Health Risk from Springs' Pollution Not Fully Understood
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by Nathan Crabbe Gainesville May 13, 2007
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Pollution in springs could cause reproductive changes in aquatic species and have implications for human health, according to emerging science on the issue.
Rising nitrate levels in the springs of the Suwannee River basin have long been linked to algae growth that disrupts aquatic ecosystems. But new research suggests nitrates could also affect reproduction and lead to allergic reactions.
"The idea that it can be a health concern at these low levels has been overlooked," said Thea Edwards, a researcher in the University of Florida's zoology department.
Edwards is studying whether nitrates interact with other contaminants to reduce the production of hormones needed for reproduction. U.S. Geological Survey researchers have been working to identify these contaminants, finding ultra-low levels of bug repellent and pharmaceuticals in the water of one spring in the basin.
State health officials also are studying whether nitrate-fueled algae growth in springs could cause rashes and other allergic reactions in people. Since 1999, at least 34 people have reported allergic reactions after visiting springs at state parks.
Nitrates are a byproduct of waste that can enter groundwater and springs through farms, septic tanks, fertilizer and wastewater spray fields. Due to concerns that nitrates cause a blood disorder in infants, the U.S. Environmental Protection Agency sets a 10-milligrams-per-liter threshold for nitrate levels in drinking water.
Edwards' research, published last year in the journal Environmental Health Perspectives, studied whether nitrates at even lower levels can affect aquatic species. The study compared mosquitofish in Fanning and Ruth springs - springs that had nitrate levels of four and 5 milligrams per liter, respectively - with species in six springs with lower nitrate concentrations.
The research found mosquitofish in the higher-nitrate springs were less likely to become pregnant and those that were pregnant had smaller babies. Edwards said the research suggests nitrates could act as an endocrine disrupter, affecting the production of hormones.
Another study involving Edwards, published last year in the journal Aquatic Toxicology, looked at tadpoles in water from Poe Springs and filtered tap water. The study compared the tadpoles when each set of water had similarly high nitrate levels.
The study found the tadpoles in the spring water tended to be smaller and had delayed metamorphosis, suggesting nitrates could be interacting with other contaminants in the spring water. The research could have implications for human health, Edwards said.
"It's not one contaminant that's the problem," Edwards said. "It's that we're exposed to a huge collection of contaminants."
U.S. Geological Survey research hydrologist Brian Katz has been studying contaminants in spring water. In a study of the Ichetucknee Springs and its basin, he found ultra-low levels of an antihistamine, an antidepressant/anticonvulsant drug and the bug repellent DEET in one of the springs.
The study serves as an illustration of how these chemicals can migrate from septic tanks and wastewater spray fields to springs, he said, rather than being a warning signal about drinking water safety.
"There's probably no health effects associated with humans, but there may be some effects with aquatic organisms," he said. "That definitely needs further study."
The Ichetucknee Springs have also been the focus of research into allergic reactions. Of the 34 incidents at state parks, more than 20 occurred at Ichetucknee Springs State Park.
Visitors have reported rashes, hives, breathing problems, nausea and incidents of passing out from allergic reactions. Such incidents led the Florida Department of Health to collect algae last year from the Ichetucknee and other springs for study.
But the algae didn't reveal toxins expected to be associated with allergic reactions, said Andy Reich, coordinator of the Department of Health's aquatic toxins program.
"Right now we're kind of a little bit perplexed," he said.
The department will continue its investigation this summer. Reich said the department will be looking to investigate soon after reported incidents, helping to determine whether other factors such as heat or the medicines taken by swimmers could be a factor. "Right now everything's on the table," he said.
State officials caution that research about the health effects of pollutants in springs is an emerging science.
Testing the effect of multiple contaminants is complicated and the effect of low levels of contaminants is barely understood at this time, said Mark Hooks, director of the Florida Department of Health's Bureau of Sewage Programs.
"Let's not raise the alarm bell," he said. "It's just too early to predict."
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Source: Gainesville
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