Controversy has swirled around the use of thimerosal, a mercury-containing stabilizer and antibacterial agent used in vaccines. Used since the 1930s, thimerosal is metabolized to ethyl mercury in the body and has been implicated in a host of ailments, including the marked increase in incidences of autism. Although no dose-dependent toxicity has been established, questions concerning genetic vulnerability to mercury have been raised and considered significant.11-12 In 1999, the Department of Health and Human Services recommended thimerosal be decreased or eliminated from childhood vaccines.
Clinical symptoms of mercury toxicity are often insidious in onset and nonspecific, making diagnosis difficult without a high index of suspicion. Complaints may include gastrointestinal symptoms, headaches, insomnia, visual disturbances, peripheral neuropathy, or ataxia.2 Exposure to inorganic mercury from mercurial salves (merthiolate) or the chronic use of mercury-based cathartics may present with the constellation of symptoms known as acrodynia or pink disease, Feer disease, Feer’s disease, Swift syndrome, Swift’s disease, Swift disease, Swift-Feer disease, vegetative neurosis, dermatopolyneuritis, erythredema polyneuritis, and trophodermatoneurosis. This is characterized by a desquamating rash, hair loss, erythema of the palms and soles, anorexia, and gastrointestinal complaints. Elemental mercury does not readily cross the blood-brain barrier, so neurological complaints are not dominant.2
Organic mercury poisoning typically presents with neurological symptoms. In-utero exposure may result in spontaneous abortion; or the infant, if delivered, may suffer mental retardation. Adult toxicity presents with sensory and motor-neurological complaints, visual field loss, hearing loss, dysarthria, or cerebellar symptoms of ataxia. Severe toxicity results in movement disorders, paralysis, and seizures.2 Evidence of kidney damage and reproductive failure are also commonly associated.
In suspected cases, obtain blood and urine levels of mercury. Levels of mercury in hair may be helpful in some instances, but false-positive findings make this method of testing less reliable.
Treatment is supportive. Employ chelating agents if the patient is acutely symptomatic. The agent of choice is BAL (dimercaprol). Administer it as directed by consultation with a poison control team. BAL is not recommended for children. TH
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- Harada M, Nakanishi J, Yasoda E, et al. Mercury pollution in the Tapajos River basin, Amazon: mercury level of head hair and health effects. Environ Int. 2001;27(4):285-290
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- Needleman HL. Mercury in dental amalgam—a neurotoxic risk? JAMA. 2006 Apr 19;295(15):1835-1836.
- National Institutes of Allergy and Infectious Diseases. NAID research on thimerosal. December 2006. Available at www.niaid.nih.gov/factsheets/thimerosal.htm. Last accessed April 19, 2007.
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