Mercury toxicity: clinical presentations in musculoskeletal medicine.

Recently, worldwide media attention has focused on the effects of mercury pollution on the environment, and the resultant health consequences in pregnant women, fetuses, and children.1 Mercury occurs naturally in the environment and is a recognized neurotoxin at high doses.2 It cannot be broken down, thus making it one of the elements of the periodic table. Mercury naturally cycles through the natural environment beginning with concentrations in the earth’s crust, emanating into the air via coal-fired power stations, industrial incinerators, or natural phenomena such as volcanoes,3 and returning to soil, water, or living organisms. Humans are exposed to mercury via several mediums including dietary intake (eg, fish consumption), dental amalgams, household agents (eg, mercury thermometers), and occupational exposure (eg, mercury in mining, dental, and pulmonary laboratories).4-6 Mercury is an effective preservative and has been used in cosmetic products, vaccines, pesticides, and fungicides.7 One incident of widespread mercury poisoning occurred in Iraq in 1956 when the population had high dietary intake of seed grains contaminated with mercurycontaining fungicides. This exposure resulted in an epidemic of neurological diseases and fatalities.8 Another notable outbreak occurred in Minimata Bay, Japan in 1956 when mercury-laden pollutants from paper mills contaminated waters containing the local populations’ fish supply.9 Severe neurological disease, birth defects, and many fatalities ensued. Hunter-Russell syndrome is the diagnostic label applied to the posthumous effects of methylmercury inhalation and poisoning and includes neuronal destruction and cerebral atrophy with cortical loss.9,10 Brain damage precipitating mental retardation and developmental disturbances, hypertension, and liver and metabolic insufficiencies were noted in those children of mothers exposed to contaminated fish. Children exposed in utero exhibited neurologic symptoms including chorea, ataxia, tremors, and seizures.11 Aside from these large-scale incidents of mercury exposures, patients presenting with more subtle symptoms suggestive of mercury toxicity need to be recognized in the ambulatory care setting. Often the pattern of exposure to mercury—high level, acute exposure versus low level, chronic exposure—can influence the severity of presenting symptoms. The most common clinical presentations of mercury toxicity include paresthesias, ataxia, and visual effects.12-14 Differential diagnostic considerations in orthopedic practice for nonAs a result of reading this article, physicians should be able to: