Unwrapping environmental benefits: Assessing the life-cycle of sterilization containers

Sterilizing the surgical instruments used in healthcare facilities is a critical procedure required to help minimize patient infection during surgery. Two primary methods are used to contain the surgical tools during sterilization processes and ensure sterility is maintained before patient use. The first is disposable surgical wrap, or blue wrap, a single-use nonwoven sheet comprising polypropylene, an inert polymer derived from petrochemicals. The disposable wrap is designed to allow the sterilant, usually steam, to penetrate and sterilize the instruments. Structural changes to the wrap during the sterilization process prevent entry of microbes and potential contamination during storage.

A second option is a reusable hard case often comprised of aluminum. Surgical tools are placed in the hard boxes which are designed to allow sterilant to penetrate through a small piece of nonwoven polypropylene to sterilize the content of the case. Similar to the disposable wrap, the hard case is used to maintain the tools’ sterility until patient use.

Healthcare facilities incur considerable annual expense in managing the surgical tool sterilization process. The ongoing purchase and disposal of the single-use wrap is a contributing factor in these costs. Similarly, the high initial cost of the reusable sterilization cases as well as handling and storage requirements can be deterring factors in their use.

The primary objective of this project was to provide a comparative life-cycle evaluation of reusable and single-use surgical tool sterilization containers to quantify extended environmental impacts of both the disposable polypropylene sterilization wraps and the reusable aluminum hard sterilization cases. A specific outcome of the project was to provide detailed environmental impact data on the sterilization container options to the healthcare industry and to aid product decision making processes and promote pollution prevention.

In 2012, a life-cycle assessment was initiated by the Minnesota Technical Assistance Program (MnTAP) in partnership with researchers at the University of Minnesota, Bioproducts and Biosystems Engineering Department, and a major surgical department at Mayo Clinic to evaluate the impact of reusable and disposable surgical sterilization containers. The work was made possible with funding from the U.S. EPA Source Reduction Assistance Grant Program and administered by EPA Region 5 offices. This project is part of MnTAP’s overarching goal of providing pollution prevention assistance within Minnesota.

“When MnTAP first approached us about being a partner in this project, we thought this would be a great opportunity to generate a big picture view of the environmental impacts of both disposable and reusable sterilization systems. Contributing to this broader view is consistent with Mayo Clinic’s fundamental mission,” says Amanda Holloway, section head of facilities operations.

The scope of this study is defined as a cradle-to-grave assessment, accounting for the environmental impacts of disposable wrap and reusable cases from raw material extraction through product manufacture and use to end-of-life disposal. Mayo Clinic surgical services division allowed MnTAP to study use impacts, material utilization and inputs to the sterilization process at the facility. The results reported here are for standard procedures that avoid contamination of the reusable cases during the use process and minimize deep cleaning requirements that could substantially increase the environmental burden. Container production impacts were estimated using vendor data when available and database information for like production processes. End-of-life scenarios modeled include incineration for the disposable wrap and repair/recycle for the reusable cases. The impact categories for this study are greenhouse gas (GHG) emissions, characterized in kilograms of CO2 equivalents, and solid waste, characterized in kilograms of solid waste. The functional unit for this study was sterilization protection for 100 surgical toolsets used 365 times per year over 10 years.

Next page: Single use equals big impact

Results from this comprehensive analysis shows that instrument sterilization using reusable cases has roughly half the GHG emissions of using disposable wrap, while generating just 12 percent of the solid waste, even after the first year of use. These results indicate significant environmental advantages of reusable sterilization containers over disposable sterilization wrappings.

The figure below shows the 10-year emissions totals for instrument sterilization using blue wrap and hard cases, as well as the breakdown of emission impact by phase of the life cycle, manufacturing, use, and end-of-life. The total impact emphasizes the nearly 2:1 ratio of emissions impact for disposable wrap sterilization to reusable case sterilization. The use phase for both systems has the greatest environmental impact. This is due to the large amount of energy consumed during the sterilization and decontamination processes and emissions associated with that energy production.

Results also revealed the solid waste impact of using reusable cases is approximately 12 percent of the disposable wraps. While the original container packaging and single use disposable components of the hard case system contribute to the solid waste burden, 650 kg/year, the overall impact is over eight times lower than the solid waste generated from the 36,500 pieces of wrap required to deliver the same extent of sterilization, 5600 kg/year. The figure below indicates the primary component of the waste for the disposable container is the wrap itself while the disposable accessories and cleaning wipes are the primary component for the reusable cases.

“When the analysis was completed, we were amazed at how much impact this change could have in our environmental profile both from a GHG and solid waste perspective,” says Hovde. “A wide variety of factors go into the product procurement decision-making process, and we’re now able to include environmental impact as an additional factor for consideration.”

In the end, it is important to keep in mind that in actual practice, additional factors influence the decision whether to use hard cases or blue wrap. These factors include cost, storage space, material handling infrastructure and wrapping of various sized tools. They may also include other environmental impacts not measured here such as on air and water quality. Each facility must evaluate the opportunities, impacts, and costs of all decisions that allow them to meet the primary goal of patient care.