What are the health risks if exposed to a HAB?
You can become sick if you swallow, have skin contact or breathe in airborne water droplets while swimming, boating, waterskiing, tubing, bathing or showering in water that has harmful algae, or by drinking water containing algal toxins. Skin irritation or rash is the most commonly reported health effect. Other symptoms range from diarrhea, cramps and vomiting, to fainting, numbness, dizziness, tingling and temporary paralysis. The most severe reactions occur when large amounts of water are swallowed.
Inhalation of aerosolized toxins may result in allergy or asthma-like symptoms. Individuals with respiratory illnesses, such as asthma or other respiratory diseases, are more susceptible to breathing difficulties and may experience more severe symptoms. Such individuals should consider avoiding exposure if possible.
What should I do if I am experiencing symptoms?
If you are currently experiencing symptoms, seek medical attention or you can contact the Poison Help line 24/7 at 800-222-1222 or by visiting PoisonHelp.org. Let the medical personnel know you have been in an area affected by a bloom and may have been exposed.
How do I report an illness?
You can report any HAB related illnesses to your local public health agency or the Department of Health and Senior Services (DHSS) Public Health Emergency 24/7 Hotline: 800-392-0272. If you are currently experiencing symptoms, seek medical attention or contact the Poison Help line 24/7 at 800-222-1222 or visit PoisonHelp.org. Let the medical personnel know that you have been in an area affected by a bloom and may have been exposed.
Is it safe to eat the fish?
Fish caught in affected waters pose unknown health risks and may have an undesirable taste. Because of the unknown risks, we recommend you do not eat fish from affected areas for two weeks after the bloom visually dissipates. If you choose to eat them, remove all fat, skin and organs before cooking because toxins are more likely to collect in these tissues. Always cook fish thoroughly.
How can I keep myself and my family safe?
Before allowing children or pets to swim in lakes, rivers, or at beaches check for posted water quality condition information. This information may be online, at the park office or posted at common access area, such as bath houses or boat ramps. Also, educate yourself on harmful algal blooms and what to look for. If the water doesn’t look or smell right or you suspect a bloom is occurring, it is best to avoid direct contact with the affected area. Don’t let pets drink or play in the water, or roll in or eat the algae.
Additional Resources
Drinking Water Information
- EPA 2015 Drinking Water Health Advisories for Two Cyanobacterial Toxins
- Harmful Algal Bloom Sampling Protocol
- EPA - Managing Cyanotoxins in Public Drinking Water Systems
Recreational Water Information
- EPA Tools for Waterbody Managers to Monitor for and Respond to CyanoHABs
- Recreational Water Quality Criteria or Swimming Advisories for Cyanotoxins
- World Health Organization (WHO) 1999 Guideline Values for Cyanobacteria in Freshwater
Additional Information for Poison Center or Medical Professionals
- Facts about Cyanobacterial Harmful Algal Blooms for Poison Center Professionals
- Harmful Algal Bloom (HAB)-Associated Illness
- CDC Physician Reference Card for Cyanobacterial Blooms
- CDC One Health Harmful Algal Bloom System (OHHABS)
Missouri Department of Health and Senior Services
Videos
- Algal Blooms Can Harm Your Health
- What makes blue-green algae dangerous? - video produced by the American Chemical Society discussing the cause of HABs, the most common toxins, the health risks and the chemistry behind them
