Are Anti-Bacterial Soaps Poisoning Our Water?

An ingredient that is common in antibacterial soaps frequently ends up in lakes and streams, where it breaks down into a suite of potentially toxic chemicals that could harm wildlife and human health, according to new research.

The ingredient, called triclosan, made headlines last month when the U.S. Food and Drug Administration announced plans to review its safety. Growing evidence suggests that triclosan can disrupt the hormones in animals that regulate growth and reproduction. There are also concerns that the chemical might contribute to the spread of antibiotic-resistant strains of bacteria.

In one of the newest studies, published this week in the journal Environmental Science and Technology, scientists reported that triclosan is responsible for a huge surge in four types of dioxins in a Minnesota lake over the last few decades. Dioxins are a class of potent pollutants that have been linked to cancers, developmental issues, immune problems, and other health effects.

"Any time we are making something accumulate in the environment that we don't fully understand, that's potential for concern," said study author William Arnold, an environmental chemist at the University of Minnesota, Twin Cities.

"We need to know what's in the products we're using. And we need to know that once they go down the drain, they don't necessarily disappear."

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Triclosan earned its patent in 1964, when it was shown to be a powerful killer of bacteria. Originally, doctors used it to scrub up before surgery, but triclosan started to appear in commercial hand soaps in the late 80s. By 2001, 76 percent of liquid hand soaps contained the chemical.

Today, triclosan (and the related triclocarban) show up in deodorants, dishwashing liquids, clothes, shaving gels and toothpaste, among more than 100 other commercial products, including pesticides. Triclosan is also infused into plastics that are used to make antimicrobial products, such as toys, food storage containers, cutting boards and baby bibs.

Most of the triclosan people use ends up going down the drain, and wastewater treatment plants fail to remove it all. Studies have found triclosan in soil and in bodies of water around the world, including in 58 percent of 139 streams sampled in 30 states by the United States Geological Survey in 1999 and 2000.

The chemical has been detected in breast milk, and it was found in the urine of 75 percent of more than 2,500 Americans tested in 2007 by the Centers for Disease Control and Prevention.

Arnold and colleagues have been looking not just at triclosan, but at what triclosan turns into after it escapes into the environment. In previous experiments, they've shown that exposure to sunlight causes triclosan to break down into four types of dioxins.

For their latest study, the researchers took a boat out into Lake Pepin, which is downstream of several wastewater treatment plants along the Mississippi River in Minneapolis and St. Paul. From two parts of the lake, they collected layers of sediment that they could date in five to 10 year increments, stretching back to 1940.

Their analyses showed steadily increasing levels of triclosan since the 1960s. They also found that -- while overall levels of dioxins have dropped by as much as 95 percent with increasing regulations since the 1970s -- the amount of the four triclosan-derived dioxins have increased by between 200 and 300 percent in the same time period.

Overall, the levels of both triclosan and dioxins remain tiny, and scientists still don't know what their health or environmental consequences will be. Dioxins come in 95 different forms, and the four in question aren't well studied.

"The point is, they're out there, and they're increasing," said Tufts microbiologist Stuart Levy, president of the Alliance for the Prudent Use of Antibiotics. "Are we going to wait for a crisis, or are we going to act on it and advise people not to buy it and stores not to carry it?"

Environmental groups along with Representative Edward Markey, a Democrat from Massachusetts, are urging the FDA and the Environmental Protection Agency to ban triclosan from consumer products, especially products used by young children. The European Union has already taken a strong stand against it.

In the meantime, consumers can avoid products with triclosan on their labels, including liquid soaps described as antibacterial. Other than the chemical's documented ability to prevent gingivitis when used in toothpaste, studies show that germs are best battled the old fashioned way.

"Soap on its own should get your hands nice and clean," Arnold said. "There's no triclosan in my house."