Here’s What Disinfectants and UV Light *Really* Do to Your Body

When a poison control center receives a call about someone who injected themselves with bleach, it’s often a tragic suicide attempt, Calello says. Occasionally, someone has a misguided idea about “cleansing” the blood, she says. “Those chemicals are just not meant to be in the human body in any way. They’re not meant to be on your skin, much less in your veins,” she says. “If you inject bleach or ammonia or any disinfectants, it automatically starts to kill the lining of your blood vessels and your blood cells and your organs.”

Household disinfectants such as Lysol work by destroying the outer layer of a virus, and they can be toxic to human cells. Wiping your hands with a disinfecting wipe won’t hurt you because it’s a dilute solution, but pouring disinfectant on your hands could cause irritation. “I think it’s important to make a distinction between what we do to clean our skin and what we do to disinfect our environment,” Calello says.

For cleaning skin, Callello continues, “The CDC (Centers for Disease Control and Prevention) recommends cleaning with soap and water, which rinses off debris and dirt.” Soap tears away the virus’s outer fatty layer gently enough that it destroys the virus without harming your skin.

What about UV light? At last Thursday’s press briefing, Bill Bryan, a senior official at the Department of Homeland Security, presented unpublished data about the effect of higher outdoor temperatures and humidity on Covid-19. That led Trump to riff in the direction of coronavirus response coordinator Dr. Deborah Birx: “Supposing we hit the body with a tremendous—whether it’s ultraviolet or just a very powerful light. And I think you said that hasn’t been checked, but you’re going to test it. Supposing you brought the light inside the body, which you can do, either through the skin or some other way. I think you said you’re going to test that too.”

UV light—particularly the shortest wavelength, known as UVC—kills viruses by damaging their DNA or RNA, crippling their ability to make copies of themselves. Hospitals have been using UVC lamps and even UVC robots to disinfect the air in rooms. But just as with disinfectants, UVC light doesn’t discriminate in what it kills. This light can also damage human cells, potentially harming the cornea, causing sunburn, and raising the risk of skin cancer, says physicist David Brenner, who is director of the Center for Radiological Research at Columbia University. That’s why hospital staff turn on the lamps only when the rooms are empty.

Theoretically, it would be possible to snake a tube with a UV light into a person’s airway, but that would be a very bad idea. “That would be damaging to all the cells inside the body,” says Brenner. And in any case, the light wouldn’t reach all areas of the lungs. “The UV light can’t go around corners,” he says. “I don’t think you’d be killing all the viruses by any means.” Any remaining viruses would simply multiply, leaving the person still trying to fight off a Covid-19 infection—but now with potential cellular damage from the UV light.

Brenner has been studying far-UVC, a wavelength that can kill viruses but can’t penetrate beyond the top layer of human skin, which is made up of dead cells. Brenner says that kind of light could be used to safely kill germs in the air, not just in hospitals, but in airports, transit stations, and other places where people gather. Still, he points out, the idea would be to use far-UVC for environmental surface decontamination, not internally to treat patients.

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Medicine, of course, works differently. Antiviral drugs being designed to kill the SARS-CoV-2 virus that causes Covid-19 would target it very specifically, rather than killing a broad spectrum of microbes or endangering human cells. So far, there are no FDA-approved medical treatments for Covid-19, although drugmakers are racing to find ways to kill the novel coronavirus.

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