Diseases Caused by Mercury or Its Compounds

1. Introduction and Definitions

Mercury is a naturally occurring heavy metal that exists in several forms, including elemental (metallic) mercury, inorganic mercury compounds, and organic mercury compounds (such as methylmercury). Exposure to mercury, particularly in industrial settings, can lead to severe health issues affecting the nervous, digestive, and immune systems, as well as the lungs and kidneys. This article aims to provide comprehensive information on diseases caused by mercury or its compounds, targeting occupational health nurses and doctors.

2. Agent Causes the Disease

Mercury exposure occurs in different forms, each with specific pathways and health effects:

  • Elemental Mercury: Typically inhaled as vapor, which is rapidly absorbed by the lungs and can cause neurological and respiratory damage.
  • Inorganic Mercury Compounds: Found in various industrial chemicals and can be absorbed through inhalation or dermal contact, causing kidney and gastrointestinal issues.
  • Organic Mercury Compounds (Methylmercury): Often found in contaminated fish and seafood, leading to exposure primarily through ingestion. It can cross the blood-brain barrier, causing severe neurological damage.

3. Workers at Risk of This Disease

Several occupations and tasks put workers at higher risk of mercury exposure, including:

  • Mining and Smelting Workers: Involved in mercury extraction and processing.
  • Dental Professionals: Using mercury amalgam in dental fillings.
  • Industrial Workers: Involved in the production of chlorine and caustic soda using mercury cells.
  • Laboratory Workers: Handling mercury-containing instruments and chemicals.
  • Manufacturing Workers: Producing electrical equipment, batteries, and fluorescent lamps containing mercury.
  • Recycling Workers: Involved in the disposal and recycling of mercury-containing products.

4. Symptoms

Symptoms of mercury-related diseases can vary depending on the form and level of exposure:

  • Acute Exposure to Elemental Mercury: Symptoms include cough, chest pain, shortness of breath, nausea, vomiting, diarrhea, fever, and a metallic taste. Severe exposure can lead to respiratory failure and death.
  • Chronic Exposure to Elemental Mercury: Symptoms include tremors, insomnia, memory loss, neuromuscular effects, headaches, and cognitive dysfunction.
  • Inorganic Mercury Exposure: Symptoms include kidney damage (proteinuria, nephritis), skin rashes, dermatitis, and gastrointestinal disturbances.
  • Organic Mercury (Methylmercury) Exposure: Symptoms include sensory impairment (vision, hearing, speech), lack of coordination, muscle weakness, and cognitive impairments. Severe cases can lead to paralysis and death.

5. Diagnosis

Diagnosing mercury-related diseases involves a combination of clinical evaluation, occupational exposure assessment, and specific tests:

  • Medical History and Physical Examination: Detailed assessment of the patient's work history and symptoms.
  • Blood and Urine Tests: Measuring mercury levels to assess exposure.
  • Neurological Evaluation: Including tests for motor function, cognitive abilities, and sensory perception.
  • Kidney Function Tests: Monitoring kidney function in cases of inorganic mercury exposure.
  • Imaging Tests: MRI or CT scans to detect neurological damage or kidney issues.

6. Treatment

Treatment for mercury-related diseases focuses on managing symptoms and preventing further exposure:

  • Remove from Exposure: Immediate removal from the source of mercury exposure is crucial.
  • Chelation Therapy: In cases of severe mercury poisoning, chelating agents such as dimercaprol, DMSA, or DMPS may be used to bind mercury and enhance its excretion.
  • Symptomatic Treatment: Providing supportive care for respiratory, neurological, and gastrointestinal symptoms. This may include medications to manage tremors, pain, and cognitive dysfunction.
  • Supportive Care: Including oxygen therapy for respiratory issues and monitoring kidney function.
  • Long-term Monitoring: Regular follow-up to monitor neurological and kidney function.

7. Prevention

Preventing mercury-related diseases involves implementing strict control measures in the workplace:

  • Engineering Controls: Using local exhaust ventilation, enclosed processes, and proper maintenance of equipment to reduce airborne mercury.
  • Work Practices: Implementing safe work practices such as proper handling and disposal of mercury-containing materials, and avoiding eating, drinking, or smoking in areas where mercury is used.
  • Personal Protective Equipment (PPE): Providing and ensuring the use of appropriate respirators, protective clothing, and gloves.
  • Health Surveillance: Regular health screenings, including blood and urine tests for workers exposed to mercury.
  • Education and Training: Informing workers about the hazards of mercury and safe work practices to minimize exposure.

Workplace Exposure Limits:

  • OSHA: The legal airborne permissible exposure limit (PEL) is 0.1 mg/m3 averaged over an 8-hour workshift.
  • NIOSH: The recommended airborne exposure limit (REL) is 0.05 mg/m3 (as Mercury vapor) averaged over a 10-hour workshift and 0.1 mg/m3 (as Mercury), not to be exceeded at any time.