cyanotoxines

Cyanotoxins are a diverse group of toxic secondary metabolites produced by cyanobacteria, organisms commonly known as blue-green algae. They can accumulate in freshwater ecosystems during harmful algal blooms and, less often, in brackish waters. Humans and animals may be exposed through drinking water, recreational contact with contaminated water, or inhalation of aerosols near affected sites.

The major classes of cyanotoxins include hepatotoxins such as microcystins and nodularins, neurotoxins such as anatoxins and saxitoxins, and the cytotoxin cylindrospermopsin. Some cyanobacteria produce additional bioactive compounds. Microcystins and nodularins primarily affect the liver, anatoxins disrupt neural transmission, saxitoxins block nerve impulse conduction, and cylindrospermopsin can damage multiple organs. Effects may be acute, such as gastrointestinal symptoms, liver injury, or neurotoxic events, and the potential for long-term health risks with repeated exposure is the subject of ongoing study.

Cyanotoxin production is influenced by environmental conditions including nutrient levels, light, temperature, and bloom dynamics. Eutrophication and climate-related factors such as warming waters promote bloom formation, increasing the likelihood of toxin presence. Public health concerns arise for both drinking-water supplies and recreational waters, requiring risk assessment for exposed populations and ecosystems.

Detection and management involve monitoring and regulation. Analytical methods include enzyme-linked immunosorbent assays (ELISA) and liquid chromatography–mass spectrometry (LC-MS). Regulatory limits vary by country; the World Health Organization provides provisional guidelines for microcystin-LR in drinking water (about 1 microgram per liter). Water treatment approaches include coagulation, activated carbon, and advanced oxidation or biodegradation, as chlorine alone may not reliably remove all cyanotoxins.