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Treatment of Mercury Intoxication


This information was provided by EMedicine.  http://emedicine.com/...emerg&topicid=813

Toxicity, Mercury Emedicine Home

Authored by Barry Diner, MD, Chief Resident, Department of Emergency Medicine, The Brooklyn Hospital Center

Co-authored by Barry Brenner, MD, PhD, Director, Division of Research, Associate Clinical Professor, Department of Emergency Medicine, Weill College of Medicine, Cornell University, The Brooklyn Hospital Cen

Barry Diner, MD is a member of the following medical societies: American College of Emergency Physicians

Edited by Michelle Ervin, MD, Chair, Department of Emergency Medicine, Howard University Hospital; John T. VanDeVoort, PharmD, ABAT, Clinical Assistant Professor, Pharmacy Manager, Regions Hospital Pharmacy, University of Minnesota College of Pharmacy; Fred Harchelroad, MD, Director, Medical Toxicology Treatment Center, Associate Professor of Emergency Medicine, Department of Emergency Medicine, Allegheny General Hospital; John Halamka, MD, Executive Director, Center for Quality and Value, Instructor, Division of Emergency Medicine, Beth Israel Deaconess Medical Center; and Raymond J. Roberge, MD, MPH, Vice-Chair, Clinical Associate Professor, Department of Emergency Medicine, Western Pennsylvania Hospital

  INTRODUCTION

Background: Throughout the centuries, there have been several incidents of reported mercury toxicity. As early as 1500 BC we know that the Egyptians used mercury, as it was found in their tombs. In the late 18th century, antisyphilitic agents contained mercury. It was during the 1800s that the phrase, "mad as a hatter" was coined due to the chronic mercury exposure felters faced.

In the 1940s and 1950s, mercury became known as the product that caused acrodynia, also known as Pink Disease. The manifestations of acrodynia included pain and erythema of the palms and soles, irritability, insomnia, anorexia, diaphoresis, photophobia, and a skin rash.

Some of the more recent exposures include Minamata Bay in Japan (1960), mercury contaminated fish in Canada, methylmercury-treated grain in Iraq (1960 and 1970) and, in the U.S. (1996), a beauty cream product from Mexico called "Crèma de Belleza-Manning."

For centuries, mercury was an essential part of many different medicines, such as diuretics, antibacterial agents, antiseptics, and laxatives. More recently, these drugs have been substituted and drug-induced signs of mercury toxicity are rare. Mercury toxicity in environmental pollution is a major concern because of increased usage of fossil fuels and agricultural products, both of which contain mercury.

Mercury poisoning usually is misdiagnosed due to the insidious onset, nonspecific signs and symptoms, and lack of knowledge within the medical profession.

Mercury is found in many industries, such as battery, thermometer, and barometer manufacturing. Mercury can be found in fungicides used in the agricultural industry. Prior to 1990, paints contained mercury as an antimildew agent. In medicine, mercury is used in dental amalgams and various antiseptic agents.

On July 7, 1999 a joint statement by the American Academy of Pediatrics (AAP) and the US Public Health Service (USPHS) was issued alerting clinicians and the public of thimerosal, a mercury containing preservative used in some vaccines.

Pathophysiology: Mercury is the only metal that is a liquid at room temperature. Its symbol is Hg, which is derived from the Greek word hydrargyrias meaning "water silver." Mercury is found in both organic and inorganic forms. The inorganic form can be further divided into elemental mercury and mercuric salts. Organic mercury can be found in long and short alkyl and aryl compounds.

Mercury in any form is toxic. The difference lies in how it is absorbed, the clinical signs and symptoms, and the response to treatment modalities. Mercury poisoning can result from vapor inhalation, ingestion, injection, or absorption through the skin.

Elemental mercury (Hg) is found as a liquid form, which easily vaporizes at room temperature and is well absorbed (80%) through inhalation. Its lipid soluble property allows for easy passage through the alveoli into the bloodstream and red blood cells (RBCs). Once inhaled, elemental mercury is mostly converted to an inorganic divalent or mercuric form by catalase in the erythrocytes. This inorganic form has similar properties to inorganic mercury (eg, poor lipid solubility, limited permeability to the blood brain barrier, and excretion in feces). Small amounts of nonoxidized elemental mercury continue to persist and account for central nervous system toxicity.

