Modern medicine is wildly successful at stopping infections that breach the body’s defenses. But far more lives have probably been saved by basic hygiene and clean water that prevent them in the first place. Good hygiene has virtually eliminated once-feared diseases like cholera, typhoid and dysentery in the developed world by breaking the chain of disease transmission. If the rest of the world had greater access to it, the World Health Organization estimates 1.4 million deaths could be prevented each year. That’s why readers of BMJ, formerly the British Medical Journal, voted the “sanitary revolution” the greatest medical advance since 1840, ahead of antibiotics and anesthesia.
Hygiene not only saves lives. It sells. Since the 1950s, companies have been adding “antimicrobial” compounds to soaps, touting their effectiveness at killing “99.9%” of germs. These antimicrobial soaps are mostly hygiene theater: Scientists say plain soap and water is just as effective. Worse, these unnecessary compounds may be contributing to a newer problem: resistance to lifesaving antibiotics. The coronavirus pandemic supercharged the use of antimicrobial products, despite their ineffectiveness against a largely airborne disease. Their active ingredients are now found in hand soap, laundry detergent, cosmetics and more — plus the blood and breast milk of many Americans. Here’s why plain soap and water remain your best bet against colds and germs — and when disinfecting makes sense. Skim your grocery store’s cleaning aisle and you’ll find antimicrobial soaps claiming to kill “99.9% of bacteria.” Plain soap a few feet away offers a similar promise to “wash away” germs.
Both claims are true, for different reasons. Soap molecules have two ends: one that loves oil and one that loves water. The oil-loving end breaks up oily grime and, like a little crowbar, pierces the exterior membrane that encloses many germs. The water-loving end then ensures everything goes down the drain with the rinse water. Soap, in other words, mostly removes rather than kills. Antimicrobial chemicals just focus on the latter: The ingredients — often a quaternary ammonium compound like benzalkonium chloride that are also known as “quats” — kill microbes directly, typically by rupturing their external membrane. The end result, however, is virtually identical: Both plain soap and antimicrobial products dispatch the offending bacteria or viruses, reducing your chances of getting sick. In fact, decades of studies have found no difference in illness between homes that use antimicrobial products and those that don’t. A 2007 peer-reviewed analysis of 27 studies in Clinical Infectious Diseases found that triclosan, a powerful antimicrobial, was “no more effective than plain soap” at preventing symptoms of infectious illness or lowering bacterial levels on people’s hands. In laboratory studies, triclosan-resistant bacteria show increased resistance to antibiotics, evidence that antimicrobials in soaps are not just ineffective, but could contribute to the evolution of superbugs. “There was no independent, peer-reviewed evidence that those soaps removed more pathogenic bacteria than plain soap in a typical hand-washing situation, or reduced illness in households,” said Rebecca Fuoco at the Green Science Policy Institute, a nonprofit seeking to reduce toxic substances in products and the environment. “It was just marketing.”
While there’s still some scientific uncertainty about whether biocides are driving resistance in human pathogens in homes, evidence from the lab suggests they share similarities to other sources of microbial resistance. How should we stay clean without potentially breeding superbugs? Fuoco frames it as a no-regrets decision: “You have the major U.S. and world public health authorities all look at the science and agree that there’s no benefit, only risks of these soaps,” she said. We don’t need — and should not have — sterile homes. Bacteria are everywhere and our microbiome, the community of microorganisms that live on and inside our bodies, depends on them being around us. The vast majority are benign or beneficial, and even keep nasty pathogens in check. Read my full column for more on why regular soap is best and when you should opt for something stronger. How do you clean your home without all the synthetic chemicals? I’m at climatecoach@washpost.com. I read all your emails.
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