Occupational exposure to lithium-nickel-cobalt-manganese oxide materials in lithium battery: Health risks and mechanisms of toxicity

Lithium-ion batteries are indispensable in modern energy storage systems-including portable electronics, electric vehicles, and grid-scale applications-because of their high energy density, long cycle life, and low self-discharge. Among cathode materials, lithium-nickel-cobalt-manganese oxide (LiNiMnCoO₂; NCM) is widely used because of its balanced electrochemical performance and strong commercial viability. With the rapid expansion of NCM production and recycling, concerns regarding occupational exposure and related health risks have increased. However, a comprehensive synthesis addressing the toxicological characteristics of NCM as a composite material-rather than its individual metal constituents-remains lacking. This review critically evaluates current evidence on the occupational health effects of NCM materials across their life cycle, with particular emphasis on inhalation exposure to NCM particulates in manufacturing and recycling settings. We integrated epidemiological data, in vivo and in vitro toxicological studies, and mechanistic research to characterize the health risks associated with NCM exposure. Following deposition in the respiratory tract, persistent particles initiate local inflammatory responses, while the gradual release of Ni, Co, and Mn ions within pulmonary and intracellular microenvironments drives sustained molecular and cellular toxicity. Major adverse outcomes include respiratory inflammation and fibrosis, neurotoxicity, hepatic and renal injury, and other systemic effects. We further summarized key toxicity mechanisms, including oxidative stress, inflammatory signaling, DNA damage, and related pathways, and discuss current occupational exposure limits and regulatory considerations for NCM-related metals. By consolidating multidisciplinary evidence, this review aimed to clarify knowledge gaps, inform future research priorities, support evidence-based regulatory decision-making, and promote safer manufacturing practices for next-generation energy storage technologies.