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Background

The Fly Facility in the School of Biosciences breeds and maintains stocks of Drosophila melanogaster, also known as fruit flies. These are used universally in biomedical research as a model organism to help us understand a wide variety of biological processes, from cell plasticity in development and disease to macrophage behaviour and neuroscience.

Until last year, all flies were kept in single-use clear polystyrene vials and plugged with cotton wool. These would be used for up to six weeks at a time before the flies were decanted into a fresh vial. The original vial and cotton stopper would be disposed of. This way of working meant that the facility was using around 285,000 single-use plastic vials and around 330 kg of cotton wool each year.

A New Approach: Washing and Reuse

Fly Facility Manager Kath Whitley was keen to explore washing and reusing vials, feeling uncomfortable about the extent of material used and waste produced by the facility. However, this idea raised several questions, including which vial material would be most suitable, the best methods for cleaning the vials for reuse, and the availability of washing facilities and technical support. Additionally, there was uncertainty about whether the lab’s technical team had the capacity to implement a reuse process and whether the environmental benefits of reducing material usage would outweigh the impacts of the washing process. 

With the help of the Environment Team in EFM, the fly technical team explored different washing techniques that would remove the stubborn residue of fly pupae, leaving the vials clean enough for reuse. Both plastic and glass vials were trialled, as were a range of dishwasher configurations and programmes. Glass vials came out best as they were not scratched or clouded by washing and reuse. A short soak in the sink, followed by manual removal of the fly pupal cases stuck to the inside of the vials, then a 10 minute run in the dishwasher with just hot water was found to be sufficient. It was deemed that they could be reused about 40 times. Custom steel mesh baskets to hold the vials in the dishwasher were made in-house by colleagues in a workshop in the Faculty of Engineering.

Kath and her team also trialled replacing the cotton wool stoppers with reusable foam bungs. They found that the alternative bungs allowed the flies to reproduce well, whilst keeping out possible contaminants such as mites. The bungs could be washed easily in a domestic washing machine. 

Quantifying the Impact

As a result, one third of the single-use plastic vials were switched out for reusable glass vials and all of the cotton wool bungs were replaced with reusable foam bungs. The partial switch to glass vials was due to the additional labour required to process the vials for washing: the Fly Facility’s technical team and the Biosciences glasswashing team have the capacity to process around 2000 vials per week for reuse. With 40 reuses, the initial order of 20,000 glass vials should last for nearly nine years!

Having established suitable washing procedures and reusable replacements for the single-use vials and bungs, Louis Garnham from the Environment Team in EFM conducted an environmental impact assessment to quantify the benefits of moving away from single-use labware. The process was similar to that of a Life Cycle Assessment, which looks at the environmental impacts of products across their entire lifetimes, from the extraction of the raw materials and manufacturing, right through to disposal. It mostly involved mapping out the different life cycle phases of various vials and bungs, and using the UK Government’s to measure impacts in . 

This analysis revealed that a glass vial washed and reused 40 times does the same job as a single-use polystyrene vial, but with 90% fewer carbon emissions; 4.5 grams of CO2e per use, versus 42 gCO2e for polystyrene. Switching out a third of the plastic vials as well as all of the cotton stoppers means that 4.8 tonnes of carbon emissions are avoided each year on average, equivalent to three economy flights to New York. Not only that, the lab is forecast to save approximately £12,000 on consumables annually. 

Naturally, these savings haven’t come for free - the changes described have created around 15 hours of work per week. Nonetheless, this has been deemed a worthwhile investment given the substantial environmental benefits and the fact that minimising emissions where practical is the direction that research must move in. 

The bar chart below shows the emissions associated with each life cycle phase of the polystyrene and glass vials. More specifically, it compares the emissions from each phase for vials in three different scenarios (single-use polystyrene, single-use glass, and reused glass) in terms of the function performed: storing fruit flies for 6 weeks. This means that when the glass vial is reused 40 times, the emissions ‘per function’ from the life cycle phases other than use and washing are reduced by a factor of 40. 

The material production of both plastic and glass is by far the most environmentally impactful phase. This is why keeping products in circulation and reusing them is more important than ensuring they are recycled. Reusing or repurposing to keep products in circulation avoids the need to keep extracting resources and manufacturing new products. Manufacturing new products is incredibly carbon-intensive, as well as being a drain on finite resources. In fact, the emissions associated with washing and drying the vials (which come from the generation and supply of electricity and water, plus wastewater treatment) are very small compared to those produced by the manufacture of the vials, and hence washing and reusing is the environmentally preferable option.

Conclusion

The Fly Facility’s switch to reusing labware highlights the importance of thoughtful, practical sustainability initiatives within research settings. By rethinking common practices and embracing reuse, the team has significantly reduced carbon emissions, minimised material consumption, and reduced their spend on consumables. 

The environmental impact analysis helps to explain exactly why reusing labware, and keeping products in circulation more generally, is superior to buying products with low embodied carbon and recycling them: the majority of the emissions associated with most products are related to extracting raw materials (from finite natural reserves) and manufacturing them. With reuse, we remove the need to continue to manufacture new products.

This approach demonstrates that even partial changes and incremental improvements can result in meaningful environmental and financial benefits, especially when it comes to single-use plastics. This project also highlights what can be achieved with collaboration between research facilities and sustainability teams, serving as an example for others to make their research more sustainable.

Kath Whitley, Manager of the Fly Facility, said: “The replacement of single use plastic vials and bungs with reusable glass and foam stoppers has reduced the carbon impact of the fly facility considerably. I hope this work will encourage other labs to improve their sustainability to ensure the University fulfils its aims of becoming a net zero campus. The team are now working to switch single use bottle bungs with washable, reusable alternatives. We are also investigating the possibility of investing in a new glass washing machine which could reduce the technical time taken or increase the numbers of vials washed per day.”

A note on the accuracy of the environmental impact analysis

Using the introduces some degree of error due to the lack of specificity. This is particularly true with the material production phase, as a generic quantity of carbon is provided for the production of polystyrene and of glass and used for this analysis, as opposed to more precise quantity based on the specific supply chains, manufacturing processes, and energy supplies of each of the polystyrene and glass vial manufacturers. Sourcing this information is not practical at this time. Nonetheless, the savings incurred by reuse far outweigh the margin of error introduced by using these generic quantities.

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Louis Garnham 

Environmental Projects Co-ordinator

Estates and Facilities Management 

If you’re interested in knowing more about the environmental impact analysis, contact Louis Garnham from the Environment Team at l.garnham@sheffield.ac.uk. For more information on what’s happening in the fly facility, contact Kath Whitley at k.whitley@sheffield.ac.uk.