Managing Cyanotoxins May 2019 Djanette Khiari, The Water Research Foundation MANAGING CYANOTOXINS CYANOBACTERIA ARE photosynthetic Health Advisories (HAs) for states and are taken up by the liver and bacteria that are common in all fresh- utilities to protect the public from cya- cause weakness and anorexia water and marine environments. They notoxins in drinking water. For children 2. Neurotoxins (usually anatoxin were historically called blue-green younger than school age, the HA was and saxitoxin), which affect the algae but their structure, genetics, set at 0.3 µg/L for total microcystin nervous system and physiology clearly identify them and 0.7 µg/L for cylindrospermopsin. 3. Dermatoxins (aplysiatoxin and as bacteria. Cyanobacteria in fresh- The corresponding values for adults lyngbyatoxin), which cause water systems are widely recognized are 1.6 µg/L and 3.0 µg/L, respectively. skin and mucous irritations as sources of toxins (cyanotoxins) and Although not enforceable, the pub- upon contact unpleasant tastes and odors in water lished HAs are intended to trigger utility supplies. Cyanobacteria are a normal actions including increased monitoring, Taste and Odor Compounds and Toxic component of the natural biota and tol- development of treatment strategies, Cyanobateria erate a wide range of climatic conditions and public notification of “do not drink/ THE MOST FREQUENTLY CITED cyano- and environments. A rise in the num- do not boil” advisories. EPA has also bacterial metabolites are geosmin and ber of cyanobacterial blooms, caused provided recommendations on how 2-methylisoborneol (MIB). Geosmin by eutrophication from decaying plant utilities can monitor and treat drinking and MIB impart unpleasant earthy/ materials and man-made pollution, water for cyanotoxins. Additionally, the musty odors to the water. Attempts is resulting in the production of more EPA Fourth Unregulated Contaminant to use taste and odor parameters as taste and odor compounds and natural Monitoring Rule (UCMR4), pub- potential indicators of the presence of toxins, which demands the attention of lished in December 2016, includes toxins have been inconclusive. Just as it water treatment authorities. Although 10 cyanotoxins/groups. is true that most cyanobacterial species cyanotoxins are less commonly found Due to the increase of cyanobacterial do not cause taste and odor problems, in drinking water than taste and odor blooms, the occurrence of several toxic it is also true that most do not produce compounds, their high toxicity is of metabolites (i.e., cyanotoxins) in water toxins. Some species that produce taste great concern. Due to global climate supplies has also increased. There is and odor compounds, however, can also change, toxin-producing cyanobacte- growing concern about the potential produce toxins. ria are spreading into more temperate for negative health effects in humans regions and becoming a more wide- and animals due to these toxins. These The Water Research Foundation spread problem. toxins enter water supplies through nat- (WRF) and Cyanotoxin Research Currently, there are no U.S. ural production and metabolic activities, WRF HAS SPONSORED RESEARCH ON Environmental Protection Agency (EPA) and through cell lysis and subsequent toxic algae since 1993, initially producing regulations for cyanotoxins. However, release of toxins. Water collection and a comprehensive resource guide for util- three cyanotoxins are included on the treatment activities may contribute to ities: Cyanobacterial (Blue-Green Algal) final contaminant candidate list (CCL3): the release of cyanotoxins. Toxins: A Resource Guide (project 925). anatoxin-a, microcystin-LR, and cylin- Presently, about 3,000 species of Since the publication of the guide, WRF drospermopsin. At present, the only cyanobacteria are known; however, has funded additional research on con- cyanobacterial toxin class that has been not all produce toxins. The organisms trol, treatment, and detection methods internationally assessed for health risk most frequently associated with toxin for cyanotoxins, much of it in collabora- is the microcystins. The World Health production are Microcystis, Oscillatoria, tion with research partners. Organization (WHO) has issued a pro- Cylindrospermopsis, Anabaena, The increased frequency of cyano- visional guideline value of 1 microgram Planktothrix, Aphanizomenon, Nodularia, bacterial blooms in the United States per liter (µg/L) for microcystin-LR in and Lyngbya. Most poisoning by the prompted WRF, in partnership with drinking water and many countries have cyanobacteria listed above involves the EPA, to fund one of the first proj- developed their own guidelines, depend- three types of toxins (specific toxic com- ects to investigate cyanotoxins as a ing on the types of cyanotoxins found in pounds are listed in parentheses): potential threat to U.S. water systems. their source waters. 