The Main Points
- Cyanotoxins can result from algal blooms.
- Cyanotoxins pose a risk to both human and environmental health.
- Cyanotoxins can be detected using ELISA assays.
Some species of cyanobacteria (blue-green algae) produce chemicals that are known collectively as cyanotoxins. In healthy aquatic systems, their concentrations are generally low. When excessive nutrients create algal blooms cyanotoxin concentrations increase to the point where they can endanger the health of both humans and wildlife. This situation is referred to as harmful algal blooms or HABs.
Microcystin-ADDA, anatoxin-a and cylindrospermopsin are the names of common cyanotoxins. At high concentrations, short-term effects of exposure to these toxins can include sore muscles, skin irritation, earaches, nausea, diarrhea, stomachache and vomiting. Long-term health effects depend on the type of toxins. Microcystin and cylindrospermopsin inhibit normal liver function, while anatoxin can damage the nervous system.
The U.S. Environmental Protection Agency has developed Health Advisories of drinking water for microcystin and cylindrospermopsin. Several states, the World Health Organization, Australia, Canada and New Zealand have adopted action levels for recreational waters. The U.S. Environmental Protection Agency issued their first draft of proposed recreational water standards in December of 2016.
The most effective way to measure cyanotoxin concentrations is to use the Enzyme-Linked Immunosorbent Assay (ELISA). Originally developed for immunology research, ELISA takes advantage of the ability of antibodies to bind to other substances, such as proteins, viruses and cyanotoxins. Essentially the ELISA assay simulates the body’s immune response in a test tube. Cyanotoxins are extremely complex molecules that occur in many different forms. Conventional water quality chemistry equipment has a hard time separating and distinguishing them. Like our own immune system, ELISA reacts to multiple toxins and thus measures the overall potential for exposure.
Because children typically spend more time in the water and tend to ingest more water (equivalent to 10% to 15% of body weight) than adults (equivalent to 2% to 4% of body weight), they are at greater risk from cyanotoxin exposure. Lake managers should monitor cyanotoxin levels and work to ensure they fall below the recreational guidelines. Even if a lake or pond is not used for swimming, pets and wildlife might still be at risk.