A recently released Associated Press investigation found traces of six pharmaceutical drugs in D.C.’s drinking water, though experts disagree on the effects these drugs may have on consumers.

Caffeine, ibuprofen, carbamazepine (an anticonvulsant and mood stabilizer), naproxen (an anti-inflammatory drug) and the antibiotics monensin and sulfamethoxazole – were all found in samples of the District’s drinking water. The AP report did not specify the concentrations of these drugs in the water samples but said that they were “tiny” and best expressed in parts per billion or parts per trillion.

The report stated that “recent studies . have found alarming effects on human cells and wildlife” resulting from long-term exposure to trace levels of pharmaceuticals. However, officials disagree on the long-term effects the drugs can have.

Tom Jacobus, general manager of the Washington Aqueduct – which supplies drinking water for the District and parts of northern Virginia – said the pharmaceuticals pose no threat to D.C. residents and visitors.

“The ability to measure these tiny amounts is scientifically very useful information, but there is no connection between these tiny concentrations and any human health effects,” Jacobus said. “I think the public should not become concerned about these trace amounts.”

Sorell Schwartz, professor emeritus of pharmacology at the Georgetown University Medical Center, agreed that the chemicals pose little threat to District residents.

“A dose of 10 milligrams of any of the drugs [found in the District’s water] . would probably be marginally active in a baby. If the concentration is one part per billion . that baby would have to have 10,000 liters of water to have that dose,” he said. “The dilution factor is so high here, if it is in parts per billion or parts per trillion, you’re not dealing with anything that portends a public health problem.”

But David Carpenter, professor emeritus of environmental health and toxicology at SUNY Albany, said that even the low level of pharmaceuticals in the water can be harmful.

“There’s increasing evidence that very low concentrations [of drugs] can have effects,” he said. “While there may be no proof that these would have a [harmful] effect on people, there’s certainly no evidence that they’re safe.”

Carpenter said that exposure to low doses of antibiotics could cause someone to build up resistance to antibiotics and that traces of estrogenic compounds like birth control pills could cause decreases in sperm count, deformation of genitalia and even “perturbation of sexual preference” in the children of pregnant mothers who drink contaminated water.

Jacobus said that D.C. residents can help limit the concentrations of pharmaceuticals in their water.

“I think that everyone should take a look at what they do with their medications, not flush them down the toilet so they go back [into treatment plants],” he said.

While disposal of medication through the sink or the toilet accounts for some of the drug content in the District’s water supply, Schwartz said pharmaceuticals most often enter the water as traces in human waste.

“Water comes from sewage, sewage contains urine and urine contains drugs,” he said.

Carpenter said that water suppliers and government authorities need to establish more rigorous standards for water filtration.

“One can remove a lot of these drugs by just having activated charcoal filters on the municipal water supplies,” he said.

Carpenter said that many treatment plants already have this capability but choose not to use it because of the expense entailed.

Schwartz said that AP’s recent detection of the pharmaceuticals in D.C. water may be a result of an improved analysis process at water treatment plants instead of increased chemical content.

“This looks like more of an accomplishment in detection than it does in something being done wrong with the water,” he said.

The D.C. area was among 24 major metropolitan areas whose drinking water supplies contain traces of pharmaceuticals, according to the results of a five-month AP investigation released on Sunday.

Of the six chemicals found in the District’s drinking water, Jacobus said that the Washington Aqueduct tests only for caffeine. He said that all six compounds are classified as “personal care and pharmaceuticals” by the Environmental Protection Agency. The EPA does not regulate the amount of compounds from this category in public drinking water.

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