Mercury Poisoning in Pediatrics

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Topic Name Introduction Types of Mercury Exposure Pathophysiology Clinical Presentation Diagnosis Management Prevention Complications

Mercury Poisoning in Pediatrics

Mercury poisoning in children represents a significant toxicological emergency with potentially devastating neurological consequences. Children are particularly vulnerable due to their developing nervous systems and higher absorption rates.

Key Points:

• Mercury exists in three main forms: elemental, inorganic, and organic
• Children are most commonly exposed through dietary sources and environmental contamination
• Neurotoxicity is the primary concern in pediatric mercury exposure
• Early recognition and intervention are crucial for optimal outcomes

Types of Mercury Exposure

Elemental Mercury (Hg⁰):

• Sources:
  • Broken thermometers and sphygmomanometers
  • Dental amalgams
  • Fluorescent light bulbs
  • Traditional religious practices
• Primary route: Inhalation of mercury vapors
• 80% absorption through lungs

Inorganic Mercury (Hg⁺, Hg²⁺):

• Sources:
  • Skin-lightening creams
  • Traditional medicines
  • Battery manufacturing
• Primary route: Ingestion and dermal absorption
• 10-15% gastrointestinal absorption

Organic Mercury (Methylmercury):

• Sources:
  • Contaminated fish and seafood
  • Maternal dietary exposure
  • Industrial pollution
• Primary route: Ingestion
• 95% absorption from gastrointestinal tract
• Readily crosses placental barrier

Pathophysiology

General Mechanisms:

• High affinity for sulfhydryl groups in proteins
• Disruption of cellular enzyme systems
• Mitochondrial dysfunction
• Oxidative stress induction
• Blood-brain barrier disruption

Specific Effects:

• Central Nervous System:
  • Neuronal death
  • Disruption of neurotransmitter systems
  • Interference with neural migration
  • Microtubule disruption
• Renal System:
  • Proximal tubular damage
  • Decreased glomerular filtration
  • Mercury accumulation in kidneys

Clinical Presentation

Acute Exposure:

• Elemental Mercury:
  • Metallic taste
  • Cough and dyspnea
  • Chest pain
  • Pneumonitis
  • Tremors
• Inorganic Mercury:
  • Severe gastrointestinal symptoms
  • Hemorrhagic gastroenteritis
  • Acute kidney injury
  • Stomatitis
  • Metallic taste
• Organic Mercury:
  • Paresthesias
  • Visual disturbances
  • Ataxia
  • Speech disorders
  • Mental status changes

Chronic Exposure:

• Developmental delays
• Cognitive impairment
• Behavioral changes
• Visual-spatial processing deficits
• Fine motor dysfunction
• Language disorders

Diagnosis

Initial Assessment:

• Detailed exposure history
• Dietary history (especially fish consumption)
• Environmental assessment
• Family practices and cultural remedies

Laboratory Testing:

• Blood Mercury Levels:
  • Normal: <10 μg/L
  • Concerning: >50 μg/L
  • Critical: >200 μg/L
• Urine Mercury:
  • 24-hour collection preferred
  • Best indicator for inorganic exposure
• Additional Testing:
  • Complete blood count
  • Comprehensive metabolic panel
  • Urinalysis
  • Chest X-ray if inhalational exposure

Management

Initial Steps:

• Source removal and exposure cessation
• Supportive care
• Airway management if needed
• Fluid and electrolyte management

Chelation Therapy:

• Indications:
  • Symptomatic patients
  • Blood mercury levels >100 μg/L
  • Significant acute exposure
• Agents:
  • DMSA (Succimer):
    • Oral administration
    • 10 mg/kg/dose every 8 hours for 5 days
    • Then every 12 hours for 14 days
  • DMPS (Unithiol):
    • IV or oral administration
    • 5 mg/kg/dose every 4 hours
  • BAL (British Anti-Lewisite):
    • For severe cases
    • 3-5 mg/kg/dose IM every 4 hours

Prevention

Primary Prevention:

• Dietary recommendations:
  • Limited consumption of high-mercury fish
  • Guidelines for pregnant women and young children
• Environmental measures:
  • Proper disposal of mercury-containing devices
  • Use of mercury-free alternatives
  • Industrial emission controls
• Education:
  • Healthcare provider awareness
  • Parent education
  • Community outreach

Secondary Prevention:

• Regular screening in high-risk populations
• Environmental assessment
• Occupational exposure monitoring

Complications

Short-term:

• Acute respiratory distress
• Acute kidney injury
• Encephalopathy
• Seizures

Long-term:

• Cognitive impairment
• Developmental delays
• Behavioral disorders
• Visual-spatial deficits
• Chronic kidney disease
• Peripheral neuropathy

Special Considerations:

• Prenatal exposure effects
• Developmental outcomes
• Educational implications
• Quality of life impact