# 3797
Two and a half years ago, the subject of what happens to Tamiflu once it is excreted by the human body (in urine) graced these pages. The blog was called The Law of Unintended Consequences, and it looked a study conducted at the Centre for Ecology and Hydrology in Oxford, England.
Their findings were released in the January 2007 issue of Environmental Health Perspectives (EHP) in a report entitled, Potential Risks Associated with the Proposed Widespread Use of Tamiflu, that illustrated what might happen if millions of people simultaneously began taking Tamiflu and releasing it into our environment.
This whole idea came about once it was discovered that the active ingredient in Tamiflu, oseltamivir carboxylate (OC), was excreted more or less intact in the urine. This led to some early speculation that you could drink your own urine and make a limited supply of the medicine go further.
Thankfully, that idea never really caught on, and according to Dr. Michael Greger – writing in The Bird Flu Book - it wouldn’t have worked very well: “Tamiflu is altered by the liver such that urinated Tamiflu would not be readily re-absorbed by the intestine.”
It did make for some interesting pandemic chat room conversations back in 2005 and 2006!
But I digress . . .
The upshot of the modeling work done in 2006 was that scientists believed enough of the metabolite OC would be present in some rivers and streams, after sewage plant processing, to present a genuine risk. They recommended further study of this issue, and the investigation of ways to minimize the release of these metabolites into the ecosystem.
Fast forward 30 months, and a new study now finds significant oseltamivir carboxylate (OC) in tests of waste water in Japan, proving for the first time the theory offered by Oxford researchers.
Researchers worry that aquatic fowl, exposed to these runoffs, could be incubating drug resistant flu viruses.
This report from ScienceNews.org.
Excreted Tamiflu found in rivers
If birds hosting flu virus are exposed to the waterborne pollutant, they might develop drug-resistant strains, chemists worry
By Janet Raloff
Web edition : Wednesday, September 30th, 2009
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.
These elevated levels of OC were discovered during the normal 2008-09 flu season in and around Kyoto, Japan and do not reflect the higher uptake of Tamiflu we are likely to see this fall and winter.
Japan has, for many years, been the largest consumer of antivirals for seasonal flu and so it makes the ideal place to do this sort of field research.
While certainly a potential concern downstream (sorry, couldn’t resist), we don’t really have a good handle on how much OC would need to be dumped into the environment before we started seeing drug resistant viruses develop.
Unfortunately, this winter, with tens of millions of people expected to take and excrete Tamiflu . . . we may end taking part in a huge, real-time, lab experiment that will answer that question.
