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Thallium
Thallium is a soft, pliable metal that was once commonly used as a homicidal poison due to its odorless and tasteless properties. It exists in several salt forms that are freely soluble in water. Thallium poisoning works by disrupting cell potassium levels and inhibiting enzyme pumps. It has a strong affinity for sulfhydryl groups and can cause alopecia. Acute thallium poisoning presents with abdominal pain, hair discoloration, neuropathy and potentially death from respiratory failure. Chronic poisoning also results in alopecia, skin rashes and long term neurological effects. Diagnosis involves tests of urine, blood, hair and tissues. Treatment requires gastric lavage and chelation therapy to enhance excretion
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Thallium
- 1. THALLIUM Dr Nikita Prabhakaran Juniorresident Dept of Forensic Medicine GMC,Tvm
- 2. Characteristics • Soft andpliable • Metal • Ideal homicidal poison
- 3. Salts sulphate*** acetate Chloride Iodide Nitrate Carbonate • Odourless •Tasteless • Freely soluble in water
- 4. Uses • Glass anddye industry • Rodenticide • Depilatory • Fireworks • Cardiac perfusion imaging
- 5. Mode of action-1 • Cellular toxin • //r to K+ • Na+ K+ ATPase pump • Low levels: replaces K+ • High levels:competitively inhibits
- 6. Mode of action-2 • Affinity for SH group Sulphydryl Crosslinking Of keratin Alopecia Nail growth affected
- 7. Fatal dose • Average: 10-15 mg/kg • Reported adult dose : 1 gm of absorbed thallium
- 8. Absorption • Inhalation • Ingestion •Intact skin
- 9. Clinical features- Acute •abdominal pain • gastroenteritis(haematemesis + haematochezia) • tachycardia • headache confusion paraesthesia hallucination convulsion • Retrobulbar neuritis ophthalmoplegia • DEATH ~ respiratory failure (due to motor neuropathy)
- 10. • Occasionally hepaticor renal failure • Bone marrow depression • Scalp hair – dark pigmented band 3-4 days • Urine –first voided greenish
- 11. Clinical features-Chronic Alopecia- 10days after Total loss (1 month) Lateral half of eyebrows – falls Survives – regrowth occurs Skin rash butterfly distribution on the face acneiform eruptions occasionally Nails dystrophy Mee’s lines
- 13. CNS • Peripheral neuropathy-sensorimotor • -primarily of the soles and foot • -unsteady gait ~ 1st to be noted • -2 to 6 days • Ataxia • Other CNS cranial nerve palsy • optic neuropathy • choreoathetosis • tremor • encephalopathy • psychotic behaviour
- 14. • Ophthalmic –ptosis, ophthalmoplegia, nystagmus • keratitis, lens opacities • abnormal colour vision and reduced acuity • CVS – Htn, cardiomyopathy, arrythmias, bradycardia, ECG changes • OTHERS: testicular toxicity • hypokalemia • renal failure • hepatic dysfn
- 15. • Bluish linein the gums: 3 to 4 weeks post-ingestion • Thallium Triad: alopecia + skin rash • peripheral neuropathy • mental confusion + lethargy • Earliest symptom complex: • painful neuropathy+ gastroenteritis • Sequelae: lasts for 30 yrs • (ataxia + tremor + flaccid paralysis + retardation)
- 16. Diagnosis • opacities inthe GIT /liver • Decreased colour sensitivity • Optic neuropathy • ECG changes • Decreased nerve conduction • Hair microscopy: dark pigmn at the roots
- 17. urine 3 drops brominewater 3 drops Sulfosalicylic acid 1 drop HCl 2 drops rhodamine B in HCl I ml of benzene Centrifuge bright yellow/fluorescent red colour
- 18. • Spectroscopy • Urineexcretion: 10-20 mg in 24 hrs ~diagnostic • Blood levels- >100 mg/dL potential poisoning • Hypocalcemia
- 19. Treatment • Stomach washwith Prussian Blue (precipitate) • Maintanence : a duodenal tube 125 mg/kg + 15 ml of 15 % mannitol • twice a day till urine 0.5 mg/day • Activated charcoal enhances elimination
- 20. • Forced diuresiswith K Cl • Haemodialysis • Diethyldithiocarbamate not recommended
- 21. • Physiotherapy- preventmuscle contractures • Shaving the head- to reduce stress of hair fall • Oral hygiene
- 22.
- 23. • Fatty degenerationof heart( Tabby cat striation of the ventricles) • Fatty degeneration of liver
- 24. • Renal damage •Pulmonary oedema • Cerebral oedema
- 25. Forensic Issues: • Accidentalpoisoning: industrial/occupational exposure • children: rodenticide • Suicidal –rare in India • common in western countries till 1960 • USA banned it in 1975 • Lot of cases for murders in western countries
- 26.