Cyanotoxine

Cyanotoxine, also called cyanotoxins, are toxins produced by cyanobacteria, organisms often referred to as blue‑green algae. They are released into water during blooms or can remain within cyanobacterial cells, making affected water unsafe for drinking, recreation, and aquatic life. Cyanotoxins occur in freshwater and, less commonly, in brackish or marine environments.

The main classes of cyanotoxins include microcystins and nodularins (primarily hepatotoxins that affect the liver), cylindrospermopsin (a cytotoxin with liver and kidney effects), anatoxins (neurotoxins such as anatoxin-a and anatoxin-a(s)), and saxitoxins (paralytic toxins). Other compounds, such as microviridins, have different modes of action. The toxins can be present inside intact cells or released into the water in dissolved form, depending on bloom dynamics and environmental conditions.

Exposure pathways include drinking water, recreational contact with contaminated water, and consumption of aquatic organisms from affected waters. Health effects vary by toxin class and can be acute or, in some cases, involve long‑term risks with repeated exposure. Microcystins are widely recognized for liver toxicity, anatoxins for rapid neurotoxic effects, and saxitoxins for interference with nerve signaling.

Management and regulation focus on monitoring cyanobacterial blooms, detecting toxin levels (often by LC-MS/MS or immunoassays), and treating water through filtration, coagulation, activated carbon, or advanced oxidation processes. Public health guidance, such as drinking-water guidelines for microcystin, varies by country but commonly sets precautionary alert and action levels during bloom events. Prevention emphasizes nutrient reduction and early warning systems to mitigate bloom formation.