Occurrence of the Microcystins MC-LW and MC-LF in  Dutch Surface Waters and Their Contribution to Total Microcystin Toxicity

Faassen, Elisabeth J.; Lürling, Miquel

doi:10.3390/md11072643

Cited by 61 publications

(50 citation statements)

References 31 publications

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“…The more critical issue may be that the underlying assumption of oral toxicity being in a similar range as that of MCYST-LR is not well understood. For microcystin-congeners other than MCYST-LR, the above mentioned recent findings by Fischer et al (2010) on toxicokinetics of MCYST-LW and MCYST-LF have led to a call for a MCYST congener specific approach in risk assessment (Faassen and Lurling, 2013). …”

Section: Discussionmentioning

confidence: 99%

Current approaches to cyanotoxin risk assessment and risk management around the globe

et al. 2014

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Toxic cyanobacteria became more widely recognized as a potential health hazard in the 1990s, and in 1998 the World Health Organization (WHO) first published a provisional Guideline Value of 1 μg L−1 for microcystin-LR in drinking-water. In this publication we compare risk assessment and risk management of toxic cyanobacteria in 17 countries across all five continents. We focus on the three main (oral) exposure vehicles to cyanotoxins: drinking-water, water related recreational and freshwater seafood. Most countries have implemented the provisional WHO Guideline Value, some as legally binding standard, to ensure the distribution of safe drinking-water with respect to microcystins. Regulation, however, also needs to address the possible presence of a wide range of other cyanotoxins and bioactive compounds, for which no guideline values can be derived due to insufficient toxicological data. The presence of microcystins (commonly expressed as microcystin-LR equivalents) may be used as proxy for overall guidance on risk management, but this simplification may miss certain risks, for instance from dissolved fractions of cylindrospermopsin and cyanobacterial neurotoxins. An alternative approach, often taken for risk assessment and management in recreational waters, is to regulate cyanobacterial presence – as cell numbers or biomass – rather than individual toxins. Here, many countries have implemented a two or three tier alert level system with incremental severity. These systems define the levels where responses are switched from Surveillance to Alert and finally to Action Mode and they specify the short-term actions that follow. Surface bloom formation is commonly judged to be a significant risk because of the elevated concentration of microcystins in a scum. Countries have based their derivations of legally binding standards, guideline values, maximally allowed concentrations (or limits named otherwise) on very similar scientific methodology, but underlying assumptions such as bloom duration, average body size and the amount of water consumed while swimming vary according to local circumstances. Furthermore, for toxins with incomplete toxicological data elements of expert judgment become more relevant and this also leads to a larger degree of variation between countries’ thresholds triggering certain actions. Cyanobacterial blooms and their cyanotoxin content are a highly variable phenomenon, largely depending on local conditions, and likely concentrations can be assessed and managed best if the specific conditions of the locality are known and their impact on bloom occurrence are understood. Risk Management Frameworks, such as for example the Water Safety Plan concept of the WHO and the ‘bathing water profile’ of the European Union are suggested to be effective approaches for preventing human exposure by managing toxic cyanobacteria from catchment to consumer for drinking water and at recreational sites.

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Section: Discussionmentioning

confidence: 99%

Current approaches to cyanotoxin risk assessment and risk management around the globe

et al. 2014

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“…The evaluation has been suggested to all the other congeners and expressing as MC-LR equivalents (MC-LR eq ). MC-LR eq are usually used for the expression of total MC varieties concentration in absence of other congeners information [7]. Mouse bioassay was the first screening method to detect MC-LR [8,9].…”

Section: Introductionmentioning

confidence: 99%

Micro-droplet Hydrodynamic Voltammetry for the Determination of Microcystin-LR Based on Protein Phosphatase

