Manganese is both essential and dangerous, which makes its toxicity easy to overlook. Your body needs small amounts of it to run critical enzymes, protect cells from oxidative damage, and support bone growth. But when exposure climbs beyond what the body can clear, manganese accumulates in the brain and produces neurological damage that can resemble Parkinson’s disease. The condition, called manganism, has been recognized since 1837, yet people are still being harmed by sources as mundane as well water and as specialized as welding fume.
Why the Body Needs Manganese at All
Manganese is an essential trace element involved in growth, digestion, immune function, energy metabolism, and reproduction.1PubMed. A review on manganese and its effect on health and distribution in selected African countries One of its best-known roles is inside mitochondria, where it forms part of manganese superoxide dismutase, an enzyme that neutralizes harmful free radicals. It is also required for enzymes like arginase and glutamine synthase, both of which play roles in the brain.2PubMed Central. Manganese Is Essential for Neuronal Health Most people get enough manganese from food, particularly whole grains, nuts, leafy greens, and tea, with the gut and liver managing uptake and excretion so that levels stay in a safe range.
The body’s main exit route for excess manganese is bile, which means the liver acts as a gatekeeper. When bile flow is impaired or the liver itself is damaged, manganese that would normally leave the body instead accumulates. This is one reason liver disease is a major risk factor for toxicity, a point that comes up again when we look at who is most vulnerable.
How People Get Exposed
When most toxicologists think of manganese poisoning, they think of occupational inhalation. But the routes are more varied than that, and some affect people who have no idea they are at risk.
Welding and Industrial Fume
Welding is the single largest source of occupational manganese exposure in industrialized countries. The metal is a component of mild steel and many welding consumables, and it vaporizes during the arc process into fine particles that lodge deep in the lungs. A study in a shipbuilding yard found that roughly two-thirds of air samples exceeded the recommended threshold for inhalable manganese, and over 90% exceeded the threshold for the finer, respirable fraction that reaches the lower airways.3PubMed Central. Characterization of Total and Size-Fractionated Manganese Exposure by Work Area in a Shipbuilding Yard The particle size matters because the smallest particles can travel from the lungs into the bloodstream and even reach the brain through the olfactory nerve, bypassing the usual gut-and-liver filtering system entirely.
Drinking Water
Manganese occurs naturally in rock and soil, and it dissolves into groundwater, particularly in regions with certain geological profiles. In some agricultural areas, concentrations in well water have been measured at many times the safe threshold set by health authorities.4Indonesian Journal of Global Health Research. Risk Management of Manganese (Mn) Contamination in Drinking Water Sources Unlike industrial exposure, drinking-water exposure is chronic and low-level, which makes it harder to detect but still capable of causing harm, especially in children. The water often looks and tastes normal, though very high levels can produce a brownish discoloration or metallic taste.
Agricultural Pesticides
The fungicide maneb, a manganese-containing compound used on crops, has been linked to Parkinson-like symptoms in agricultural workers. A study of fifty male farm workers chronically exposed to maneb found significantly higher rates of rigidity, headache, fatigue, nervousness, and memory complaints compared to unexposed workers.5PubMed. Chronic exposure to the fungicide maneb may produce symptoms and signs of CNS manganese intoxication At least one case of permanent parkinsonism was documented in a man whose symptoms began two years after his maneb exposure ended, suggesting that the neurological damage can continue to develop even once contact with the chemical stops.6PubMed. Parkinsonism after chronic exposure to the fungicide maneb (manganese ethylene-bis-dithiocarbamate)
Parenteral Nutrition
People receiving intravenous feeding, known as total parenteral nutrition or TPN, can develop manganese toxicity because the standard formulations deliver manganese directly into the bloodstream, skipping the gut’s ability to limit absorption. Toxicity has been observed in as few as 15 days on TPN, and the manganese dose in commercial products may routinely exceed clinical guidelines, which recommend limiting intake to 55 micrograms per day.7PubMed Central. Manganese Toxicity Associated With Total Parenteral Nutrition: A Review The risk climbs steeply in patients who also have cholestasis, a condition where bile flow is reduced, since that impairs the liver’s ability to excrete excess manganese.8PubMed. Manganese Provision in Parenteral Nutrition: An Update
What Manganese Does to the Brain
