Common Chemical Disrupts Muscle Function

BPA. Phthalates. Now, there’s some concern over triclosan, an antibacterial chemical widely used in hand soaps and other personal care products that could disrupt muscle contraction.

Researchers at the University of California, Davis and the University of Colorado have found that the chemical impairs heart and muscle activity and strength. Their findings appear online in the Proceedings of the National Academy of Sciences of the United States of America.

“Triclosan is found in virtually everyone’s home and is pervasive in the environment,” says Isaac Pessah, professor and chair of the Department of Molecular Biosciences in the UC Davis School of Veterinary Medicine and principal investigator of the study. “These findings provide strong evidence that the chemical is of concern to both human and environmental health.”

Not only is triclosan — first developed to prevent bacterial infections in hospitals — commonly found in antibacterial personal care products such as hand soaps, but it is also present in deodorants, mouthwashes, toothpaste, bedding, clothes, carpets, toys, and trash bags. The U.S. EPA in 1998 estimated that more than one million pounds of triclosan are produced annually in the country. The chemical is detectable in waterways and in aquatic organisms ranging from algae to fish to dolphins, as well as in human urine, blood, and breast milk, according to a press release from UC Davis.

The researchers studied heart muscle cells and skeletal muscle fibers exposed to triclosan in test tubes. When they applied electrical stimulation, they expected the muscles to contract, but they found that triclosan seemed to impair two proteins involved in contractions, causing the skeletal and cardiac fibers to fail at the cellular level, reports Live Science. The website further described the team’s research:

The team also tested two groups of live animal subjects. They exposed sedated mice to the chemical and observed up to a 25 percent reduction in heart function levels within 20 minutes. And to mimic the effect of triclosan in marine environments, the researchers exposed fathead minnows to the chemical in the water for seven days. The exposed fish showed significantly diminished swimming ability compared to controls.

“We have shown that triclosan potently impairs muscle functions by interfering with signaling between two proteins that are of fundamental importance to life,” Pessah says. “Regulatory agencies should definitely be reconsidering whether it should be allowed in consumer products.”

Translating results from animal models to humans is a large step and would require further study, says Nipavan Chiamvimonvat, professor of cardiovascular medicine at UC Davis and a co-author of the study. However, because the results using animals were so striking under different experimental conditions, there is strong evidence that triclosan could have effects on animal and human health at current levels of exposure, he says.

“In patients with underlying heart failure, triclosan could have significant effects because it is so widely used,” Chiamvimonvat says. “However, without additional studies, it would be difficult for a physician to distinguish between natural disease progression and an environmental factor such as triclosan.”

Triclosan chemically resembles other toxic chemicals that persist in the environment. Because of this, EPA and the U.S. Food and Drug Administration are conducting new risk assessments of the chemical.

“We have shown that triclosan potently impairs muscle functions by interfering with signaling between two proteins that are of fundamental importance to life,” Pessah says. “Regulatory agencies should definitely be reconsidering whether it should be allowed in consumer products.”

Source: “Chemical widely used in antibacterial hand soaps may impair muscle function,” UC Davis press release, 8/13/12
Source: “Common Soap Chemical May Impair Muscle Function,” Live Science, 8/13/12
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