Elemental mercury as a vapor has the ability to penetrate the CNS, where it is ionized and trapped, attributing to its significant toxic effects. Elemental mercury is not well absorbed by the GI tract and, therefore, when ingested (eg, thermometers), is only mildly toxic.

Inorganic mercury, found mostly in the mercuric salt form (eg, batteries), is highly toxic and corrosive. It gains access to the body orally, or dermally, and is absorbed at a rate of 10% of that ingested. It has a nonuniform mode of distribution secondary to poor lipid solubility and accumulates mostly in the kidney, causing significant renal damage. Although poor lipid solubility characteristics limit CNS penetration, slow elimination and chronic exposure allow for significant CNS accumulation of mercuric ions and subsequent toxicity. Chronic dermal exposure to inorganic mercury may also lead to toxicity.

Excretion of inorganic mercury, as with organic mercury, is mostly via feces. Renal excretion of mercury is considered insufficient and attributes to its chronic exposure and accumulation within the brain, causing CNS effects.

Organic mercury can be found in 3 forms, aryl and short and long chain alkyl compounds. Organic mercurials are absorbed more completely from the GI tract than are inorganic salts because of intrinsic properties, such as lipid solubility and mild corrosiveness (though much less corrosive than inorganic mercury). Once absorbed, the aryl and long chain alkyl compounds are converted to their inorganic forms and possess similar toxic properties of inorganic mercury. The short chain alkyl mercurials are readily absorbed in the GI tract (90-95%) and remain stable in their initial forms. Alkyl organic mercury has high lipid solubility and is distributed uniformly throughout the body, accumulating in the brain, kidney, liver, hair, and skin. Organic mercurials also cross the blood brain barrier and the placenta and penetrate erythrocytes, attributing to neurological symptoms, teratogenic effects, and high blood to plasma ratio, respectively.

Methylmercury has a high affinity for sulfhydryl groups, which attributes to its effect on enzyme dysfunction. One enzyme that is inhibited is choline acetyl transferase, which is involved in the final step of acetylcholine production. This inhibition may lead to acetylcholine deficiency, contributing to the signs and symptoms of motor dysfunction.

Excretion of alkyl mercury occurs mostly in the form of feces (90%), secondary to significant enterohepatic circulation. The biological half-life of methyl mercury is approximately 65 days. Organic mercury is found most commonly in antiseptics, fungicides and industrial run-off.

Frequency:

  • In the U.S.: The 1998 annual report of the American Association of Poison Control Centers' toxic exposure surveillance system noted 4,039 exposures to mercury. Of these, 1,039 were in children younger than 6 years, and 1,385 were older than 19 years. Overall, 68 patients were reported to have moderate effects, 12 patients had major effects, and 3 patients died as a result of mercury exposure.

Race: There is no scientific evidence that demonstrates any difference in outcome following exposure to mercury that is attributable to race.

Sex: There is no scientific evidence that demonstrates any difference in outcome following exposure to mercury that is attributable to gender.

  CLINICAL

History: The clinical presentation of mercury toxicity can manifest in a variety of ways depending on the nature of the exposure, the intensity of the exposure, and the chemical form. Acute toxicity usually is related to the inhalation of elemental or ingestion of inorganic mercury. Exposure to organic mercury leads to chronic toxicity and, occasionally, acute toxicity.

