microcystinen

Microcystins are a family of hepatotoxic peptides produced by certain cyanobacteria, commonly referred to as blue-green algae, in freshwater systems. The most studied member is microcystin-LR, but dozens of congeners exist, varying slightly in toxicity. Microcystins are cyclic heptapeptides that are chemically stable, resisting many common disinfection methods and persisting in water and sediments.

The primary mechanism of toxicity is potent inhibition of protein phosphatases 1 and 2A in liver cells, leading to cytoskeletal disruption, hepatocyte injury, and, at high exposures, acute liver failure. Acute effects include abdominal pain, nausea, vomiting, and jaundice; chronic exposure may contribute to liver damage and has been studied for cancer risk in animals. Exposure can occur via drinking water, recreational exposure through skin contact or inhalation of aerosols, and, to a lesser extent, consumption of contaminated fish or shellfish.

Microcystins are produced by bloom-forming cyanobacteria such as Microcystis, Anabaena (Dolichospermum), Planktothrix, and Nostoc. Blooms are favored by warm temperatures, high nutrient loads (especially phosphorus and nitrogen), and calm, stratified water.

Detection and regulation: Microcystin concentrations are monitored in drinking-water sources using LC-MS/MS or immunoassays. The WHO guideline for microcystin-LR in drinking water is 1 µg/L, with separate considerations for total microcystins. Treatment options include coagulation, activated carbon, and oxidation; some congeners are more resistant to chlorine.

Prevention focuses on reducing nutrient inputs, monitoring blooms, and communicating risks to the public.