Once excess manganese reaches the brain, it concentrates in a region called the globus pallidus, part of the basal ganglia circuitry that coordinates movement. From there, it disrupts signaling in connected structures, including the subthalamic nucleus and the substantia nigra.9PubMed. Manganese neurotoxicity: behavioral disorders associated with dysfunctions in the basal ganglia and neurochemical transmission The damage involves mitochondrial dysfunction, inflammation, and direct cell death.10PubMed Central. The Role of Oxidative Stress in Manganese Neurotoxicity: A Literature Review Focused on Contributions Made by Professor Michael Aschner
One reason iron status matters for manganese toxicity is that the two metals share transport pathways. Iron transporters in both the brain and peripheral tissues can carry manganese, so when someone is iron-deficient, the body upregulates those transporters, inadvertently pulling in more manganese along with the iron it is trying to capture.11PubMed Central. Influence of iron metabolism on manganese transport and toxicity Lab studies in brain cells have confirmed that iron deprivation increases manganese uptake through the divalent metal transporter, one of the key channels.12PubMed. Increased manganese uptake by primary astrocyte cultures with altered iron status is mediated primarily by divalent metal transporter This means that anemia and manganese exposure are a dangerous combination, an issue particularly relevant in developing countries where both are common.
Symptoms of Manganese Toxicity
The symptoms of manganism evolve in stages. Early on, many people notice psychiatric and mood changes before anything obviously physical appears. Irritability, emotional instability, compulsive behaviors, and difficulty concentrating are typical early complaints. A study of former ferro-alloy plant workers found that those with higher cumulative manganese exposure had significantly elevated scores for depression, anxiety, hostility, and a cluster of physical stress symptoms, even years after exposure had ended.13PubMed. Neuropsychiatric symptoms and past manganese exposure in a ferro-alloy plant Workers in the highest exposure category were roughly seven and a half times more likely to score above the clinical threshold for hostility and about three times more likely to exceed the threshold for anxiety than unexposed workers.
As the condition progresses, motor symptoms take over. These include slowness of movement, widespread muscle stiffness, and a distinctive gait disturbance with a tendency to fall backward. The motor picture overlaps enough with Parkinson’s disease to cause confusion, but there are important differences. Manganism tends to produce less resting tremor and more dystonia, which involves sustained abnormal postures rather than the rhythmic shaking associated with classic Parkinson’s. Perhaps most clinically important, manganism does not respond well to levodopa, the standard Parkinson’s medication, because the damage occurs in different parts of the basal ganglia circuitry.14PubMed. Manganism and idiopathic parkinsonism: similarities and differences If someone with unrecognized manganese exposure is misdiagnosed with Parkinson’s and started on levodopa, the lack of response is itself a clue.
Who Is Most Vulnerable
Certain groups face outsized risks from manganese, either because they absorb more, excrete less, or have developing nervous systems that are more easily damaged.
Children
Children are particularly susceptible because their brains are still developing and their bodies absorb a higher proportion of ingested manganese than adults do. Studies of children drinking water with manganese concentrations at or above roughly 0.24 milligrams per liter for three or more years have found poorer performance in language, math, and overall school grades, along with lower scores on IQ and neurobehavioral tests.15PubMed. Manganese exposure and neurotoxic effects in children Research has also focused on prenatal exposure. A large Taiwanese cohort study found that manganese exposure during mid-pregnancy was associated with delays in gross motor, fine motor, language, and social developmental milestones in the children.16PubMed. Child neurodevelopment is related to maternal manganese exposure: A Taiwan national prospective cohort study The most recent research emphasis is on early-life exposure and its effects on cognitive and executive functions, areas governed by the frontal cortex.17PubMed Central. Manganese and Developmental Neurotoxicity
People With Liver Disease
Because manganese is excreted primarily through bile, individuals with liver dysfunction can accumulate toxic levels without any unusual external exposure.18PubMed Central. Hepatic Dysfunction and Neuropsychiatric Sequelae Through Manganese Toxicity Research has shown that both portal-systemic shunting, where blood bypasses the liver, and direct liver cell damage contribute to manganese deposition in the brain’s basal ganglia.19Gastroenterology. Manganese deposition in basal ganglia structures results from both portal-systemic shunting and liver dysfunction A case report highlighted how cirrhosis combined with iron-deficiency anemia created a “double hit” that led to chronic manganese neurotoxicity.20PubMed Central. Chronic Manganese Neuro-Toxicity in a Patient With Cirrhosis and the Role of Iron-Deficiency Anaemia The iron deficiency increased manganese absorption via shared transporters while the liver disease prevented its removal.
