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Sophie Benson
“An LCA only gives you so much of the picture. It’s not the be all and end all of environmental impact,” says Simon Hann, principal consultant and LCA specialist at sustainability consultancy Eunomia. This is applicable to every product and material out there, but in plastic's case there are myriad unquantifiable environmental and social impacts - some that are newly emerging - that either don’t make it into an LCA or don’t make it into wider reporting. After years of inaccuracy and assumptions, it’s time to put the plastic LCA under the microscope.
In order to really dive into this issue, it’s important to understand the limitations of LCAs in general. As we explored in our article, Mythbusting: LCAs are reliable comparative analyses, depending on the practitioner, their experience, their interpretation, and the data they use, two LCAs examining the exact same product or material could have markedly different outcomes. One may use specific data supplied by a producer, for instance, while one may use generalised industry data. “An LCA of the same product completed by 10 different LCA practitioners has the potential to yield 10 somewhat different results,” says Baijia Huang, sustainability manager at Rockwool Group.
One may be commissioned by a manufacturer, and the question being asked will be shaped accordingly, while one may be commissioned by a sceptical NGO. “A properly peer reviewed, credible study will have a system boundary that reflects both alternatives equally. That being said, you can produce studies that answer the question you want to ask. They can be fully compliant and peer reviewed, but aren’t particularly asking the right questions or [are] asking a question from the perspective of the company who wants to prove something,” says Hann. “So there’s always vested interests and perspectives to take into account.”
In Eunomia’s 2020 report, “Plastics: Can Life Cycle Assessment Rise to the Challenge?”, written by Hann, the results of the 2018 Danish LCA comparing carrier bags, which led to the '20,000 uses' figure, were analysed. There were multiple issues with the accuracy of the LCA, including the functional unit for the organic Cotton tote being overestimated and therefore doubling all impacts, and the modelling of organic cotton production being based upon modified conventional cotton data. “The cotton datasets in this study would likely fail to meet an assessment of data quality for at least time and technology aspects,” says the Eunomia report. These oversights, combined with the misleading reporting - which we’ll cover later - significantly altered both the results and the public's understanding of the comparison.
While there are certainly limitations to what's included in LCAs, we must also consider what they don’t include. “One of the problems is LCAs essentially have carbon blinders on,” says Sonalie Figueiras, co-founder of Source Green. “And when you limit everything to just carbon, plastic can sometimes look attractive compared to other materials.” For instance, if you only focus on carbon emissions when comparing Glass to plastic, you could conclude that glass is the ‘worse’ material because it's heavy and energy intensive to recycle. What this analysis misses, however, is impacts such as plastic’s persistence in the environment and its interference with the food chain. “If you look at the entire lifecycle of plastic packaging, or a plastic material like PET that goes into clothing, and you go from extraction all the way to end-of-life, you find that the real cost of plastic is far greater than any of the other alternatives,” says Figueiras. “The problem is these reports live in this universe of wishcycling, whereby the end-of-life is assumed as recycling.”
A 2015 comparative LCA by Quantis studied the difference between a single-serve coffee system and bulk coffee, and declared the single-serve system to have “better environmental performance” despite the fact that “it generates more packaging waste”. However, the report assumed recycling at average North American residential recycling rates, overlooking the fact that coffee capsules are notoriously difficult to recycle. There was also “no indication that the selected packaging [was] actually recyclable”, according to a report by Zero Waste Europe. Even when plastic is recycled, there's no accounting for leakages in the system after collection, whether that’s to the environment or via irresponsible exportation - not to mention that plastic is only ever downcycled, given one more life before it eventually ends up in landfill.
“If you look at the data over the last 50 to 60 years, recycling is a giant failure. If you look at the rates of what happens to plastic at the end-of-life, the bulk of it is getting ... incinerated and causing pollution, ending up in landfill, or getting lost in the environment,” Figueiras continues. “Then eventually the sun or water exposure is breaking it down into ... microplastics, which are environmentally damaging to biodiversity and the ecosystem.”
