Drugs Found in Tap Water
Teen finds antibiotics in public supplies
By Kathleen Fackelmann, USA TODAY
High school student Ashley Mulroy was reading a science magazine two years ago when she learned that European scientists had made a disturbing discovery: Drugs of all kinds, including antibiotics, were flowing in rivers, streams, groundwater and even in tap water.
That began a science project in which the 17-year-old searched for and found antibiotics in the Ohio River. She also found those drugs in the drinking water in her hometown of Wheeling, W.Va. She is one of the first in the USA to look for such drugs in the nation's drinking water supply. Mulroy's work recently won the Stockholm Junior Water Prize, an international science competition sponsored by ITT Industries. More important, her study highlights an emerging scientific issue with alarming implications.
Some experts fear that even low levels of antibiotics fouling the nation's water supply may help create superbugs: microorganisms that have evolved to survive an antibiotic's lethal assault. Public health experts already have noted the rise of infection after infection that cannot be stopped with the usual arsenal of antibiotics.
And the superbugs may be causing "tens of thousands" of deaths in the USA each year, says Abigail Salyers, an expert on antibiotic resistance at the University of Illinois at Urbana-Champaign.
Consider these reports:
U.S. Environmental Protection Agency researchers have found antibiotics in North Carolina's Neuse River, a source of drinking water.
Another EPA chemist reports finding several drugs, including a common antibiotic, in river water outside a southern U.S. city.
Scientists at the U.S. Geological Survey have found antibiotics in many water samples taken from streams across the nation.
These findings "raise a big red flag," says Stuart Levy at Tufts University in Boston. The antibiotics aren't harmful on their own. Rather, Levy and others worry that waters laced with these drugs could breed bugs that can shrug off the killing effects of the wonder drugs, such as penicillin.
Mulroy's science project got started after she read "Drugged Waters," a 1998 article in Science News that gave a chilling account of the drugs, including antibiotics, floating in European waters. "I remember thinking the story had really bad implications," Mulroy says. So she decided to test for antibiotics in the Ohio River near her home. Over a 10-week period, Mulroy and her mom got into the family car and drove for miles to test sites along the Ohio River.
In the end, she got her river water samples back to the Linsly School, a private school that she attended in Wheeling . She looked for three common antibiotics: penicillin, tetracycline and vancomycin. She found all three drugs in low concentrations (parts per trillion) in the Ohio River. Water samples taken from sites near livestock or dairy farms had the highest concentrations of antibiotics, Mulroy says. Large farming operations in the USA often keep hogs, chickens and other animals in crowded, dirty pens and rely on low doses of antibiotics to keep diseases at bay. Antibiotics also are given to healthy animals to fatten them for market.
Scientists know that antibiotics given to animals (or to humans) don't get fully metabolized in the digestive system and end up being excreted. In a farming operation, that waste can make it into the runoff or groundwater, which eventually makes it into a nearby stream, and in this case, the Ohio River.
River samples taken near local hospitals also revealed antibiotics, albeit at slightly lower concentrations, Mulroy says. Antibiotics may leach into the groundwater around hospitals if cases or bottles of expired drugs are dumped into a landfill, she says. Do such drugs get into water flowing out of the kitchen tap? Mulroy's study suggests that they do. Mulroy also took samples of water from three taps in Wheeling, Moundsville and Procter. All three, including water from the drinking fountain at her school, were contaminated with the antibiotics in question. The concentrations were less than those found in the river water, she says. Water flowing from the Wheeling tap comes from a municipal water-treatment facility that relies on sand filtration to clean the water. That method, the primary method of water treatment in the USA, doesn't remove antibiotics or other drugs from the water.
The other two samples of public water came from wells. The fact that they also had antibiotics suggests that groundwater is contaminated, Mulroy says.
However, Mulroy's study also suggests a potential fix for waters laced with drugs such as antibiotics. She says that an activated charcoal filtration system removed most of the antibiotics in the tap water.
