinetic models that were developed under rigorous laboratory conditions (Stanford et al ).…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the purposes of this study were to (1) compare two commonly applied analytical methods (i.e., ELISA and LC‐MS/MS) for the detection of cyanotoxins (i.e., MCs and CYN) and (2) provide kinetic data (e.g., percentage removal of the toxins and oxidant decay) for the validation of CyanoTOX v.1.0, which is based on the best available kinetic models that were developed under rigorous laboratory conditions (Stanford et al ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison of ELISA and LC‐MS/MS Analytical Methods and Validation of AWWA Hazen‐Adams CyanoTOX

He¹,

Stanford²,

Adams³

et al. 2018

Journal AWWA

Self Cite

E nzyme-linked immunosorbent assay (ELISA) has been widely applied as a convenient screening method for cyanotoxins such as microcystins (MCs). However, differing sensitivities of MC congeners, interference of background water quality conditions, and analytical procedures can cause variations in ELISA readings relative to those quantified by liquid chromatographytandem mass spectrometry (LC-MS/MS). In this study, these two analytical methods were evaluated using samples with and without oxidation treatment over a range of experimental conditions and water qualities. The degradation kinetics were further compared with predictions using version 1.0 of the AWWA Hazen-Adams Cyanotoxin Tool for Oxidation Kinetics (CyanoTOX). 1 This version of the CyanoTOX model was also tested at two full-scale sites, and the subsequent validation and kinetics data were used to update the program (version 2.0). This study provides useful information on model validation and guidance for using the improved tool to predict cyanotoxin removal efficiency using routinely monitored parameters relevant to concentration times time (C × T; mg-min/L) or oxidant dose decay. cyanotoxin-related issues, including their detection, treatment, fate, and toxicological aspects. Benjamin D. Stanford

“…The pH impacts the inactivation efficacy of chlorine, and it is more effective at inactivating MC, CYN, and STX at low pHs. Stanford et al () created a tool for managing extracellular cyanotoxins in drinking water treatment by chemical oxidation called CyanoTOX. This model can be used to assess how changes in treatment such as pH, chemical, and residence time impacts cyanotoxin (MC, ANA, and CYN) inactivation.…”

Section: Treatment Processesmentioning

confidence: 99%

A Cyanotoxin Primer for Drinking Water Professionals

Westrick

Szlag²

2018

Journal AWWA

Cyanobacteria and cyanotoxins became an emerging issue for the drinking water industry in 1998 by appearing in the first US Environmental Protection Agency drinking water Contaminant Candidate List (CCL 1). Before CCL, cyanotoxin contaminants did not fit into the two prevailing paradigms: synthetic chemicals and pathogens. Cyanotoxins added a new paradigm: natural chemical toxins. Driven by anthropogenic influences, nutrient loading, and climate change, cyanobacterial blooms are increasing in frequency and distribution. To efficiently produce potable water from a source impacted by a toxic cyanobacterial bloom, drinking water practitioners need to take a multidisciplinary approach. Bloom dynamics (biology), surrogate and analytical methods (chemistry), inactivation/removal of intra-and extracellular toxins and multibarrier treatment (engineering), and risk management (public health) must all be part of a comprehensive management strategy. This article provides a holistic primer for water professionals on cyanotoxin treatment and management using pertinent literature, technical sources, case studies, and experience.