Chronic Arsenic Poisoning
Forensic Toxicology: Long-term Metallic Exposure
1. Pathophysiology
Arsenic acts as a metabolic poison by inhibiting sulfhydryl enzymes and disrupting ATP production. Chronic exposure—most commonly via contaminated groundwater—results in systemic accumulation, particularly in the hair, nails, and skin.
2. Clinical Triad (The “Arsenic Skin Changes”)
| Clinical Finding | Description |
|---|---|
| Pigmentation | “Raindrop” pigmentation (hyper-pigmented patches on a pale background). |
| Keratosis | Thickening of the skin, especially on the palms and soles (Arsenical Keratosis). |
| Mee’s Lines | Transverse white bands on the fingernails. |
3. Chronic Systemic Effects
- Peripheral Vascular Disease: “Blackfoot disease,” caused by severe damage to the microvasculature.
- Peripheral Neuropathy: Sensory-motor polyneuropathy, often described as a “stocking-glove” distribution.
- Carcinogenesis: Strongly associated with skin, lung, and bladder cancers.
4. Forensic Pearls
- Sample Collection: Because arsenic is stored in keratin, hair and nail clippings are the gold standard for detecting chronic exposure, rather than blood or urine.
- Differential: Must be distinguished from other causes of pigmentary skin changes and peripheral neuropathies.
- Educational Resource: For further study on toxicological screening and practice questions, please visit mymedschool.org.