- Tons of chemicals in antibacterial soaps
used in the bathrooms and kitchens of virtually every home are being released
into the environment, yet no government agency is monitoring or regulating
them in water supplies or food.
-
- About 75% of a potent bacteria-killing
chemical that people flush down their drains survives treatment at sewage
plants, and most of that ends up in sludge spread on farm fields, according
to Johns Hopkins University research. Every year, it says, an estimated
200 tons of two compounds -- triclocarban and triclosan -- are applied
to agricultural lands nationwide.
-
- The findings, in a study published last
week in Environmental Science & Technology, add to the growing concerns
of many scientists that the Environmental Protection Agency needs to address
thousands of pharmaceuticals and consumer product chemicals that wind up
in the environment when they are flushed into sewers.
-
- > From dishwashing soaps to cutting
boards, about 1,500 new antibacterial consumer products containing the
two chemicals have been introduced into the marketplace since 2000. Some
experts worry that widespread use of such products may be helping turn
some dangerous germs into "superbugs" resistant to antibiotics.
-
- Triclocarban, an ingredient of antibacterial
bar soaps and toothpaste, is "potentially problematic" because
it breaks down slowly, which means it is accumulating in soil and perhaps
water, said Rolf Halden, an assistant professor at Johns Hopkins' Department
of Environmental Health Sciences, who led the study.
-
- "What we are finding is this chemical
is building up in the environment," Halden said. "This is an
example of an emerging contaminant. It has been in the environment for
almost five decades, and we manufacture large volumes of it, but we don't
know what happens to it."
-
- The scientists calculated that a large,
modern East Coast sewage treatment plant spreads sludge containing more
than 1 ton of triclocarban onto farm fields every year. The plant was not
identified by the researchers, but data in the study indicated that it
was in Baltimore.
-
- Southern California's sludge has not
been analyzed for antibacterial chemicals. But households in the Los Angeles
region are likely to be a major source, because sewage plants in the area
produce hundreds of thousands of tons of sludge every year.
-
- Sludge is the solid waste that is left
when sewage is processed in treatment plants. Billions of pounds are produced
annually in the United States -- 47 pounds per person -- and two-thirds
is hauled to agricultural fields for disposal. Federal regulations limit
metals and pathogens in sludge, but not other chemicals.
-
- Triclocarban is used in bar soaps, deodorants,
toothpaste, kitchen supplies such as cutting boards and countertops, and
baby toys. Triclosan, which is more abundant because it is used in liquid
soaps, has been detected in human breast milk and fish in streams in Europe.
-
- Toxicological tests have shown that the
chemicals seem safe for human exposure, even in the high doses applied
to skin. However, in water, triclosan can react with chlorine and turn
into chloroform and dioxins linked to cancer. The chemicals also might
kill microbes beneficial to ecosystems or promote new pathogens that resist
antibiotics.
-
- Allison E. Aiello, an assistant professor
of epidemiology at the University of Michigan's School of Public Health
who has studied antibacterial soaps, calls the new report an important
finding that "suggests these types of chemicals are persistent and
prevalent in the environment."
-
- "From these findings, it seems likely
that microorganisms in the environment are often exposed to these chemicals
at various concentrations," Aiello said. The next step, she said,
is to assess whether these microbes show reduced resistance to antibiotics.
-
- Previous research by Halden suggested
that triclocarban was among the top 10 contaminants in waterways, while
triclosan was among the most prevalent in a national analysis of streams
by the U.S. Geological Survey.
-
- Yet no one knows whether the chemicals
are contaminating crops or groundwater. Drinking water also is not monitored
for them. The EPA is exploring the prevalence of pharmaceuticals and personal
care products in the environment, but it has nowhere near enough data to
consider regulations for sludge.
-
- Rick Stevens, national biosolids coordinator
at the EPA's Office of Science and Technology, said the discovery of triclocarban
in the plant's sludge was "of interest" to the EPA, but "at
this time, the agency cannot determine what significance [the concentrations
found] may represent to humans or the environment due to the limitations
in the database."
-
- Stevens said there were no national data
-- not even an accepted, standardized technique for measuring the chemicals.
"One facility is not a nationally representative sample," he
said.
-
- Triclocarban in the plant's sludge averaged
51 parts per million, considered a high concentration for an environmental
contaminant. But Stevens said people regularly rubbed triclocarban into
their hands at levels 100 times higher. Also, the chemicals would be degraded
and diluted on farm fields, he said.
-
- Hans Sanderson, director of environmental
safety at the Soap and Detergent Assn., which represents manufacturers,
said the new research was "important and analytically sound"
and was helping address what happens to the chemicals in soaps and other
household products.
-
- But Sanderson said it was wrong to assume
that the presence of them in the sludge meant that they were posing risks.
Most sludge is applied to fields and forests that do not produce food crops,
he said.
-
- "It is clear that the majority of
exposure to triclocarban is direct exposure, when you actually use these
materials in hand soap or toothpaste or whatever," Sanderson said.
But, he said, laboratory tests have shown that even those exposures have
no effects on animals, are not toxic to aquatic life and pose no known
threat to people.
-
- Ann Heil, a senior engineer at the Sanitation
Districts of Los Angeles County, said many environmental precautions were
required on lands where sludge was applied. The material is plowed into
soil within 24 hours and no runoff is allowed.
-
- Heil said it probably was better that
treatment plants removed the antibacterial chemicals from wastewater and
concentrated them in the sludge, because otherwise the chemicals would
be discharged into streams where they could harm wildlife.
-
- Farm disposal of sludge is controversial
in California. On June 6, residents of Kern County, which takes in one-third
of the state's sludge, will vote on whether to ban its use on farms. If
the measure passes, as expected, Southern California will have to ship
more sludge to Arizona at an extra cost of millions of dollars a year in
Los Angeles alone.
-
- About 37% of the 160,000 tons produced
last year by the Sanitation Districts of Los Angeles County was applied
on land. The county's sludge is subjected to an extra process called thermal
treatment, which Heil said probably removed more antibacterial chemicals
than the East Coast plant studied in the report.
-
- But, Halden said, even newer tests, yet
to be published, showed that the heat treatment was "not very effective"
in eliminating antibacterial chemicals. So this "Type A" sludge,
the type used on food crops, still could contain high amounts.
-
- In October, an advisory panel of the
Food and Drug Administration reported that there was no evidence that the
household products protected people any better than regular soap. The panel
urged the agency to study their risks and benefits. The American Medical
Assn. has opposed routine use of antibacterial soaps since 2002.
-
- "The bottom line," Halden said,
"is [that] we are mass-producing chemicals in the environment that
are not helpful and potentially are harmful."
-
- But Sanderson of the Soap and Detergent
Assn. said it would be foolish to eliminate products that could stem the
spread of diseases when there was no evidence they posed a threat.
-
- http://www.latimes.com/news/nationworld/nation/la-na-
antibacterial10may10,0,3219699.story
|
