cyanotoxins

Cyanotoxins are toxic compounds produced by cyanobacteria, or blue-green algae, during blooms in freshwater, brackish, and occasionally marine systems. Many cyanotoxins remain inside cells, but others are released when cells lyse, increasing exposure for humans, pets, and wildlife.

The major cyanotoxins include microcystins, cylindrospermopsins, anatoxins, saxitoxins, and BMAA. Microcystins are hepatotoxins, cyclic peptides that inhibit protein phosphatases and can damage the liver (microcystin-LR is among the most studied). Cylindrospermopsins are hepatotoxic and cytotoxic, affecting liver and other organs. Anatoxins are neurotoxins causing rapid neural symptoms, while saxitoxins block sodium channels and can cause paralysis; these toxins are also found in freshwater blooms on occasion. BMAA, a non-protein amino acid, has been reported in some cyanobacteria, with ongoing research on health implications.

Exposure occurs mainly through drinking water, recreation, or ingestion of contaminated fish or shellfish. Acute poisoning can involve liver or nervous system effects; chronic exposure risks are still being investigated and depend on the specific toxin and dose.

Monitoring relies on toxin screening (ELISA for microcystins, LC-MS for congeners), toxin-gene assays, and bloom surveillance. Water treatment may use coagulation, activated carbon, or advanced oxidation to remove toxins. International guidance varies; the World Health Organization has a drinking-water guideline of 1 µg/L for microcystin-LR equivalents.

Cyanotoxins impact aquatic ecosystems by harming organisms and reducing water quality. Blooms are linked to nutrient pollution and climate-related factors, highlighting the need for prevention, monitoring, and public health response.