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16
Aug

Researchers Show Impaired Muscle Function from Antibacterial Chemical, Call on Regulators to Reconsider Consumer Uses

(Beyond Pesticides, August 16, 2012) The antibacterial chemical triclosan, found in popular personal care products such as Colgate® Total toothpaste and Dial® Liquid Hand Soap, hinders muscle contractions at a cellular level, slows swimming in fish, and reduces muscular strength in mice, according to scientists at the University of California (UC) Davis, and the University of Colorado. UC Davis’s press release explains that the chemical’s effects are so striking that the study “provides strong evidence that triclosan could have effects on animal and human health at current levels of exposure.”

The study, “Triclosan impairs excitation–contraction coupling and Ca2+ dynamics in striated muscle,” published in the Proceedings of the National Academy of Sciences, enlarges a growing body of work linking triclosan to human and environmental health issues. In “test tube” experiments, triclosan impairs the ability of isolated heart muscle cells and skeletal muscle fibers to contract. Specifically, researchers evaluated the effects of triclosan on molecular channels in muscle cells that control the flow of calcium ions, creating muscle contractions. Normally, electrical stimulation (“excitation”) of isolated muscle fibers under experimental conditions evokes a muscle contraction, a phenomenon known as “excitation-contraction coupling” (ECC), the fundamental basis of any muscle movement, including heartbeats. However, in the presence of triclosan, the normal communication between two proteins that function as calcium channels is impaired, causing skeletal and cardiac muscle failure.

The research team found that triclosan also impairs heart and skeletal muscle contractility in living animals. Anesthetized mice had up to a 25 percent reduction in heart function measures within 20 minutes of exposure to the chemical. Study co-author Nipavan Chiamvimonvat remarked that in this case, triclosan is acting “like a potent cardiac depressant.” Additionally, Mice exposed to triclosan show an 18 percent reduction in grip strength up to an hour after being given a dose of the chemical.

Lastly, researchers looked at the effects of triclosan exposure on fathead minnows, a small fish commonly used as a model organism when studying the potential impacts of aquatic environmental pollutants. Those exposed to triclosan in the water for seven days had significantly reduced swimming activity compared to controls during both normal swimming and swim tests designed to imitate fish being threatened by a predator. “You can imagine in animals that depend so totally on muscle activity that even a 10-percent reduction in ability can make a real difference in their survival,” said co-author of the study Bruce Hammock.

Beyond Pesticides has provided extensive documentation of the potential human and environmental health effects of triclosan and its cousin triclocarban. Previous studies have linked the chemicals to endocrine disruption, bacterial resistance, adverse fetal development, water contamination and an ever increasing body burden expressed in breast milk, urine and even umbilical cord blood.

Last year, a study published in the journal PLoS One identified a fatal outbreak of the bacterium P. aeruginosa in a hospital as coming from the contamination of triclosan soap dispensers, which acts as a continuous source of the bacterium. A 2010 study by the U.S. Department of Agriculture (USDA) and partners reveals that triclosan can persist at low levels in the environment for long periods of time as a result of biosolid (sewage sludge) fertilizer applications. When triclosan containing biosolids are applied to agriculture fields, sunlight can break down the chemical into dioxin, a highly carcinogenic substance linked to decreased fertility, weakened immune system functions, altered sex hormones, miscarriage, and birth defects.

The Centers for Disease Control and Prevention (CDC) also has found that triclosan is present in the urine of 75% of the U.S. population, with concentrations that have increased by 42% since 2004. It is one the most detected chemicals in U.S. waterways; about 96 percent of triclosan from consumer products is disposed of in residential drains. Moreover, triclosan-containing products can react with chlorine present in tap water to form chloroform, a possible carcinogen linked with human bladder cancers and miscarriages.

In 2009 and 2010, Beyond Pesticides submitted petitions to the U.S. Food and Drug Administration (FDA) and the U.S. Environmental Protection Agency (EPA), calling for the removal of triclosan from consumer products. Since then, many major companies are quietly removing triclosan from their products. Colgate-Palmolive, makers of SoftSoap, and GlaxoSmithKline, makers of Aquafresh and Sensodyne toothpastes, have reformulated some of their products to exclude triclosan, according to media reports. Others, including Johnson & Johnson, L’Oreal, The Body Shop, and Staples, have started phasing it out of products. After opening the petition for public comment in 2011, over 10,000 individuals told EPA via email and docketed comments to ban triclosan. Additionally, scores of public health and advocacy groups, local state departments of health and the environment, as well as municipal and national wastewater treatment agencies submitted comments requesting an end to triclosan in consumer products.

Canadian officials are set to declare triclosan toxic to the environment, an action which triggers a process to find ways to curtail a chemical’s use, including a possible ban in a range of personal-care products. The U.S. Food and Drug Administration has stated that existing data raises “valid concerns” about the possible health effects of repetitive daily exposure to triclosan, and it is expected is unveil its own risk assessment for the chemical. Principal investigator of the UC Davis study, Isaac Pessah, reiterates these concerns. “We have shown that triclosan potently impairs muscle functions by interfering with signaling between two proteins that are of fundamental importance to life,” he says. “Regulatory agencies should definitely be reconsidering whether it should be allowed in consumer products.”

Take Action: Be sure to read the label on personal health care products such as soap, toothpaste, toys and other plastics and avoid purchasing those containing triclosan. Join the ban triclosan campaign and sign the pledge to stop using triclosan today. Encourage your local schools, government agencies, and local businesses to use their buying power to go triclosan-free. Urge your municipality and workplace to adopt the model resolution that commits to not procuring or using products containing triclosan.

Source: University of California, Davis Press Release

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

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