San Diego — San Diego city water staffers have long been pushing the idea of "toilet-to-tap" water treatment, a controversial plan to convert raw sewage into drinking water using a high-tech filtering system. The program has never gotten far beyond a gleam in a public relations person's eye, though officials continue their efforts to revive it.

Backers claim the treated water would be safe to drink, but some experts say it would be virtually impossible for any filtration system to remove deadly viruses and synthetic hormone molecules. Now there is another argument over a certain ingredient of San Diego's sewage, and this time it comes courtesy of the Bush administration's Office of National Drug Control Policy (ONDCP).

In September, Christopher Williamson, a Navy lieutenant commander and policy analyst with the White House drug office, contacted Alan Langworthy, deputy director of San Diego's Metropolitan Wastewater Department, seeking a favor. "He asked if we would be willing to provide composite samples of the wastewater entering our treatment plants for their use in analyzing them for cocaine," according to a September 8 e-mail from Langworthy to the office of Mayor Jerry Sanders obtained from the City under the California Public Records Act.

The White House was curious to know just how much coke ingested by illicit users in San Diego found its way into the city's sewers, wrote Langworthy. "Once completed, the results will provide leaders with a better understanding of the scope of illicit drug consumption within their communities, justifying the expenditure of resources necessary to treat and improve those impacted."

San Diego was not alone, he said. "Since March 2006, ONDCP has led an effort to collect wastewater samples from regional facilities to develop a protocol for estimating national cocaine consumption," the e-mail said. "Over 34 municipal facilities volunteered to participate, providing over 160 samples. From these samples, researchers were able to assess metabolite concentrations and derive an estimate for regional consumption.

"The methodology does not target any specific individual, class of persons, or neighborhood; rather it provides a mechanism to pulse the community to identify trends.

"It is the intent of the ONDCP to honor the privacy of all participants and not to disclose individual participation or results during the validation process," the e-mail said. "ONDCP is conducting this research under the authority...granted by their congressional reauthorization, with assistance and support of other governmental organizations.

"Our participation would provide a wealth of knowledge in developing national protocols and validating the research objectives. I could easily accommodate their request."

Despite Langworthy's reassurances, his memo triggered worry in at least one mayoral staffer. Sanders press secretary Fred Sainz sent a copy of the White House request to mayoral policy director Julie Dubick with a warning. "I think this is ripe (no pun intended) with civil liberty issues," wrote Sainz. "CAUTION!!!"

The White House drug office didn't return repeated phone calls asking for more information about the status of the study or why San Diego was to be included.

Contacted by phone last week, Langworthy said he needed to get permission to discuss the project's status and that he would call back; he never did.

Langworthy's public relations staffer subsequently called to say he would look into the matter; he never called back.

In spite of the hush-hush atmosphere surrounding the project, the story broke briefly in Washington, D.C. Testing has already been done in nearby Fairfax County, Virginia, where county officials readily agreed to the program last spring, though there were skeptics. "It's a very strange request," board of supervisors chairman Gerald E. Connolly, a Democrat, told the Washington Post in March. "We're ready to do anything and everything we can do to eliminate illicit drug use. But I'd want to know a lot more about what this will actually lead to."

The County reportedly took five days' worth of samples in mid-March and shipped them off to the Armed Forces Institute of Pathology in Rockville, Maryland, to be analyzed for benzoylecgonine, the chief metabolic product of cocaine found in urine. No results were announced.

David Murray, special assistant to national drug czar John P. Walters, would not tell the Post the identities of other cities and counties testing for cocaine. "We think it will be very, very useful," Murray would only say about the testing program.

The Post reported that the White House study was inspired by a similar effort last year in Italy. There, according to an August 2005 report in the London Times, Ettore Zuccato of the Mario Negri Institute for Pharmacological Research in Milan tested water from the Po River in the northern part of the country and discovered that it was carrying the equivalent of 4 kilograms a day of the drug.

Put another way, Zuccato concluded from that result that 30 out of 1000 young adults must have been doing 100 milligrams of coke each day, much greater than previous estimates.

"The economic impact of trafficking such a large amount of cocaine would be staggering," Zuccato told the Times. "The large amount of cocaine -- at least 1,500kg -- that our findings suggest is consumed per year in the River Po basin would amount, in fact, to about $150 million in street value, based on an average US street value of $100 per gram."

The Italians said they hoped others would adopt their methods. "The approach tested here, which is in principle adaptable to other illicit drugs, could be refined and validated to become a general, rapid method to help estimate drug abuse at the local level," Zuccato and his associates wrote in an article published in the journal Environmental Health.

"With its unique ability to monitor changing habits in real time, it could be helpful to social scientists and authorities for continuously updating the appraisal of drug abuse."