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The cyanobacteria toxins, microcystins – emerging risks to human health
Citation:
Hilborn, E. The cyanobacteria toxins, microcystins – emerging risks to human health. Pathology 527: Emerging Issues and Research on Harmful Cyanobacterial Algal Blooms: Impact on Populations, Ecosystems, and Water, Urbana, IL, February 27, 2015.
Impact/Purpose:
Microcystins are cyanobacterial toxins listed among the CCL drinking water contaminants. Uncommonly, microcystins have been implicated as a source of intoxications among renal insufficiency patients receiving contaminated hemodialysis. We plan to provide an overview of the toxic principles of microcystins, and then discuss in some detail the effects on a group of exposed patients during 2001. The majority of the content for this presentation was published in 2013: Hilborn, E.D.; Soares, R.M.; Servaites, J.C.; Delgado, A.G.; Magalhães, V.F.; Carmichael, W.W.; Azevedo, S.M. Sublethal microcystin exposure and biochemical outcomes among hemodialysis patients. PLoS One 2013, 8, e69518. doi: 10.1371/journal.pone.0069518.
Description:
Dialysis patients appear to be at increased risk for exposure to cyanobacteria toxins; episodes of microcystin (MCYST) exposure via dialysate during 1996 and 2001 have been previously reported. During 2001, as many as 44 renal insufficiency patients were exposed to contaminated dialysate at dialysis centers in Rio de Janeiro State in Brazil. Drinking water used to prepare dialysate and patient sera were analyzed for MCYST using an ELISA in a research laboratory. Biochemical assays on patient’s biological samples were performed in a hospital-based clinical laboratory. We describe the physiologic effects of MCYST and perform descriptive and statistical analysis of serum concentrations of MCYST and associations with biochemical outcomes among patients receiving hemodialysis. Statistical analyses included linear regression models predicting biochemical outcomes from serum MCYST concentrations and patient characteristics. Descriptive analyses were informed by normal ranges of biochemical values. Thirteen dialysis patients were monitored for two months after detected MCYST exposure for serum MCYST concentrations and biochemical outcomes. Patients ranged in age from 16–80 years, 50% were male. Serum MCYST concentrations ranged from <0.16 ng/mL (LOD) to 0.96 ng/mL. Some biochemical values were outside of the normal range, including measures of liver injury and function, but only the international normalized ratio (INR), a measure of clotting time, was associated with maximum serum MCYST concentrations in linear models. We report a mild – moderate mixed liver injury associated with sublethal microcystin exposure among patients receiving hemodialysis. Clotting times were negatively associated with serum microcystin concentrations in adjusted linear models. Dialysis patients’ physiology may differ from the general population; investigation of exposed, healthy individuals is needed to further characterize microcystin-associated health effects.