Where It Comes From
Warm, nutrient‑rich lakes/rivers during cyanobacterial blooms; produced by Raphidiopsis (formerly Cylindrospermopsis), Aphanizomenon, and others; toxin is relatively stable in water. [2][3]
How You Are Exposed
Drinking contaminated tap or surface water; swallowing or breathing spray during swimming/boating/showers; eating fish or shellfish from bloom waters. [1][3]
Why It Matters
Can cause nausea, vomiting, diarrhea, headache, and fever; higher or repeated doses can injure the liver and kidneys. EPA has short‑term drinking‑water health advisories to limit risk. [1][2]
Who Is at Risk
Infants and young children, pregnant people, those with liver/kidney disease, people using untreated surface water or small systems near blooms, and pets/livestock. [1][3]
How to Lower Your Exposure
Follow bloom advisories; avoid discolored or scummy water; do not boil suspected water; use alternate water or properly operated treatment (activated carbon or reverse osmosis); trim fish and avoid organs. [1][3][2]
References
- [1]U.S. EPA. Drinking Water Health Advisory for the Cyanobacterial Toxins Microcystins and Cylindrospermopsin. Office of Water, 2015.
- [2]WHO. Cyanobacterial toxins: Cylindrospermopsins. Background document for WHO Guidelines for drinking‑water quality, 2020.
- [3]CDC. Harmful Algal Blooms (HABs): Cyanobacteria (Blue‑Green Algae) and Cyanotoxins – Prevention and Health Information.