Notice of Availability of Notification Level Recommendations for Four Cyanotoxins in Drinking Water

May 6, 2021

June 16, 2022 update: The saxitoxins value has been superseded. The value is now 0.5 ug/L.

The Office of Environmental Health Hazard Assessment (OEHHA) has submitted to the State Water Resources Control Board (SWRCB) notification level (NL) recommendations for four cyanotoxins as follows:

Cyanotoxin	Recommendation	Health Effect	Peer-Reviewed Study
Anatoxin-a	NL: 4 µg/L	Neurotoxicity	Fawell et al., 1999
Saxitoxins	Interim NL: 0.6 µg/L	Neurotoxicity	EFSA, 2009
Microcystins	Interim NL: 0.03 µg/L	Spermatotoxicity	Chen et al., 2011
Cylindrospermopsin	Interim NL: 0.3 µg/L	Liver Toxicity	Chernoff et al., 2018

Cyanotoxins are toxins produced by cyanobacteria, also known as blue-green algae, during algal blooms. Notification levels are health-based advisory levels established by the SWRCB Division of Drinking Water (DDW) for chemicals that lack drinking water regulatory standards (maximum contaminant levels, or MCLs). When chemicals are found at concentrations greater than their NLs, certain requirements and recommendations apply. The NL recommendation memo for anatoxin-a and the memo for the other three cyanotoxins are available for download below, and links to access the peer-reviewed studies for their derivation can be found in the references section of each.

If you would like to receive further information on this announcement or have questions, please contact Hermelinda Jimenez at PHG.Program@oehha.ca.gov or at (916) 324-7572. Written inquiries can also be addressed to:

Pesticide and Environmental Toxicology Branch
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency
P.O. Box 4010, MS-12B
Sacramento, California 95812-4010
Attention: PHG Program