Manganese

Manganese is one of the most abundant metals in the earth's crust, found naturally in rock, soil, and water [1]. It has been used industrially since the 18th century in steel production (where it gives steel strength and hardness) and later in dry-cell batteries, fertilizers, and as an additive in gasoline (methylcyclopentadienyl manganese tricarbonyl, or MMT, was used in unleaded gasoline in Canada and some US states) [2]. The occupational disease was first described in Chilean manganese miners in 1837 by Dr. John Couper, who observed a syndrome of tremors, muscle rigidity, and shuffling gait in miners exposed to manganese dust — a clinical picture almost identical to Parkinson's disease. Modern cases appear primarily among welders exposed to manganese fumes from welding rods, and among ferroalloy plant workers [3]. In water, manganese is released naturally from iron-bearing aquifer sediments, particularly in areas with low-oxygen groundwater, and can exceed health limits in private wells across the eastern US.

The most significant non-occupational exposure pathway for most people is drinking water [1]. Manganese occurs naturally in groundwater, particularly from private wells in the Northeast, upper Midwest, and Southeast. Concentrations can reach levels of concern even where water looks clear and tastes normal — manganese is not always detectable by taste or odor. Infants who drink formula mixed with high-manganese water face proportionally higher exposures because they consume more water per body weight [2]. Food provides modest intake — whole grains, nuts, legumes, and tea all contain manganese naturally. Welding is the critical occupational route: welding with manganese-containing electrodes generates fine fumes that are deeply inhaled and reach the brain far more efficiently than ingested manganese [3]. MMT in gasoline contributed to air emissions in areas where it was used.

The brain accumulates manganese via the olfactory nerve and bloodstream, depositing it preferentially in the basal ganglia — the same region damaged in Parkinson's disease [1]. This explains why manganism and Parkinson's disease look so similar: both cause tremor, rigidity, slow movements, and balance problems. The key differences are that manganism often causes a characteristic "cock walk" gait, psychiatric symptoms (anxiety, impulsivity, emotional lability) emerge earlier, and the disease can stabilize if exposure stops — unlike Parkinson's [2]. In children, lower-level manganese exposure from drinking water has been associated with reduced IQ, impaired memory, and ADHD-like symptoms — the developing brain is more sensitive to manganese neurotoxicity than the adult brain. The issue is dose: you need some manganese to function, but the line between essential and neurotoxic is narrower than with many nutrients [3].

Welders — especially those who weld in enclosed or poorly ventilated spaces — face the highest risk of manganism [1]. Workers in ferroalloy production, battery manufacturing, and dry-cell battery recycling also have elevated exposures. Infants drinking formula prepared with well water high in manganese are a special concern — the EPA lifetime health advisory for manganese in drinking water is 300 µg/L, but some researchers argue much lower levels (50–100 µg/L) affect children's neurodevelopment [2]. People on private wells in the eastern US, particularly in Maryland, Pennsylvania, and New England, should test for manganese. Individuals with liver disease have impaired manganese excretion and accumulate it more readily [3].

Test your private well for manganese — this is not included in standard municipal water testing reports [1]. If levels exceed 300 µg/L (the EPA health advisory), use a certified filter: greensand filtration, oxidizing filters, or reverse osmosis all remove manganese. Do not prepare infant formula with unfiltered water if your well exceeds 100 µg/L — use bottled water or a certified filter for infant feeding [2]. Welders should use local exhaust ventilation systems that capture fumes at the source, choose low-manganese welding consumables when the application allows, and wear a P100 respirator during confined-space welding. Manganese blood and urine testing can assess current exposure; brain MRI shows manganese deposition in the basal ganglia in exposed workers [3]. If you notice tremor or emotional changes and have occupational manganese exposure, seek neurological evaluation promptly.