Introduction Accumulation of manganese in the brain may result in a neurological condition with cognitive, psychiatric, and movement abnormalities. The clinical and toxicological literature demonstrates that manganese accumulates in the basal ganglia which may result in parkinsonism. There is little published about the prevalence of Parkinsonism among manganese exposed workers. We present a case series of 6 workers from a single factory and discuss methods of neurological assessment of the manganese exposed worker for the occupational health provider.

Methods IH sampling of a large tire factory employing 527 production workers was conducted for heavy metals. A walkthrough was performed assessing safety, hygiene, ventilation and use of personal protective equipment. Workers in the departments with manganese concentrations above NIOSH REL completed a symptoms survey and were assessed by occupational medicine physicians, with a specific focus on neurological assessments.

Results Environmental sampling of manganese concentration was above 1 mg/m³ in three departments; highest measurement was 6.7 mg/m³. Walkthrough survey revealed inadequate ventilation in all three departments and improper PPE use among 72% workers. 27 exposed workers were evaluated with symptom questionnaire and clinical exam focusing on neuropsychologic and neuropsychiatric findings; 4 of those workers had evidence of parkinsonism on exam and symptom survey. Those workers were immediately removed from the worksite. Biomarkers were sent for evaluation and the workers were sent for neurological referral.

Conclusion Manganese exposure at work is associated with increased risk of Parkinsonism. We identified a cluster of manganese exposed workers with Parkinsonism in a factory with inadequate ventilation and poor hygiene practice. Based on the findings from this case study we are able to develop a simple neurological assessment tool for the exposed worker.