1. Hepatotoxins (microcystin [usu- Published in 2001, the comprehensive The 2014 cyanotoxin event in Toledo, ally microcystin-LR and study, Assessment of Blue-Green Algal Ohio has sparked significant regulatory microcystin-LA], cylindrosper- Toxins in Raw and Finished Drinking Water activity. In June 2015, EPA issued 10-day mopsin, and nodularin), which (project 256), assessed microcystin 2 OF 8 © 2019 THE WATER RESEARCH FOUNDATION. ALL RIGHTS RESERVED. LAST UPDATED: MAY 2019 occurrence and treatment removal Water Professionals (project 4548b), is and Communication Strategies. This capabilities. During the project, 45 util- an action-oriented synthesis of relevant Focus Area has already funded three ities in the United States and Canada literature for utility personnel and the relevant projects: were surveyed for two years during water utility community, providing infor- l “Refinement and Standardization cyanobacterial blooms. mation necessary to guide the develop- of Cyanotoxin Analytical Microcystin was found in 80% of the ment of a technically sound evaluation of Techniques for Drinking Water” source waters. Only two of the finished cyanotoxins as a water quality concern (project #4716) water samples were above the WHO for drinking water supplies and appro- l “Developing Guidance for guidelines (1 µg/L). The study also priate mitigation measures. The guide Evaluation and Implementation showed that almost all utilities had ade- summarizes the most recent infor- for Control of HABs in Source quate procedures to reduce microcystin mation about cyanotoxin occurrence, Water” (project #4912) to safe levels in finished water. analytical methods and monitoring, l “Utility Response to In 2014, WRF and the American and management strategies. Like the Cyanobacteria/Cyanotoxin Event; Water Works Association (AWWA) co- first guide, it is also intended to benefit Case Studies, and Lessons sponsored project 4548, Cyanotoxin water utility managers, operators, and Learned” (project 4914) Guides for Water Utility Managers, which consultants. More specifically, though, distilled and summarized information it is intended for users working for, or Treatment from the last 20–25 years of cyanotoxin with, water utilities that have already THERE ARE SEVERAL CONVENTIONAL research. This purpose of this project been determined to be at risk of having and advanced treatment options avail- was to develop two cyanotoxin utility cyanobacteria and possibly cyanotoxin able for the removal of cyanotoxins. action guides designed for use by water issues. While this second guide contains The key is in understanding the specific utility management and personnel, and more detailed information than the first toxin of concern, because different tox- the drinking water community. These guide, it is organized to help readers ins are removed/inactivated at varying guides were intended to synthesize navigate the issues and make informed degrees by different treatment technol- existing knowledge on cyanobacterial decisions about appropriate mitigation ogies. For example, several research and cyanotoxin events and provide prac- measures and how to be prepared in studies indicate that water treatment tical tools to help the water community case of toxic cyanobacteriablooms. plants that meet Stages 1 and 2 of the prepare for, and respond effectively to, In addition, an Emerging Disinfectants/Disinfection Byproduct potential events. Opportunities project, Cyanobacterial Rule by using ozone have a considerable The first manual, A Water Utility Blooms and Cyanotoxins: Research level of protection from several types of Manager’s Guide to Cyanotoxins (proj- Priorities for Drinking Water Protection cyanotoxins (such as microcystin), but ect 4548a), is a succinct summary of (project #4657), consolidated and not from saxitoxin. On the other hand, cyanotoxin occurrence trends, poten- synthesized the existing literature on pre-oxidants such as potassium per- tial health effects, preemptive and cyanotoxins into a summary document, manganate, ozone, and chlorine (which mitigation strategies, and potential which was reviewed during a facilitated are used to mitigate cyanobacteria) challenges. This guide is intended to expert symposium held in Boulder, CO, have been found to lyse cyanobacteria, help water utility managers recognize in June 2016. The presentations and a which releases toxins; therefore, it is if cyanotoxins may be an issue for their video from the workshop are available recommended that coagulation be used utility and what initial steps to consider. for viewing. Workshop participants prior to oxidation to remove whole cells.