Hard to swallow

Do tiny quantities of drugs in drinking water pose a threat to human health?

By Chris Lydgate

Pamplin Media Group, Jul 8, 2008, Updated Oct 30, 2009 (11 Reader comments)

One of the most unpalatable environmental stories of the year landed with an alarming splash in March, when The Associated Press reported that water supplies across America are contaminated by trace amounts of pharmaceuticals.

Drugs detected in tap water range from mood stabilizers in Southern California to anticonvulsants in New York City to sex hormones in San Francisco. Altogether more than 100 different compounds have been found in water supplies serving 41 million people, albeit in exceedingly small quantities.

The AP report came in the wake of several scientific studies showing that America’s reservoirs, rivers and lakes are increasingly contaminated with tiny doses of unwelcome pollutants such as steroids, insect repellent, detergents and plasticizers.

Unfortunately, we are not immune. Last week, officials with the Portland Water Bureau told Sustainable Life that inspectors detected extremely minute quantities of two hormones in groundwater samples; previous tests of Portland water found trace amounts of caffeine and pain relievers.

At first glance, the appearance of drugs in the water supply seems the perfect example of how modern technology is driving the planet’s ecosystems to the breaking point.

“There’s widespread concern,” says Dr. Ilene Ruhoy, a Nevada physician and environmental scientist who has researched the issue for the Environmental Protection Agency. “We’ve got to look at this further.”

Ruhoy (who comes to Portland next week to present a lecture titled, “Drugs in the Water: How our Medicine Cabinets are Contaminating Nature”) is one of a swelling tide of scientists looking at the proliferation of “emerging contaminants” such as pharmaceutical compounds and personal care products in the environment.

But many experts say there is no evidence that such minuscule traces pose any threat to human health.

First, they point out, the contaminants are being detected at extraordinarily minute levels — levels that bankrupt the imagination. For example, the highest concentration of any pharmaceutical ever found in Portland’s water supply was acetaminophen, the active ingredient in Tylenol, which was detected last year at 18 parts per trillion.

To ingest the equivalent of two Tylenol pills, you’d have to drink 10 gallons of water a day, every day, for 4,021 years.

“It shouldn’t be dismissed,” says David Shaff, administrator of the city’s water bureau. “But it’s a very, very, tiny, tiny amount.”

Even at the highest levels detected, and even with the strictest margin of safety, the pharmaceutical compounds so far discovered in drinking water stand at concentrations thousands of times below the therapeutic dose.

In a study published in January in the journal Ozone: Science & Engineering, for example, toxicologist Shane Snyder, research and development product manager for the Southern Nevada Water Authority, tested water samples from 20 cities across the country.

The most concentrated pharmaceutical he could find was the sedative meprobamate, which has been shown to be toxic in mice; the acceptable daily intake is a mere 180 parts per billion.

However, the highest concentration of meprobamate measured by Snyder stood at the level of 42 parts per trillion. To approach the margin of safety, you’d have to drink more than 4,000 glasses of water a day.

“From all the data we have in front of us now, we don’t see any impacts on human health from these extremely minute quantities,” Snyder told Sustainable Life.

Experts say that pharmaceuticals now are cropping up in water supplies not because pollution is getting worse, but because tests are getting better.

“In the ’50s and ’60s, we could detect pharmaceuticals in parts per million,” says chemist Andrew Eaton, laboratory director of Montgomery Watson Harza Laboratories in Monrovia, Calif. “In the ’70s and ’80s, parts per billion. Starting in this decade, we went to parts per trillion, and now we’re pushing it lower and lower.”

The technical advances mean that chemists now can find contaminants in water that previously would have been considered pure.

Snyder compares the development of better water testing to the evolution of the telescope. “In the early 19th century, telescopes could only pick out a few thousand stars,” he says. “Now Hubble can see billions. But it doesn’t mean they weren’t there before.”

A drop in 10,000 buckets

Portland’s water comes from two sources. The main supply is Bull Run, a remote chunk of wilderness on the flank of Mount Hood that feeds a system of rivers, lakes and reservoirs stretching for 102 square miles.

Most of the time, the water bureau relies on Bull Run alone, but during severe storms or summer drought it also can draw groundwater from wells fed by underground aquifers.

The first hint that pharmaceuticals might be seeping into Portland’s drinking water came in August 2006, when an untreated sample from Bull Run water showed caffeine at 9.2 parts per trillion.

Subsequent tests of the groundwater revealed caffeine, acetaminophen, ibuprofen and sulfamethoxazole.

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