The inability of LCAs to incorporate these far-reaching impacts, at least numerically, hasn’t gone overlooked. A 2022 paper explored the possibilities of a methodology to account for further potential impacts of plastic emissions. Stating that present LCAs “do not consider possible risks caused by the emission of plastics into the environment”, the paper proposed characterisation factors (CFs) for plastic emissions, allowing for the calculation of impacts of plastic pollution based on plastics’ time in the environment. The CFs included fate factor, “the transmission and distribution of a plastic item between the environmental compartments and its degradation within the environmental compartments”; exposure factor, which “addresses the probability of exposure of humans or animals to the plastic emission”; the effect factor, “the sensitivity of a species to the pollutant”; and the severity factor, “the expected severity of damage”. The implementation of such a methodology would be welcome, but it’s not standard, and ultimately the decision rests with the practitioner as to whether or not they would include it in their calculations.
Hann describes environmental plastic pollution as “a parallel stream to deal with separately”. “You can say that plastic is great for what it does. It may reduce environmental impact, but that doesn’t mean you should ignore the other side - you should work on these two strands in parallel,” he continues. For the time being, Hann says that factors that are as yet unquantified or unquantifiable should be addressed within the body of the report to ensure the reader has the full picture beyond the ‘score list’.
While a more thorough approach to research will add clarity and caveats to plastic LCAs, there is no guarantee these details will be translated into wider reporting, meaning the headline remains the same: plastic is better. Circling back to the tote bag LCA, many publications ran with the 20,000 figure because it was explosive and seemed to completely blow the perception of tote bags being an environmentally responsible choice out of the water. However, as the Eunomia paper points out, that figure is from the perspective of ozone-depleting emissions. Cotton bags may well be worse than PE for ozone depletion, however, after data normalisation and accounting for global warming potential, just 31 reuses are necessary to break even with a single-use PE bag. Not quite as headline grabbing.
Similarly, a 2020 LCA of beverage packaging stated that “in each category there was a less impactful beverage packaging than plastic bottles”, however the headline from one outlet stated that “glass bottles have a larger environmental impact than plastic bottles”. The article itself went into further detail, but such headlines are what tend to stick. “You look at [the reporting] and it’s just a PR statement, it’s not a study, it’s barely even an executive study. I tend to ignore anything that isn’t a fully published study,” says Hann.
Alongside external oversimplification of data is an internal oversimplification of plastic use and its impact, rooted in the present with no consideration for what's coming down the line. “We don't have studies that conclusively say exposure to each different type of plastic or microplastic has an X, Y, Z impact, but more research is coming,” says Figueiras. And as research around the impacts of pollution and toxicity grows, as waste landscapes change, and as more data can be quantified, it will become harder to paint plastic in a positive light.
One change that's coming, Hann points out, is the increasing use of plastic as a waste-to-fuel substitute for food waste in the EU's incineration waste stream. Binding contracts means municipalities must 'feed' incinerators with a certain volume of fuel, a quota that was previously met with food waste. Now food waste is being diverted to compost facilities instead, plastic has stepped in as a fuel substitute because of the abundance of plastic waste in the region. The impact of this burning is not currently factored into the material's end-of-life impact, but it will be, and it will sway negative. Equally, there is no consideration for how reuse systems may scale or improve, so single use is often compared to current systems, which may be inefficient or not fully realised. A company making a packaging decision for the next 10 or 20 years based on an LCA which uses data from today’s reuse system is blinkered, ignoring the rapid industry shifts which could completely transform the picture in just a few short years.
Without taking into account the many hidden costs of plastic, an LCA simply cannot provide the basis for a holistic comparison.
LCAs, for any material, are not perfect. They are only as good as the data used, the approach and experience of the practitioner, and the questions being asked. They are a useful tool for estimating impacts but their limitations should always be kept in mind when digesting the results.
Many LCAs assume best case scenarios for plastic's end-of-life, using average recycling figures where they may not apply, or discounting inevitable leakages after collection. Take care to scrutinise, and challenge, the end-of-life scenarios being proposed.
From microplastic pollution to toxicity and its impact on human health, many of the impacts of plastic simply aren't quantifiable, as research is still emerging. Be aware that such impacts may be addressed within the body of an LCA rather than being reflected in the scores. If they are not addressed, a healthy dose of cynicism is recommended.