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Cedar Rapids, Iowa 52401
That paint-like scum that covers some Iowa lakes every summer isn't just gross and smelly. People, pets and livestock coming into contact with or ingesting toxins produced by the algae are at risk of skin rashes, gastrointestinal issues and, in high doses, liver failure.
The toxin, called microcystin, is a liver toxin produced by some strains of cyanobacteria, commonly called blue-green algae. It has been tracked in Iowa state lakes since 2005. When concentrations rise above 20 micrograms per liter, signs are posted to warn the more than 1 million beachgoers and boaters making 12 million visits to the lakes each year.
Although the number of reports of human and animal illness from the toxin has remained fairly steady, some scientists say the annual algal blooms may be growing more severe.
'I think we can be fairly confident in saying that the number of blooms, or the severity of the blooms, appears to be increasing,” said Mary Skopec, who heads the Iowa Department of Natural Resources beach monitoring program.
In fact, two microcystin advisories posted this week brought the total number of warnings this year to 25, surpassing a record of 24 set in 2013, according to the Iowa Environmental Council.
This increase seems to mirror national trends, Skopec said. Longer periods of warm temperatures as well as the high levels of nutrients, like nitrogen and phosphorus, could be contributing to the increase in severity, but the exact cause isn't known, she said.
State toxicologist Stuart Schmitz said the Iowa Department of Public Health and the Iowa Department of Natural Resources have participated in a surveillance program of harmful algal bloom illness since 2008. He said five to 14 cases of suspected human exposure to microcystin are reported each year.
He said people should shower after using lakes that have an active bloom and 'if they don't have to go in there, stay out.”
He said cases of exposure likely aren't reported to the state but that it is hard to estimate how many cases there might be.
Microcystin is relatively new on the scene of environmental concerns. The Iowa Department of Natural Resources beach monitoring program has tested for E. coli since 2000.
TESTING WATER QUALITY
In order to track toxin levels at state parks, DNR sends people to lakes to gather water at the swimming beaches.
Connor Nicholas, 22, an Iowa State University senior, did just that this summer.
Nicholas, an environmental science major, said the blooms can look different, varying from a green, powder-like substance to something that 'looks like fish eggs.”
Large blooms, like the one he saw at Green Valley State Park in Union County, have a certain smell.
'It's kind of like a sharp, putrid smell. Not like eggs or sulfur-based. But once you've smelled it, you don't forget it,” he said.
Despite the warning signs and occasional news coverage, many people don't seem to know much about the toxin, Nicholas said.
Anke Hildreth, of Fort Myers, Fla., and her husband were running through North Twin Lake in Calhoun County in west-central Iowa and stopped to talk to Nicholas about the algae bloom.
Hildreth said she'd decided to skip the swimming portion of an upcoming triathlon, opting for just the biking and running.
Skopec, who tests the water samples, said it is hard to predict when or if an algae bloom is going to produce the microcystin toxin.
In order to test for the toxin, the samples go through three freeze-thaw cycles to break apart the cyanobacteria cells that can hold the toxin inside.
In a DNR lab in Des Moines, Skopec looks at the frozen test tubes - her 'Popsicles.” The five vials of water samples emit small popping and cracking noises as they warm up from the minus 80 degree Celsius freezer.
One was dark green, another a murky brown, a third was layered blue and green, one was hazy green and one looked like pure, clear water. Both the blue-green and the clear ones tested above the health advisory levels for microcystin.
'Therein lies our problem,” she said.
Skopec said she thought the U.S. Environmental Protection Agency might release new, lower guidelines for microcystin in recreational waters after the EPA released new microcystin drinking water advisory levels this year. So far, it has not.
Although the science behind the toxins can be complicated, Skopec said simply using common sense when enjoying Iowa's lakes is key to decreasing one's risks.
'If all the indications are that things are fine - clear water, hasn't had a recent bloom - I wouldn't be scared to go into that water,” she said. 'I don't want people to panic. I just want people to use common sense and good information.”
Caution extends to pets and other animals, such as livestock.
Information is available on the department's beach monitoring website as well as its beach monitoring hotline. However, she said not all beaches are monitored.
'In Iowa, officially we are only testing about 40 beaches,” she said. 'So just because it's not posted with an advisory, people should still exercise caution if they see very green, blue-green scummy water. Because not all water bodies are going to be tested and posted.”
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