Wednesday, April 1, 2020

An ode to hydrogen peroxide

OK, so this may not be that poetic but there’s good news on how science is helping us to survive the coronavirus. I’ll start small and then scale up.

Finding disinfectant wipes can itself be a chore - and an unrewarding one given the demand to protect against the coronavirus. It turns out that lots of household cleansers work quite well. Here is one from [a review by NBC News.][nbnc]

Richard Sachleben, an organic chemist and a member of the American Chemical Society, said most of the cleaning products we call soap are actually detergents that not only remove the germs from surfaces, but also kill them.

Hydrogen peroxide is not as strong as bleach, so it’s less likely to cause damage, but it can discolor some fabrics, Sachleben said. Don’t dilute it, use it straight. Hydrogen peroxide decomposes into water and oxygen.

Back when the Scribers were traveling aboard scuba diving boats I got turned onto hydrogen peroxide as an antibiotic for small wounds. And now I rediscovered it as a disinfectant to get rid of coronavirus from household surfaces.

Hydrogen peroxide is also is being used to disinfect and extend the useful life of those face masks worn by health professionals. Rabbit Hole at the Daily Beast reports on Ultraviolet Baths, Disinfecting Saunas: How Science Is Saving Docs by Saving Their Gear.

That report is appended after the break.

Vaporwave: In Ohio, researchers at the Battelle Memorial Institute, a nonprofit research group, have built on their existing research in personal protective equipment (PPE) disinfection to develop the Critical Care Decontamination System.

When health-care workers and hospitals in the OhioHealth network, a statewide health-care nonprofit, are done using a mask, they mark it with a code, package it up in plastic, and ship it out to Battelle for decontamination.

Once Battelle receives the gear, workers hang the N95 masks on racks and put them into 20-foot metal chambers. When the racks are full, the doors are closed and a generator pumps hydrogen peroxide vapor in for two and a half hours, making the chamber a kind of decontamination sauna for the masks.

Hydrogen peroxide, a key ingredient in a range of disinfectants like hand sanitizer, is effective at killing everything from bacteria from viruses, and when turned into a vapor in a confined space surrounds and permeates the masks. Battelle researchers say the method is effective at killing anything from anthrax to COVID–19 that might appear on the masks. In fact, hydrogen peroxide vapor was used to help decontaminate the Hart Senate office building and Washington, D.C.-area mail facilities after the 2001 anthrax attacks.

Easy on your delicates: The vapor isn’t just good at killing pathogens, it’s also easy on the equipment. In a previous study, Battelle researchers found that the vapor “did not degrade the performance of the aerosol filtration media” in the model of N95 masks they tested. The straps alongside the masks experienced did suffer some degradation after going through 30 repeated cycles of the machines.

But that’s not as big a problem as it may seem. The FDA says that respirators are safe to undergo up to 20 cycles through the Battelle system, meaning that individual masks aren’t going to see the same amount of exposure that caused degradation in previous tests.

Scaling up: When the outbreak first took place, Battelle began decontaminating masks with its system at a rate of about 1,000 pieces of PPE per cycle. Following a public plea from Ohio Gov. Mike DeWine, the FDA allowed Battelle to increase its rate to 10,000 pieces of equipment a day. Right now, Battelle is decontaminating PPE for OhioHealth, but the organization plans to make more for national distribution, and one system is already en route to the New York metropolitan area to address shortages there.

Off the shelf: Battelle’s method is promising not just because prior research has shown it to be effective but because it relies in large part on equipment that’s already available commercially. At the heart of the system are commercial hydrogen peroxide generators. The devices can be small, luggage-sized mobile devices available for a few thousand dollars. They’re already used widely for decontamination purposes across the health-care industry, including for decontaminating operating rooms, research laboratories, and other sensitive areas.

The decontamination chambers themselves are standardized 20-foot CONEX box shipping containers, a common design around the world that has been in use since the Korean War. And of course hydrogen peroxide is a simple, cheap, and easily made and widely available commodity with a proven history in decontamination.

Origins: We’ve known for a while that a pandemic influenza could be coming and that it would cause a run on PPE. A 2009 interagency working group on respirators (dubbed “Project BREATHE”) recommended the FDA develop standards for cleansing and reusing face masks because “during a crisis in which respirators may be in short supply, respirators that are durable enough to be repeatedly reused may be necessary.”

It’s a recommendation that public health experts have been warning about for a long time.

Battelle researchers were able to spin up their industrial-strength PPE cleanser because their research on the subject had a head start of a few years. In 2016, Battelle researchers pointed to the threat of a pandemic influenza as a motivation for their report on the use of hydrogen peroxide vapor to decontaminate N95 masks. The authors cited a 2006 study by the National Academy of Sciences on the need for reusable respirators, which warned that “demand for N95 respirators by the healthcare sector could exceed 90 million for a 42-day outbreak.”

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