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EPA Holds Informative Webinar on Human Health Risks from Harmful Algal Blooms

This week, EPA conducted a two-day webinar entitled, “Human Health Risks Associated with Cyanobacteria and Cyanotoxins Exposure.”  During the webinar, a variety of speakers from EPA, states, universities, and other organizations provided informative presentations about their research, experience, policies, and other efforts to study and address human health effects from exposure to cyanobacteria and their toxins.  Some useful information from the presentations and discussions that should be of interest to state drinking water programs include:

  • Dr. Ian Stewart of Griffith University in Queensland, Australia noted that hazard assessments for recreational waters should prioritize studies on acute health effects from ingestion and inhalation, as previous studies (and the scientist’s personal submersion experiment) have shown that dermal exposure does not penetrate the skin, though it can cause allergic skin reactions in sensitive people.
  • Brazil’s regulations now include drinking water MCLs for cyanotoxins.  Though epidemiologists’ who examined patients’ after a dialysis exposure event there found it difficult to make any conclusive toxicity level determinations based on the reactions from these types of patients because their livers are already compromised.
  • Representatives from the states of Wisconsin, Oregon, Florida, and Washington shared information about their states’ harmful algal bloom (HAB) surveillance programs, as well as public outreach, education, and health advisory development efforts.  These states are collecting information from the public, health institutions, and site studies as a means to ensure public health for citizens engaging in recreational activities and consuming fish in waters affected by HABs.  For drinking water, Washington State shared information about its only known occurrence of contamination that took place in 1995 at a water system where copper treatment exacerbated the toxicity of the finished drinking water and the community subsequently had to abandon its water supply until the problem was resolved.
  • Ingrid Chorus, a representative of Germany’s Federal Environment Agency spoke about the World Health Organization’s (WHO) guidance and national approaches on regulating cyanotoxins as follows:
  • Chorus noted that countries across the globe are increasing the use of risk-based management frameworks to address toxic cyanobacteria in water.  She stated that most countries that regulate cyanotoxins use some parameter reflecting the number of cells or biomass (cell volumes) to come up with exceedance numbers (e.g., an MCL).  These regulatory approaches require a comprehensive management program to determine targets for toxicity levels, and these countries mostly regulate Microcystin-LR, while other toxins have provisional regulations that are not legally binding.
  • WHO is currently revising its 1999 guidance document entitled, “Toxic cyanobacteria in water: A guide to their public health consequences, monitoring and management.”  The revised guidance will not be available for at least one more year.   The primary change in the guidance will be to measure biomass rather than cell numbers as part of a decision-making process, using the WHO water safety framework to ensure public health.  The Water Safety Framework (plans) includes steps to define health-based targets and conduct monitoring to ensure that controls are working.  For drinking water treatment, the control measure is to use filtration with turbidity monitoring to ensure removal of cyanotoxins.  The existing WHO guidelines for cyanotoxins are provisional and will be revised as toxicity data becomes available (e.g., for microcystin and phytoplankton).  Chorus noted that defining regulatory requirements is challenging, and that they must be developed for site specific circumstances.  In addition, WHO will not be developing nutrient criteria because there is not a direct enough correlation with the reduction of nitrogen and phosphorous to show that the occurrence of HABs and associated cyanotoxins would be prevented.
  • As part of the discussion, it was also noted that in the U.S., EPA has three cyanotoxins on the contaminant candidate list (CCL), though methods are not yet available to develop a regulation.  However, EPA is developing a public health advisory guidance document for drinking water, and afterward plans to develop ambient water quality criteria for recreational water.

For more information about Cyanobacterial Harmful Algal Blooms (CyanoHABs), visit EPA’s web site HERE.  The presentations and audio recording from this webinar will be posted on the site within the next few weeks.