  • Acute exposure due to inhaled elemental mercury can lead to pulmonary symptoms. Initial signs and symptoms, such as fever, chills, shortness of breath, metallic taste, and pleuritic chest pain, may be confused with metal fume fever. Other possible symptoms could include stomatitis, lethargy, confusion, and vomiting.
  • Recovery is usually without sequela, but pulmonary complications of inhaled toxicity may include interstitial emphysema, pneumatocele, pneumothorax, pneumomediastinum, and interstitial fibrosis. Fatal ARDS has been reported following elemental mercury inhalation.
  • Chronic and intense acute exposure causes cutaneous and neurological symptoms. The classic triad found in chronic toxicity is tremors, gingivitis, and erethism (ie, a constellation of neuropsychiatric findings that includes insomnia, shyness, memory loss, emotional instability, depression, anorexia, vasomotor disturbance, uncontrolled perspiration and blushing).
  • Additional findings may include headache, visual disturbance (eg, tunnel vision), peripheral neuropathy, salivation, insomnia, and ataxia.
  • Without a complete history, mercury toxicity, especially in the elderly, can be misdiagnosed as Parkinson's disease, senile dementia, metabolic encephalopathy, depression, or Alzheimer's disease.
  • Elemental mercury has poor GI absorption and, therefore, oral or rectal exposure to elemental mercury from a thermometer should have no toxic effect. Dental amalgams also contain elemental mercury. Dental professionals who are in contact with amalgam must follow specific guidelines in order not to be exposed to toxic amounts of aerosolized elemental mercury. Patients with dental amalgam fillings have slightly elevated levels in their urine, but these findings have not correlated with any systemic disease.
  • Inorganic mercury or mercuric salt exposure mainly occurs through the oral and GI tract. Its corrosive properties account for the majority of the acute signs and symptoms. The acute presentation can include ashen-gray mucous membranes secondary to precipitation of mercuric salts, hematochezia, vomiting, severe abdominal pain, and hypovolemic shock. Systemic effects usually begin several hours after ingestion and may last several days. These effects include metallic taste, stomatitis, gingival irritation, foul breath, loosening of teeth, and renal tubular necrosis leading to oliguria or anuria.
  • Batteries contain inorganic mercury but are rarely the cause of systemic symptoms. Ingestion of batteries by pediatric patients is a common problem, and its complications are related to local corrosive complications.
    • Patients who ingest mercury-containing batteries should receive chelation therapy if symptoms of mercury toxicity are present.
    • The use of cathartics and water-soluble enemas is useful for increasing transit time of released mercury, but is not indicated for intact batteries.
  • Chronic exposure usually results from prolonged occupational exposure to elemental mercury that is converted into the inorganic form, topical application of mercurial salves, and the chronic use of diuretics or cathartics.
    • Chronic exposure results in renal failure, dementia, and acrodynia.
    • Acrodynia, known as pink disease and is considered to be a mercury allergy, presents with erythema of the palms and soles, edema of the hands and feet, desquamating skin rash, hair loss, pruritus, diaphoresis, tachycardia, hypertension, photophobia, irritability, anorexia, insomnia, poor muscle tone, constipation, or diarrhea.
    • Acrodynia does not present in everyone who is exposed to inorganic mercury, but is an indicator of widespread disease.
  • Organic mercury poisoning usually results from ingestion of contaminated food. The long chain and aryl forms of organic mercury have similar characteristics of inorganic mercury toxicity.
    • The onset of symptoms usually is delayed (days-to-weeks) after exposure.
    • Organic mercury targets enzymes and the depletion of these enzymes must take place prior to the onset of symptoms.
    • Symptoms related to toxicity typically are neurological, such as visual disturbance (eg, scotomata, visual field constriction), ataxia, paresthesias (early signs), hearing loss, dysarthria, mental deterioration, muscle tremor, movement disorders, and, with severe exposure, paralysis and death.
    • There are specific sights in the brain that organic mercury targets, including the cerebral cortex (especially visual cortex), motor and sensory centers (pre-and postcentral cortex), auditory center (temporal cortex), and cerebellum.
  • All forms of mercury are toxic to the fetus, but methylmercury most readily passes through the placenta. Even with an asymptomatic patient, maternal exposure can lead to spontaneous abortion or retardation.

Physical: The physical examination should be focused on the areas most commonly affected.

  • Perform a complete neurological examination, including a detailed cerebellar exam. Do full visual field evaluation.
  • Perform abdominal and rectal exams, with stool guaiac testing, and include documentation of a skin exam.

