Multi-Metal Exposure Profiling in ALS Patients in South Korea via Hair Analysis: A Cross-Sectional Study

Objectives: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease with an unclear etiology. This study aimed to assess chronic heavy metal exposure in ALS patients in South Korea by comparing hair concentrations of common (Hg, Pb, Cd) and rare (U, Th, Pt) metals with healthy controls. Methods: Hair samples were collected from 66 ALS patients and 70 healthy individuals at Rodem Hospital between 2022 and 2025. Metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS) following standardized washing and digestion protocols. Results: ALS patients showed significantly higher levels of Hg, Pb, Cd, Al, As, and U than controls (p < 0.05). Notably, 40% of ALS patients had Hg levels exceeding 50% of the reference upper limit, compared to only 10% of controls. Elevated levels of uranium and other rare metals were also observed in specific ALS cases. Conclusions: These findings suggest a possible association between heavy metal exposure and ALS in South Korea. Hair analysis may serve as a useful tool for identifying environmental factors contributing to ALS pathogenesis.