People on Long-Term Intravenous Feeding
As mentioned earlier, TPN bypasses the gut entirely, so even standard formulations can deliver more manganese than the body can handle. Clinicians are advised to exercise caution when TPN is used for more than a month and to withhold manganese supplementation if blood levels rise or if bile flow becomes impaired.8PubMed. Manganese Provision in Parenteral Nutrition: An Update Patients with underlying cancer or prolonged vitamin D deficiency may also face higher risk of developing toxicity from TPN-delivered manganese.7PubMed Central. Manganese Toxicity Associated With Total Parenteral Nutrition: A Review
Why Diagnosis Is Difficult
One of the frustrating aspects of manganese toxicity is that there is no reliable, widely available blood test for it. Blood and urine manganese levels in non-occupational settings do not correlate well with actual exposure or tissue accumulation.21PubMed. Biomarkers of environmental manganese exposure Even among welders with known, measurable air exposure, blood and urine concentrations did not reflect cumulative exposure over the prior year, and changes during a single work shift did not match the amount of manganese inhaled.22PubMed Central. Toenail, Blood and Urine as Biomarkers of Manganese Exposure Nail manganese has shown some promise in distinguishing between higher- and lower-exposed groups, but the evidence is still thin, and hair measurements are inconsistent.21PubMed. Biomarkers of environmental manganese exposure
The most useful diagnostic tool is brain MRI. Manganese is paramagnetic, meaning it shows up as a bright, symmetric signal in a specific type of MRI scan. The characteristic finding is bilateral high signal intensity in the globus pallidus on T1-weighted images, and this pattern is visible across different causes of manganese overload, whether occupational, dietary, or medical.23PubMed. Brain magnetic resonance imaging and manganese exposure The same MRI pattern has been observed in hemodialysis patients who developed manganism symptoms, helping to establish the connection in a population not traditionally associated with manganese exposure.24American Journal of Neuroradiology. A Preliminary Study Revealing a New Association in Patients Undergoing Maintenance Hemodialysis: Manganism Symptoms and T1 Hyperintense Changes in the Basal Ganglia Researchers have also confirmed that this MRI signal appears in children exposed to manganese through drinking water, even before overt signs of poisoning are visible.25Neurotoxicology. MRI pallidal signal in children exposed to manganese in drinking water
In practice, most clinicians arrive at a diagnosis by combining a compatible exposure history, the right pattern of symptoms, and the MRI finding. No single biomarker is considered definitive on its own.
Workplace Prevention
For workers in welding and other metal-fume industries, engineering controls are the first line of defense. Local exhaust ventilation, which captures fume at or near the point where it is generated, has been shown to cut manganese exposure by more than half in real-world construction settings. In controlled experiments, the reduction reached about 75%.26PubMed. Manganese and welding fume exposure and control in construction That is a meaningful improvement, though the field results make clear that ventilation alone does not eliminate exposure entirely, especially in confined or poorly ventilated spaces. Respiratory protection, job rotation to limit cumulative time in high-fume zones, and choosing welding processes or consumables with lower manganese content are all additional strategies.
Outside occupational settings, prevention looks different. For communities with manganese in their groundwater, water treatment or switching to a tested municipal supply is the main intervention. Home water-filtration systems can reduce manganese, but their effectiveness varies and they need regular maintenance. If you rely on well water, testing for manganese (not just the usual bacterial and nitrate panels) is a prudent step, particularly if you have young children or are pregnant. For clinicians managing patients on TPN, monitoring blood manganese levels and being prepared to reduce or eliminate manganese supplementation when liver function deteriorates are important preventive measures.
