Harmful Algal Blooms (HABs)

OEHHA performs risk assessment and hazard evaluation activities relating to Harmful Algal Blooms (HABs) in lakes, rivers, and ocean environments. An algal bloom is a rapid growth of algae and/or cyanobacteria in water. An algal bloom is harmful when the algae or cyanobacteria produce toxins that can adversely impact humans, wildlife, or domestic animals. Non-toxic algal blooms are harmful when they adversely impact the aquatic ecosystem through crowding out other species, depleting dissolved oxygen, or disrupting other ecological factors. OEHHA’s work focuses on the toxic impacts of HABs on humans and animals. Marine HABs commonly consist of an overgrowth of certain types of algae (diatoms or dinoflagellates) that produce biotoxins. Cyanobacterial HABs are made up of large populations of a type of photosynthetic bacteria (cyanobacteria, also known as blue-green algae) that produce cyanotoxins. In California, cyanobacteria are commonly found in freshwater and estuaries. Factors promoting HABs include warmer temperatures and excess nutrients. Currently, OEHHA’s work on HAB-related toxins focuses on consumption of contaminated seafood, exposure during swimming and other recreational activities, and impacts on domestic animals and wildlife.

OEHHA’s work relating to HABs includes:

HABs News

02/26/2020: Blue-Green Algae: A Veterinarian Reference
Blue-green algae (also known as cyanobacteria) are non-pathogenic photosynthetic bacteria that grow in outdoor water bodies and produce toxins such as microcystins, cylindrospermopsin and anatoxin-a. This fact sheet is meant to help veterinarians with diagnosis and treatment options.
06/25/2018: Dog Owners Fact Sheet (HABs)
Health risk information on cyanobacteria (blue-green algae) for dog owners near lakes, ponds, and rivers.
04/11/2017: Domoic Acid Workshop
Domoic Acid Workshop will be held at the UC Davis Buehler Alumni Center, AGR Hall. Registration, agenda, and meeting materials are available.
03/28/2017: Domoic Acid Workshop
OEHHA and UC Davis scientific workshop on May 4, 2017 exploring “Domoic Acid: Evaluating the State of the Science and Implications for Human Toxicity”. This workshop will explore dose levels that induce adverse effects and the spectrum of health endpoints.