Drugs in drinking water: Do we need to care?

McClatchy NewspapersApril 11, 2008 

MBR

Bottled water for sale.

MICHAEL TERCHA — Michael Tercha / Chicago Tribune / MCT

WASHINGTON — Lots of people lunged for bottled water after they were told last month that tap water in many U.S. cities contains traces of pharmaceuticals.

"They wanted 5-gallon bottles, half-liter cases, anything that wasn't municipal water," said Jennifer Brandon, who was taking phone orders for home-delivered Deer Park water the day the Associated Press story broke.

Benjamin Grumbles, the Environmental Protection Agency's assistant administrator for water, sought to cool the furor at a Senate water-quality subcommittee hearing Tuesday. Grumbles blamed "alarmist headlines" and said that "emerging contaminants are exactly that." There's insufficient evidence, he said, to suggest that the contaminants present a "clear and present danger" to humans.

Many water-quality researchers who work on pharmaceutical contaminants share Grumbles' lack of concern. They continue to drink local tap or well water, a half-dozen of them told McClatchy.

For one thing, they know that bottled water is less regulated than municipal supplies are. The big reason, however, is that researchers are less anxious than senators and a public jolted by another new environmental scare for which risk and remedy are unknown.

Goodness knows, there are lots of reasons to worry about the safety of drinking water.

Contaminants now commonly found in drinking water include tiny traces of pesticides, herbicides, flame retardants, DEET, mosquito repellant, aircraft de-icers, lead, arsenic, mercury and esters, ketones and other chemicals found in personal care products. Not to mention additives in toothpaste meant to retard gum and tooth disease.

The unending list of contaminants in water and elsewhere — now often called "micro-constituents" to scrub off the old word's onus — is a growing public burden. Asked whether they faced more health risks than past generations, majorities of Americans polled in 1980 said yes. Asked a similar question in 2003, they said yes again.

So why are experts relatively unfazed? Here are six reasons:

_ Improved detection technology means that we're concerned about levels of contamination that were undetectable in years past.

In the 1970s, the best detection technology picked up compounds at concentrations of one part per million. Today, concentrations of one part per trillion or even quadrillion are detectable.

With each zero of added sensitivity, "myriads of other chemicals are evident," in water, said Christian Daughton, a research scientist at the Environmental Protection Agency's National Exposure Research Laboratory in Las Vegas. Among them are many of the drugs now reported in drinking water.

Given today's levels of detection, Daughton continued, what we consider to be clean drinking water resembles "a chemical sea of human-made chemicals and chemicals manufactured by the environment."

That's alarming to a public whose definition of a trace hasn't changed since the 1970s and whose ideal, Daughton said, remains "pure" water. "It's a tremendous problem when you're interpreting risk for the public." he said.

What causes his problem, however, is an unjustified worry. As Greg Kail, spokesman for the American Water Works Association in Denver, put it: "Just because you get a bigger telescope, that doesn't mean there are more stars in the sky. And better detection in water doesn't mean that the risk has increased."

_ Even poisons aren't always toxic.

Toxicology's most basic principle, researchers explained, is the maxim that "the dose makes the poison." One margarita is fine for most people, in other words, but 10 could be fatal, depending on vulnerability and timing.

Toxicologists apply this principle to all poisons, but the public doesn't, according to a landmark 1991 study that examined differences in how the two groups regard risks. Its lead author was University of Oregon psychology professor Paul Slovic, the founder of Decision Research Inc., a research center for risk assessment based in Eugene, Ore.

According to Slovic, people take an "all or none" view of toxicity when it comes to unwanted exposures. Unlike the government, academic and industry toxicologists he surveyed, they ignore key hazard factors such as concentration, exposure and dose. Nearly nine out of 10 lay people, for example, told Slovic's interviewers that if exposed to a toxic chemical, you're likely to get sick. (Two-thirds of toxicologists disagreed.)

"What's critical to understand is that it's the dose that's important," said Daughton. "Just because a toxic substance is around, doesn't mean you're exposed to it. Your body has to come in contact with it. Your body has to absorb it. Your exposure has to be of some duration and during a critical period of time."

_ Effects on animals may not predict effects on humans.

In Slovic's study, two-thirds of lay people believed that a substance that causes cancer in animals is reasonably sure to cause cancer in humans. (Six in 10 toxicologists disagreed.)

In the case of drugs in water, reproduction in fin- and shellfish and amphibians seems to be the most affected, and the suspected culprits are natural and synthetic forms of the female hormone estrogen and substances that mimic them. In a widely cited experiment, fish in an otherwise pristine Canadian lake lost reproductive vitality when they were exposed to under six parts per trillion of a commonly used synthetic form of estrogen.

The findings "raise a red flag" about other effects these drugs may be having on wildlife and possible risks to humans, said Karen Kidd, an environmental toxicologist at the University of New Brunswick's Canadian Rivers Institute who led the study.

But it is important to realize, Kidd said, that estrogens are rarely found in drinking water. Moreover, one reason fish are affected is that they're always taking up compounds through their gills. Hence, "they're getting exposed to more drugs than the average human would be from drinking water," she said.

No research has found a hazard to humans from estrogen or any other pharmaceutical in drinking water, Kidd and others noted, and Kidd said she continues to drink tap water.

_ Scientists understand big numbers and use them to gauge risk. Most other people get lost in the zeroes.

"There's no evolutionary reason for them to understand very big or very small numbers," said Ellen Peters, a colleague of Slovic's at the University of Oregon and at Decision Research.

"Our ancestors knew the number in their families and their villages," she said, "but those numbers were more like a few and up to 50 or 100."

Even now, people have so little real feel for millions and billions that they often confuse them.

When faced with a probability such as one chance in a million, Peters and others said, most people glom onto the "one" and exaggerate its importance. That works well for lottery operators, because people overestimate their chances of winning. But it works badly for understanding health risks, Peters said, because people overestimate their vulnerability.

She suggests describing one in a million as a 0.000001 chance. Six more zeroes and you've got the concentration of estrogen in Kidd's lake.

_ Most people think irrationally about risks.

According to David Ropeik, a risk communication consultant based in Boston, people feel less threatened by health risks that they choose, such as smoking, than by risks that are imposed on them, such as contaminated drinking water. They accept familiar risks, such as riding a bicycle, more than risks that surprise them. They also tolerate visible risks, such as choppy seas, better than invisible ones, according to Ropeik. Drugs in drinking water earn mistrust on all those counts.

_ News accounts of new environmental risks often overstate them.

The Associated Press investigative report in March, for example, waited roughly 1,000 words before telling readers: "Many independent scientists are skeptical that trace concentrations will ultimately prove to be harmful to humans."

The report also referred to "traces" of contaminants that were "far below the levels of a medical dose" and "in quantities of parts per billion or trillion," but it never defined these levels in ways that readers might better understand them. The stories also didn't mention the role that improved detection technology plays in exposing new contaminants.

According to Ropeik, "the series played down the ameliorating facts."

Richard Pienciak, the series' editor, referred a request for comment to Paul Colford, the AP's director of media relations.

Colford said the story contained ample cautions against overreaction. Many government and academic researchers, he added, "are thanking AP for sounding an alarm and bringing the situation to the attention of millions of Americans."

ON THE WEB

The Environmental Protection Agency's primer on ground water and drinking water.

A fact sheet and introduction to U.S. Geological Survey work on pharmaceuticals in drinking water.

A deeper look at the topic.

(McClatchy special correspondent Sarah Murray and researcher Tish Wells contributed to this story.)

McClatchy Newspapers 2008

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