Chronic poisoning with heavy metals such as lead, mercury, arsenic, and cadmium occurs through occupational exposure, contaminated food or water, cosmetics, herbal medicines, and industrial pollution. These metals accumulate slowly in the body and cause multi-system damage. Identifying long-term symptoms and initiating appropriate chelation therapy are essential in clinical toxicology practice.
1. Lead Poisoning
Sources
- Lead-based paints
- Contaminated soil and water
- Battery and smelting industries
- Traditional cosmetics and herbal products
Clinical Features
- Neurological: irritability, headache, cognitive impairment, peripheral neuropathy (“wrist drop”)
- Gastrointestinal: abdominal pain (“lead colic”), constipation, anorexia
- Hematological: microcytic anemia, basophilic stippling
- Renal: interstitial nephropathy
- Bone: lead lines on X-ray in children
Diagnosis
- Blood lead levels
- Peripheral smear for basophilic stippling
- X-ray showing metaphyseal lead lines
Management
- Removal from exposure
- Chelators: EDTA, dimercaprol (BAL), DMSA (succimer)
- Supportive therapy for anemia
2. Mercury Poisoning
Sources
- Industrial vapors (elemental mercury)
- Contaminated fish (methylmercury)
- Broken thermometers and fluorescent bulbs
Clinical Features
Elemental Mercury
- Tremors (“mercurial tremors”)
- Irritability and emotional instability
- Memory impairment
Organic Mercury (Methylmercury)
- Ataxia
- Peripheral neuropathy
- Constricted visual fields
- Hearing impairment
- Developmental delay in children
Diagnosis
- Urine mercury levels (for elemental mercury)
- Blood mercury levels (for organic mercury)
Management
- Remove from exposure
- Chelation: DMSA, DMPS
- Supportive neurologic care
3. Arsenic Poisoning
Sources
- Contaminated groundwater
- Pesticides
- Herbal medicines
- Industrial smelting
Clinical Features (Chronic)
- Skin: hyperpigmentation, raindrop pattern, hyperkeratosis
- Neurological: peripheral neuropathy
- GI: abdominal pain, diarrhea
- Cardiovascular: prolonged QT interval
- Cancer risk: skin, lung, and bladder cancer
Diagnosis
- 24-hour urine arsenic levels
- Hair and nail analysis (long-term exposure)
Management
- Chelators: BAL (dimercaprol), DMSA
- Hydration and electrolyte management
- Monitor cardiac rhythm
4. Cadmium Poisoning
Sources
- Battery manufacturing
- Industrial welding fumes
- Contaminated food (rice, vegetables)
- Cigarette smoke (major source)
Clinical Features
- Renal: proximal tubular dysfunction → proteinuria
- Bone: osteomalacia and osteoporosis (Itai-Itai disease)
- Respiratory: chronic cough, emphysema (inhalation exposure)
Diagnosis
- Urinary cadmium levels
- Blood cadmium levels
- Renal function tests
Management
- Eliminate exposure source
- Supportive renal care
- Chelation is generally ineffective for cadmium poisoning
General Principles of Heavy Metal Poisoning Management
- Identify and remove exposure source
- Perform baseline blood and urine levels
- Start appropriate chelation therapy
- Monitor organ functions (renal, hepatic, neurological)
- Provide long-term follow-up due to chronic accumulation
Detailed Notes:
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PATH: PHARMD/ PHARMD NOTES/ PHARMD FOURTH YEAR NOTES/ CLINICAL TOXICOLOGY/ CLINICAL SYMPTOMS AND MANAGEMENT OF CHRONIC POISONING WITH THE FOLLOWING AGENTS – HEAVY METALS.