EPA has finalized Health Advisories (HAs) for the algal toxins microcystin and cylindrospermopsin. The HAs are unchanged from the values announced in early May prior to EPA’s public meeting held to gather information on “Potential Actions To Prepare for and Respond to Cyanotoxins in Drinking Water.” The final HAs maintain separate values for young children and for school age children and adults based on a 10-day exposure period. The advisory levels for microcystin are 0.3 micrograms per liter for young children and 1.6 micrograms per liter for school age children and adults. For cylindrospermopsin, the corresponding values are 0.7 and 3.0 micrograms per liter.
Accompanying the final HAs, EPA has published several criteria documents supporting the development of the advisory values. A new guidance document, “Recommendations for Public Water Systems to Manage Cyanotoxins in Drinking Water” outlines steps that water systems can take to proactively evaluate and manage water supplies and treatment systems to prevent exceedances of microcystin and cylindrospermopsin HA levels.