Manganese
Cities measured
87
Detected in
87 / 87
EU limit
50 μg/L
Highest
145 μg/L — Karachi
Overview
Manganese occurs in anoxic (low-oxygen) lake bottom layers and in many groundwaters. Lake Mälaren's stratified bottom water contains elevated manganese that can reach the intake during autumn turnover. It causes black staining and a bitter, metallic taste above 0.1 mg/L.
Health Relevance
Manganese is essential for enzyme function. Chronic excess exposure — particularly in infants consuming formula made with high-manganese water — is associated with neurodevelopmental effects (lower IQ, motor dysfunction). Occupational exposure (manganism) resembles Parkinson's disease.
Regulatory Limits
Drinking Water Directive 2020/2184
50 μg/L (indicator). WHO guideline: 0.4 mg/L.
Controversy & Contested Science
Manganese is now recognised as an emerging neurotoxin at concentrations previously considered safe. A 2010 Montreal study found children drinking > 100 μg/L Mn had IQ scores 6 points lower than children drinking < 1 μg/L. Multiple subsequent cohort studies have replicated neurodevelopmental effects well below the EU 50 μg/L indicator value. The WHO's 400 μg/L guideline — set based on adult studies — is regarded by many researchers as inadequate for infant protection. EFSA has recommended lowering the EU limit to 10 μg/L, but this has not been implemented.