nodularins

Nodularins are a family of hepatotoxic cyclic peptide cyanotoxins produced primarily by Nodularia species, such as Nodularia spumigena, during freshwater and brackish-water cyanobloom events. They are structurally related to microcystins and share the Adda moiety that is essential for their biological activity.

The toxins exert their effects by inhibiting protein phosphatases 1 and 2A, disrupting cellular signaling and leading to hepatocyte injury. Nodularins are relatively stable to heat and pH, allowing them to persist in water and sediments and to remain present during bloom decay.

Occurrence of nodularins is widespread in temperate regions, with blooms often concentrated in estuarine and brackish zones. They are associated with nutrient enrichment and warm temperatures, and nodularins can be released into the water column and accumulate in aquatic organisms, potentially entering the food chain.

Exposure to nodularins occurs primarily through drinking water, recreational water use, or ingestion of contaminated seafood. Acute exposure can cause liver damage, abdominal pain, and vomiting; the long-term effects are not fully understood, and risks extend to wildlife and livestock in affected habitats.

Detection and management rely on analytical methods such as LC-MS/MS and immunoassays (ELISA). Water treatment can reduce nodularin levels, but removal efficiency varies depending on the treatment process; activated carbon, ozonation, and advanced oxidation can contribute to degradation.

Regulatory and public health responses vary by country, with advisory limits and monitoring programs in place in many jurisdictions. Guidance for cyanotoxins generally informs drinking-water safety, risk communication, and source-water protection to reduce exposure risk.