Some Council members were upset to learn from an Associated Press investigation, instead of the Philadelphia Water Department, that the city's water supply carries minute concentrations of many pharmaceuticals.
Water officials will arrive at the hearing bearing corrected test results, saying that their department accidentally inflated the number of detected pharmaceuticals when it first released data to the AP earlier this year. The department made another correction to its corrections in a follow-up statement to the AP on Friday.
The changes now put the number of pharmaceuticals or their byproducts found in the city's drinking water at 17, instead of 56; and 32 in its watershed, instead of 63. A department spokesman, Ed Grusheski, said the mistakes occurred during the preparation of a spreadsheet.
The first numbers appeared March 10-12 in an AP investigative series based on survey responses from the Philadelphia Water Department, along with information from other water providers around the country.
Even with the downward revisions, more drugs turned up in Philadelphia than in any of the 24 major metropolitan areas where detections were reported in drinking water.
On Friday, the department made its second correction to the number of pharmaceuticals tested for. It first told the AP that 73 pharmaceuticals had been screened for in its drinking water and watershed; it recently said the correct number was 70. In its latest statement Friday, in response to an AP request for clarification on all of its corrections, department officials said the actual number was 75.
The department was besieged with calls from alarmed residents in the days following the AP's disclosure that pharmaceuticals had turned up in the drinking water systems of at least 41 million Americans, including those in Philadelphia.
The AP also reported that water utilities, including Philadelphia's, rarely inform the public when drug traces are found.
To be sure, the drug concentrations in the drinking water for Philadelphia, and elsewhere, are minute, typically in parts per billion. Any risk is poorly understood. Drug companies, water utilities, and some scientists say any risk to humans is probably negligible, but they acknowledge that much is unknown.
The Philadelphia Water Department says that a resident would need to drink eight glasses of water daily for at least 40,000 years to acquire a medical dose of acetaminophen, a non-prescription pain reliever found in the city's water.
However, because drugs are designed to impact the human body, some scientists believe that even these tiny amounts may cause harm over decades, especially in combination with other drugs. Scientific studies indicate that some drugs, including sex hormones and psychiatric drugs, can harm aquatic species. A smaller, emerging body of research suggests that tiny concentrations of some drugs can interfere with functions in human cells.
Laura Copeland, a city water spokeswoman, said Friday that her department had nothing to add to its views about the potential risk. In past statements, it has characterized its water as safe and high-quality.
In its series, the AP reported that a vast array of pharmaceuticals have been found in water supplies across the nation - including antibiotics, anti-convulsants, mood stabilizers and sex hormones.
The residues come largely from ordinary people who take medications. Their bodies absorb some, but the rest is excreted. Traces of veterinary drugs also are released in farm runoff. Ordinary treatments of wastewater and drinking water do not remove all pharmaceutical residues.
Philadelphia draws its drinking water from the Delaware and Schuylkill rivers, which travel past many populated areas on their way to the city. So far, the federal government has set no national standards for how much of any pharmaceutical is too much in waterways or taps.
