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For Forensic Toxicology, Forensic Medicine, Toxicology and Internal Medicine Experts

By Nachman Brautbar, M.D.

  • Welding, Manganese
  • Manganese and Neurological Diseases, Parkinsonism
  • Neuropathology and Pathophysiology of Manganese Toxicity
  • Idiopathic vs. Manganese, Parkinsonism?
  • Levels of Exposure to Manganese
  • State of the Art
  • Establishing Causation

In Forensic Toxicology:
Welding is a common industrial process - so common that up to 2% of the working population in industrialized countries has been engaged in some sort of welding. Although the types of welding are many, it has been estimated that shielded metal arc welding (SMAW), gas metal arc welding (GMAW) on mild steel, stainless steel and aluminum are performed by 70% of welders. Arc welding causes emission of manganese.

Manganese (Mn) is an element that is an essential nutrient, but that can be toxic at high exposures. Mn is ubiquitous in the ambient environment, being present in the soil, water, air, and food. The main source of Mn intake for most individuals is food.

Welding may produce fumes and gases hazardous to health. Avoid breathing these fumes and gases. Use adequate ventilation. See ANSI Z49.1-1967, Safety in Welding and Cutting, published by American Welding Society. The type of welding identified in all companies was electric arc welding and 90% was MIG on mild steel. A total of 42 welders were monitored for personal exposure to welding fumes. Nearly 60% were overexposed to manganese and 19% were overexposed to iron. Two welders from two different companies had the two highest manganese exposures. Both had worked in isolated welding stations.

Facts for the Forensic Toxicologist, Forensic Medicine, Toxicology and Occupational Physician:
Manganese, which enters the body primarily via inhalation, can damage the nervous system and respiratory tract, as well as have other adverse effect. Occupational exposures occur mainly in mining, alloy production, processing, ferro-manganese operations, welding and work with agrochemicals. Among the neurologic effects is an irreversible Parkinsonian-like syndrome (Degenerative neurologic disease). A wide spectrum of neuropsychiatric illnesses have been described with manganese toxicity.

Manganese and Parkinssonism
Manganese can cause an irreversible Parkinsonian-like syndrome, characterized by fixed gaze, bradykinesia, postural difficulties, rigidity, tremor, dystonia, and decreased mental status. This neurologic condition, first described in two manganese ore-crushing mill workers by Couper in 1837 has been referred to as manganism.

Neuropathology and Pathophysiology of Manganese Nervous System Damage
Manganese deposits in the brain have been described within the basal ganglia of the brain,the cortex and the medulla. Manganese can reduce dopamine in the caudate nucleus, norepinephrine in the hypothalamus, and neuromelanin in the substantia nigra. It appears that manganese may increase dopamine oxidation with associated free radical formation.

Imaging Studies
Some preliminary magnetic resonance imaging studies have shown that manganese accumulates in the globus pallidus. Manganese causes neuronal loss and gliosis in the striatum, subthalamic nucleus, and pallidum, but little change in the substantia nigra.

Positron emission tomography (PET) scans of two welders showed abnormalities typical of idiopathic Parkinson's disease. The authors concluded that parkinsonism in welders cannot be distinguished from idiopathic Parkinson's disease, except by early age of onset. (Discussion of their findings can be found in an accompanying editorial and subsequent letters to the editor).

1. Illustrative of Some Case Reports and Case Studies of Manganese Exposure and Neurologic Disorders

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The Racette Study
Racette et al (2001) performed a case control study of 15 career welders and two groups of control subjects with idiopathic Parkinson's disease. They found that the welders developed parkinsonism at a younger age (on average, 46 years) than sequentially ascertained controls (63 years; p<0.0001). They found no difference between groups in the following parameters: tremor, bradykinesia, rigidity, asymmetric onset, postural instability, dementia drug induced psychosis, motor fluctuations and dyskinesias. Since manganese toxicity can cause a wide spectrum of neurological diseases, there is no scientific "check box" list to determine that the Parkinsonian like syndrome in front of the treating and evaluating expert is "idiopathic." Causation analysis is based on differential diagnosis, history, review of records, environmental data and Material Safety Data Sheets (MSDS). See the paper on causation.

Levels of Exposure To Manganese and Neurological Damage
Sinczuk-Walczak et al (2001) assessed the effects of manganese on the nervous systems of 62 welders and 13 battery production workers. Increased emotional irritability, memory impairment, concentration difficulties, sleepiness and limb paresthesias were found in the manganese-exposed workers. The authors concluded that manganese exposure up to 2.67 mg/m3; geometric mean, 0/15 mg/m3 (arithmetic mean, 0.4 mg/m3; geometric mean 0.15 mg/m3 ) induces subclinical nervous system effects.

Exposure Limits
  • OSHA GENERAL INDUSTRY PEL: 5 mg/m3 Ceiling
  • ACGIH TLV: 02 mg/m3 TWA Elemental and inorganic compounds
  • NIOSH REL: 1 mg/m3 TWA; 3 mg/m3 STEL

State of the Art
State of the art knowledge that manganese from welding was hazardous and associated with Parkinson's. In 1932, a German study was published that associated the exposure to manganese laden welding fumes to the onset of manganism. The author found that electric arc welding was a health risk to the welder because of the manganese in the fumes.

Symtoms and Response To Treatment
  • The Racette paper demonstrates that clinically idiopathic Parkinson's cannot be distinguished from manganese induced Parkinson's.
  • Imaging studies of the brain are not conclusive

Most Rescent Niosh Study
The Racette paper demonstrates that clinically idiopathic Parkinson's cannot be distinguished from manganese induced Parkinson's. Imaging studies of the brain are not conclusive.

Data That The Experts in Forensic Toxicology, Forensic Medicine, Toxicology and Internal Medicine Should Know

Materials Needed for Causation
  • Material Safety Data Sheets
  • Modeling range of level of exposure
  • Rule out other causes, pesticides, carbon monoxide, certain medications
  • Temporal relationship between exposure and development of symptoms
  • Scientific papers connecting manganese in welding and neurologic damage (animals, humans)
  • Team: MD Toxicologist, industrial hygienist, neurologist, neuroradiologist

[Updated Manuscript in preparation]

From Racette, B.A. et al, Weldikng-related parkinsonism, Clinical features, treatment and pathophysiology, Neurology, 56; p. 8-13; January, 2001

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Dr. Brautbar is a board-certified internist and nephrologist, and certified in forensic medicine. If you are interested in retaining Dr. Brautbar for forensic and expert witness testimony services, please submit the Contact Form.

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