Back in January, I wrote a post about the potential hazards of traditional cleaning chemicals. Based on questions and comments from friends and family, I am going to continue on that path, this time focusing on the antibacterial chemical triclosan. Triclosan gained some media attention earlier this year when a law was passed in Minnesota to ban it from soaps and cleaning products.

The odds are very good that you have used a product that contains triclosan. It is in many products that you have encountered labeled as “antibacterial,” such as hand soap, body wash, and dish soap. Somewhat surprisingly, it is in many other everyday items. Next time you are using them, check the label on your toothpaste, deodorant, shaving gel, cosmetics, or laundry detergent. Some manufacturers also include triclosan in these products because of its antibacterial properties.

What makes triclosan antibacterial?

Initially, people believed that triclosan worked to kill bacteria in a non-specific way. This means that the chemical does not kill bacteria by disrupting one specific thing (for example, a protein on the exterior of the bacteria that helps to bring in essential nutrients). Examples of non-specific antibacterial agents are ethanol (many hand sanitizers use this) and rubbing alcohol (horrific flashbacks of mom putting this on my cuts as a child). These kill bacteria by dissolving various parts of their outer coating (the cell membrane). There is very little concern that bacteria can become resistant to non-specific antibacterial agents, because these agents disrupt many essential parts of the bacteria.

Unfortunately, it was discovered that triclosan works by reducing the function of one specific protein (called enoyl-acyl carrier protein reductase in case you want to impress your friends)¹. Since triclosan works on one specific protein, it is easier for bacteria to become resistant to it, because the bacteria could develop a slightly modified (triclosan-resistant) version of this specific protein, or potentially find a way around using that protein altogether. It was even discovered in one study that some bacteria that developed antibacterial resistance to triclosan also became resistant to several other antibiotics that you may know, such as amoxicillin and erythromycin². What we should take away from this is it is not likely for bacteria to become resistant to non-specific antibacterial agents like rubbing alcohol, but bacteria are more likely to become resistant to specific antibacterial agents like triclosan. This has important implications for public health because it has the potential to decrease the efficacy of some very important antibiotic drugs we rely on to help with a variety of infections. This is the first reason I suggest we should not use triclosan, but instead stick to plain old soap and hot water (which also gets rid of bacteria).

Triclosan in the environment

About half of the triclosan that is washed down the drain makes it through waste water treatment plants untouched. This means that a large amount of triclosan is released into our environment’s streams and soils. A study conducted in 1999-2000 found triclosan in 60% of streams surveyed across 30 different states³. By digging deeper and deeper into sediments at the bottom of lakes and rivers, researchers can look back in time to determine when chemicals first started entering that environment. Research conducted at Lake Pepin, which is shared by Wisconsin and Minnesota, showed triclosan first accumulating in the environment in the 1950’s. Additionally, the amount of triclosan present has increased over time⁴. This is concerning for two main reasons:

• Triclosan is not degraded quickly in the environment. Much of the triclosan that we wash down the drain ends up in the environment, and it stays there for a long time.
• Bacteria in the environment can frequently encounter the triclosan that is building up in the environment, which increases their chances of developing resistance to it.

Is triclosan safe?

The answer to this question, like many other chemicals, depends on how much a living organism encounters. Nearly every chemical, even H₂O, can be unsafe and even toxic in excess. In a 2008 study, triclosan was found in the urine of 75% of people tested.⁵ Currently, the amount of triclosan found in humans and the environment is typically below what causes most negative effects. On the other hand, if we continue to use triclosan, it has the potential to accumulate to more concerning levels in both our bodies and the environment. Triclosan has been found to hinder heart and skeletal muscle contraction⁶ (even at levels found in some human blood samples), disrupt the function of important hormones in our bodies (and many other animals) like estrogen,⁷ and kill fish and inhibit aquatic plant growth at high concentrations, just to name some of its side effects. To top it off, one study conducted in several households over one year concluded that triclosan-containing hand soap failed to reduce infections as compared to non-antibacterial hand soap.⁸

So what should you do?

Here is what I do. Based on several factors – concern of an increase in antibacterial resistance, accumulation in the environment, potential impacts on the health of many organisms including ourselves – I avoid buying and using products containing triclosan. Plain old soap and hot water are more than capable of meeting your hand cleaning needs! I challenge you to become an informed consumer and make an effort to understand what is in the products you are buying. I always try to ask myself more than just “lavender & lilac or cooling cucumber, fresh mint or extra whitening?”

I believe it is important that we as a society continue to make scientific research a priority so we can fully understand the implications of the products we all use and generally take for granted each and every day. The story of triclosan highlights the point that the burden of proving a chemical is both safe and effective should be dealt with before we are faced with wondering how to deal with its negative effects years down the road. This is exactly the goal of myself and all the other scientists in the Center for Sustainable Nanotechnology, where we are working to understand nanomaterials on a fundamental level so we can help guide the development of safe and effective nanomaterials.

References (subscription required for most):

¹ McMurry, Laura M., Margret Oethinger, and Stuart B. Levy. “Triclosan targets lipid synthesis.” Nature 394.6693 (1998): 531-532.

² Aiello, Allison E., Elaine L. Larson, and Stuart B. Levy. “Consumer antibacterial soaps: effective or just risky?.” Clinical Infectious Diseases 45.Supplement 2 (2007): S137-S147.

³ Kolpin, Dana W., et al. “Pharmaceuticals, hormones, and other organic wastewater contaminants in US streams, 1999-2000: A national reconnaissance.” Environmental science & technology 36.6 (2002): 1202-1211.

⁴ Buth, Jeffrey M., et al. “Dioxin photoproducts of triclosan and its chlorinated derivatives in sediment cores.” Environmental science & technology 44.12 (2010): 4545-4551.

⁵ Calafat, Antonia M., et al. “Urinary concentrations of triclosan in the US population: 2003-2004.” Environmental health perspectives 116.3 (2008): 303.

⁶ Cherednichenko, Gennady, et al. “Triclosan impairs excitation–contraction coupling and Ca2+ dynamics in striated muscle.” Proceedings of the National Academy of Sciences 109.35 (2012): 14158-14163.

⁷ James, Margaret O., et al. “Triclosan is a potent inhibitor of estradiol and estrone sulfonation in sheep placenta.” Environment international 36.8 (2010): 942-949.

⁸ Larson, Elaine L., et al. “Effect of Antibacterial Home Cleaning and Handwashing Products on Infectious Disease SymptomsA Randomized, Double-Blind Trial.” Annals of Internal Medicine 140.5 (2004): 321-329.