[Dialogue] Threat Seen From Antibacterial Soap Chemicals

[Harry Wainwright]

Published on Wednesday, May 10, 2006 by the Los Angeles
<http://www.latimes.com>  Times 

Threat Seen From Antibacterial Soap Chemicals
The compounds end up in sewage sludge that is spread on farm fields across
the country.



by Marla Cone

 

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. 

Copyright 2006 Los Angeles Times

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