The Truth about Antibacterial Soap
by Isabelle T. walker
Antibacterial soaps are ubiquitous now. They’re dispensed in millions of American homes, office buildings, and health clubs. In a parade of décor-enhancing colors and aromas, it’s hard to resist their promise of protection from real and imagined bugs lurking about. But if I’ve learned anything during my journey to middle age, it’s that there is no such thing as a free lunch. Ever. So what’s the catch with these suds-upped soaps? Everybody knows doctors have prescribed oral antibiotics so frequently to patients in the past — even in cases when they aren’t actually needed — that some bacteria have adapted to circumvent one or more drugs’ line of attack. Sometimes physicians have to give patients a series of progressively stronger antibiotics in order to finish off the bacteria once and for all. In rare cases — usually among the frail elderly — the bacteria win.
Are antibacterial soaps contributing to this process, too? To find out, I called Mary-Louise Scully, the infectious disease expert at the newly renamed, but same old, tried-and-true Sansum Clinic. Scully didn’t fit my imagined prototype of an infectious disease specialist. She doesn’t wear glasses or have a pocket protector in her white coat. She doesn’t even wear a white coat — to interviews, anyway. She’s young, has a girl-next-door face, and a ready sense of humor, probably a prerequisite in her line of work. Scully believes antibacterial soaps present us with a Catch-22 situation. “My feeling is they can [contribute to resistant strains]. Although you could flip it around and say we wouldn’t be developing these products if we weren’t having a problem with resistant bacteria.”
Scully sent me a copy of the Centers for Disease Control and Prevention’s (CDC; www.cdc.gov) guideline on hand hygiene in healthcare settings, and explained that there is a big difference between hand hygiene in healthcare settings and hand hygiene in the community. Since hospitals in particular are breeding grounds for the gamut of bacteria, viruses, and fungi — including varieties that are multi-drug resistant — the use of a range of potent soaps and antiseptics there saves lives.
The active ingredient in most of the antibacterial soaps available at drug stores and grocery markets is triclosan (pronounced trick·lo·san). It’s a chemical that’s been around since the 1960s and is becoming extremely popular. Sales of it are expected to grow to about $6.9 billion by 2009. Triclosan is also in some dishwashing liquids and toothpastes. The CDC guideline — which is not a page-turner, I might add — indicates that, so far, in real-life situations, bacteria aren’t mounting a big resistance to triclosan, although the chemists and biologists who study these things aren’t ruling out the possibility that they might later on.
Killing disease-causing bacteria that have taken root in someone’s body is complicated because not all bacteria are bad. Some are not only good but necessary — especially the ones in the digestive tract. Good bacteria (called “beneficial flora”) are locked in an eternal battle with bad bacteria for dominance, thereby keeping each other in check. When someone takes an antibiotic, the good and the bad bacteria die, leaving the field open for hardier, resistant strains to gain a toehold.
Apparently, on our hands, antibacterial soap kills bacteria that have just arrived, i.e., the transient, surface stuff. So the natural balance of good and bad organisms isn’t affected, according to the CDC’s guideline.
It seems the bigger problems with triclosan start when it disappears down the drain. Triclosan is considered a pre-dioxin, meaning it can transform into compounds belonging to the class of dioxins. As potentially carcinogenic dioxins go, the ones that triclosan is prone to produce aren’t the worst of the bunch, but that doesn’t make them good either. Triclosan is persistent in the environment; researchers are finding it not only in stream and river water, but in breast milk and in the bile of fish.
Rolf Halden, assistant professor at Johns Hopkins Bloomberg School of Public Health, recently published a study in the journal Chemosphere that analyzed what happens to triclosan when it arrives at a wastewater treatment plant. He found that about 50 percent of the mass coming into the plant was still there in the sludge that’s produced as a byproduct of treatment. More disquieting is the fact that many of our agricultural fields today use such treated sludge as fertilizer. The City of Santa Barbara sends 90 percent of its sludge to be used on Kern County’s cotton fields — providently, a non-edible crop. But many scientists, including Halden, are concerned about what it might be doing to the soil.
The best thing that can be said for triclosan is that it kills one of the strains of resistant bacteria doctors are worried about — methicillin-resistant staphylococcus aureus, a k a MRSA. This strain of staph is difficult to eradicate because it’s actually a human bacteria; it lives in people’s noses and on their skin. I f it enters the body through a cut, problems can occur. It wasn’t until a decade ago that MRSA began sickening people who hadn’t been in or near a hospital. And, according to Scully, MRSA infections have an annoying habit of coming back, which is why infectious disease experts recommend antibacterial soap to people who have it colonized on their body.
But what about those of us who aren’t colonizing MRSA and aren’t working in a healthcare setting? Do we need to use antibacterial soap too? Scully said no. “It’s sometimes appropriate to use these things, to break the cycle [of a MRSA infection]. But for people who are healthy and having no problems, basic good hand hygiene is usually plenty,” she said. And in case you need a refresher, that means washing with soap and water for at least 30 seconds (preferably 60 seconds) after using the bathroom, changing a diaper, scooping the dog’s poop, gardening, before preparing or consuming food — you get the picture. It also means rubbing your hands together for that length of time because it’s the friction that loosens dirt and bacteria.
Here’s the good news in all of this. According to the CDC guideline on hand hygiene, alcohol-containing hand sanitizers killed more bacteria and viruses than either antibacterial or plain soap, but only when the alcohol concentration was between 60 and 90 percent and only when the person used 3 milliliters of the gel. They take the uzi approach to bactericide: few, if any, live to tell the tale.
“They’re a pretty indiscriminant killer of bacteria,” said Frank Alvarez, Santa Barbara County’s director of infectious diseases, who recommends them. Of course, that also means they kill good bacteria. But plain soap does, too. And so far, there doesn’t seem to be any evidence that bacteria are finding ways to resist alcoho