Product-based approach to sustainable plastic management focusing on consumers’ necessity of 50 daily-use products in Japan

In the plastic product lifecycle, consumers are the main stakeholders who purchase, consume, and dispose of plastic products. To be able to take optimal measures to induce changes in consumer behavior to achieve sustainable plastic management, daily-use plastic products should be classified by consumers' necessity. However, consumers' evaluations of the necessity of individual plastic products remain to be examined. Here, we selected 50 plastic products from the Japanese households that are used and disposed of by consumers on a daily basis, and then conducted a large-scale questionnaire survey of 10,000 residents of Japan in which we asked respondents to evaluate the subjective necessity and substitutability of each of the targeted 50 products. To discuss future measures tailored to individual products or groups of similar products, we conducted hierarchical clustering analysis based on the respondents' evaluation of each of the products. The classified seven clusters could be divided into two groups, which were characterized by a low and high necessity for consumers. In the four clusters characterized by a low necessity, most of the products were single-use plastic products and the rate of the options indicating a lack of necessity was more than 44% for each product. In contrast, the other three clusters included plastic containers and packaging, durable products, and products made from synthetic fibers, but few single-use plastic products, and showed a higher response rate of more than 55% for the options indicating necessity. Then we also investigated domestic consumption of each product and obtained the Japanese total consumption of the 50 targeted products as 3.619–4.007 million t per year. As a result of our estimation, if the consumers can stop their use of the unnecessary products or have access to suitable substitutes, millions of tons of products could be eliminated as a maximum reduction potential. Overall, our survey highlighted the importance of classification of plastic products based on the consumers’ necessity and proposed possible targets of policy intervention on future sustainable management in terms of individual plastic products.