Where It Comes From
Produced by bloom‑forming cyanobacteria (e.g., Microcystis); can build up in surface water and in fish/shellfish [1][2].
How You Are Exposed
Drinking contaminated water, swallowing water while swimming, breathing spray near blooms, eating contaminated fish or algae supplements [1][2][4].
Why It Matters
Microcystins damage the liver (nausea, vomiting, diarrhea, abdominal pain); severe cases can lead to liver failure. Long‑term exposure raises cancer concerns (IARC classifies microcystin‑LR as possibly carcinogenic) [1][4][5]. Health benchmarks for drinking water are very low (WHO 1 µg/L; EPA 0.3–1.6 µg/L, reported as microcystins) [2][3].
Who Is at Risk
Young children, pregnant people, those with liver/kidney disease, people using untreated surface water or on dialysis, anglers who eat fish organs, and pets (especially dogs) [1][4].
How to Lower Your Exposure
Avoid discolored/scummy water and obey bloom advisories; keep pets out. Do not boil contaminated water; use safe alternative supplies or certified treatment (activated carbon or reverse osmosis) and contact your utility. Trim skin/viscera from fish [2][3][4].
References
- [1]ATSDR. Toxicological Profile for Cyanobacterial Toxins (including Microcystins). Agency for Toxic Substances and Disease Registry, 2023.
- [2]WHO. Cyanobacterial toxins: Microcystins. Background document for WHO drinking‑water guidelines, 2020 update.
- [3]US EPA. 2015 Drinking Water Health Advisory for Microcystins. EPA 822‑R‑15‑100.
- [4]CDC. Cyanobacterial (Harmful Algal) Blooms — Health information. https://www.cdc.gov/harmfulalgalblooms/
- [5]IARC. Ingested Nitrate and Nitrite, and Cyanobacterial Peptide Toxins. IARC Monographs, Vol. 94, 2010.