Beyond the battery paradox: A technical review of 4th-Generation ENDS architecture and a strategic circular design framework.

The global rise of 4th-generation Electronic Nicotine Delivery Systems (ENDS) has triggered a critical environmental crisis driven by an integrated architecture that prevents material separation-a phenomenon termed the "battery paradox.' While clinical impacts are well-documented, the engineering challenges of circular design remain underexplored. This review systematically describes the architectural evolution of ENDS through a bibliometric analysis of 21 key studies (2010-2026), mapping the transition from chemical assessments to contemporary circular-economy challenges. The study identifies a systemic failure in material recovery across monitored regional streams, though global data coverage is currently uneven, so extrapolating to all markets requires caution. However, forensic analysis from key markets reveals that lead concentrations in ENDS leachate can reach up to 50 mg/L, exceeding hazardous waste limits by tenfold. To address these failures, a strategic redesign framework based on the Life Cycle Design Strategy (LiDS) is proposed for "disposable ENDS'. Achieving material circularity requires a mandatory shift toward modularity, supported by Digital Product Passports (DPP) and Deposit Return Schemes (DRS). Such measures are essential to transform ENDS from a hazardous environmental liability into a viable source of technical nutrients within a circular economy.