Skip to Main Navigation
Skip to Page Content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Nomination Summary for Microcystin LR (N20031)

Nominated Substances: Microcystin LR

Nomination Date: 05/18/2000

Nominator: NIEHS

Rationale: Cyanobacteria, a blue-green algae associated with eutrophication, and their toxins have been identified by the EPA as drinking water contaminants with high health research priority. Research shows that microcystins, the most common toxins associated with blue-green algae blooms, are hepatotoxic. Incidences of gastroenteritis affecting 1000's of people have been associated with algae blooms. However, very little is known about the chronic low dose effects of microcystin exposure associated with drinking water.

NTP Principles: 1, 2

Agents and Status

The following information relates to the specific agent and may include history from earlier or later nominations for this same agent.

CASRN: 101043-37-2

Agent Name: Microcystin LR