Harmful Algal Blooms (HABs) cause a variety of mild to serious illnesses in people. The most severe reactions occur when large amounts of water are swallowed.
HABs can be found throughout Missouri, most commonly in lakes, ponds and slow-moving or pooled streams. People can be exposed to the toxins in HABs by coming into contact with polluted water, drinking contaminated water or consuming tainted fish or shellfish. The toxins can also be inhaled through airborne water droplets while swimming, boating, waterskiing, tubing, bathing or showering in water that has harmful algae.
Prevent Exposure
First and foremost, learn about harmful algal blooms and what to look for. Higher levels of toxins are typically associated with cyanobacteria blooms that appear as thick foam or scum on the water’s surface. Their color can vary from bright green and blue-green, to white, red or yellowish-brown. The water may look like pea soup or the surface may look as if paint has been spilled on it. As the cyanobacteria begin dying and decomposing they may release an unpleasant odor similar to rotting plants.
- If the water does not look or smell right or you suspect a bloom is occurring, it is best to avoid direct contact with the affected area.
- Before allowing children 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. You can also check the Missouri HAB Response Team's Harmful Algal Bloom Reports Map for locations where HABS have been reportedly observed in Missouri.
- 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.
Symptoms and Actions
Symptoms depend on the type of harmful algal bloom you come in contact with, how much toxin is present, how you are exposed and how long you are exposed. Common symptoms include:
- Skin irritation or Rash
- Vomiting
- Cramps
- Diarrhea
- Dizziness
- Fainting
- Numbness
- Tingling
- Temporary paralysis
Inhaling 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.
If you are concerned you may have been in contact with contaminated water, remove any clothing that made contact with the bloom and wash all areas of contact off with soap and fresh water. If you are experiencing symptoms and suspect you were exposed to contaminated water, seek medical attention. Let the medical personnel know you have been in an area affected by a bloom and may have been exposed. You can also contact Poison Help by telephone at 800-222-1222 or by visiting PoisonHelp.org. You can report any HAB related illnesses to your local public health agency or the Department of Health and Senior Services Public Health Emergency Hotline at 800-392-0272.
Resources
General Information
- Blue Green Algae & Me - DHSS
- Cyanobacteria Blooms
- Directory of Local Public Health Agencies - DHSS
- Harmful Algal Blooms and Blue-green Algae - PUB3051
- Harmful Algal Blooms and Your Health - CDC
- Look Out Harmful Algal Blooms - PUB2889
- Natural Water Areas - DHSS
- What makes blue-green algae dangerous? - ACS
- Algal Blooms Can Harm Your Health - EPA video
- Harmful Algal Blooms and Health - CDC video
- What Makes Blue-Green Algae Dangerous? Speaking of Chemistry - ACS video