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.The FDA, which regulates it, says:
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."
"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."