The Mystery of the White Mist

28 Sep

Cleaning before use is common practice

More and more containers and devices are being processed in cart washers using standard cycles with recycled water (sometimes softened) and a new dose of chemical agent each time it’s run. We are told to wash off fruits and vegetables during food preparation or we can get sick from fungicides and other toxic pesticides. We know that all reusable medical devices must be cleaned and rinsed before sterilization or disinfection can occur. Devices need to be monitored and certainly visibly inspected before use. If we see any residue or retained soil, the device must go back to decontam to be processed all over again. So, what’s the story with white residue and why are some manufacturers saying it does no harm to form or function of their products? Are we missing something? And why is its presence so prevalent now?


White powder residue can be so many things from detergent residue on devices not thoroughly rinsed, to corrosion or oxidation after repeated use of environmental wipes instead of cleaning and rinsing, to aluminum oxide on container surfaces after frequent use in vaporized hydrogen peroxide, to salt or sodium particles from softened water treatment gone amuck, or even from the addition of anionic surfactants in drying agents. Water quality can factor into the equation with chemical additives in the water supply and steam generator. Then, of course is the increase in processing containers and instrumentation in cart washers with recycled water. And, the frequent use of the same container several times a day for moisture and temperature sensitive devices in low temperature sterilizers without proper cleaning and rinsing.


In the cart washer, the cleaning process is followed by a final step applying a drying or sheeting agent to the product. That can be okay for stainless steel carts or your car at the neighborhood car wash, but not for containers or other devices that must be free of any residue for sterilization. Furthermore, several low temperature sterilizers are using highly concentrated hydrogen peroxide, a strong oxidizer, at concentrations above 90%. A colleague of ours with knowledge of sterilization science frequently saw a white mist after processing in a low temperature sterilizer, and a white powder residue after vaporized hydrogen peroxide sterilization on containers and on single use wrap as well. We have never seen white residue or mist after steam sterilization. We have noticed that manufacturers of automated washer disinfectors are reducing the number of rinses and rinse times while increasing the amount of detergent to compensate. In researching drying agents applied as a last step in the cart washer, we discovered that some are alkaline and contain anionic surfactants that can contribute to an increase in pH. Meanwhile containers used in low temp and steam last a lot longer than those used exclusively in low temperature sterilizers.

The Perfect Storm

Imagine when a combination of factors comes into play. The mystery is harder to solve. A perfect storm is when a “critical or disastrous situation is created by a powerful concurrence of factors”. The book the Perfect Storm and the film that followed was about the 1991 Perfect Storm that hit North America between October 28 and November 4, 1991, and features the crew of the fishing boat Andrea Gail, from Gloucester, Massachusetts, who were lost at sea during severe conditions while longline fishing for swordfish 575 miles (925 km) out. I remember the Perfect Storm that hit us here in the northeast from Hurricane Sandy in October 2012, and the disastrous flooding that occurred to our building and the greater NY area.

Be prepared and be informed

In this scenario that we are trying to solve, there are so many factors to consider that we may not be able to figure out the cause in each case…whether it is the use of alkaline detergents, the water quality, the cart washer, the drying agent, water softening treatment, corrosion from overuse? And if the container is used so frequently during the day, whether there is truly any time left between cases to clean and rinse off the mysterious white residue after each use. Sometimes a mystery cannot be solved at all.

No matter the cause, we have a solution.

Always use a pH neutral or enzymatic or non-enzymatic detergent to clean containers after each use. Rinse thoroughly under the flow of water. If you decide to use a cart washer to clean your containers and instrumentation, always use the instrument or container cycle and follow with a thorough rinse with clean preferably high purity water. Never apply a sheeting or drying agent or lubricant. If you sterilize devices in low temperature units, plan for proper cleaning, rinsing and drying beforehand. Bring your container and devices to room temperature. And if you see white powder, wash it away. If you have cancelled cycles and see a white mist, call your sterilizer manufacturer for service.

Problem solved…It’s always chemical

Keep it simple. Use less chemicals. Use our validated, EPA Safer Choice certified cleaners to retain the useful life of our SteriTite containers and for other devices you may have. They are free rinsing, high performing, biodegradable, non-toxic and safer for patients and staff. If you must use a wipe, use one that is pH neutral, non-caustic and validated for the intended purpose, like our PentaWipes. Then follow with a thorough rinse under the flow of water. It’s not hard to do. Avoid the use of hazardous chemicals for cleaning and decontamination. They are not helping to speed the process nor are they needed for decontamination when sterilization or disinfection follow. You can avoid cancelled cycles and save time and money, too. Remember damage to medical devices is usually due to chemical agents…use less. Case closed. In the end it’s up to you, and we are here to help!

Case Medical is a US EPA Safer Choice Partner of the Year, Best in Class Midsize Employer for NJIT, Enterprising Women in Commerce 2023 for CIANJ and Sustainable Manufacturing 2022, and finalist in Life Science Leader in Manufacturing, and currently a finalist for NJ Innovator of the Year.

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Kindest Regards,

Marcia Frieze and the Case Medical team

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