On a recent rainy spring morning, a sea of coffee-colored sludge bubbles in the bioreactors at Missoula's wastewater treatment plant, just south of Mullan Road by North Reserve Street. Each square cell in the long channel of bioreactors houses a unique tribe of microbial warriors. Aerobic levels—high, medium, and no oxygen—are tailor-made. Such conditions make good bacteria feel at home. They thrive here, growing strong enough to eat bad bugs like e-coli, salmonella, and giardia. "They're chewing away, doing their thing," says Starr Sullivan, the plant supervisor, as he stands above the percolating pools.
The wastewater is then sent to a clarifier, where any remaining bacterial bits are removed. UV lights resembling fluorescent tubes further sterilize rogue bacteria before the water is pumped into the Clark Fork River. "You have an instant kill," Sullivan says. "Whatever can die, we're killing it."
The problem may be that there are things in the water that apparently can't die. Manufactured chemical compounds, for example, such as the residue of drugs we take, linger. Curious about those things that linger, Tabetha Lynch made them the focus of her recent thesis project for a master's degree in geosciences at the University of Montana.
Lynch, who is 29, gathered sediments at various points around Missoula to chart the ways that everyday drugs such as ibuprofen and caffeine, as well as more exotic drugs such as MDMA and cocaine, degrade over time. She tested groundwater, and she tested drinking water, sampling from the deep production wells that bring it from the Missoula aquifer up to city faucets. A previous study had shown that drugs migrate from human users into shallow groundwater, but no one had ever tested for them in production wells, which draw from a deeper place. Working with support from the Mountain Water Company and Missoula's water quality district, Lynch also tested treated wastewater from the plant off Mullan Road. Human waste is a primary source of pharmaceuticals in the environment. It made sense to start at the source.
Her results are like a chemical profile of Missoula: caffeine and anti-anxiety drugs with a dash of muscle relaxants, among other things.
"We found carbamezipine, which is an anticonvulsant," says Lynch, who graduated last winter and now works as a hydrogeologist for the international consulting firm ARCADIS U.S.
Both times that she tested at the treatment plant, in September and March of 2010, she also found fluoxetine, the active ingredient in Prozac. Traces of that drug also showed up in the Clark Fork near the university, which perhaps shouldn't be surprising. Fluoxetine has been showing up in waterways across the country.
And then there's the hardy antibiotic sulfamethoxazole, which is prescribed for infections of the ear and the urinary tract as well as for bronchitis and acne. It shows up in water all over the world, Lynch says—including in two Mountain Water wells, one at Maurice Avenue and the other at Palmer Street.
To get a pill's worth of these drugs, a human would have to drink in the neighborhood of two million gallons of treated wastewater. Still, the traces are there, as scientists such as Lynch are discovering, armed with new, more precise testing systems. It's not known what effects such drugs in the environment have on humans, but studies show they're changing aquatic life. Male fish are losing their secondary sex characteristics. And some biologists say such disturbances in fish indicate that humans could be next.
Missoula's groundwater moves fast. And there's a lot of it. However, as population growth meets a rise in pharmaceutical use, Lynch says, it's important to study impacts of such compounds now.
"Eventually, they do build up. And they become possibly a problem, especially things like sulfamethoxazole...It is a very low therapeutic dose for people. But we don't really know what putting antibiotics into the environment is doing to other things. There's been studies that have shown that antibiotics disrupt things in fish and they disrupt different life cycles of microbes. If you put antibiotics in the water, are you killing the natural fauna in the river? Or, are you building up antibiotic resistance? I mean, there are bigger questions."