Causes:

  • The causes of elemental mercury toxicity include barometers, batteries, bronzing, calibration instruments, chloralki production, dental amalgams, electroplating, fingerprinting products, fluorescent and mercury lamps, infrared detectors, jewelry industry, manometers, neon lamps, paints, paper pulp production, photography, silver and gold production, semiconductor cells, and thermometers.
  • The causes of inorganic mercury toxicity include antisyphilitic agents, acetaldehyde production, chemical laboratory work, cosmetics, disinfectants, explosives, embalming, fur hat processing, ink manufacturing, mercury vapor lamps, mirror silvering, perfume industry, photography, spermicidal jellies, tattooing inks, taxidermy production, vinyl chloride production, and wood preservation.
  • The causes of organic mercury toxicity include antiseptics, bactericidals, embalming agents, farming industry, fungicides, germicidal agents, insecticidal products, laundry/diaper products, paper manufacturing, pathology/histology products, seed preservation, and wood preservatives.
  • Another cause is thimerosal, an additive preservative that is used in vaccines to prevent bacterial contamination. The most commonly used vaccines that contain Thimerosal are DTP(whole cell), HIB, and Hepatitis B.
  DIFFERENTIALS

Acute Respiratory Distress Syndrome
Amyotrophic Lateral Sclerosis
Dermatitis, Exfoliative
Disk Battery Ingestion
Gastroenteritis
Myasthenia Gravis
Pediatrics, Bronchiolitis
Pediatrics, Fifth Disease or Erythema Infectiosum
Renal Failure, Acute
Toxicity, Arsenic
Toxicity, Carbon Monoxide
Toxicity, Iron
Toxicity, Phenytoin
Toxicity, Theophylline

Other Problems to be Considered:

Elemental mercury toxicity
Adverse effects of therapeutic medication (eg, lithium, theophylline, phenytoin)
Alzheimer's disease
Cerebellar degenerative disease or tumor
Delayed neuropsychiatric sequela of carbon monoxide poisoning
Ethanol or sedative hypnotic drug withdrawal
Lacunar infarction
Metabolic encephalopathy
Parkinson's disease
Senile dementia

Inorganic mercury toxicity (mercury salts)
Acid ingestion
Alkali ingestion
Arsenic toxicity
Iron toxicity
Phosphorus toxicity
Similar to the causes of acute gastroenteritis

Organic mercury toxicity
Cerebral palsy
Intrauterine hypoxia
Teratogenic effects in the embryo

  WORKUP

Lab Studies:

  • The diagnostic approach to the patient with suspected mercury toxicity starts with a thorough history, including occupation(s), hobbies, and degree of seafood intake. All toxic presentations, whether acute, chronic or subacute, are difficult diagnoses because the multiple organ systems affected (eg, CNS, kidney, mucous membranes) can mimic a variety of other diseases. If no such history exists, clinical suspicion can be confirmed by laboratory analysis.
  • Complete blood count and serum chemistries: To assess possible anemia secondary to GI hemorrhage, determine the onset of acute and chronic renal failure and rule out the possibility of electrolyte abnormality.
    • Pregnancy testing should be considered in women of childbearing ages.
    • Whole blood mercury levels are normally < 2 mcg/dL in unexposed individuals (exceptions are those individuals with a high dietary intake of fish). Methylmercury concentrates in erythrocytes; therefore, its levels in blood will remain high in acute toxicity. The blood level correlation with chronic methylmercury toxicity is more variable. Methylmercury exhibits a blood-to-plasma ratio of 20:1, a characteristic of inorganic mercury. This higher ratio may be of utility in determining if organic or inorganic mercurials have poisoned the patient. Aryl mercury compounds accumulate in RBCs but are metabolized to inorganic mercury more rapidly, thus demonstrating lower blood-to-plasma ratios than that seen with methyl mercury exposures. Following high exposure to inorganic mercury salts, the blood-to-plasma ratio ranges from a high of 2:1, to 1:1. Paraesthesias are expected if blood mercury levels are > 20 mcg/dL.

      Inorganic mercury redistributes to other body tissue and its levels in the blood only are accurate after an acute ingestion. In general, blood levels of mercury are helpful for recent exposures, as well as determining if the toxicity is secondary to organic or inorganic mercury, but they are not useful for a guide to therapy.

  • Urine mercury levels (normally < 10-20 mcg/L): Excretion of mercury in urine is a good indicator of inorganic and elemental mercury exposure but is unreliable for organic mercury (methylmercury), since elimination occurs mostly in the feces. There is no absolute correlation between the levels in the urine and the onset of symptoms, but levels above 300 mcg/L are associated with overt symptoms. Mercury levels in the urine can also be used to gauge the efficacy of chelation therapy. For workers chronically exposed to mercury compounds, urinary excretion > 50 mcg/L is associated with an increased frequency of tremor.
  • Hair has a high sulfhydryl content. Mercury forms covalent bonds with sulfur and, therefore, it can be found in abundance in hair samples. The rate of false positives is high with hair analysis secondary to environmental exposure. Hair analysis should not be used solely as a means to confirm mercury toxicity or exposure.

