Mercury (Hg)

1. Properties:

• Mercury is a heavy, silvery-white liquid metal at room temperature. It is also highly volatile, meaning it easily evaporates into the air.
• Mercury has no taste or smell and is insoluble in water, but it dissolves in nitric acid.
• It is a highly toxic element that can accumulate in the body, leading to serious health problems.

2. Forms of Mercury:

• Elemental Mercury (Hg): This is the most common form of mercury and is found naturally in the environment. It is also used in various industries, including mining, manufacturing, and dentistry.
• Mercury Salts (Hg2+): These are formed when mercury reacts with acids.
• Organic Mercury Compounds (Methyl Hg): These are the most toxic form of mercury and are formed when mercury reacts with organic compounds in the environment. Methylmercury is particularly dangerous because it can easily accumulate in the food chain, especially in fish.

3. Routes of Entry into the Body:

• Skin Absorption: Hg can be absorbed through the skin, especially if the skin is damaged.
• Inhalation: Mercury is volatile and can easily enter the body through the lungs when inhaled.
• Ingestion: Mercury can accumulate in fish and shellfish, and humans can become exposed through consuming these contaminated seafood.

4. Health Effects:

• Mercury is highly toxic and can damage various organs in the body, including:
  • Nervous system: Mercury can cause neurological disorders, memory loss, tremors, numbness, and tingling in the extremities.
  • Digestive system: It can lead to gastritis, diarrhea, nausea, and vomiting.
  • Respiratory system: Mercury can cause pneumonia, shortness of breath, and lung inflammation.
  • Cardiovascular system: It can disrupt heart rhythm and blood pressure.
  • Reproductive system: Mercury can cause infertility and birth defects.
• Methyl Hg: This form is particularly harmful to the brain, especially in developing children. It can cause irreversible brain damage, leading to learning disabilities, developmental delays, and behavioral problems.
• Mercury can disrupt chromosomes and interfere with cell division.
• Mercury can cause tissue necrosis (death).

5. Symptoms of Mercury Poisoning:

• Acute Mercury Poisoning: Symptoms can include nausea, vomiting, diarrhea, abdominal pain, tremors, dizziness, and loss of consciousness.
• Chronic Mercury Poisoning: Symptoms include neurological disorders, memory loss, tremors, numbness, and tingling in the extremities.
• Dark Line at the Gum Line: This is a characteristic symptom of mercury poisoning.

6. Mercury Analysis:

• Atomic Absorption Spectrometry (AAS): This technique utilizes cold vaporization to analyze mercury in samples.
• Chemical Methods:
  • Formation of a complex with diphenylcarbazide: This forms a blue precipitate.
  • Hg2+ forms a red complex: This occurs when mercury reacts with specific complexing agents.
  • Detection of Hg in the system using a pink complex with I2 and Cu2I2.
  • Hg2+ + KI in a neutral or slightly acidic medium: Forms a red precipitate that dissolves in the reaction medium.

7. Management and Prevention:

• Acute Mercury Poisoning: Immediate medical attention is crucial. Patients require hospitalization for treatment.
• Chronic Mercury Poisoning: Treatment involves detoxification and rehabilitation.
• Preventive Measures:
  • Use mercury in well-ventilated areas, ensuring workplace safety measures are in place.
  • Avoid direct contact with mercury.
  • Limit consumption of fish and seafood known to be high in mercury.

Additional Information:

• Dimercaprol (BAL) is used to treat mercury poisoning. BAL forms a complex with mercury, aiding in its removal from the body.
• Mercury has a strong inhibitory effect on enzymes: It interferes with enzymes that contain two SH groups, hindering their activity.
• Mercury can be removed from the body using chelating agents: These agents bind to mercury, facilitating its elimination.

References:

• Chemistry textbook for grade 11.
• Website of the Ministry of Health.
• Wikipedia: https://en.wikipedia.org/wiki/Mercury_(element)