Home >> Science & Nature >> Nature

Risks of Blue-Green Algae

Blue-green algae (BGA) are a group of photosynthetic bacteria also known as cyanobacteria. BGA can be many different colors. The algae grows in lakes, ponds and slower streams where water is warm and full of nutrients such as nitrogen. BGA can grow very quickly and floats to the surface of the water, a process known as an algal bloom. While some species of BGA produce toxins, others do not and only lab testing can tell the difference. BGA toxins can cause health problems for people, pets, livestock, fish and wild animals that come in contact with water contaminated by blue-green algae toxins.

Health Effects in Humans
- Humans can be affected by BGA toxins by drinking contaminated water, by bathing or swimming in the water and by cooking or washing dishes with bad water. Boiling the water will not get rid of the toxins, although it will kill the algae. Symptoms of consuming algae-toxic water include nausea, vomiting, diarrhea, abdominal pain, gastroenteritis, headache, muscle weakness, pneumonia and paralysis. Other symptoms can occur from contact with the water on the skin, including rashes, swollen lips, eye irritation, sore throat, ear problems, asthma and possible skin tumors. All water experiencing an algal bloom should be avoided.
Health Effects on Pets and Livestock
- Pets can experience diarrhea, vomiting and even seizures after swimming or drinking toxin-contaminated water. Since dogs often lick their coats after swimming, they must be kept away from algae blooms in water. Give pets a bath, washing their fur carefully if they've gotten into bad water. Drinking contaminated water can cause death in livestock. If no other water source is available, filtering the water is an option, especially with activated charcoal.
Eating Fish from BGA-Affected Water
- While eating fillets of fish (muscle tissue) of otherwise healthy fish from affected waters causes no known problems, eating shellfish is bad news. One species of blue-green algae in Australia contained a neurotoxin that causes "Paralytic Shellfish Poisoning." People have eaten shellfish contaminated by BGA and died. Queensland authorities warned Australians against eating any shellfish from algae-infested waters.
Blue-Green Algae Food Supplements
- Some manufacturers of blue-green algae products harvest the algae from controlled, tested ponds. Others harvest algae from the wild, usually from lakes. In 1999, Health Canada tested algae food supplement products for toxins and found that while one form of blue-green algae (spiralina) was free of toxins, many other products were not. Blue-green algae naturally produces a toxin known as microcystins. Microcystins can accumulate in the liver and impair liver function. Canada now recommends that children, pregnant women and people with damaged livers should avoid blue-green algae products.

Nature