TOTAL MICROCYSTINS

Made by cyanobacteria in warm, nutrient-rich water; blooms are fueled by runoff and heat. Toxins can persist after blooms die and enter drinking water. “Total microcystins” is the combined amount of variants, often measured as MC‑LR equivalents [1][2][3].

Drinking contaminated water; swimming/boating in bloom-affected water; breathing spray; eating contaminated fish (especially organs) or produce irrigated with tainted water; rare dialysis exposures [1][3][5].

Primarily a liver toxin—can cause nausea, vomiting, diarrhea, abdominal pain, and jaundice; severe cases can injure the liver. IARC: microcystin‑LR is possibly carcinogenic (Group 2B) [1][4]. WHO guideline: 1 μg/L (as MC‑LR); EPA 10‑day advisories: 0.3 μg/L (young children) and 1.6 μg/L (older children/adults) [2][3].

Infants and young children, pregnant people, those with liver/kidney disease, people using untreated surface water, frequent swimmers/boaters near blooms, and pets [1][3][5].

Follow HAB/drinking water advisories; avoid water that looks like paint/pea soup or has scum; do not boil contaminated water; use safe alternate water; rinse fish fillets and discard guts; keep pets out; shower after water activities [2][3][5].