Tuesday, August 21, 2012

The Ubiquitous Antibacterial, Triclosan, Found To Weaken Muscle

A new study in PNAS finds that triclosan, an antibacterial agent, weakens cardiac and skeletal muscle in mice:

Triclosan Impairs Excitation–Contraction Coupling And Ca2+ Dynamics In Striated Muscle, Proceedings of the National Academy of Sciences, 13 August 2012

Triclosan is all over the place. It's been used since 1972, and is present in soaps, deodorants, toothpastes, shaving creams, mouthwashes, dish detergents, hand sanitizers, cleaning supplies. It's infused in products such as kitchen utensils, toys, bedding, socks, and trash bags. It's a component in pesticides, mattresses, insulation, underlayments, and carpeting.

Triclosan has been shown to act as an endocrine disruptor, blocking the metabolism of thyroid hormone.

Here's a summary from ScienceNews:
Antibacterial Agent Can Weaken Muscle, Triclosan impairs power of heart and other muscles, 14 August 2012
"Doses of the chemical, called triclosan, needed to diminish muscle strength and blood flow in mice roughly matched those already measured in people in some parts of the United States.

Although the agent was tested in mice and fish, the mechanism by which it impaired muscle activity also exists in people. U.S. surveys have found triclosan in fluid samples from about three-quarters of people tested. So the new data “provide strong evidence that the chemical is of concern to both human and environmental health."

Calcium channels drive the activity of many cells, including those in muscle. Since the heart is muscle, Pessah [study author] decided to test whether triclosan might be capable of perturbing cardiac activity in exposed animals. He initially selected a dose that was less than 1 percent of what should have been lethal to animals. The first mouse tested died of heart failure within a minute of being dosed.

Stunned, the researchers dramatically ratcheted down the dose and were then able to show that in mice the chemical could reduce both the heart’s ability to move blood and the strength of leg muscles."
The FDA, which regulates it, says:
"In light of questions raised by recent animal studies of triclosan, FDA is reviewing all of the available evidence on this ingredient’s safety in consumer products. FDA will communicate the findings of its review to the public in winter 2012."


Bix said...

Triclosan is fat soluble, and so, would bioaccumulate, would be found in higher concentrations as you move up the food chain. Unless it degrades. This site says it doesn't degrade that much:

Over 90 percent of triclosan products are washed down the drain. Once down the drain, they wreak havoc with the environment–converting to highly toxic forms of dioxin, accumulating in sewage sludge (biosolids), contaminating waterways, and destroying fragile ecosystems.

USDA scientists found that triclosan is only slowly degraded in biosolids and persists at low levels in the environment for long periods of time. Biosolids are typically recycled onto agricultural lands. This persistent chemical can then be taken up and translocated in plants like the soybean, a cornerstone of the American diet.

Bix said...

And there may be an additive effect?

Triclosan and "other ubiquitous environmental contaminants, including certain polychlorinated biphenyls and a family of flame retardants known as polybrominated diphenyl ethers, also impair the operation of ryanodine receptors."

While I believe that diet plays a powerful role in health, I do wonder how strong the effect of environmental contaminants are. I've read more than a few studies over the years that found higher levels of POPs (Persistent Organic Pollutants) in people with metabolic disorders ... like diabetes.