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