By Sally Squires
Washington Post Staff Writer
Thursday, March 13, 2008
Several experts said this week that there is no need for people to alter their water-drinking habits for now, despite a journalistic investigation that found trace amounts of numerous pharmaceuticals, from prescription drugs to hormones, in tap water in 25 of 28 cities tested, including the District.
Members of Congress, however, called for hearings on the safety of drinking water. Sens. Barbara Boxer (D-Calif.) and Frank Lautenberg (D-N.J.) said that committees they chair will hold oversight hearings in April.
Scientists said they, too, are concerned about the findings of the water testing commissioned by the Associated Press, but several said that there is no need for people to stop drinking tap water.
The contaminants present are "in the parts-per-billion level and essentially at homeopathic doses," said Phyllis Gardner, a Stanford University physician and pharmacologist. "It can't possibly have an effect."
The fact that the substances are in tap water at all concerns Gardner and others. "I wish they weren't there," said Mary Vore, a professor of toxicology at the University of Kentucky. "But I will keep drinking the water."
Vore likened detection of the contaminants to miners using a canary to indicate the presence of toxic gases in a mine. "The amounts that we are getting are small," she said. "The canary hasn't passed out yet." But she and others urged continued monitoring "to make sure that the concentrations don't get too high."
The wire service reported that water tested in the District contained trace amounts of six contaminants, including caffeine; the over-the-counter painkiller ibuprofen; a mood stabilizer, carbamazepine; and the antibiotic sulfamethoxazole, used to treat urinary infections in people. Substances from hormones to antibiotics to naproxen, better known as Aleve, were found in very tiny amounts in about 20 other locations.
"The antibiotics are what worry me the most," Gardner said, noting that over time their presence could help fuel the growing antibiotic resistance in a host of microbes, including methicillin-resistant staphylococcus (MRSA) to the bacterium that causes tuberculosis.
The discovery of contaminants in tap water reflects the growing use of the medications in both people and animals, including livestock and pets. It also reflects the increasing sensitivity of testing technology.
"We are becoming more and more expert in being able to detect lower and lower levels of whatever you want to measure," said Terrence Monks, head of the department of pharmacology and toxicology at the University of Arizona's College of Pharmacy. "So it's not surprising that we are detecting these comparatively low levels, given the increased pharmaceutical usage over the past decades."
Boiling water does not remove pharmaceutical contaminants and can even concentrate them, but some home filtering systems may remove a few of them, specialists noted. So can reverse osmosis, a process often used by laboratories, hospitals and some bottled water producers to produce purified water.
The process can be adjusted to remove molecules "the size of most antibiotics, a lot of our antidepressants and most of the pharmaceutical agents that were found," said Stephen Edberg, of Yale University. He is a consultant to the International Bottled Water Association.
Reverse osmosis costs more than traditional water treatment. Even so, some municipal water systems, including the one in Dunedin, Fla., are already using the process to produce potable water.
"My gut feeling at this point is that the levels that are presently there . . . are likely to have precious little effect," Monks said. "But there has been so little work on the presence of multiple pharmaceuticals that even at these low levels, I would like to hedge my bets."