Regulatory Perspective and Associated Human Health Effects with Cyanotoxin Exposure

Harmful Algal Blooms, especially cyanobacterial blooms, are of concern for freshwater systems because of their potential to produce toxins, also known as cyanotoxins, and the possible adverse impacts on drinking and recreational waters. In order to protect human health from exposure to cyanotoxins in drinking water, EPA published Drinking Water Health Advisories for the cyanotoxins microcystins and cylindrospermopsin, and Health Effects Support Documents for microcystins, cylindrospermopsin and anatoxin-a. Health advisories describe non-regulatory concentrations of cyanotoxins at or below which adverse health effects are not anticipated to occur over a period of 10-day exposure. EPA recommends health advisory levels at or below 0.3 micrograms per liter for microcystins and 0.7 micrograms per liter for cylindrospermopsin in drinking water for children pre-school age and younger (less than six years old). For school-age children through adults, the recommended HA levels for drinking water are at or below 1.6 micrograms per liter for microcystins and 3.0 micrograms per liter for cylindrospermopsin. Health Advisories are developed for young children since children younger than 1-year-old are more susceptible than older children and adults as they consume more water relative to their body weight. Exposure to the HABs and toxins via drinking water ingestion can result in adverse health effects including liver damage from exposure to microcystin, and kidney damage from exposure to cylindrospermopsin in drinking water. Other health effects such as reproductive damage, neurological damage, and gastrointestinal illness were also associated with exposure to cyanotoxins in drinking water. More research is needed to assess the carcinogenic potential of these cyanotoxins.