The USA produces more than 50 million pounds of antibiotics each year. Experts estimate that 60% are used to treat humans. The other 40% go to farming operations. New research suggests that the latter doesn't stay on the farm.
Joseph Bumgarner at the EPA, Michael Meyer at the U.S. Geological Survey and their colleagues have identified antibiotic contamination of surface water near two North Carolina hog farms. Such farms, which often keep 50,000 animals in close quarters, create huge pools of manure called "lagoons." These hogs routinely receive doses of antibiotics, including chlortetracycline, lincomycin and sulfamethiazine. Sure enough, the team found those three antibiotics in the lagoons and in samples from nearby streams, which empty into the Neuse River. The river water samples also contained the antibiotics, Bumgarner says. The Neuse River supplies the Raleigh-Durham area with its public water. The researchers have yet to test the tap water there.
The team did find an antibiotic flowing from a tap on one of the hog farms. That tap drew its water from a well, a finding that suggests groundwater is laced with the drugs, Meyer says. Preliminary results from this study also suggest that bacteria in the streams have acquired resistance to common antibiotics, Bumgarner says. Studies on a hog farm in Iowa and a chicken farm in Ohio produced similar results, Meyer says. Some experts, including Karen Florini of the Environmental Defense in Washington, D.C., are urging the Food and Drug Administration to ban the use of antibiotics to speed the growth of farm animals.
Recently, the FDA took a step in that direction by announcing its intent to ban two antibiotics used by poultry farmers. Florini's group and others also are calling on EPA to control the pollution in runoff from factory-farming operations. But EPA's Bumgarner says the agency doesn't have enough information to take such a step.
Human waste also contains antibiotics, and instead of going into a lagoon, it gets flushed down the toilet. EPA chemist Tammy Jones-Lepp wanted to find out whether the antibiotics in sewage would survive a wastewater-treatment facility.
Jones-Lepp collected water downstream from two such facilities in an unnamed southern city. She found that the treated river water contained low levels of azithromycin, an antibiotic often prescribed to children for ear infections. The results suggest that treatment plants, although they filter out some contaminants, don't remove all traces of drugs such as antibiotics.
Effects still unknown
"It's clear antibiotics get into the environment," says Tamar Barlam, director of the Antibiotic Resistance Project at the Center for Science in the Public Interest in Washington, D.C. But scientists have yet to determine the impact of such contamination on human health, especially when the antibiotics, and other drugs, are present at minute levels, she says David Bell at the Centers for Disease Control and Prevention in Atlanta says there's not enough scientific data to say that environmental contamination plays a big role in generating antibiotic resistance. Far more important, he says, is the fact that humans have abused antibiotics by taking them unnecessarily. The overuse of antibiotics by the agricultural industry also plays a big role in creating superbugs, Bell says.
Farmers who feed healthy animals a steady stream of antibiotics can set the stage for human illness in this way: Bacteria in the digestive system of the animal can develop resistance to antibiotics. Humans who then eat undercooked meat from the infected animal can suffer an infection one that can't be treated with that antibiotic, Bell says Levy and others would argue that environmental contamination might pose a more serious problem than previously recognized. Levy says those relatively harmless bugs, like the E. coli in Mulroy's study, can develop genetic traits to repel antibiotics. Once they have that genetic ammunition, they can trade the information to other bugs relatively easily, he says.
That means that a bug that doesn't cause human disease could pass along its genetic trick to a bug that does. The result, Levy worries, would be a bacterium that has evolved the capability to do an end-run around the most powerful drugs of the modern century.
The USA lags about a decade behind researchers in Europe who have found antibiotics and many other drugs in the waters there. Indeed, Mulroy's study is one of the first to look at the public water supply in the USA.
Although other scientists must confirm her study, Mulroy has contributed something important to the field.
"This really is a testimony to our kids," Levy says.