Toxic algae grow in a large bloom in the Copco Reservoir on the Klamath River near Portland, posing health risks to people, pets and wildlife. Photo by Oregon State University

CORVALLIS, Ore., Aug. 13 (UPI) -- Unchecked blooms of cyanobacteria, or blue-green algae, in rivers, lakes and reservoirs pose a growing health risk to animals and possibly humans, according to researchers in a new analysis of waterways in the United States.

Cyanobacteria are often fatal to pets and wildlife that drink contaminated water. In humans, the toxin microcystin, produced by cyanobacteria, is a liver toxin and may cause liver cancer. Some forms of the algae also cause gastrointestinal illnesses and acute skin rashes.


Researchers said part of the problem is the lack of national standards for monitoring algae growth, as well as no requirements for reporting illnesses they cause to the Centers for Disease Control and Prevention.

"At this point we only have toxicology data for a handful of these toxins, and even for those it remains unclear what are the effects of chronic, low-dose exposures over a lifetime," said Tim Otten, a postdoctoral scholar in the Oregon State University Department of Microbiology, in a press release. "We know some of the liver toxins such as microcystin are probable carcinogens, but we've really scratched only the surface with regard to understanding what the health effects may be for the bioactive metabolites produced by these organisms."

Cyanobacteria, found around the world, are believed to be among the oldest organisms on Earth and responsible for at least some of the oxygen that gave rise to more complicated forms of life on the planet. Researchers call the issue they're bringing to light complex because some forms of the algae play a positive role in lakes and rivers.

In their paper, published in Current Environmental Health Reports researchers from OSU and the University of North Carolina write that increases in algal blooms are expected to get worse due to global climate change -- especially rising temperatures and increasing levels of carbon dioxide in the atmosphere -- as well as nutrient over-enrichment due to fertilizer misuse, wasterwater discharges, and hydrologic modifications of the environment such as damming rivers, among other reasons.

The researchers said better monitoring of bodies of water are needed, as is a wider awareness of the potential dangers of animals and humans ingesting cyanobacteria.

The toxins can't be killed by boiling water, however passing the water through carbon filtration devices can reduce the health risk. Additionally, researchers suggest people learn what the algae looks like -- a greenish, paint-like surface scum on water -- in order to avoid recreation in a lake or river where they are present, as well as keeping pets away from them.

"In my mind, these bacteria should be considered guilty until proven innocent, and in drinking water treated as potential pathogens," Otten said. "I think cyanobacteria should be approached with significant caution, and deserve better monitoring and regulation."