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Health Impacts of Harmful Algal Blooms at Beaches

Health ImpactsHarmful Algal Blooms (HABS)

Harmful algae blooms (also known as cyanobacteria) secrete toxins, including microcystin, that can cause a variety of health problems.

Microcystin has been identified at fresh water lakes and beaches in Iowa.

How People & Pets are Exposed

According to the Iowa Department of Public Health:

  • People can get sick from microcystin toxin if they have direct contact with a blue green algae bloom, by either intentionally or accidentally swallowing water, by having direct skin contact (as when swimming, wading, or showering), or by breathing airborne droplets containing the toxins, such as during boating or waterskiing.
  • Pets and other animals that drink from the water’s edge, where scum layers accumulate, can be exposed to deadly levels of microcystins. Pets can get sick if they have been swimming in water where algal blooms have been and ingest significant amounts of microcystins by licking themselves after leaving the water.

Health Symptoms/Impacts:

According to the Iowa Department of Public Health:

  • Getting blue-green algae/microcystin on the skin may produce a rash, hives, or skin blisters (especially on the lips and under swimsuits).
  • Swallowing water containing blue-green algae/microcystin may cause gastrointestinal symptoms such as stomach pain, nausea, vomiting, diarrhea, severe headaches, and fever.
  • Inhaling water droplets containing blue-green algae/microcystin can cause runny eyes and nose, cough, and sore throat, chest pain, asthma-like symptoms, or allergic reactions.
  • Exposure to large amount of microcystin can cause liver damage

Pay close attention to pets and children: 

  • Pets that swim in or drink the water can suffer serious harm or even death, sometimes in a matter of hours. Avoid letting them eat or roll in scums along the shoreline.
  • Children have higher risks because they are more likely to ingest the water, and they usually play near the shoreline where blooms are often thickest.

How to Identify Harmful Algal Blooms

Visible signs that a lake, beach or other water-body is experiencing a potentially harmful blue-green algae bloom, include:

  • A visible surface scum resembling spilled paint, pea soup or streaking of green lines on the surface.
  • Algae ranging in color from bright, iridescent blue to green, red or brown.
  • A foul odor.

Not all algae is toxic. Click here to view helpful pictures of harmful algal blooms contrasted with other types of algae and plants that may be found in midwestern surface waters.

Preventing Exposure

According to the Iowa Department of Public Health:

  • Avoid swimming, wading, or playing in lake water that appears covered with scum or blue-green algae or recently had blue-green algae.
  • Avoid drinking or swallowing recreational water from lakes, streams, and other surface waters.
  • Do not play in, or use, areas that have warning signs or have otherwise been designated by the Iowa DNR to be at risk for blue-green algae/microcystin.

Responding to Exposure

According to the Iowa Department of Public Health:

  • If you have gotten into, swallowed, or breathed in water where a blue green algae bloom has formed:
    • Wash off with fresh water and soap after skin contact with algae 
    • Check with your doctor if you experience symptoms, and mention your exposure to possibly toxic blue green algae.
    • Avoid drinking alcohol
    • Do not use acetaminophen

If you have a question about the health of your pets, consult your veterinarian.