Human Health and HABs

FAQs for Human Health

How can I or my family be exposed to HABs?

lake swimming

Human exposure to cyanobacteria and associated toxins (cyanotoxins) most commonly occurs through ingestion or skin contact with contaminated water. Inhalation of spray or mist coming off water with high cyanotoxin concentrations may also contribute to exposure during activities such as water-or jet-skiing. Cyanotoxins may also accumulate in fish and shellfish. Children are considered more susceptible to effects from cyanotoxin than adults.

How can I keep myself and my family safe from HABs?

What are signs of possible cyanobacterial toxin poisoning in people?

The following symptoms may occur within 48 hours of exposure to a waterbody with a suspected or confirmed algal bloom:

man fly fishing

  • sore throat or congestion;
  • coughing, wheezing, or difficulty breathing;
  • red, or itchy skin, or a rash;
  • skin blisters or hives;
  • earache or irritated eyes;
  • diarrhea or vomiting;
  • agitation;
  • headache; and/or,
  • abdominal pain.

If people show symptoms of cyanotoxin exposure after contact with water, or with scums or mats of algae, they should receive immediate medical attention.  Additional resources are available from the Centers for Disease Control and Prevention (CDC), and by contacting the California Poison Control Center (1-800-222-1222).

Resources for Medical Professionals

Hospitals can be alerted to look for signs of cyanotoxin exposure in other patients, especially if these facilities are located near water where HABs may be present. Hospitals should be encouraged to report any suspected or confirmed cases of cyanotoxin exposure to the local health department and to the HAB Portal bloom incident form.


One Health Harmful Algal Bloom System (OHHABS)


The California Environmental Health Tracking Program at the California Department of Public Health (CDPH) will attempt to collect details of reported HAB-related illnesses. CDPH is implementing California’s HAB-related human and animal illness reporting to the Centers for Disease Control and Prevention (CDC) One Health Harmful Algal Bloom System (OHHABS).


For general information on HABs please refer to the HABs FAQ webpage