Guidelines for Canadian Drinking Water Quality: Guideline Technical Document – Cyanobacterial Toxins

Under the right environmental conditions, microcystins and other cyanobacterial toxins are naturally formed in water in the environment. They are produced and stored in the cells of cyanobacteria, and released when the cells rupture or die. Most scientific studies on cyanobacterial toxins focus on microcystins, which are generally regarded as the most important of the freshwater cyanotoxins. A seasonal maximum acceptable concentration (MAC) of 0.0015 mg/L (1.5 µg/L) is established for total microcystins in drinking water.