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Cambridge study on lateral flow test critiques environmental costs

Cambridge Design Partnership has conducted a study of lateral flow tests to assess why they use so much plastic and how they can be made sustainable, with results that could affect the billions of tests that will be made as a commercial product sold to the public rather than being made available via the NHS in the next couple of years.

Billions of lateral flow tests will be made in the next couple of years
Billions of lateral flow tests will be made in the next couple of years

Over two billion tests have been provided in the UK alone during the Covid-19 pandemic to date, but the casework has caused dismay, especially on social media – why so much plastic to house such a tiny test strip?

“Now is the ideal time to look more closely at the sustainability of these lateral flow tests, and to seek the data to demystify some of the emotional assumptions being made,” says the analysis by Matt Morris, sustainability lead at CDP and Dan Haworth, CDP’s head of diagnostics.

The development of the lateral flow test required a low-cost, low-risk device from a mature supply chain – “with proven, readily available materials that wouldn’t compromise analytical or clinical performance”.

This meant using existing plastic casework designs to retain and protect the nitrocellulose test strip. Plastic is robust, low-cost, lightweight, easy to transport, and easily printed for QR codes and LOT numbers. Critically, it’s a consistent material proven for the highest volume manufacturing and won’t interfere with the immunoassay chemistry.

To test the product, CDP “broke down a test into its constituent components and weighed them to calculate the approximate environmental impact, using standard emissions factors to calculate the carbon footprint of a single test”.

The metrics were greenhouse gas emissions and plastic waste (see diagrams).

Greenhouse gas emissions from lateral flow tests. Graphic: CDP
Greenhouse gas emissions from lateral flow tests. Graphic: CDP

They found that components needed to conduct the test account for around half of the carbon footprint and around two-thirds of the plastic waste. Packaging makes up most of the rest.

The test strip caseworks, which attracts the most comment online, is responsible for 30 per cent of the carbon footprint and 40 per cent of the plastic waste. This adds up to a lot – the UK’s lateral flow tests have a carbon footprint equivalent to around 0.5 per cent of the total NHS carbon footprint.

The research concludes that, while the casework is best left unchanged, there could be reductions from not using a waste bag, by putting more tests into a box and cutting down on cardboard packaging.

More intriguingly, the study proposes that the liquid solution could be pre-filled into the casing. This makes a difference because “the separate plastic vial used in the test kit we studied accounts for around 5 per cent of the carbon footprint and plastic waste”. Some lateral flow tests already use a pre-filled tray.

Plastic waste from a lateral flow test. Diagram: Cambridge Design Partnership
Plastic waste from a lateral flow test. Diagram: Cambridge Design Partnership

“In the short term,” concluded Matt Morris, “we recommend optimising what we have – recognising that any regulated product takes a long time to develop from scratch, and the important role that lateral flow tests are playing in management of Covid-19. But that doesn’t mean that we need to accept them as they are – they should be optimised to the extent possible within the regulatory framework, and we give some suggestions for this that could take away a surprisingly large percentage of the environmental impact.

“In the longer term, billions of lateral flow tests will be used globally in the next five years, and we should think more ambitiously about how we can re-imagine lateral flow tests for minimal environmental impact. Because it will take time to develop this design and take it through the regulatory process, we should start this now. At the same time though, we should also recognise the modest environmental impact of lateral flow tests in the context of the other things we do day to day – one lateral flow test has an equivalent carbon footprint to driving less than a quarter of a mile in an average UK car.

“In relation to pre-filling the extraction tube with buffer solution – this is actually already done on some lateral flow test kits supplied by the NHS – just not the one we analysed. Our suggestion is that should be the standard, as a minimum.

Billions of lateral flow tests will be made in the next couple of years
Billions of lateral flow tests will be made in the next couple of years

“On commercial opportunities – we think there are commercial opportunities for test kits that are well optimised to minimise the amount of material, particularly plastic, where consumers are clearly worried about excessive material use. We also think there are opportunities to develop new materials and designs for the tests, for example those from a renewable source, or even that can be recycled in household waste or returned for recycling.

“We’ve already had discussions with start-ups looking into new materials for lateral flow test kits, so it’s an opportunity that others have identified too. And we don’t think it’s just a short-term opportunity for Covid – the pandemic has demonstrated the wider potential of lateral flow tests and in future it’s clear they will be widely used in the home.”

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