Editorial: The sustainability series: the plastics problem - investigating socio-economic dimensions of plastic pollution

The urgent need to tackle plastic waste problems is undeniable. Cumulative production of plastic since the inception of mass production after the second world war is estimated to be 9544 million metric tons (Mt), produced between 1950-2019, and more than 7000 Mt of plastic waste has been generated over that period (Geyer et al., 2017;Geyer, 2020;Our World in Data, 2023;OECD, 2023). Primarily because of river discharge and mismanaged waste, plastic waste enters the ocean, leading to marine plastic pollution (Chenillat et al., 2021;Jambeck et al., 2015;Lebreton et al., 2017;Meijer et al., 2019;Schmidt et al., 2017).There have been growing modeling and simulation studies on how plastic pollution changes in the long run with different scenarios (Borrelle et al., 2020;Chenillat et al., 2021;Cordier et al., 2021;Cordier and Uehara, 2019;Geyer et al., 2017;Hohn et al., 2020;Lau et al., 2020;van Wijnen et al., 2019;OECD, 2022;Jambeck et al., 2015;Lebreton and Andrady, 2019;Yan et al., 2022). While there are variations in their approaches and results, there are two common findings. First, all business-as-usual scenarios project an increase in plastic waste. Second, it requires an unprecedented and significant effort to reduce the amount of plastic waste accumulation. It requires system change (Lau et al., 2020), transforming the global plastic economy (Borrelle et al., 2020), or combining solutions (Cordier and Uehara, 2019;Hohn et al., 2020;Lau et al., 2020). Furthermore, as a study claims that technological solutions are insufficient, there is an urgent need to implement measures regarding non-technological solutions including changing people's behavior (Alcock et al., 2020;Cordier and Uehara, 2019;Martin et al., 2020;Oturai et al., 2022;.The four articles in this research topic shed light on the importance of socio-economic dimensions of plastic pollution from various perspectives. Conducting citizen science nationwide in the UK, where 9,701 citizens were engaged, Purkiss et al. (in this topic) reveal that home compostable packaging was not socially and environmentally effective. It was not easy for citizens to identify home compostable packaging. Furthermore, home compost experiments demonstrated that some certified home compostable packaging did not fully disintegrate, providing important information for technological advancement of the biodegradable and compostable plastics tested under different home composting conditions. They report the majority did not fully disintegrate, including 60% of those that were certified "home compostable." Therefore, Purkiss et al. concluded that home composting is not an effective or environmentally beneficial waste processing method for biodegradable or compostable packaging in the UK. examined how college students' learning the correct rules of plastic waste separation improves their separation behavior on campus. Although proper plastic waste separation is critical to efficient disposal, people do not always comply with designated rules, possibly resulting from a lack or misunderstanding of the correct rules related to local variability. Knowing the rules can effectively enhance plastic waste separation on campus. They demonstrated it using a hybrid of before-after and treatment-control designs. Their results revealed that the learning improved the plastic waste separation behavior on campus in Japan. Before learning the rules, 12.8% of the treatment group followed the correct rules. After learning the rules, this number increased to 38.3%. Abiola et al. (in this topic) explored how to reduce the sale of plastic bags and increase the uptake of reusable bags at a retail shop in South Africa. They tested three interventions to reduce plastic bag use: (i) a monetary intervention based on giving reusable bags away for free; (ii) a nonmonetary intervention framed around a plastic-free July campaign (including nudges such as campaign messages for consumers, store-level campaigns, and changes in the default question asked by cashiers); and (iii) a monetary intervention involving a subsidy on reusable bags. The study found the second intervention, the non-monetary one based on nudges, was the most effective. They show non-monetary interventions could have more potential impact in promoting pro-environmental behavior than monetary incentives. The results also agree with the literature on the ineffectiveness of subsidies for the purpose of discouraging the use of plastic bags.Winterstetter et al. (in this topic) applied material flow analysis to estimate mismanaged plastic packaging and small non-packaging plastic items (PPSI) waste generated in 33 European countries based on observed data for each country for 2012 and 2018. This is an important topic since PPSIs represent the most extensive application of virgin plastics produced and the largest fraction of post-consumer plastic waste. Their results indicate that most countries generated higher amounts of PPSI waste in 2018, both in absolute amounts and per capita (42.9 kg per capita in 2018, compared to 38.7 kg per capita in 2012). This was also the case for PPSI mismanaged waste. They estimate that 3.01 million tons of PPSI mismanaged waste were generated in 2018 for the whole region compared to 2.90 million tons in 2012, even if most countries managed to reduce their shares of mismanaged PPSI waste. The study suggests that reductions in the share of mismanaged PPSI waste seem to be mainly driven by efforts at the end-of-life stages of plastics (i.e., waste collection, recycling, disposal) but that these were not sufficient to offset higher amounts of PPSI waste generated in 2018, compared to 2012. They propose responses through waste management and waste prevention are needed to transition to a circular economy and reduce the amount of plastic waste that ends up in the marine environment.The four articles demonstrate the importance of tackling the socio-economic dimensions of plastic pollution to effectively reduce it. How we behave is a critical part of the solution to plastic pollution. Furthermore, as Purkiss et al. (in this topic) demonstrate, we citizens can help advance the development of technological solutions.