- A scare rippled through Washington, D.C., earlier this
year when residents learned their drinking water contained lead, a metal
linked to lower IQs in children and other maladies. The lead had leached
into the water from aging pipes and fixtures. The city's water authority
responded with a common remedy: It added a chemical called orthophosphate,
which coats the inside of the pipes to contain the lead. But a month later,
the city found the water contained elevated levels of bacteria, a side
effect of the treatment.
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- Both the city and the US Environmental Protection Agency
(EPA) assured residents the situation was not an emergency, and that the
bacteria could be treated within months. Still, the city notified consumers
of the situation and suggested that at-risk households, such as those with
young children, seek medical advice.
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- So what should consumers believe about the safety of
their drinking water?
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- Drinking water in the United States is among the best
in the world - a United Nations study ranked it 12th among 122 countries.
US water is treated and closely monitored so that isolated problems like
the one in Washington, D.C., can be dealt with quickly. But scientists
also are detecting for the first time substances - called "emerging
pollutants" - that occur more routinely than had been thought. With
new tests and technologies turning up these previously undetectable contaminants,
a mixed picture is emerging of America's rivers, aquifers, and other freshwater
sources that supply an estimated five out of six Americans.
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- What's disturbing is what's showing up in the water:
industrial chemicals, human and veterinary drugs, feces, natural and synthetic
hormones, microorganisms, detergents, and even fire retardants. Water companies
do not yet test for most of these substances, and their effects on health
and the environment are largely unknown.
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- Just one drop
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- These contaminants occur in such tiny amounts, however
- at most, a drop of ink in the largest tanker truck - that so far most
do not seem to pose a danger, scientists say. The mere fact that contaminants
are being detected at these levels also means that the nation's water,
already much cleaner than two generations ago, could be purified even more.
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- "I'm not too worried, because most occur at levels
that are several orders of magnitude lower than a health concern,"
says Alan Roberson, director of regulatory affairs at the American Water
Works Association (AWWA), a Washington, D.C. group of 57,000 water professionals.
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- "I drink water from the tap, and I'm comfortable,"
adds Ephraim King, director of the Standards and Risk Management Division
of the EPA's Office of Water in Washington. "We've made pretty impressive
progress in the last 25 to 50 years."
-
- One example of that progress is cryptosporidium, a single-celled
parasite that spreads when infected human or animal feces get into surface
waters. It is relatively immune to chlorine, and its eggs can pass readily
through most existing treatment plants. In 1993, it was linked to the largest
recorded outbreak of a waterborne disease in US history, sickening 400,000
people and killing 50 in Milwaukee. From 1990 to 2000, at least 10 such
outbreaks in the US were traced to impure water.
-
- "Microbials are the problem we have been wrestling
with the most over the past 10 years," says the AWWA's Mr. Roberson.
"The EPA proposed a rule last year to require utilities to monitor
source water for cryptosporidium, and if there are higher levels, then
they have to put in additional treatment technologies to kill it or take
it out."
-
- Researchers have found that exposing it to ultraviolet
light at treatment plants or bringing the water to a rolling boil for one
minute seems to be effective. The EPA's proposed rule should be published
in its final form this summer, Mr. King says.
-
- But the list of emerging pollutants continues to grow
as scientists conduct new tests. The US Geological Survey (USGS) released
a study in 2002 on 95 organic contaminants such as prescription drugs and
detergent byproducts that it looked for in US surface waters. The group
tested 139 streams located downstream from major cities or animal feeding
operations in 30 states and found 82 of the 95 chemicals on its list. No
drinking-water standards or health-advisory requirements exist for many
of the chemicals, whose effects have yet to be studied fully. The USGS
will repeat and expand the study next year, and it hopes to release an
updated report in early 2007, says Herb Buxton, coordinator of the USGS
toxic substance hydrology program.
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- Gulping Prozac
-
- The USGS already has a list of more than 130 emerging
contaminants that Mr. Buxton considers "sentinels" of potential
environmental and human health effects. For example, Fluoxetine (Prozac),
which has been found in waters in Britain and the US, can delay the development
of fish. And substances that are thought to interfere with the body's hormone
system and hinder fertility, known as endocrine disruptors, were found
in treated wastewater and municipal drinking water in Atlanta in 1999.
-
- "Finding these contaminants from households, animal
agriculture, and industry makes us realize that the chemicals we use, even
in very small amounts, can be concentrated in our wastewater and then deposited
in streams that in turn are water resources," Buxton says.
-
- While the effect of small amounts of pharmaceuticals,
including antibiotics and antidepressants, in the water remains unknown,
one researcher believes it could be relatively easy to remove some of them
from drinking water with existing technologies. Water treatment operators
could cut trace levels of drugs that get through sewage treatment systems
by adjusting the amounts of activated charcoal and chlorine used to purify
water now, says Craig Adams, a professor of environmental engineering at
the University of Missouri-Rolla. Simply increasing the amount of activated
charcoal can remove up to 90 percent of the drugs, he says.
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- The AWWA's Roberson says there is no magic bullet for
drinking water contaminants. Thousands of potential contaminants are in
the water, but the EPA has established drinking-water standards for only
about 90 of them. The EPA is continuing to examine newly discovered pollutants
to see if they need to be regulated. Local utilities also are required
to test their water, usually once every three months, and every July they
are required to send a water-quality report to homeowners. The reports
are posted on the EPA's website (www.epa.gov/safewater/dwinfo.htm).
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- "Most people just throw the report away, but it
can be incredibly useful," says Helen Rogan, executive editor at Organic
Style magazine, which surveyed five contaminants in the water of 25 cities
this past fall. She suggests that consumers who want to feel secure about
their drinking water read the utility company's water report, have their
tap water tested, and keep the EPA's Safe Drinking Water Hotline number
handy (800-426-4791). The hotline also can suggest solutions (a filter,
for example) if local water fails to meet federal standards.
-
- "Your tap water is safe unless you have reason to
believe otherwise," Ms. Rogan adds. "And if there is something
wrong, you'll find out pretty fast."
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- Copyright © 2005 The Christian Science Monitor.
All rights reserved.
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- http://www.csmonitor.com/2004/1230/p14s01-sten.html
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