[Pharmwaste] excrete Tamiflu found in rivers
Laurie.Tenace at dep.state.fl.us
Thu Oct 1 07:39:54 EDT 2009
Excreted Tamiflu found in rivers
If birds hosting flu virus are exposed to the waterborne pollutant, they
might develop drug-resistant strains, chemists worryBy Janet Raloff
The premier flu-fighting drug is contaminating rivers downstream of
sewage-treatment facilities, researchers in Japan confirm. The source:
urinary excretion by people taking oseltamivir phosphate, best known as
Concerns are now building that birds, which are natural influenza carriers,
are being exposed to waterborne residues of Tamiflu's active form and might
develop and spread drug-resistant strains of seasonal and avian flu.
For their new study, Gopal Ghosh and his colleagues at Kyoto University
sampled water discharged from three local sewage treatment plants and water
at several points along two rivers into which the treated water flowed.
Sampling started early in December 2008, as flu season got underway. The
researchers sampled again at the height of the seasonal flu's onslaught in
early February and again as infection rates waned.
Tamiflu's active form, oseltamivir carboxylate or OC, turned up in the
treated sewage on every occasion, the researchers report online September 28
in Environmental Health Perspectives. Values were in the low nanograms per
liter range during the first and last samplings, and reached a high of almost
300 ng/L at one outflow during the flu's peak, a week when there were 1,738
recorded flu cases in Kyoto.
River residues showed up during only that second sampling - from low nanogram
levels at most sampling points to a high of 190 ng/L in a portion of the
Nishitakase River where treated sewage accounts for 90 percent of the flow.
Computer modeling has shown that OC should survive sewage treatment, notes
Wolf von Tümpling Jr. of the Helmholtz Center for Environmental Research, a
federal institute in Magdeburg, Germany. Ghosh's team is now the first to
confirm this, he says. Von Tümpling's own data show that once exposed to
sunlight, OC will break down, albeit slowly. Concentrations would fall at
best by half every three weeks, he says.
If correlations predicted by earlier studies are correct, concentrations
measured at some river sites in the new Kyoto study seem "high enough to lead
to antiviral resistance in waterfowl," Ghosh says.
And the Kyoto team didn't test during a pandemic, when Tamiflu prescription
rates might be 10 times higher, von Tümpling notes.
Indeed, the expected coincident hits by seasonal and H1N1 swine flu this
winter, could send Tamiflu use skyrocketing. In a July 14 letter, Food and
Drug Administration deputy commissioner Joshua Sharfstein noted that "there
is no adequate, approved and available alternative to the emergency use of
certain oseltamivir phosphate products for the treatment and prophylaxis of
Once ingested, virtually all Tamiflu will end up in the environment in the
active form, notes environmental chemist Jerker Fick of Umeå University in
Sweden. The reason: Tamiflu becomes active once the body converts it into a
carboxylate form. Roughly 80 percent of an ingested dose becomes this OC,
which the body eventually excretes. The body sheds the remaining 20 percent
of Tamiflu in its original form, but this phosphate form is immediately
turned into the active, carboxylate form when it reaches a water treatment
plant, he says.
Two years ago, Fick's team published data showing that most sewage-treatment
technologies will remove "zero percent" of any OC present. And ducks love
hanging out around warm, nutrient-rich outflows of treated water during
winter-flu season. While sampling for waterborne OC last year in Japan, "I
saw it myself," he says.
If Tamiflu resistance does develop in exposed birds, the affected flu strains
will probably be conventional seasonal and avian flu strains, which claim
thousands of lives each year, and not H1N1. That's because H1N1 seems to
bypass birds as it spreads among people, notes William Schaffner, chair of
preventive medicine at the Vanderbilt University School of Medicine in
He also notes that U.S. policy is more conservative than Japan's when it
comes to Tamiflu use. Federal guidelines, he says, recommend that "Tamiflu be
reserved for treatment of the very sick and anyone who is immunocompromised."
Waste Reduction Section
Florida Department of Environmental Protection
2600 Blair Stone Rd., MS 4555
Tallahassee FL 32399-2400
Laurie.Tenace at dep.state.fl.us
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