Prescription drugs are contaminating Lake Michigan two miles from Milwaukee’s sewage outfalls, suggesting that the lake is not diluting the compounds as most scientists expected, according to new research.
“In a body of water like the Great Lakes, you’d expect dilution would kick in and decrease concentrations, and that was not the case here,” said Dana Kolpin, a U.S. Geological Survey research hydrologist based in Iowa.
It is not clear what, if any, effects the drugs are having on fish and other creatures in Lake Michigan. But this ability to travel and remain at relatively high concentrations means that aquatic life is exposed, so there could be “some serious near-shore impacts,” said Rebecca Klaper, an associate professor at the University of Wisconsin-Milwaukee and senior author of the study published in the journal Chemosphere.
In addition, Milwaukee draws its drinking water from Lake Michigan, although no pharmaceuticals have been detected in the city’s water, according to Milwaukee Water Works.
The scientists tested effluent from two sewage outfalls and water and sediment from Lake Michigan (up to two miles from the outfalls) for 54 chemicals used in pharmaceuticals and personal care products. Twenty-seven chemicals were found in the lake, with four found most frequently: an anti-diabetic drug called metformin, caffeine, the antibiotic sulfamethoxazole and triclosan, an antibacterial and antifungal compound found in some soaps, toothpastes and other consumer products.
“Wastewater treatment plants are simply not designed to remove these chemicals,”
Klaper said. “This tells us we shouldn’t assume that dilution solves the problem of putting these into the environment.”
Metformin was detected at the highest levels – up to 840 parts per trillion a mile from the outfalls, and up to 160 parts per trillion two miles away.
The researchers reported that 14 of the chemicals "were found to be of medium or high ecological risk" and that that concentrations found “indicate a significant threat to the health of the Great Lakes, particularly near shore organisms.”
“You’re not going to see fish die-offs [from pharmaceuticals], but subtle changes in how the fish eat and socialize that can have a big impact down the road,” said Kolpin, who did not participate in the study. “With behavior changes and endocrine disruption, reproduction and survival problems may not rear their ugly head for generations.”
There is a lot of research measuring pharmaceuticals in water, so “now we need to figure out what impact they may have,” Kolpin said.
“The problem is the effluent and water don’t have one compound but a chemical mixture soup,” Kolpin said. “It’s going to be hard to tease out which of these compounds may do harm” to people or fish.
Pharmaceutical and personal care product compounds are found in wastewater around the world. Studies have consistently found prescription drugs in drinking water at parts-per-trillion levels. U.S. Geological Survey scientists sampled 74 waterways used for drinking water in 25 states in 2008 and found 53 had one or more of the three dozen pharmaceuticals they were testing for in their water.
The compounds mostly get into sewage through people excreting them.