Weighing reuse against single use in healthcare
Choosing between a reusable healthcare product and a single-use one trades one environmental impact against another, and patient safety can be counted for the individual patient or for the population. Many single-use products can be designed for reuse, and the COVID-19 pandemic's masks and respirators showed what reuse demands: decontamination that works, leaves the item usable, is cheap and does not depend on a stable energy supply.
Trading one environmental impact against another
A goal such as carbon neutrality might be met through changes that make other aspects worse, such as a carbon reduction that comes at the price of increased water use. One example from companies is the switch from metal vats to plastic ones: metal vats are more sustainable from a waste perspective but need a lot of water to clean them between manufacturing runs, whereas plastic vats are used once and thrown away, terrible from a waste perspective but better from a water perspective. One researcher of the pharmaceutical supply chain had no answer for how such trade-offs are made, and saw more and more scope to bring philosophers and ethicists into the conversation. In her view, a change that can be shown to have a positive impact on one area and the least possible negative impact on another would be the way to go.
Designing devices for reuse
Healthcare's unintended negative impact on the environment, and so on human health, has gained attention in recent years, and implementing circular economy principles can help tackle the healthcare industry's waste generation and make its procurement policies more sustainable.
By 2021 the circular healthcare economy had been applied to the reprocessing and recycling of medical and pharmaceutical devices and instruments, and the move away from single-use materials is attractive both environmentally and financially. The COVID-19 pandemic highlighted the supply-chain vulnerabilities of single-use equipment, as shortages of single-use personal protective equipment led to its reuse. Many single-use products can be designed for reuse: steel surgical instruments can be sterilised and reprocessed, non-infectious waste can be recycled, and endoscopes or blood-pressure cuffs can be disinfected for reuse. Even devices that can only be single-use on safety grounds, such as needles and catheters, could be recycled to recover their base materials. In 2021 many hospitals were already reusing products designated as single-use to decrease costs, and some manufacturers were starting to move towards this model. Medical device manufacturers could also sell a service instead of a product, maintaining equipment rather than replacing it, as in the refurbishment of imaging equipment or the resharpening of blades. A service model encourages manufacturers to design repairability into their products, could help companies expand their markets by reducing upfront costs, and could help businesses achieve both ecological and economic balance.
Patient safety for the individual and for the population
When considering patient risk, regulatory bodies and professional societies tend to favour single-use medical devices for the safety of the individual patient, for example to minimise the risk of infection. One review of the circular healthcare economy argues that if patient safety is expanded to population health, the social and environmental damage and pollution associated with the single-use supply chain must be taken into account, and single-use devices do not appear so attractive. It holds that regulation and oversight should promote population health as well as individual patient health and prioritise circular product design and reuse where safe, with single-use labelling only for products whose safe reuse cannot be achieved.
Single use and the pandemic's shortages
Throwaway culture has risen steadily within the healthcare sector, and disposable healthcare consumables have progressively replaced reusable staples since the 1960s. The shift went largely unremarked, or may even have been welcomed by harassed healthcare professionals who no longer needed to sterilise much of their kit: don, doff, discard, done. As the COVID-19 pandemic accelerated in 2020, it exposed the unsustainable nature of such a generalised single-use-only approach. In early 2020 the global demand for personal protective equipment far exceeded manufacturing capacity, and the World Health Organization anticipated a global monthly requirement of 89 million masks, 76 million gloves and 1.6 million goggles. To combat critical shortages, the WHO issued interim guidance on rationing personal protective equipment and recommended its reuse in March 2020. One virologist who trialled decontamination techniques at the time reads this call, on its face a measure to make more surgical masks and respirators available during the crisis, as an important step towards a more sustainable circular healthcare economy.
The footprint of a single-use mask
Life cycle analyses, which take into account greenhouse gas emissions from production to disposal, put the carbon footprint of a single mask at between 32.7 g and 65.5 g of carbon dioxide equivalents. The total global warming potential of all disposable surgical masks supplied in a single year of the pandemic has been calculated at 1.1 megatons of carbon dioxide equivalents. Since the beginning of the pandemic, discarded single-use items have caused widespread environmental pollution and a "shadow pandemic" of plastic protective-equipment rubbish. In 2020 alone, 1.56 billion surgical masks were reported to have entered the world's oceans, where they degrade into micro- and nano-plastics, leach toxic heavy metals and pose significant dangers to flora and fauna. Depending on the reprocessing method used, reusing a mask or respirator reduces its carbon footprint by 58% to 85%, and may help alleviate the burden of illegally dumped protective equipment.
Decontaminating masks and respirators for reuse
An item of personal protective equipment must be decontaminated before it can be safely reused, so the WHO's guidance galvanised virologists worldwide. A team of virologists at the University of Liège in Belgium was one of many groups that began trialling decontamination techniques, and it increasingly prioritised sustainable and equitable methods of readying masks and respirators for reuse beyond the immediate emergency.
Early in the pandemic little was known of SARS-CoV-2, and even tried and tested decontamination techniques had to be retested against it. The Liège team first trialled traditional methods on artificially contaminated masks and respirators: dry heat in an oven, germicidal ultraviolet irradiation and vaporised hydrogen peroxide. All three inactivated both a porcine coronavirus standing in for SARS-CoV-2 and a norovirus. Noroviruses are notorious for their hardiness, and it is a fairly safe bet that any treatment able to inactivate one will make short work of most other viruses. A disintegrated mask is no more useful than a contaminated one, so textile researchers performed breathability and filtration efficiency tests, which showed that even thrice-decontaminated masks and respirators let wearers breathe easily and protected them from airborne pathogens. Traditional methods, however, depend on expensive equipment and a stable energy supply, so they are costly and may not be feasible in low-resource settings. Electricity remains unavailable to nearly 16% of the world's population, and electricity prices have fluctuated greatly in recent years. Equitable and truly sustainable decontamination of protective equipment must be cheap and energy-independent.
In 2020 the team joined an interdisciplinary consortium of researchers from academia and industry, supported by the WHO and the research and grantmaking foundation Open Philanthropy, that was pioneering a low-tech, low-cost, low-energy decontamination technique: antimicrobial photodynamic inactivation. The technique combines light with colourants, called photosensitisers, which transfer energy from light to oxygen in the air and so generate reactive singlet oxygen, and singlet oxygen inactivates viruses and other pathogens by breaking apart their chemical bonds. The team chose methylene blue, a textile dye used since the 1870s and a WHO-listed essential drug. Contaminated masks and respirators were sprayed with a methylene blue solution and exposed to light for half an hour. One gram of methylene blue is enough to spray over 3,000 masks or respirators, so a single item can be decontaminated for less than €0.01. The light first came from custom-built LED light boxes, but sunlight did the job just as well, and the method decontaminated the equipment efficiently even under a cloud-shrouded sun on an overcast day. After three years of research the team had found a near-energy-independent way to decontaminate masks and respirators. In 2024 research into decontaminating protective equipment this way was continuing.