TL;DR

• Healthcare accounts for 5–8% of national carbon emissions, with about 20% of healthcare waste classified as hazardous and requiring specialized disposal.
• Incineration and steam autoclaving handle most hazardous medical waste, each with different environmental, operational, and cost trade-offs.
• Operating rooms generate large volumes of waste, and studies suggest up to 90% of materials placed in infectious waste streams could be disposed of as regular waste.
• Medical device developers can reduce waste by minimizing disposable materials, exploring reusable components, and selecting recyclable materials with clear labeling.

Did you know that 5-8% of total national carbon footprints come from the healthcare sector? Much of this (around 80%) is general waste – such as from office work – and the rest (~20%) requires special handling due to its dangerous nature.

Let’s examine hazardous medical waste types, their treatments, and what can be done better.

Types of Hazardous Medical Waste

• Organics (tissues, contaminated medical devices) (15% of medical sector total)[1]
• Chemical/ Pharmaceutical (3%)
• Sharps/needles (1%)
• Genotoxic and heavy metals (1%)

How is Hazardous Medical Waste Disposed Of?

An estimated five sixths (~83%) of hazardous waste is either incinerated or autoclaved.

• Incinerated (roughly half[2])
  • There are a few methods, but generally speaking the waste is heated to over 1000^oC.
  • Sometimes incinerated residue is further processed (liquid, particulate, or air pollution control devices – though these can be rare (2% in one study[3]))
• Steam Autoclaved (roughly one third)
  • Only works with highly exposed surfaces. Often the waste is shredded first to increase surface area, adding a step to the process, depending on the desired materials to be processed. [4]
  • Heats steam to ~150^oC[5]
  • Resultant “safe” waste is then handled like common waste
• Comparison
  • Incinerated residue is only about 3% of the original mass[6], whereas autoclaving does not transform any mass to gas, for better or for worse.
  • Autoclave machines require less maintenance but cost more up front[7].
  • Autoclave machines tend to function more effectively, meaning the resultant materials tend to have fewer surviving microbes.
  • Autoclave machines don’t have to be as centralized to be efficient: some waste processing machines are as small as ovens and operate in hospitals.
  • Both have environmental drawbacks and mitigations depending on the facility and location, meaning one is not always more ‘environmentally friendly’ than the other.[8]
• A note on batteries:
  • Disposable or reusable non-contaminated batteries are disposed of the same way you would at home: landfill or recycling
  • Disposable contaminated batteries, like those embedded in medical devices, are processed along with the device they are embedded in (incinerated or autoclaved).  
  • Reusable contaminated batteries are first disinfected and then recycled. Reusable lithium-ion batteries generally cannot be incinerated.

What Waste Materials are Generated by Medical Devices?

• Shipping Containers
  • Often cardboard with plastic packing
• Sterile Barriers
  • Common materials include Polyethylene, Tyvek, PVC, PA (nylon).
• Backer Cards, Wrapping, or Other Support Materials
  • Backer cards are often Polyethylene, Polystyrene, paperboard
  • Sterile wrapping can be made from Polypropylene
• The Medical Device Itself
  • Often plastic, sometimes includes some metal

Are These Materials Recycled?

In theory and if clean, the outer packaging, sterile barrier, and support materials can all be disposed of in the same manner as office waste: recycled or landfilled. In reality, this doesn’t happen. Here are some facts[9] [10]:

• The medical device industry is trending away from reusable towards disposables.
• 20-33% of hazardous healthcare waste comes from operating rooms (ORs)
  • Each operation generates about 12kg of waste, much of which is draping, gowns, and breathing tubes. Blue wrap (sterile wrap) alone accounts for 11.5% or 1.4kg of all OR waste.
  • OR waste is supposed to be separated into general waste and infectious waste, but up to 90% of material sorted into the infectious waste system should have been sorted as common waste.
    • Up to 40% of that waste is packaging materials including blue wrap.
• Often, syringes and needles are disposed of together in sharps bins unnecessarily. Sharps are 200x more expensive to dispose of by weight.
• The greatest barrier to recycling was found, in one study, to be confusion about what is recyclable. The same study found that only 20% of medical plastics are labelled with recycling symbols.

Other Points of Interest

Concerns are higher in developing countries, where improperly handled waste can cause more acute pollution or harms, such as leaching into water tables or needle stick injuries.

Sterilization, especially radiation sterilization, can change the chemical structure of plastics. How this may impact their recyclability would have to be examined on a case-by-case basis.

References

[1] hcwmanagement-factsheet-rfhe.pdf

[2] What Is a Medical Waste Incinerator and How Does it Work? | Knowledge Center | Daniels Health

[3] https://www3.epa.gov/ttnchie1/ap42/ch02/final/c02s03.pdf

[4] Autoclave vs incineration: which is best for medical waste disposal?

[5] Autoclaves For Medical Waste 101 | Healthcare | Stericycle

[6] Autoclave or Incinerator for Medical Waste, which one is better?

[7] Incineration or Autoclave? A Comparative Study in Isfahan Hospitals Waste Management System (2010) – PMC

[8] Autoclave Vs. Incinerator: Which is the right choice for you

[9] Managing barriers to recycling in the operating room – ScienceDirect

[10] (PDF) Reducing the Environmental Impact of Sterilization Packaging for Surgical Instruments in the Operating Room: A Comparative Life Cycle Assessment of Disposable versus Reusable Systems

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