Treatment Once Toxicity Develops
The first and most important step in treatment is removing the source of exposure. For occupational cases, that means taking the person out of the manganese-heavy environment. For TPN patients, it means reformulating the nutrition to exclude or reduce manganese. For liver disease patients, treating the underlying hepatic condition can improve biliary excretion and help the body clear the metal naturally. In many mild cases, removing the source is sufficient, and the MRI signal in the brain gradually fades as manganese is cleared.
When exposure has been heavy or symptoms are advanced, chelation therapy is sometimes used. The most studied chelating agent for manganese is sodium para-aminosalicylic acid, commonly known as PAS, which was originally developed as a tuberculosis drug. PAS has the advantage of crossing the blood-brain barrier, something most conventional chelators struggle with. In animal studies, PAS reduced manganese levels in the brain and major organs and helped restore normal iron and copper concentrations in the body.27PubMed Central. Chelation Therapy of Manganese Intoxication with para-Aminosalicylic Acid (PAS) in Sprague-Dawley Rats Beyond simply pulling out metal, PAS appears to have anti-inflammatory and anti-apoptotic properties that may help protect neurons from further damage.28PubMed. Treatment of manganese and lead poisoning with sodium para-aminosalicylic acid: A contemporary update
The clinical evidence for PAS in humans is still limited to case reports and small series rather than randomized trials. One well-known case followed a severely poisoned worker for 17 years during PAS treatment and found sustained clinical improvement, suggesting the drug can be effective even in advanced cases.29PubMed Central. Effective Treatment of Manganese-Induced Occupational Parkinsonism With p-Aminosalicylic Acid: A Case of 17-Year Follow-Up Study Researchers have also explored combining PAS with another chelator, CaEDTA, as a strategy to more effectively mobilize manganese from binding sites in the brain.30PubMed Central. Chelation Combination-A Strategy to Mitigate the Neurotoxicity of Manganese, Iron, and Copper? Chelation for manganese toxicity remains a specialized area, and treatment decisions are best made by a toxicologist or neurologist experienced with the condition.
The Iron Connection and Its Practical Meaning
The overlap between iron and manganese transport deserves special attention because it has practical consequences that most people are unaware of. If you are iron-deficient, your body ramps up production of metal-transport proteins to scavenge more iron from your environment. But those same proteins do not discriminate well between iron and manganese, so you end up absorbing more of both. This means that iron-deficiency anemia, one of the most common nutritional deficiencies worldwide, can quietly amplify the harm of manganese exposure that would otherwise be tolerable.11PubMed Central. Influence of iron metabolism on manganese transport and toxicity
This interaction helps explain some otherwise puzzling patterns. Agricultural communities in developing countries often have both high manganese levels in water or pesticide exposure and widespread iron-deficiency anemia. Women of childbearing age, who lose iron through menstruation, are more often iron-deficient, and if they are also exposed to environmental manganese during pregnancy, both they and their developing fetuses may face greater risk. It also explains why the cirrhosis patient mentioned earlier developed such severe toxicity: the combination of liver dysfunction blocking manganese excretion and iron-deficiency anemia boosting its absorption created the worst possible scenario.20PubMed Central. Chronic Manganese Neuro-Toxicity in a Patient With Cirrhosis and the Role of Iron-Deficiency Anaemia Correcting iron deficiency is therefore not just about treating anemia; in populations with manganese exposure, it may be a meaningful protective measure.
An Old Hazard Still Causing New Problems
The first documented case of manganese neurotoxicity was reported in 1837 by a Scottish physician named John Couper, who observed neurological illness among workers at a bleach factory near Glasgow where manganese was used in chlorine production.31PubMed. The early history of manganese and the recognition of its neurotoxicity, 1837-1936 Nearly two centuries later, exposure limits continue to be revised downward as researchers discover effects at lower and lower doses. The American Conference of Governmental Industrial Hygienists has progressively tightened its recommended threshold for respirable manganese, and yet workplace measurements in some industries still routinely exceed it.3PubMed Central. Characterization of Total and Size-Fractionated Manganese Exposure by Work Area in a Shipbuilding Yard Meanwhile, the lack of a reliable biomarker for non-occupational exposure means that low-level harm in communities drinking contaminated groundwater may be going largely undetected, particularly in children whose cognitive effects are subtle enough to be attributed to other causes. The gap between what we know about this metal’s toxicity and how effectively we prevent exposure remains wider than it should be.