The first report about the presence of cyanobacterial toxins in Polish lakes.

The occurence of toxic freshwater blooms of cyanobacteria (blue-green algae) has been reported in many countries. These toxic water blooms have caused the deaths of domestic animals and wildlife. Cyanobacteria may produce acute toxins such as hepatotoxic peptides (microcystins, nodularins and cylindrospermopsin) and neuro-toxic alkaloids (anatoxin-a, anatoxin-a(s), homoanatoxin and aphanotoxins). Very important toxins are microcystins (MCYST) with high biological activities and wide distribution all over the world. They have been produced by Microcystis, Oscillatoria, Anabaena and Nostoc. All MCYST can play the role of tumor-promoting activators. This paper for the first time presents results showing the presence of microcystin hepatotoxin in Polish lakes and drinking water.