Mercury Poisioning Notes Forensic Toxicology

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Mercury is a toxic (poisonous) metal. It can be present in many diffrent forms like:

1.Elemental Mercury: The best example is mercury present in old thermometer 

2.Inorganic Mercury: Looks like powder or crystals, more likely to be swallowed

3.Organic Mercury: Found in fish and food  

4.Mercuric chloride: colorless crystals, odourless

5.Mercuric cyanide: used in medicine

6.Mercuric oxide and Mercuric sulphate: used in industries

7.Mercuric sulphide: vermillion

Fatal Dose Of Mercury - The fatal dose of mercury for adults is generally considered to be between 0.5-4 gm (mercuric chloride) However, the exact lethal dose can vary depending on the individual's health status, the form of mercury, and the route of exposure. 

Action Mechanism of Mercury Poisioning 

Acute mercury poisoning occurs after sudden exposure to high doses of mercury. It causes multi organ failure, especially in the brain, lungs, kidneys, and GI tract. 

1. Affinity for Sulfhydryl (-SH) Groups : Mercury binds strongly to thiol (-SH) groups in proteins this will leads to enzyme inactivation , Disruption of cellular metabolism and protein in body looses function and get disrupted. 
2. Generation of Reactive Oxygen Species : Mercury interferes with mitochondrial respiration. This causes production of free radicals which leads to Lipid peroxidation DNA damage and cell death. 
3. Inhibition of Ion Transporters : Mercury blocks essential ion pumps like Na⁺/K⁺-ATPase and Ca²⁺-ATPase and leads to ion imbalance, swelling of cells,neural dysfunction.

Symptoms of Acute Mercury Poisioning 

• After Swallowing symptoms like irritation with burning pain and metallic taste in the mouth.
• Constriction of throat , sunken eyes, dilated pupils
• Mouth, tongue and fauces become corroded and mucous membrane appears greyish white
• Nausea, vomiting, abdominal pain, diarrhea, and gastrointestinal bleeding
•  cold clampy skin, pale anxious face, Tremors, ataxia, impaired vision, hearing, and speech, as well as mental disturbances
• Fever, chills, rash, and progressive kidney and liver damage, fainting ,convulsions

Post-Mortem Findings in  Mercury Poisoning

Kidney Damage : Autopsy may reveal severe, acute kidney injury and necrosis due to the accumulation of mercury in the renal system.

Liver Damage: The liver is also a target organ for mercury, and post-mortem analysis may show signs of acute hepatic necrosis and dysfunction.

Brain Damage: Microscopic examination of the brain may reveal neuronal degeneration, cerebral edema, and other signs of mercury-induced neurotoxicity.

Sources of Mercury Exposure

1. Occupational Exposure : Workers in industries like mining, manufacturing, and dentistry may be at risk of chronic mercury exposure.
2.  Environmental Contamination : Mercury pollution can contaminate soil, water, and the food chain, leading to ongoing exposure.
3. Consumer Products: Some consumer items like certain electronics, batteries, and medical devices may contain mercury