ObjectiveThe manufacture of lithium-ion batteries involves hazardous substances such as nickel and cobalt, which may adversely affect the respiratory and dermatological health of workers. With the rapid growth of the electric vehicle and energy storage system industries, the production of lithium-ion batteries-and consequently the use of nickel and cobalt-has been steadily increasing. This study aims to assess occupational exposure to nickel and cobalt and to evaluate their potential health effects among male workers in the lithium-ion battery industry.MethodsWe conducted a cross-sectional study to analyze urinary nickel and cobalt concentrations in 1298 male workers from 22 workplaces across nine industry types in Korea's lithium-ion battery sector. Work history and symptom data were collected via questionnaires, and the odds ratios for respiratory and skin symptoms were calculated relative to the reference value exceedances.ResultsUrinary nickel concentrations were highest in lithium manufacturing and recycling industries (maximum: 753.84 mu g/L), while cobalt concentrations were elevated in cathode active material manufacturing and recycling industries (maximum: 378.58 mu g/L). Exceeding reference values for nickel and cobalt were significantly associated with respiratory symptoms (odds ratio [OR] 2.06-3.97) and skin symptoms (OR 1.70-2.28).ConclusionsElevated urinary concentrations of Ni and Co were closely associated with respiratory and skin symptoms among workers in the lithium-ion battery industry. As the structure of the industry evolves, it is crucial to conduct continuous exposure assessments and establish comprehensive health management systems to better protect worker health.