Microplastic fibers and leachates from cigarette butts: environmental impacts, toxicological concerns, and circular...

Cigarette butts constitute the most ubiquitous plastic litter worldwide, serving as a persistent source of microplastic fibers and toxic chemical leachates in terrestrial and aquatic ecosystems. Primarily made of cellulose acetate, discarded butts degrade slowly via physicochemical processes, liberating cigarette butt-derived microplastics alongside hazardous additives such as nicotine, heavy metals, and polycyclic aromatic hydrocarbons. This PRISMA-guided narrative review consolidates evidence on the environmental prevalence, transport, and fate of these microplastics, rigorously appraises progress in analytical detection methods, and evaluates their ecotoxicological impacts across food web levels. Studies reveal induction of behavioral changes, elevated mortality, and bioaccumulation in aquatic species, with particles functioning as carriers for persistent organic contaminants and metals. The review also addresses the considerable economic costs of cigarette butt pollution and scrutinizes mitigation options, including cutting-edge removal techniques, extended producer responsibility schemes, and circular-economy pathways such as cellulose acetate reclamation and composite sorbent fabrication. Persistent gaps exist in long-term degradation patterns, realistic exposure limits, and practical remediation efficacy, necessitating focused research to support evidence-based policies and sustainable waste management.