Antibacterials in the Household
1 History of Antibacterial Soap
3 Efficacy and Risks of Triclosan
4 Alternative Antibacterials
History of Antibacterial Soap and Hand Washing
In 1847, Hungarian physician Ignaz Semmelweis enacted one of the first known rules requiring the physicians in his hospital to wash their hands. At first, soap was not a staple household product. Bacteria was first linked with disease in the 1870s. Soon after, hand washing was considered necessary as a means to stay healthy. In the 1950s and 1960s, triclosan and triclocarban, a related chemical, were first introduced in hospitals. Trioclosan is the active ingredient in most antibacterial soaps.
Hand washing is extremely important to kill pathogens. Regular soap, which does not contain antibacterial agents, may be equally effective in this way as triclosan-containing soap. Moreover, antibacterial soap is likely only effective in removing harmful bacteria if it is left on the skin for two minutes. In studies, most people do not wash their hands for that amount of time, and so do not receive the benefits of antibacterial soap. However, antibacterial soap can simultaneously kill the beneficial bacteria that live on our skin and that we need to survive. Scientists are also researching whether repeated use of antibacterial soap may cause bacteria to develop resistance to it and other antibiotics. The Centers for Disease Control (CDC) claim that antibacterial soap is not necessary, but rather washing hands well with plain soap and water is suffient.
Traditionally, antibacterial agents have been used to protect patients with vulnerable or weak immune systems. Now we are seeing an escalation in the number of products with antibacterial agents incorporated into their formulas. From a few dozen in the mid-1990s , the EPA now has more than 5,000 products registered containing antimicrobial pesticides. One of the most common antimicrobial agents present in household products is triclosan, an antibacterial that works to kill or inhibit the growth of harmful bacteria.
Triclosan is a synthetic, broad-spectrum antibacterial agent that prevents the active site of the enoyl-acyl carrier protein reductase enzyme (ENR) from functioning properly . This enzyme makes it possible for bacteria to synthesize fatty acid, which is essential for the production of cell membranes and reproduction.
Triclosan has been reported to be present in a variety of personal care products, such as deodorant soaps, underarm deodorants, shower gels, and health care personnel handwashes. Furthermore, triclosan has been found to be present in dental care products, cosmetics, shave gel, sponges and wipes, kitchenware, computer equipment, clothes, children’s toys, furniture and paints. For some of these products, triclosan acts as a preservative to prevent damage that might be caused by bacterial growth.
The incorporation of triclosan into personal products is believed to be because of its safety profile. Despite there being no evidence that incorporating antibacterial agents will provide an added health benefit , antibacterial agents are still being incorporated into common consumer products because of the belief that antibacterial agents give a product a hygienic boost.
Triclosan: Efficacy vs. Risk
In recent years, with triclosan as the most prevalent antibacterial chemical in consumer antibacterial liquid hand soaps, there has been increasing controversy among epidemiologists and microbiologists regarding its use. A number of studies have been conducted in recent years, especially in past decade or so, investigating the purported benefits and possible dangers of triclosan’s ubiquity. These studies, in general, attempt to answer the following question: is triclosan soap more effective than plain soap against harmful bacterial contamination and infection, and what are the risks of using it?
In general, studies have shown that there is no added benefit of using triclosan-based antibacterial soaps over regular soap — as early as 2000, the American Medical Association released a statement saying just that. When triclosan has been shown to be effective in helping control the spread of pathogenic bacteria, it has been 5 to 10 times more concentrated than is common in consumer soaps.” In 2007, Allison Aiello, Elaine Larson, and Stuart Levy, who have established themselves as the indubitable leaders in this field, published a comprehensive review of all data on the domestic use of triclosan-containing hand soap. They found that the vast majority of studies conducted in a non-clinical and non-laboratory setting (in other words, examining actual consumer use) showed that antibacterial soap was hardly more effective in reducing illness than plain soap.
While triclosan may not be any more effective than plain soap, the potential dangers of its continued use are many and profound. Foremost among these risks, numerous studies suggest, is the potential of bacteria to acquire resistance — often called reduced susceptibility when speaking of biocides — and for that bacteria to develop cross-resistance to antibiotics. The majority of relevant studies found that at least one bacterial species examined (including the potentially fatal Escherichia coli, Staphylococcus aureus, and Salmonella enterica) developed cross-resistance to at least one antibiotic (including tetracycline, erythromycin, chloramphenicol, ampicillin, and methicillin) after they were exposed to triclosan. Several studies in Japan indicate a direct connection between domestic triclosan use and the emergence of community-acquired MRSA (versus hospital-acquired).
There are also dangers in the potential toxicity of triclosan. Multiples studies show that triclosan exposed to sunlight changes into a chemical dioxin, which can be disruptive to the aquatic ecosystems where it is often detected (likely because of its seeping into the groundwater and inadequate wastewater treatment) and harmful to human hormonal processes, even carcinogenic, if we are exposed. In addition, a 2005 study suggested that when the chlorine found in tap water is combined with triclosan, they react to produce dangerous chloroform gas that humans can inhale or absorb through skin. Still, as research into the true effectiveness and risks of triclosan is largely a recent development, most in the scientific community agree that more research is needed to answer these questions.
While triclosan is one of the most popular antibacterial agents in household products, other similar chemicals are also used. In a study of US stores, 76% of 395 liquid soaps and 29% of 733 bar soaps contained antibacterial agents. Most of the liquid soaps contained triclosan while most bar soaps contained triclocarban, a compound related to triclosan.
Besides these, many other antibacterials are available to consumers including pine oil, chlorhexidine, nanosilver, and alcohol. Pine oil comes from various species of pines, and is a disinfectant and antiseptic. It is active ingredient in the popular cleaning product Pine-Sol. Chlorhexidine gluconate (CHG) is an antiseptic that is found many hand washing and mouth washing products. One study shows that when compared to triclosan, CHG was more effective in eliminating most of the bacteria on hands. However, it did not eliminate staphylococcus aureus, while triclosan did.
Nanosilver is another product on the market that has caused concern. Particles of silver can be added to products to release ionic silver (Ag+), which has antimicrobial properties. This technology has been used in toothpaste, shampoo, cloth, medical masks, detergent, toys and humidifiers. However, there is concern that the silver particles may contaminate water and aquatic life, as well as pollute air. As yet there has been no government regulation of nanosilver.
Alcohol also has antiseptic and disinfectant properties that, in some studies, prove more effective than other antibacterials. In one such study, rubbing hands with an alcohol-based product eliminated more bacteria than washing hands with an antibacterial soap.
Since triclosan and other cleaners are controversial for possibly producing drug resistant bacteria, it is important to use other products as well or avoid using chemical antibacterial cleaners altogether. Eliminating use of antibacterial chemicals like triclosan has vast potential benefits for our health and safety, and for the health of the planet.
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Authors: Patty Boyer, Evan Horwitz, Isabel Sippel, Frances Soctomah Students of Rachel Larsen's Biology 083 Class at Bowdoin College