Islam

Sazawa

Sugawara

et al. 2019

J. of Wat. & Envir. Tech.

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Microcystin-LR (MC-LR) is one of the most frequent and most lethal toxicants and a vital environmental pollutant due to its toxicity and persistence. It is hepatotoxins and have been shown to be potent tumor-promoters which pose a serious threat to human health in the form of chronic exposure through drinking water. In this study, a novel electrochemical method for the determination of MC-LR has been developed using protein phosphatase 2A (PP2A) enzyme inhibition. The rapid and simple determination of PP2A activity was accomplished by means of hydrodynamic voltammetry in a 50 µL micro-droplet with a rotating disk electrode (RDE). The chronoamperometric response were obtained from the electrochemical oxidation of p-aminophenol (PAP) following the enzymatic conversion of p-aminophenyl phosphate (PAPP) as a substrate. PP2A activity estimated by using PAPP substrate is affected by MC-LR, and this phenomenon decreases the current signal of PAP. The IC 50 value was calculated as 0.08 µg/L which is well below the World Health Organization (WHO) provisional guideline value for total MC-LR of 1 µg/L in drinking water. The enzymatic reaction using RDE is possible to perform using fewer chemicals in a rapid manner. Therefore, the method can be very attractive for MC contaminated drinking water routine assessment.

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“…Despite the absence of stronger cytotoxic responses or detectable disruptions of MAPK signal transduction, the toxin was apparently accumulated by the cells and interacted with several cellular proteins. While MC-LR represents the most studied structural variant among MCs because of its high acute hepatotoxicity and frequent environmental occurrence, cyanobacterial blooms frequently contain multiple MC variants at the same time, some of them demonstrating even higher toxicity and cell permeability than MC-LR [21,22,73,74].…”

Section: Discussionmentioning

confidence: 99%

Microcystin-LR Does Not Alter Cell Survival and Intracellular Signaling in Human Bronchial Epithelial Cells

Brózman

Kubíčková

Babica

et al. 2020

Toxins

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Changes in ecological and environmental factors lead to an increased occurrence of cyanobacterial water blooms, while secondary metabolites-producing cyanobacteria pose a threat to both environmental and human health. Apart from oral and dermal exposure, humans may be exposed via inhalation and/or swallowing of contaminated water and aerosols. Although many studies deal with liver toxicity, less information about the effects in the respiratory system is available. We investigated the effects of a prevalent cyanotoxin, microcystin-LR (MC-LR), using respiratory system-relevant human bronchial epithelial (HBE) cells. The expression of specific organic-anion-transporting polypeptides was evaluated, and the western blot analysis revealed the formation and accumulation of MC-LR protein adducts in exposed cells. However, MC-LR up to 20 µM neither caused significant cytotoxic effects according to multiple viability endpoints after 48-h exposure, nor reduced impedance (cell layer integrity) over 96 h. Time-dependent increase of putative MC-LR adducts with protein phosphatases was not associated with activation of mitogen-activated protein kinases ERK1/2 and p38 during 48-h exposure in HBE cells. Future studies addressing human health risks associated with inhalation of toxic cyanobacteria and cyanotoxins should focus on complex environmental samples of cyanobacterial blooms and alterations of additional non-cytotoxic endpoints while adopting more advanced in vitro models.Keywords: microcystin-LR; human bronchial epithelial cells; in vitro; HBE1; 16HBE14o-, mitogen-activated protein kinase; cytotoxicity; OATP Key Contribution:The study demonstrated the uptake of microcystin-LR into human bronchial epithelial cells HBE1 and 16HBE14o-. No significant changes in the cell viability, impedance (cell layer integrity) or activation of MAPKs ERK1/2 and p38 were detected in multiple exposure and concentration scenarios.

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Occurrence of the Microcystins MC-LW and MC-LF in Dutch Surface Waters and Their Contribution to Total Microcystin Toxicity

Cited by 61 publications

References 31 publications

Current approaches to cyanotoxin risk assessment and risk management around the globe

Current approaches to cyanotoxin risk assessment and risk management around the globe

Micro-droplet Hydrodynamic Voltammetry for the Determination of Microcystin-LR Based on Protein Phosphatase

Microcystin-LR Does Not Alter Cell Survival and Intracellular Signaling in Human Bronchial Epithelial Cells

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