Troubled Water

Health / by Josh Braun /

How do trace amounts of pharmaceuticals in the water affect our bodies?

troubledh2o.jpg Jimmy Turrell

The Associated Press recently announced, after a five-month inquiry, that researchers have found trace amounts of prescription drugs in the drinking water supplies of at least 41 million Americans. Scientists have known for years that the drugs we swallow end up in our drinking water, but whether these small concentrations—in the parts per billion or trillion range—can cause harm over long periods of time or in combination with other drugs is still a very open question.

In the 1970s, a few scientists began speculating on a potential environmental problem. They realized that oral medications—pills, capsules, tablets, and so on—are inefficient methods of administering drugs to the body. By comparison with an IV or an injection, it takes a lot of drug administered orally to get just a little into the bloodstream. The rest of the medicine goes right through the body and is passed into wastewater in urine and solid waste. Since water and waste treatment plants have never been designed to remove pharmaceuticals, it was likely, posited researchers, that the contents of our medicine cabinets were being passed on directly into the environment, and eventually into the water supply.

But it wasn’t until the late 1990s that the equipment became available that could cheaply and easily test for these chemicals in the environment. “It still takes specialized equipment,” says Dana Kolpin, an expert on emerging contaminants at the US Geological Survey. “Not every lab is set up to analyze for these compounds. But in reality they’ve probably been out there as long as we’ve been using pharmaceutical products.”

Large-scale studies of pharmaceutical environmental contaminants began in Europe in the mid-1990s, spurred on by an active environmental movement. In North America similar studies lagged, with the USGS launching its first large-scale survey in 2002. By now it’s clear that if it’s a pill you can pop, it’s probably ending up in the environment. 

Surveys of US waterways have so far have identified the presence of over 80 compounds from drugs including painkillers, blood-pressure and heart medications, birth control pills, anti-fungal agents, antidepressants, caffeine, erectile dysfunction tablets, anti-seizure medications, steroids, nicotine byproducts, and antibiotics.

It’s clear that the drugs are playing a role in the environment. Hormones in the water skew the sex ratios of fish and amphibians that lay eggs in rivers and streams. And antibiotics may alter the natural balances of microbial flora and fauna in different ecosystems, with unforeseen effects.

Studies on drugs in the environment have at times raised hackles among the public, a prime example being the controversy in the late 1990s over whether environmental estrogen stemming from the release of the birth control pill in wastewater, among other sources, could be contributing to previously mysterious phenomena such as dropping rates of male fertility and the increasingly early onset of puberty in women.

Ultimately, though, many scientists point to the fact that all these pharmaceutical contaminants are present only in trace amounts. A 2005 joint USGS-CDC study which found the anti-seizure medication carbamazepine in a stream, for instance, noted that a person would have to drink two liters of stream water daily for 70 years to get even a tenth of a therapeutic dose of the medication.

But merely pointing to low drug concentrations doesn’t allay the concerns of a growing number of researchers. On the contrary, it deepens several mysteries as to the ultimate effect of pharmaceutical contaminants on the environment and on people.

First of all, FDA studies are geared toward determining the effects of therapeutic doses of a drug over a short period of time. Clinical trials are not designed to tell researchers the effects of taking subtherapeutic doses of a drug over a lifetime, and no one knows how extensive these might be. Additionally, in some cases such contaminants may become more concentrated as they move up the food chain—so we may be consuming more of the chemicals than we think.

Second, even if no particular drug is present in high enough concentration to have adverse effects by itself, the interaction between the veritable cocktail of medications present at subtherapeutic levels may add up to pack a punch.

Finally, low levels of antibiotics in the environment may be contributing to increasing rates of antibiotic resistance among bacteria, with potentially deadly consequences.

Researchers are just beginning to understand the complexity of these puzzles. Making headway in solving them will prove even more difficult.

“It’s all extremely complicated,” says Kolpin. “We don’t want to sensationalize the data or try to scare people. But frankly we don’t know yet what these trace amounts mean.”

Originally published March 10, 2008

Tags climate medicine policy water

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