Where It Comes From
Produced by bloom-forming cyanobacteria (e.g., Microcystis) in warm, nutrient-rich waters; can enter drinking-water sources and accumulate in aquatic life [1][2].
How You Are Exposed
Drinking contaminated tap or surface water; swallowing water while swimming; breathing spray from boating or showers; eating fish from bloom-affected waters; skin contact with scummy water [2][3].
Why It Matters
Causes stomach illness and liver injury; severe cases can lead to liver failure. WHO’s drinking-water guideline for microcystin-LR is 1 µg/L. It’s classified as possibly carcinogenic to humans (IARC Group 2B) [1][4].
Who Is at Risk
Young children, people with liver disease, pregnant people; those using small systems/private intakes drawing from surface water; frequent recreators/anglers; pets and livestock are very vulnerable [1][3].
How to Lower Your Exposure
Follow bloom/drinking-water advisories; do not boil suspected water (boiling can concentrate toxins); use alternative water until authorities say it’s safe; consider certified filters that reduce microcystins or reverse osmosis; rinse off after water contact and keep pets away; avoid eating fish organs from bloom waters [2][3].
References
- [1]WHO. Guidelines for Drinking-water Quality; and Toxic Cyanobacteria in Water, 2nd ed.
- [2]U.S. EPA. Recommendations for Public Water Systems to Manage Cyanotoxins; Microcystins Health Advisory.
- [3]CDC. Cyanobacterial (Harmful Algal Bloom) information and prevention guidance.
- [4]IARC. Monographs, Volume 94: Ingested Nitrate and Nitrite, and Cyanobacterial Peptide Toxins (2010).