No silver bullet to a Sustainable Design: A case for high-performance plastics.
During the design stage of a product, the designer decides to select a plastic material with a lower carbon footprint after considering several design iterations during the Design for Sustainability (DfS). The final product design achieved the lowest carbon footprint solely based on the global warming potential values of the screened materials. During the distribution and use phase of the product, there was a significant level of plastic leakage which later found its way into the environment. Taking several steps back to the DfS stage, if we assume the design decision was not based solely on its minimal carbon footprint but on other environmental impact categories like Acidification, Eutrophication, Human toxicity, etc. The designer would still have focused on the GWP due to the level of importance given to the impact category by almost all corporate strategies and the lack of adequate interpretation of other impact categories for decision-making. A typical example is the AWARE water deprivation potential indicator, how well can this LCIA value be explained to a non-LCA practitioner during product or organizational LCA? We’ll leave the discussion about LCIA interpretation for another day.
Back to the product, it is no fault of the product designer and an LCA practitioner would not have necessarily made a better decision. The current LCA methodologies do not account for the impact of microplastics caused by plastic leakage. The closest impact indicator is human ecotoxicity which currently accounts for the chemical additive effects of plastics but not the physical effects on aquatic organisms such as entanglement, smothering, etc.
According to The International Union for Conservation of Nature (IUCN), Plastic leakage is the potential amount of macro and microplastics that are not kept in a circular loop or properly managed at their end-of-life, and thus leak into the environment. In simple terms, the percentage of a known amount of plastic in a plastic product that is lost due to human activities. Check the wheels of your travel luggage, are they still as perfectly round t as when you got them? Obviously not; little scratches due to friction have caused a change in the size of the wheels. Where did the tiny pieces (micro-plastics) at the edges go? Yeaaa! That’s plastic leakage at the use phase, think of it as the crumbs from your bread during breakfast that ends up in the bin, call it “bread leakage”. Now, think of millions of plastic products that have gone through different types of friction or abrasion, in their use phase. This also happens at the EOL of the product due to waste mismanagement at transportation and disposal (see fig 1). According to research co-published by the Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, and American Chemical Society, the potential impacts of microplastic include oxidative stress, DNA harm, organ malfunction, metabolic imbalance, immune reactions, neurotoxic effects, and reproductive or developmental harm. Furthermore, epidemiological findings indicate potential associations between microplastic exposure and various chronic ailments.
The potential amount of leakage depends on several factors such as the fragmentation rate(FR) of the plastics which is related to the mechanical property. Studies have shown that most microplastics are products of commodity plastics such as PP, PE, and PVC which have inherent higher FR compared to engineering and higher-performance plastics (see fig 2).
Back again to our product designer, have we created more confusion than answers for the little guy? Of course we have, maybe we should start focusing on more environmental indicators than just carbon footprint. A product designed with plastic with a low fragmentation rate with very low potential of causing harm to humans and aquatic environment due to microplastic or a product with a lower carbon footprint that has all the potential of chemical and physical ecotoxicity?
There is never a straightforward answer to a sustainable product and climbing up the plastic pyramid wouldn’t be easy for our product designer, this further stresses the importance of extended producer responsibility by knowing the impact of your product at the use phase and EOL.
