Microcystins (which includes total microcystin, microcystin-LA, microcystin-LF, microcystin-LR, microcystin-LY, microcystin-RR, microcystin-YR) and nodularin are toxins produced by certain species of cyanobacteria. Cyanobacteria, formerly known as blue-green algae, are sometimes found in surface water when conditions favor growth and formation of algal blooms.
Cyanobacteria are capable of releasing toxins that can persist for weeks to months, and microcystins are the most commonly observed cyanotoxins in the United States. Toxicity to the liver is the greatest concern, but microcystins can also irritate the skin, eyes and throat. After exposure, symptoms may take hours or days to appear.
Nodularin is similar to microcystins in chemical structure. Therefore, while there isn’t as much information on nodularin as there is on microcystins, based on what information is available we assume that nodularin and microcystins have similar properties, including health effects.