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Understanding Cyanobacterial Toxins in Canadian Drinking Water

Learn about cyanobacterial toxins in Canada, their history, health effects, sources of exposure, and guidelines for safe drinking water. Get insights into toxin production, management strategies, and the collaborative efforts of federal and provincial agencies to ensure water quality.

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Understanding Cyanobacterial Toxins in Canadian Drinking Water

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  1. Blue Green algae: an overview Monique D’Amour Safe Environments Programme (Longueuil, Québec) and Michèle Giddings Water Quality & Microbiology Division (Ottawa, Ontario) Health Canada

  2. Federal (Health Canada) advice research risk assessment/management with provinces drinking water quality on Federal lands Provincial/Territorial provision of safe DW source water protection water treatment monitoring & surveys research Federal-Provincial Roles and Responsibilities for Drinking Water Responsibilities divided among levels of government

  3. Representatives from each province, territory, and the federal government 30+ year working collaboration Meets twice yearly Establishes the Guidelines for Canadian Drinking Water Quality Health Canada’s Water Quality and Health Bureau is the Technical Secretariat to the Committee Federal-Provincial-Territorial Committee on Drinking Water

  4. Drinking Water Guideline Development Process Identification Assessment Evaluation • costs • benefits • consultation

  5. Cyanobactieria in Canada • Identification of a problem • Assessment was required

  6. Cyanobacterial Toxins in Canada: The History, Part I • 1990-1992-1993: M-LR identified in Alberta lakes, detected in Shoal Lake, Winnipeg’s drinking water source, and in the city’s distribution system • Manitoba requests an ‘Emergency Health Advisory’ (EHA) from Health Canada in 1994 • EHA of 0.5 µg/L derived for M-LR in DW • EHAs are developed for specific situations; they do not have the rigorous review/consultation of full guidelines

  7. Cyanobacterial Toxins in Canada: The History, Part II • M-LR added to the priority list for evaluation • Canadian surveys to date indicate Microcystin-LR is the most common hepatotoxin present in water supplies

  8. Blooms of Cyanobacteria in Canada • Blooms occur in all provinces (Prairies, Québec etc) Tend to occur repeatedly in same supply • small shallow, slow-moving bodies of water common to prairies generally affected

  9. Bloom

  10. Cyanobacteria: General Description • Cyanobacteria (blue-green algea) • May produce neurotoxins, hepatotoxins • Skin irritants, other toxins • Surface water supplies (Hepatotoxins/neurotoxins) • Hepatotoxins more widespread

  11. Microcystin -LR Microcystin L-R: hepatotoxins Produced by Microcystis aeruginosa (an others blue-greens algal species) Monocyclic heptapeptides (L–amino acids; L=Leucine; R=arginine)

  12. Microcystin-LR Structure

  13. Sources of Human Exposure • Consumption of drinking water • Recreational use of lakes and rivers • oral, dermal • Showers • inhalation, dermal • Algal food tablets • oral

  14. M-LR Effects on Animals & Humans • Humans • Stomach cramps, vomiting, diarrhea, fever, headache, painful muscles & joints • Acute gastroenteritis • Liver damage • Animals • Primarily hepatotoxin • Kidney damage • Lung damage • Tumour promotor

  15. Critical Effects • Microcystin administered by gavage to mice at levels of 0, 40, 200 and 1000 µg/kg bw/day for 13 weeks 40 µg/kg bw : no definite effect 200 µg/kg bw : slight liver changes in some animals 1000 µg/kg bw : liver changes in all animals • No-Observed-Adverse-Effect Level (NOAEL) set at 40 µg/kg bw/day

  16. 0.040 mg/kg bw/day 1000 TDI = = 0.00004 mg/kg bw 0.00004 mg/kg/day x 70 kg x 0.80 1.5 L/day MAC = = 0.0015 mg/L (1.5 µg/L) M-LR Guideline Derivation Where • x10 for intraspecies variation • x10 for interspecies variation • x10 for less than lifetime study

  17. Factors Affecting Bloom Formation & Toxin Production / Persistence • Bloom Formation • Inorganic nutrients • Water temperature • pH level: 6-9 • Daylight • Turbidity • Turbulence • Water flow • Toxin production • Environmental factors • Temperature, light, nitrogen levels, carbon dioxide and/or pH • Genetic differences • Metabolic processes • Toxin release • Persistence • Stable in water • Resistance to pH extremes • Heat resistant

  18. Microcystins – Water Management • Reservoir management • Nutrient deprivation practices • Algal cell removal • Coagulation, clarification, filtration, disinfection • Must not damage cells • Toxin removal • Oxidation (ozonation); other methods such as UV, chloramination & hydrogen peroxide not as effective • Activated carbon (wood-based products best) • Slow sand filtration-biodegradation

  19. Flow chart: Management Water supply

  20. Find more information To obtain the supporting document on M-LR http://www.hc-sc.gc.ca/hecs-sesc/water/ pdf/microcys.pdf To obtain information onDW http://www.hc-sc.gc.ca/hecs-sesc/water/index.htm

  21. Acknowledgements Michèle Giddings for providing technical supports, advices and specific expertise on Microcystine L-R and Drinking Water Guidelines

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