Blue-Green Algae Dangers

Blue-green algae thrives in bodies of warm, undisturbed water.

Blue-green algae can produce a variety of toxins that can affect the health of humans and animals. Children and pets are especially vulnerable to the effects of these toxins. It can also have a negative impact on other forms of life in its surrounding aquatic environment. However, many blooms of blue-green algae do not produce toxins at all, and small amounts of those that do are usually harmless to people.

Identification

Blue-green algae colonies, or blooms, float on water, although they are impossible to see as an individual organism without the use of a microscope. This organism is a type of bacteria known as cyanobacteria. It requires sunlight and carbon dioxide to survive, along with other chemical nutrients. Some blue-green algae can produce harmful toxins.

Ingestion

Swallowing water that contains toxins produced by blue-green algae can have a range of adverse effects on humans and pets. In humans, ingesting blue-green algal toxins such as gastrointestinal toxins can cause symptoms associated with gastroenteritis, including abdominal cramping, diarrhea and vomiting. Ingestion of hepatoxins and cytotoxins from blue-green algae can cause more serious problems such as liver damage. In serious cases, swallowing another type of blue-green algal toxin called neurotoxins can affect the nervous system, resulting in seizures or paralysis. High levels of these toxins can be fatal to pets and livestock. In dogs, reactions can include seizures, respiratory failure and death.

Inhalation

When the toxins present in some forms of blue-green algae become airborne --- during water sports, for example, people or animals may inhale them. Breathing in these toxins can cause symptoms such as a sore throat, runny nose or swelling of the respiratory tract. In some extreme cases, hepatoxins in blue-green algae can cause respiratory failure.

Skin Reactions

When the skin comes into contact with blue-green algae, either in outdoor bodies of water or when it enters the water supply and is present in household water, skin irritation can occur. However, small amounts of blue-green algae only affect those who are particularly sensitive to the organism. Symptoms may include hives, blistering and the appearance of a rash. The types of toxins that affect the skin are called dermatoxins.

Environmental Consequences

Excessive growth of blue-green algae can have a negative effect on other aquatic life forms by reducing the amount of light that reaches below the surface of the water. A lack of light makes it harder for plants to grow underwater, which in turn reduces the numbers of other life forms such as fish due to the resultant lower level of vegetation for them to consume. The presence of large amounts of blue-green algae can lower the amount of oxygen in a body of water due to the amount of oxygen used up when microbes break down dead algae. A lack of oxygen can in turn deplete fish populations.

References

• New York State Department of Health: Blue-Green Algae
• Wisconsin Department of Natural Resources: Blue-Green Algae In Wisconsin Waters Frequently Asked Questions
• New Mexico Environment Department: Understaing Exposure and Health Effects: Blue-Green Algae