Where It Comes From
Freshwater cyanobacteria in warm, nutrient‑rich lakes and rivers; one variant in the microcystin family [1].
How You Are Exposed
Drinking contaminated tap/well water, swimming or boating in bloom areas, inhaling spray, or eating fish/shellfish from bloom waters (especially organs) [1][3].
Why It Matters
Can cause nausea, vomiting, diarrhea, and liver injury; repeated exposure may harm the liver. Health benchmarks for microcystins are low: 0.3–1.6 µg/L (short‑term drinking water), 1 µg/L (lifetime, microcystin‑LR), and 8 µg/L for recreation [1][2][4][3].
Who Is at Risk
Infants and young children, pregnant people, those with liver disease, and pets (dogs) [1][2].
How to Lower Your Exposure
Follow bloom advisories; keep kids and pets out of scummy water; don’t boil contaminated water; use alternate water or certified treatment; rinse off after contact; avoid eating fish organs from bloom areas [1][2][3].
References
- [1]ATSDR. Cyanobacterial Toxins (Cyanotoxins) ToxFAQs, 2023. https://www.atsdr.cdc.gov/toxfaqs/cyanobacterial_toxins_cyanotoxins/index.html
- [2]EPA. Drinking Water Health Advisory for the Cyanobacterial Microcystins, 2015. https://www.epa.gov/sites/default/files/2017-06/documents/microcystins-report-2015.pdf
- [3]EPA. Recreational Ambient Water Quality Criteria/Swimming Advisories for Microcystins and Cylindrospermopsin, 2019. https://www.epa.gov/sites/default/files/2019-05/documents/microcystins-cylindrospermopsin-recreational-criteria-2019.pdf
- [4]WHO. Microcystin‑LR in Drinking-water: Background document for development of WHO Guidelines for drinking-water quality, 2020. https://www.who.int/publications/i/item/WHO-CED-PHE-WSH-19.14