Statewide study shows algae toxin a minor threat
The researchers analyzed the water taken from 187 lakes in 38 counties during a period of one year, and found that almost three quarters of the samples had detectable levels of microcystin chemicals. Only 7 percent of the samples exceeded the guidelines of the World Health Organization for drinking water, which is one microgram of microcystin per liter.
The results should reassure those swimmers, boaters and fishermen, said Dan Canfield, a professor with the UF Institute of Food and Agricultural Sciences and an author of the study, published in the current issue of Lake and Reservoir Management.
“On a population basis for the state, not a big problem,” said Canfield. “But if it is a concern for you as a person can obtain a test kit for $ 20 and use it to make a decision.”
Test kits, available online, are not as accurate as laboratory tests, but provide immediate results, he said. People with impaired immune systems or hypersensitivity to microcystin may want to exercise caution on the use of the lake.
The chemical is produced by certain species of blue green algae, but can damage the liver and has been implicated in human and animal diseases.
In the study, microcystin levels are highest in lakes with algae growing more abundant. A few samples of Lake Jessup in Seminole County and Lake Hunter Polk County exceeded the WHO guidelines for recreational waters, 20 micrograms of microcystin per liter.
Microcystin levels vary from day to day, and part of a lake to another, said Dana Bigham, a UF graduate student and study author. For these reasons, each lake is shown six times during 2006 at intervals of two months, and water was taken from several locations.
Because the chemical is associated with algae blooms, lake users should avoid contact with large mats of floating algae, Bigham said.
The main danger came from swallowing water containing microcystin said. Research indicates that the effects of microcystin vary between individuals, depending on your sensitivity and the amount ingested. Exposure to the toxin can cause symptoms ranging from upset stomach to severe liver damage.
Microcystin was identified in the 1980s, Bigham said. Scientists have determined that many species of blue green algae can produce, although its cause is unknown.
The chemical has received media attention, particularly in the Midwest, where it is associated with algal blooms in summer. In Florida, the chemical can produce virtually all year, he said. The study indicated that microcystin highest levels occurred in September and December.