Health Effects of Toxin-Producing Cyanobacteria: “The CyanoHABs”

TLDR

Harmful algal blooms, driven by eutrophication, climate change, and increased monitoring, are increasingly reported worldwide; cyanobacteria toxins—cytotoxins and biotoxins such as neurotoxins (anatoxin‑a, saxitoxins) and hepatotoxins (microcystins, nodularins, cylindrospermopsins)—occur in fresh and brackish waters across 40 genera, posing acute to chronic poisoning risks to humans and animals and prompting WHO compilations of health, safety, and remediation guidelines. This paper reviews current knowledge of cyanobacteria toxin poisonings and their risk to human health. Human deaths from cyanotoxins have been confirmed only in a 1996 renal dialysis incident in Caruaru, Brazil.

Abstract

Increasingly, harmful algal blooms (HABs) are being reported worldwide due to several factors, primarily eutrophication, climate change and more scientific monitoring. All but cyanobacteria toxin poisonings (CTPs) are mainly a marine occurrence. CTPs occur in fresh (lakes, ponds, rivers and reservoirs) and brackish (seas, estuaries, and lakes) waters throughout the world. Organisms responsible include an estimated 40 genera but the main ones are Anabaena, Aphanizomenon, Cylindrospermopsis, Lyngbya, Microcystis, Nostoc, and Oscillatoria (Planktothrix). Cyanobacteria toxins (cyanotoxins) include cytotoxins and biotoxins with biotoxins being responsible for acute lethal, acute, chronic and sub-chronic poisonings of wild/domestic animals and humans. The biotoxins include the neurotoxins; ana-toxin-a, anatoxin-a(s) and saxitoxins plus the hepatotoxins; microcystins, nodularins and cylindrospermopsins. Confirmations of human deaths from cyanotoxins are limited to exposure through renal dialysis at a haemodialysis center in Caruaru, Brazil, in 1996. A major effort to compile all available information on toxic cyanobacteria including issues of human health, safe water practices, management, prevention and remediation have been published by the World Health Organization. This paper will review our current understanding of CTP's including their risk to human health.