Imaging Studies:

  • Obtain a flat plate radiograph of the abdomen in order to visualize ingested elemental mercury, which is radiopaque.

 

  TREATMENT

Prehospital Care: Prehospital management includes gathering information on the time, type and mode of exposure.

  • Initial assessment (ABCs)
  • Oxygen
  • IV access

Emergency Department Care: Supportive care begins with the ABCs, especially when dealing with inhalation of elemental mercury and the ingestion of caustic inorganic mercury, both of which may cause the onset of airway obstruction and failure. The next step in supportive care is the removal of contaminated clothing and copious irrigation of exposed skin. The need for aggressive hydration may be required for acute inorganic mercury poisoning due to its caustic properties.

  • Do not induce emesis if the compound ingested is of the caustic inorganic form.
    • Gastric lavage is recommended for organic ingestion, especially if the compound is seen on the abdominal x-ray series. Gastric lavage with protein-containing solutions (eg, milk, egg whites, salt-poor albumin) or 5% sodium formaldehyde sulfoxylate solution may bind gastric mercury and limit its absorption.
    • Activated charcoal is indicated for GI decontamination, as it will bind both inorganic and organic mercury compounds to some extent.
    • Whole bowel irrigation may be used until rectal effluent is clear and void of any radiopaque material. However, it is doubtful to be efficacious in decreasing the GI transit time of elemental mercury because of the high density of elemental mercury and the low density of the whole bowel irrigant solutions. Likewise, whole bowel irrigation has no adsorptive effect on any type of mercury within the GI tract.
    • Use chelating agents if the patient is symptomatic, if systemic absorption is anticipated, or if increased blood or urine levels are present. Chelating agents all contain thiol groups, which compete with endogenous sulfhydryl groups.
    • Hemodialysis is used in severe cases of toxicity when renal function has declined. Regular hemodialysis' ability to filter out mercury is limited because of mercury's mode of distribution between erythrocytes and plasma. However, hemodialysis, with L-cysteine compound as a chelator, has been successful.
    • Neostigmine may help motor function in methylmercury toxicity. This toxicity often leads to acetylcholine deficiency.

      Polithiol is a nonabsorbable resin that can help in facilitating the removal of methylmercury (short chain alkyl organic mercury), which is then excreted in the bile after enterohepatic circulation.

    Consultations: Consultation with the regional poison control center or your local medical toxicologist (certified through the American Board of Medical Toxicology and/or the American Board of Emergency Medicine) may provide additional information and patient care recommendations.

    • Recommendation: The American Academy of Pediatric and US Public Health Service states that the use of products containing thimerosal is preferable to withholding vaccinations, which protect against diseases that represent immediate threat to young infants (ie, pertussis, Haemophilus Infuenzae). For the hepatitis B vaccine, adjustments in timing within the ranges proposed in the immunization schedule provide additional opportunities to minimize exposure of small infants to thimerosal. If thimerosal-free vaccine is not available Hepatitis B virus vaccination should be initiated in infants aged 6 months.

     

      MEDICATION

    The use of chelating agents should be instituted if the patient is symptomatic, systemic absorption is anticipated or increased blood or urine levels present.

    Drug Category: Chelating Agents - The thiol groups in the chelating agent compete with endogenous sulfhydryl groups.

