Cyanobacteria, also known as Blue-Green algae,  are aquatic photosynthetic procariotes. Some species of cyanobacteria produce toxins that affect animals and humans. People may be exposed to cyanobacterial toxins by drinking or bathing in contaminated water. Toxins from marine or sweet water blue-green algae may endanger marine and sweet-water biosphere. They may contaminate drinking water, water used in pools, water used in infusion solutions. Cyanotoxins are secondary metabolites produced by cyanobacteria, of varied chemical nature and toxic effects.  Among other classes of bioactivities, there are: neurotoxins such as anatoxin-a, anatoxin-a (S), paralytic shellfish toxins, β-methylaminopropionic acid, N-(2-aminoethyl) glycine and 2,4-diaminobutyric acid, cytotoxins/dermatotoxins  and hepatotoxins –cylindrospermopsins, microcystins and nodularins—with microcystins being the most frequently reported. Some Cyanobacterial toxins are cyclic peptides, other are alkaloids or non proteic amino acids, lipopolysacharides.