The United States Environmental Protection Agency (EPA) recently issued health advisory values that states and utilities can use to protect Americans from elevated levels of algal toxins in drinking water. Algal blooms in rivers, lakes, and bays sometimes produce harmful toxins. Because utilities often use these water bodies as sources of drinking water, EPA has determined algal toxin levels in tap water that are protective of human health based on the best available science. EPA is also recommending how utilities can monitor and treat drinking water for algal toxins and notify the public if drinking water exceeds protective levels. EPA will issue the final documents containing the health advisory values, recommended monitoring and treatment approaches, and all supporting technical information before summer, which is prime season for algal blooms because of warmer temperatures. Last August a harmful algal bloom in Lake Erie left half-a-million residents of Toledo without drinking water for two days. EPA estimates that between 30 and 48 million people use drinking water from lakes and reservoirs that may be vulnerable to algal toxin contamination. “Nutrient pollution and harmful algal blooms are among America’s most serious and growing environmental challenges,” said EPA Administrator Gina McCarthy. “EPA has released health advisory values on algal toxins based on the best available science to ensure the safety of America’s drinking water. We will work closely with our partners at the state and local levels on monitoring, treating, and communicating about the toxins, as well as addressing the sources of nutrients that fuel these harmful algal blooms.” Health advisories are not regulations, but provide technical guidance to help state and local officials and managers of water systems protect public health. They identify concentrations of contaminants above which adverse health effects are possible and provide testing methods and treatment techniques. The health advisory values for algal toxins recommend 0.3 micrograms per litre for microcystin and 0.7 micrograms per litre for cylindrospermopsin as levels not to be exceeded in drinking water for children younger than school age. For all other ages, the health advisory values for drinking water are 1.6 micrograms per litre for microcystin and 3.0 micrograms per litre for cylindrospermopsin. Potential health effects from longer exposure to higher levels of algal toxins in drinking water include gastroenteritis and liver and kidney damage. The health advisory values are based on exposure for 10 days. While briefly exceeding these advisory levels may not indicate an immediate emergency, EPA recommends utilities use treatment techniques to lower levels as quickly as possible. Steps that can protect the public from algal toxins in drinking water include:
- Watching for harmful algal blooms in water bodies used as a source of drinking water;
- Monitoring source water and drinking water for detections of algal toxins;
- Treating drinking water as necessary to reduce and remove algal toxins;
- Notifying the public that younger than school age children should not drink or boil the water if levels are above 0.3 micrograms per litre for microcystin and 0.7 micrograms per litre for cylindrospermopsin;
- Notifying the public that no one should drink or boil the water if levels are above 1.6 micrograms per litre for microcystin and 3.0 micrograms per litre for cylindrospermopsin.
EPA will seek input from stakeholders on the recommended actions and other information the Agency can provide to best support states and utilities in addressing algal toxins in drinking water. Based on input, EPA may provide additional technical support documents before the peak of algal bloom season. EPA worked with Health Canada to develop the health advisories. The World Health Organization has indicated it will use the health advisories developed by EPA to re-evaluate global recommendations for levels of algal toxins. As the science on the health impacts of algal toxins continues to improve, EPA will track developments and update recommendations as appropriate.
U.S EPA, 6 May 2015 ;http://www.epa.gov ;