- Findings presented at the first major American symposium
on pharmaceuticals in water, held as part of the American Chemical Society's
spring national meeting in San Francisco last week, said that water pollution
by drugs "is a newly emerging issue," according to Christian
G. Daughton, a symposium co-organizer and chief of environmental chemistry
at the Environmental Protection Agency's National Exposure Research Laboratory
in Las Vegas.
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- EPA scientists examining the sludge from a U.S. sewage-treatment
plant 20 years ago found that the incoming sewage contained excreted aspirin,
caffeine, and nicotine. At about the same time, the cholesterol-lowering
drug clofibric acid turned up in a groundwater reservoir being used by
the Phoenix, AZ area. The drug had entered with treated sewage, which the
city had been using to replenish the aquifer. Experts at that time didn't
pay attention to the finding. It should have been a wake-up call, experts
now argue, because if clofibric acid could pass through a sewage-treatment
plant and percolate through soil unscathed, so could a host of other drugs.
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- Now new studies by Chris Metcalfe of Trent University
in Peterborough, Ontario, reports finding a broad mix of drugs, including
anticancer agents, psychiatric drugs, and anti-inflammatory compounds.
"Levels of prescription drugs that we have leaving sewage-treatment
plants in Canada are sometimes higher than what's being seen in Germany,"
he says.
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- He explains that many North American cities employ more
rudimentary sewage treatment than those in Germany. Daughton observes also
that some 1 million U.S. homes send their essentially untreated sewage
directly into the environment.
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- Two years ago, the symposium's other co-organizer, Thomas
A. Ternes, documented unexpectedly high concentrations of drugs "many
measured in parts per billion (ppb)" both in raw sewage and in water
leaving treatment plants in Germany. The chemist, who is at the Institute
for Water Research and Water Technology in Wiesbaden, Germany, now finds
that these drugs enter groundwater.
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- Sewage effluent can amount to at least half the water
in many of Germany's smaller rivers, he notes. Groundwater fed by streams
carrying relatively undiluted effluent can be tainted with 1 ppb carbamazepine,
an anticonvulsive drug. Ternes has also detected similar amounts of the
anti-inflammatory drug diclofenac and up to 2.4 ppb of iodine-based drugs
used to improve contrast in X rays.
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- Because people discard their excess drugs, the town dump
can also be a source of pharmaceutical pollution. Under one landfill, Ternes
found groundwater tainted with 12 ppb clofibric acid and 1 ppb phenazone,
an analgesic.
-
- The latter medication also turned up in groundwater "but
at far higher concentrations" under a leaking dump in Zagreb, Croatia,
notes Marijan Ahel of the Rudjer Boskovic Institute in Zagreb. Some of
his water samples had the drug at as much as 50 times the concentration
detected by Ternes. In the United States, federal scientists recently began
probing another source of drug pollution's large feedlots for livestock.
An estimated 40 percent of the antibiotics produced in the United States
is fed to livestock as growth enhancers. Geochemist Mike Meyer of the U.S.
Geological Survey in Raleigh, N.C., and his colleagues have begun looking
for antibiotics in hog-waste lagoons.
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- Three drugs frequently show up, one in concentrations
approaching 1 part per million. The same three antibiotics, which are also
prescribed for people, often appear in local waters, though usually only
at one-tenth to one-hundredth the concentrations in the lagoons, Meyer
notes. "So, it appears we're getting transport of these antibiotics
into surface and groundwater's," he told Science News.
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- His colleagues at the Centers for Disease Control and
Prevention in Atlanta have begun sampling bacteria from the tainted waters
to investigate their responses to the antibiotics present, Meyer says.
Their findings could begin to resolve a long-standing question: What is
the contribution, if any, of livestock to potentially dangerous reservoirs
of bacteria resistant to common antibiotics?
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- Traces of drugs are sometimes making it all the way into
tap water. Thomas Heberer of the Technical University of Berlin reported
finding traces of at least three pharmaceuticals in samples from his home
tap. The concentrations, however, were near the limits of detection, a
few parts per trillion. Moreover, he found that running this water through
an activated-carbon filter removes all vestiges of the drugs.
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- Ternes' studies confirm that two disinfection agents
"activated carbon and ozone'" which are used in many European
drinking-water plants, generally remove any traces of drugs. It's because
these relatively costly technologies aren't employed for treating sewage,
he notes, that a large share of the drugs flushed down toilets can reach
open waters.
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- To date, the symposium's scientists noted, few if any
toxicological studies have evaluated risks posed by chronic exposure to
trace concentrations of drugs. Most of the participants suspect, however,
that the biggest risks face aquatic life, which may be bathed from cradle
to grave in a solution of drugs of increasing concentration and potency.
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- David Epel of Stanford University's Hopkins Marine Station
in Pacific Grove, Calif., expressed special concern about new drugs called
efflux-pump inhibitors. Designed to keep microbes from ejecting the antibiotics
intended to slay them efflux-pump inhibitors also impede the cellular pumps
that nearly all animals use to get rid of toxicants, he says. If pump-inhibiting
drugs enter the aquatic environment, Epel worries that they might render
wildlife vulnerable to concentrations of pollution that had previously
been innocuous.
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- Organic Consumers Association - <http://www.purefood.orgHome
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