Another Problem with Triclosan?

I’ve written here a number of times about some of the potential risks associated with the misuse and overuse of anti-microbial agents.  One such substance is triclosan, an antibacterial agent used in soaps, toothpaste, deodorant, mouthwash, other cosmetic products, and household cleaning supplies.  There have been some suggestions that widespread use of triclosan  may contribute to the development of antibiotic resistant bacteria; the chemical is also suspected, based initially on data from animal experiments, of being an endocrine disruptor.

A group of researchers at the University of California, Davis, and the University of Colorado, has now found evidence that triclosan hinders muscle functioning in mice and in fish.

Triclosan, an antibacterial chemical widely used in hand soaps and other personal-care products, hinders muscle contractions at a cellular level, slows swimming in fish and reduces muscular strength in mice, according to researchers at the University of California, Davis, and the University of Colorado. The findings appear online in the Proceedings of the National Academy of Sciences of the United States of America.

(The abstract for the published paper is here.)

The investigators found that the presence of triclosan, at levels that might reasonably be encountered in practice, inhibits muscle contraction by interfering with the action of two proteins that serve to regulate the transport of calcium ions.  The effect was sizable:

Anesthetized mice had up to a 25-percent reduction in heart function measures within 20 minutes of exposure to the chemical.

The mice also exhibited reduced grip strength after exposure to triclosan.  Fathead minnows exposed to triclosan in their environment had reduced swimming ability, compared to a control group.

The growing body of evidence suggesting that triclosan may not be entirely benign is of some concern, because the chemical is so widely used.

The U.S. Environmental Protection Agency in 1998 estimated that more than 1 million pounds of triclosan are produced annually in the United States, and that the chemical is detectable in waterways and aquatic organisms ranging from algae to fish to dolphins, as well as in human urine, blood and breast milk.

The FDA is currently reviewing the safety status of triclosan, although the results, originally due in April 2011, are still not completed.  Triclosan does have one use for which the FDA has given explicit approval: it is used in some toothpastes to help prevent gingivitis.  Otherwise, the FDA makes this statement on its page Triclosan: What Consumers Should Know:

For other consumer products, FDA has not received evidence that the triclosan provides an extra benefit to health. At this time, the agency does not have evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water.

Many people seem to be fixated on the idea, imported from cloud-cuckoo land, of getting an entirely microbe-free environment, using not just anti-bacterial soap, but toys and even trash bags.  (Do they intend to autoclave all their rubbish?)  And yet it can be difficult to get some of the same people to wash their hands.