Anti-bacterial soaps: why they do far more harm than good


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There is an entire aisle in the supermarket devoted to cleaning products, many of which contain antibacterial chemicals. The most common, Triclosan, is found in about 75% of antibacterial soaps. Triclosan (2,4,4’ –trichloro-2’-hydroxydiphenyl ether) is a synthetic antibacterial chemical that was developed in the 1970s for use in hospital scrub rooms, but it has since made its way into hundreds of the products we use every day, all without formal FDA approval or safety studies.  Not only is Triclosan a common ingredient in hand soap, it’s also in children’s toys, toothpaste, deodorant, cosmetics, bedding, clothing, cutting boards, and much more, often marketed under trade names such as Microban®.

It doesn’t stay in those products…

A Center for Disease Control study in 2008 found that 75% of people have Triclosan in their urine. The chemical has also been found in breast milk, amniotic fluid, nasal secretions, and blood plasma, so it is obviously absorbed quite easily into our bodies.

Why is this bad?

Studies in animals and in cultured human cells have shown that Triclosan reduces heart and muscle function by as much as 25%. And this is after just 20 minutes, at doses equal to normal daily exposure. While a healthy person might not notice any difference, this could be a real problem for someone with already impaired cardiac function.

Triclosan has also been shown to alter levels of hormones, including estrogen and testosterone, and can have negative effects on thyroid function. In children, exposure to the chemical increases incidence of allergies. It isn’t yet known if this is a direct effect, or if Triclosan simply kills off too many of a child’s normal, protective bacteria, altering their developing immune function.

Killing off your ‘friendly’ bacteria is never a good idea, because it leaves that formerly occupied space wide open for infection, or to be covered by a bacterium that is resistant to antibacterials. Remember how Triclosan is absorbed into your bloodstream and later turns up in nasal secretions? It turns out that this enables Staph. aureus to bind to certain proteins in the nasal cavity and colonize it. Three in ten people carry Staph naturally in small, harmless amounts, but when it’s given an opportunity to take over, it will, and 85% of Staph infections are caused by our own bacteria

What about all of that Triclosan going down the drain?

Triclosan is one of the most frequently found chemicals in our rivers and streams, and it doesn’t break down easily, so it tends to build up in the environment (and, by the way, in our own bodies). When it reacts with chlorinated water, commonly found in homes in cities and towns with a central water supply, it can form chloroform, a potentially carcinogenic compound.

It does kill bacteria, as promised by those ads…

But it doesn’t work any better than plain soap and water would, even the FDA says so.  And this completely unnecessary chemical is adding to the growing problem of antibiotic resistance.  Triclosan works by blocking an enzyme that bacteria need to make a certain fatty acid that is part of their cell membrane.  The mechanisms bacteria develop to get around this problem and become resistant to Triclosan are often the same mechanisms they use to develop resistance to antibiotics.  Studies have shown that bacteria which have developed resistance to Triclosan are also now resistant to important antibiotics, including erythromycin, ciprofloxacin, ampicillin and gentamicin. All without ever coming in contact with these drugs.

Ironically, Triclosan has no effect at all on viruses, which cause the majority of the illness people are trying to avoid in the first place, such as colds, flu, and the norovirus.

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What about alcohol-based hand sanitizers?

They are safe and relatively effective, as long as the alcohol content is at least 60%. Less than that, and they are too dilute to kill bacteria, with 70% being the most effective concentration. Alcohol kills bacteria and viruses physically, not chemically like antibacterials and antibiotics, so they can’t develop resistance to it. Alcohol disrupts lipids (fats) in the bacterial membrane (its ‘skin’), causing it to begin to fall apart. The alcohol can then enter the cell and denature the proteins there, killing the bacterium. If the percentage of alcohol to water is too high (greater than 75% or so) it evaporates before it can get inside the bacterial cell, and doesn’t do any good. Keeping this in mind, you need to use enough alcohol-based hand sanitizer so that it doesn’t evaporate too quickly from your skin.  Your hands should feel wet for at least 15 seconds, or longer.

And what works best of all for germ-free hands?

That’s right, plain old soap and water. Soap works in two ways. First, it loosens dirt and germs from our skin and washes them away. Second, it has the same kind of physical killing power as alcohol. Remember those fats that hold bacterial cell membranes together? Just think about how well soap breaks up the grease on your dishes. It breaks apart bacteria in much the same way. To eliminate the majority of germs from your hands, you should wash them for at least 24 seconds

Why doesn’t soap and alcohol hurt our own cells?

Our cells have the same kind of lipid-based membrane as bacterial cells do, but we are much better protected. The outer layers of our skin have high amounts of a protein called keratin that forms a tough barrier to protect them from physical assault. As the keratin builds up and gets too thick, the outer cells die, which is why our skin is constantly shed and replaced. When soap gets into a cut, our nasal passages or our eyes, which are not protected by keratin, it stings. This is because the soap is damaging our cells just like it damages bacteria. Your body protects itself from this damage by increasing fluids to wash the irritant away, which is why your eyes and nose water when you get soap in them.

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References:

Allmyr, M. et.al. 2006. Triclosan in plasma and milk from Swedish nursing mothers and their exposure via personal care products. Science of the Total Environment 372(1): 87-93

Calafat, A.M. et.al.  2008.  Urinary concentrations of Triclosan in the U.S. population: 2003-2004. Environ. Health Perspect. 116(3): 303-307

Cherednichenko, G., et.al. 2012. Triclosan impairs excitation-contraction coupling and Ca2+ dynamics in striated muscle. PNAS 109(35)

Rule, K.L, Ebbett, V.R., and Vikesland, P.J. 2005. Formation of chloroform and chlorinated organics by free-chlorine-mediated oxidation of Triclosan. Environ. Sci. Technol. 39(9): 3176-3185

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One thought on “Anti-bacterial soaps: why they do far more harm than good

  1. Thank you for sharing this information that I didn’t know about. It’s back to plain old soap and water for me. I’ve got enough health problems, I don’t need anything else to worry about.:)

    Like

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