Tamiflu in afvalwater

[Cees Binkhorst]

REPLY TO: D66 at nic.surfnet.nl

Hetzelfde moet bij ons toch ook wel lukken met een paar miljoen doses?

Groet / Cees

http://www.usnews.com/articles/science/2009/10/01/tamiflu-the-primary-flu-fighting-drug-found-in-rivers.html
Tamiflu, the Primary Flu-Fighting Drug, Found in Rivers
Birds hosting flu virus could develop drug-resistant strains if exposed to
the waterborne pollutant
Posted October 1, 2009

By Janet Raloff, Science News

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
Tamiflu.

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 influenza.”

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 Nashville, Tenn.

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.”

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