Sustainable design of a plastic toothbrush: a case study of design for disassembling and materials recycling

Toothbrush is one of the most widely used oral care items in the world. Growing awareness of the environmental implications in the use of disposable toothbrushes has prompted all major manufacturers to develop "eco-friendly" products, whose approach is based on three different strategies: the use of biopolymers; the use of natural materials such as bamboo; or the use of replaceable heads. However, each of these solutions hides critical issues: most bamboo toothbrushes have mechanically anchored nylon bristles that cannot be disassembled and are vulnerable to early aesthetic degradation; biopolymer toothbrushes do not show significant lifecycle environmental benefits when compared to their traditional polymer equivalents; and toothbrushes with replaceable heads are often abandoned in use due to a perception of poor hygiene, which grows with time. Based on previous LCA analyses that highlight the potential environmental benefits of a fully recyclable toothbrush embedded within an economic scheme of recovery and reuse of its materials, the paper aims to describe the environmental redesign process of a plastic disposable toothbrush made through the multi-shot injection moulding process. The project is characterized by innovative technical and formal solutions that can improve the environmental performance of the product through the strategy of design for disassembling.