    Drug Name BAL (British Anti-Lewisite) - BAL is used only in acute ingestion. BAL(dimercaprol in an oil solution) is contraindicated for use in organic (methylmercury) toxicity because it can raise levels in the brain causing further neurotoxicity.
    Adult Dose 3-5 mg/kg/dose deep IM injection q4h the first 2 d; followed by 2.5-3 mg/kg/dose IM q6h for 2 d; then 2.5-3 mg/kg/dose IM q12h for 1 wk
    Pediatric Dose Administer as in adults
    Contraindications Methylmercury toxicity; G-6-PD deficiency, unless a life-threatening situation exists; Severe peanut allergy, as the excipient for the dimercaprol is peanut oil.
    Pregnancy C - Safety for use during pregnancy has not been established.
    Precautions Caution with patients that are G-6-PD deficient, as it may produce hemolysis. Side effects include abdominal pain, nausea, vomiting, headache, elevated blood pressure, tachycardia, burning sensation to the lips and throat, constricting feeling of the throat, conjunctivitis, blepharospasm, lacrimation, rhinorrhea, salivation, burning sensation to the penis and urticaria (some side effects responsive to diphenhydramine cotherapy).
    Drug Name Penicillamine (Cuprimine , Depen) - PCN (D-penicillamine) forms a complex with mercury and is excreted in the urine; therefore, it should not be used in renal failure. It cannot be considered a first line agent because of the safer and more efficacious agent, dimercaptosuccinic acid.
    Adult Dose 15-40 mg/kg/d, up to a maximum of 250-500 mg PO q6h ac (Continue 1 wk until decline in urine mercury levels)
    Pediatric Dose 20-30 mg/kg/d PO once or twice daily before meals (ac)
    Contraindications Avoid in patients with penicillin allergy.
    Interactions Antacids, digoxin, iron
    Pregnancy D - Unsafe in pregnancy
    Precautions Side effects include GI disturbances, rash, leukopenia, thrombocytopenia and proteinuria.
    Use in caution during renal insufficiency. Therapy with d-penicillamine may be dangerous since the main route of elimination of this complex is renal.
    Drug Name DMSA (2,3-dimercaptosuccinic acid, Succimer, Chemet) - DMSA (2,3-dimercaptosuccinic acid) is used in both inorganic and organic mercurials. It is considered superior to PCN. DMSA is an oral medication that has fewer side effects than do PCN and BAL. Because of its ease of use, good efficacy and safety, initiate treatment with this agent if there is good evidence that significant absorption will occur, as mercury levels may not be readily available.
    Adult Dose 10 mg/kg PO tid for 5 d, followed by 10 mg/kg PO bid for 14 d
    Pediatric Dose 10 mg/kg or 350 mg/m2 PO q8h for 5 d, followed by 10 mg/kg PO bid for 14 d
    Contraindications Hypersensitivity to Succimer
    Pregnancy C - Safety for use during pregnancy has not been established.
    Precautions Side effects include mild GI disturbances and a transient rise in liver enzymes. The product has a strong sulfur smell.
    Thrombocytosis, eosinophilia, and neutropenia have all been reported with therapeutic use, and all are reported to resolve when therapy ends.

     

      FOLLOW-UP

    Prognosis:

    • Outcome depends on the form of the mercury compound and the severity of the exposure. Mild exposure to inorganic (ie, elemental, mercuric salt) and organic compounds can result in a complete recovery. Death is usually the result of a severe exposure to mercuric salt. Most organic mercury exposures leave a neurological sequela. Very minimal dermal exposure to dimethyl mercury has resulted in progressive neurologic deterioration and death, with initial symptoms delayed for several months.
    • Patients that need to be admitted to the hospital include:
      • Patients who ingested mercury salts (or those suspected)
      • Patients suspected of elemental mercury inhalation who have pulmonary injury
      • Patients who require intensive chelating therapy.

       

      MISCELLANEOUS

    Medical/Legal Pitfalls:

    • Failure to obtain a history of exposure to mercury compounds in a patient with significant historical features of the signs and symptoms of mercury exposure.
    • Failure to initiate treatment in a patient with significant exposure, and symptoms, prior to receiving the confirmatory laboratory analysis (which may be delayed for a week.)
    • Failure to consult your local medical toxicologist or regional poison control center for updated information on this rare poisoning.

    Special Concerns:

    • Significant oral ingestion of elemental mercury may lead to significant environmental contamination as the mercury is passed, essentially unabsorbed, through the GI tract, and expelled in the feces.

     

      TEST QUESTIONS

    CME Question 1: The mother of a 7-year-old male presents to the ED in rural Ohio and states that her son drank an unknown amount of liquid from a bottle in their shed. She brings the bottle with her; it is a fungicide that contains methylmercury. The patient is complaining of difficulty seeing, has trouble walking, and senses a funny feeling in his hands. Presuming that this is an organic mercury poisoning, which of the following chelating agents is contraindicated?

