Lake James Environmental Association
Blue-green algae (cyanobacteria) background information

In February 1996, the world of water science received a wake-up call when 65 dialysis patients in Caruaru Brazil died after exposure to a liver toxin. The source of the toxin was traced to the use of treatment water contaminated with the blue-green algae, Microcystis aeruginosa. The clinic allowed toxins into the patients’ dialysis process by using poorly filtered reservoir water treated with chlorine (1).

The World Health Organizations additionally reports that, "Elsewhere in South America, in 1988, more than 80 deaths and 2,000 illnesses due to severe gastroenteritis have also been directly linked with toxic cyanobacteria in a newly constructed dam. In China, a high incidence of primary liver cancer has been linked to the presence of cyanobacterial toxins in drinking water (Chorus and Bartram, 1999)." (2)

Since the 1996 incident, a survey of 1,000 water samples from reservoirs in the US and Canada found that 80% contained measurable amounts of algal toxins and 20% exceeded the World Health Organization standard for microcystin (3). Freshwater Blue-green algae produce both nerve toxins and liver toxins that account for some of an estimated 900,000 illnesses and 900 deaths every year due to contaminated water (4).

According to Dr. Wayne Carmichael of Wright State University, “A large amount of liver disease here that is attributed to alcoholism may actually be due to the water.(4)”

Blue-green algae (cyanobacteria) have survived on earth over 3 ½ Billion years and inhabit virtually all fresh water bodies(5). Sunlight, warm water, and an excess of nitrogen and phosphorus trigger the blooms and when the bacteria die, the toxin (present in about 1/4 the blooms) is released into the water(6). According to the US EPA, "essentially an ambient total phosphorus (TP) concentration of greater than about 0.01 mg/L and or a total nitrogen (TN) of about 0.15 mg/L is likely to predict blue-green algal bloom problems during the growing season. Similarly, chronic overenrichment leads to lake quality degradation manifested in low dissolved oxygen, fish kills, algal blooms, expanded macrophytes, likely increased sediment accumulation rates, and species shifts of both flora and fauna." (7) In recent years, toxic blooms were reported across the US, from Lake Santeetlah in western North Carolina(8) to Lake Sammamish near Seattle, Washington(9).

Toxins from cyanobacteria are among the most lethal substances known. Where Cyanobacteria are well dispersed, there is no immediate risk to animals or humans, however, recent investigations in China strongly link cyanobacterial toxins with liver cancer(10).

There is no known antidote for blue-green algal toxins once a lethal dose has been ingested. The only way to tell if the bloom water is toxic is by injecting it into a lab animal. Conventional treatment and disinfection afforded most public drinking water supplies are not effective in removing or deactivating blue-green algae toxins. Boiling is similarly ineffective. Water that is free of blue-green algae following a bloom may not be free of the toxin. The time to control a toxic algae bloom is before the bloom develops (11).

Citations:
(1) Seattle Times, December 7, 1997, Death by pond scum: blue-green neurotoxin
(2) WHO Report, Human Health and Dams: Box 4, Freshwater cyanobacterial toxins
(3) The Progressive Populist, Weeds coincide with toxic algae blooms
(4) UPI News, August 6, 1999, Toxic algae taints city water supplies
(5) UC Berkeley, Introduction to cyanobacteria
(6) Soil & Water Conservation Society of metro Halifax, The Blue-Green Algae (Cyanobacteria)
(7) EPA-822-B00-001, Nutrient Criteria Technical Guidance Manual - Lakes and Reservoirs, First Edition
(8) The Graham Star, 21 September 2000, Santeetlah's water concerns citizens
(9) King County, Washington, Department of Natural Resources, Toxic Bloom in Lake Sammamish
(10) The Irish Times, January 5, 2000, Warning on danger of toxic microbes in water
(11) Montana Department of Environmental Quality, Toxic Algae Fact Sheet