Radiation poisoning, also known as acute radiation syndrome (ARS), occurs after exposure to high doses of ionizing radiation over a short period. Radiation causes cellular injury by damaging DNA, impairing rapidly dividing tissues such as bone marrow, gastrointestinal mucosa, and hair follicles. Understanding the mechanisms, clinical stages, and treatment approaches is crucial in toxicology and emergency preparedness.
Types of Ionizing Radiation
- Alpha particles: high-energy but low penetration; harmful if ingested or inhaled
- Beta particles: moderate penetration; cause skin burns
- Gamma rays: highly penetrating; systemic damage
- Neutrons: deeply penetrating; significant external hazard
Mechanism of Toxicity
Ionizing radiation interacts with biological tissues to produce free radicals that damage DNA, proteins, and cell membranes. This leads to:
- Cell death
- Bone marrow suppression
- Gastrointestinal mucosal damage
- Microvascular injury
- Organ system failure at high doses
Clinical Stages of Acute Radiation Syndrome (ARS)
1. Prodromal Stage (Minutes to Hours After Exposure)
- Nausea and vomiting
- Anorexia
- Fatigue and headache
- Fever in higher exposures
2. Latent Stage (Hours to Days)
Symptoms temporarily improve as the body attempts to compensate, but cellular injury continues silently.
3. Manifest Illness Stage
The presentation depends on radiation dose and affected organ system.
Hematopoietic Syndrome (1–6 Gy)
- Bone marrow suppression
- Leukopenia and thrombocytopenia
- Infections and bleeding tendencies
Gastrointestinal Syndrome (6–10 Gy)
- Severe vomiting and diarrhea
- Bloody stools
- Dehydration
- Loss of intestinal mucosa leading to sepsis
Cerebrovascular Syndrome (>20–30 Gy)
- Confusion and seizures
- Ataxia
- Coma
- Cardiovascular collapse
This form is rapidly fatal within hours to days.
Organ System Effects
1. Bone Marrow
- Depleted stem cells
- Severe anemia
- Reduced immunity
2. Gastrointestinal Tract
- Mucosal sloughing
- Malabsorption
- Sepsis risk
3. Skin (Cutaneous Radiation Syndrome)
- Erythema and blister formation
- Dry or moist desquamation
- Ulceration and tissue necrosis
4. Thyroid
- Hypothyroidism (especially after radioactive iodine exposure)
Diagnosis
- History of exposure
- Serial blood counts for lymphocyte depletion
- Cytogenetic analysis for chromosome aberrations
- Electrolytes and renal function tests
- Imaging for burns or internal contamination
Management
1. Initial Management
- Remove contaminated clothing (reduces 90% of external contamination)
- Wash skin with soap and water
- Provide airway and circulatory support
2. Hematopoietic Support
- Broad-spectrum antibiotics for infection prevention
- Antifungals and antivirals as needed
- Colony-stimulating factors (G-CSF, GM-CSF)
- Blood transfusions for severe anemia
- Bone marrow transplantation in selected cases
3. Gastrointestinal Management
- IV fluids and electrolyte correction
- Antiemetics
- Nutritional support (parenteral if severe mucosal injury)
- Infection control
4. Decontamination for Internal Emitters
- Potassium iodide (KI): for radioactive iodine exposure
- Prussian blue: for cesium and thallium
- DTPA (Ca-DTPA or Zn-DTPA): for plutonium, americium
5. Skin and Local Injury Care
- Topical steroids for early inflammation
- Wound care for ulcers or necrosis
- Surgical intervention for deep tissue injury
Prognostic Indicators
- Time to onset of vomiting
- Rate of lymphocyte decline
- Total absorbed dose (Gy)
- Presence of neurological symptoms
Detailed Notes:
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PATH: PHARMD/ PHARMD NOTES/ PHARMD FOURTH YEAR NOTES/ CLINICAL TOXICOLOGY/ RADIATION POISONING.