    A: DMSA (2,3-dimercaptosuccinic acid)
    B: Calcium disodium ethylenediaminetetraacetic acid
    C: PCN (D-penicillamine)
    D: Dimercaprol
    E: None of the above

    The correct answer is D: Dimercaprol (BAL) is contraindicated for use in organic mercury toxicity because it can raise the mercury levels in the CNS causing further neurotoxicity. Calcium disodium ethylenediaminetetraacetic acid is indicated for the treatment of acute lead and cadmium poisoning, not mercury poisoning; however, it is not specifically contraindicated.

    CME Question 2: The parents of an 8-year-old female run into the ED screaming, "My daughter is going to die. She has been poisoned with mercury from the thermometer that broke in her mouth." Which of the following is the next appropriate step?

    A: Begin GI decontamination.
    B: Start chelating therapy.
    C: Reassure parents that their child will be okay and send them home.
    D: Call poison control.
    E: Begin hemodialysis.

    The correct answer is C: Elemental mercury is very poorly absorbed by the GI tract and, therefore, is only mildly toxic. Certainly, the physician should examine the oropharynx of the patient to assess any intra-oral lacerations from the glass.

    Pearl Question 1: How does chronic elemental mercury poisoning present?

    The correct answer is : Tremors, gingivitis, and erethism (ie, insomnia, shyness, decreased memory, uncontrollable sweating, blushing)

    Pearl Question 2: What are the most common causes of elemental mercury ingestion?

    The correct answer is : Batteries and thermometers

    Pearl Question 3: What medical condition can mercury toxicity simulate?

    The correct answer is : Parkinson`s disease

    Pearl Question 4: What are common causes of inorganic mercury poisoning?

    The correct answer is : Fur hat production, embalming, ink manufacturing, and tattooing.

      BIBLIOGRAPHY
    • Abramson JS: Thimerosal in vaccines-An interim report to clinicians. American Academy of Pediatrics. Committee on Infectious Disease and Committee on Environmental Health. Pediatrics 1999; 104: 571-574.
    • Bates B: Heavy Metals and Inorganic Agents. Clinical Management of Poisoning and Drug Overdose 1998; 55: 750-756.
    • Ford M: Heavy Metals. Tintinalli 1996; 158: 839-841.
    • Goyer RA: Toxic effects of metals. Casarett and Doull's Toxicology: The Basic Science of Poisons 1991; 4th ed.: 646-651.
    • Graeme KA, Pollack CV: Heavy Metal Toxicity Part 1: Arsenic and Mercury. J Emerg Med 1998; 16: 45-56.
    • Kershaw TG, Dhahir PH, Clarkson TW: The relationship between blood levels and dose of methylmercury in man. Arch Environ Health 1980; 35: 28-36.
    • Klaasen C: Heavy Metals and Heavy Metal Antagonists. Goodman and Gilman's The Pharmacological Basis of Therapeutics 1985; 69: 1611-1614.
    • Norseth T, Clarkson TW: Studies on the biotransformation pf 203Hg-labeled methyl mercury chloride in rats. Arch Environ Health 1970; 21: 717-727.
    • Taueg C, Sanfillipo DJ, Rowens B, et al: Acute and chronic poisonings from residential exposures to elemental mercury - Michigan 1989-1990. J Toxicol Clin Toxicol 1992; 30: 63-67.
    • Young J: Mercury. Goldfrank's Toxicology Emergencies 1994; 74: 1051-1062.
    NOTE:
    Medicine is a constantly changing science and not all therapies are clearly established. New research changes drug and treatment therapies daily. The authors, editors, and publisher of this textbook have used their best efforts to provide information that is up-to-date and accurate and is generally accepted within medical standards at the time of publication. However, as medical science is constantly changing and human error is always possible, the authors, editors, and publisher or any other party involved with the publication of this text do not warrant the information in this text is accurate or complete, nor are they responsible for omissions or errors in the text or for the results of using this information. The reader should confirm the information in this text from other sources prior to use. In particular, all drug doses, indications, and contraindications should be confirmed in the package insert.

 

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