March 24, 2020

Slow Cooker to Sterilize Many Items Against COVID-19 Quickly

I have seen a few posts on physician forums regarding heat inactivation of COVID-19 based on SARS data... Mainly that rapid inactivation occurs at low temperatures; surfaces "were converted to be non-infectious after 90-, 60- and 30-min exposure at 56 degrees Celsius, at 67 degrees Celsius, and at 75 degrees Celsius, respectively." [link]

Based on this data, there is a cost effective way for small offices (or at home if you are concerned as you shouldn't use your home oven) to sterilize many items quickly that I have not seen or read about anywhere.

Use a large portable slow cooker or roaster oven that can even fit a turkey (less than $100!). In spite of its "slow" cooker moniker, these cookers can quickly achieve sustained temperatures up to an overkill temperature of 230° Celsius to mass sterilize any items touched during a regular clinic day that may become contaminated via touch including clipboards, pens, regular masks, paper, paperclips, etc. Or if you are in a home situation items like car keys, eyeglasses, shoes, toys, pens, etc...

You can just throw things in the slow cooker as items get used/exposed and at end of the day, it is turned on. Things do not melt when raised up on the included tray at the recommended temperatures.

I feel this may work better than UV-C sterilizers as not all parts of a given item may be equally exposed to appropriate levels of UV-C, especially if many items are bulk processed at same time.

Also, wiping down many frequently used non-medical items repeatedly throughout the day with cleaning products is wasteful when supplies are already limited. Also, can one honestly say they truly wiped down every little ridge and crevice of a pen after use or clipboard thoroughly, EVERY single time???

Please note, I personally still sterilize all medical equipment the standard way (cidex for endoscopes, alcohol wipes for otoscope handles and exam chairs, door handles, etc, and autoclave for surgical instruments). The slow cooker sterilization is really only meant for NON-medical items that also needs sterilization due to pandemic concerns (ie, pens, paper, clipboards, clips, keys, etc).

The data is less clear whether this sterilization method would work on N95 masks. The mask will certainly be sterilized... but would the mask retain its important filtration properties afterwards? The only thing I was able to find to answer this question suggesting slow cooking N95 masks should be fine is based on research out of Stanford (courtesy of Dr. Larry Chu on Twitter from a PowerPoint presentation). Please note, I am not recommending N95 masks be sterilized using a slow cooker and only point readers to this preliminary data in order for individuals to draw their own conclusions.

Standard disclaimer being everyone should strictly adhere to your hospital's policies and procedures.

In any case, look at the first row.... You can draw your own conclusions.


There is also this information put out by University of Tennessee who has made similar recommendations who stated additionally that N95 masks should NOT touch any metal surface while undergoing heat inactivation.

Should you decide to use a slow cooker, beware that the built-in temperature dial is not very accurate. I would double-check the temperature with a separate thermometer to ensure the slow cooker reaches the target temperature (between 75-93 degrees Celsius; going higher risks melting plastic items). With the 2 slow cookers we are using, one required the dial to be set just past 150 degrees F while the other required the dial to be set just below 150 degrees F.

Read some other simple steps you can take at home to minimize COVID-19 spread around yourself and loved ones beyond the well-known steps of washing hands frequently, stay home, avoid touching your face, maintain social distancing, cleaning surfaces routinely, wearing a mask, etc.

References:
Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation. Biomed Environ Sci. 2003 Sep;16(3):246-55.

Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine. March 17, 2020.

Can Face Masks be Disinfected After for Re-Use? Stanford University. Taken from PowerPoint presentation.

Information and FAQs on Performance, Protection, and Sterilization of Masks Against COVID-19. UTRF News, 3/25/20.


Fauquier blog
Fauquier ENT

Dr. Christopher Chang is a private practice otolaryngology, head & neck surgeon specializing in the treatment of problems related to the ear, nose, and throat. Located in Warrenton, VA about 45 minutes west of Washington DC, he also provides inhalant allergy testing/treatment, hearing tests, and dispenses hearing aids. He is also the chief medical officer of O2Labz, a medical and scientific 3D animation company.

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