Mercury and Movement Disorders: The Toxic Legacy Continues

Abstract

Mercury (Hg) exists in the environment as inorganic (metallic Hg vapor, mercurous and mercuric salts) or organic (bonded to a structure containing carbon atoms) forms. Neurotoxic effect of Hg is known for years. While the organic form (methylmercury (meHg)) led to the Minamata incidence in Japan and “wonder-wheat” disaster in Iraq, the “mad hatters” and “Danbury shakes” were related to the inorganic elemental form (Hg vapor). Human exposure to toxic Hg continues in the modern world to a large extent by artisanal gold mining, biomass combustion, chloralkali production, and indigenous medicine use to name a few. Heavy industrial use of Hg contaminates air and landfills, affecting the aquatic ecosystem and marine food chain. A detailed social and occupational history with a high index of clinical suspicion is required to not miss this toxic etiology for movement disorders like ataxia, tremor, or myoclonus. In this review, we have discussed the past and present global health impact of Hg from a movement disorder perspective. The connection of Hg with neurodegeneration and autoimmunity has been highlighted. We have also discussed the role of chelating agents and the preventive strategies to combat the neurotoxic effects of Hg in the modern world.

Acute onset parkinsonism after consumption of traditional Chinese medicine: A cause for vigilance

“…Diseases like Minamata Disease, induced by methylmercury, specifically damage the central nervous system, distinguishing it from inorganic mercury poisoning, which primarily targets the kidneys. Despite these distinctions, mercury exposure has been associated with classic parkinsonian symptoms, including ataxia, tremors, and myoclonus [ 4 ]. Research indicates that mercury, in various chemical forms, exerts neurotoxic effects, contributing to neurochemical and neuropathological changes akin to those observed in Parkinson's disease [ 5 ].…”

Parkinsonism before James Parkinson: The “Marília de Dirceu” Case

“…There remains the remote possibility of mercury toxicity, a metal used in artisanal gold extraction, the most important economic activity in Vila Rica at that time. However, parkinsonism is not a complication of exposure to mercury 5 …”

“…However, parkinsonism is not a complication of exposure to mercury. 5 The old gentleman described in "Marília de Dirceu" may be the first person with parkinsonism, possibly caused by PD, described in the American continent. This case adds to the literature indicating that the shaking palsy is not a disease of the Industrial Revolution, with probable cases being reported in Asia, Europe and now, America.…”

Electrochemical Determination of Hg2+ on a Poly (Eriochrome Blue Black R) Modified Carbon Paste Electrode

“…"Mercury (Hg), one of the representative heavy metals, is ranked third on the list of toxicological dangerous substances by the United States Toxicology and Disease Registry" [1]. "Hg is emitted into the environment from anthropogenic activities or natural sources" [2]. Anthropogenic actions such as inappropriate industrial waste management and illegal artisanal gold mining resulted in Hg contamination of ecosystems leading to the public health concern [3] caused by chronic exposure through the intake of food and water [4].…”