What is aluminium (Al) phosphide used for?

Aluminum Phosphide: A Highly Toxic Pesticide and Rodenticide

Aluminum phosphide tablets are NOT used therapeutically in medicine—they are a highly toxic pesticide and rodenticide used for grain storage protection that causes severe poisoning with mortality rates of 18-59% when ingested. 1, 2, 3

Primary Use (Non-Medical)

• Aluminum phosphide is marketed as a fumigant and insecticide to protect stored grain from pests and rodents, sold under brand names including Celphos, Phostek, Quickphos, and Phosphume 3
• The tablets contain approximately 56% aluminum phosphide and 44% inert elements (ammonium carbonate) to prevent tablet disintegration 4
• When exposed to moisture or stomach acid, aluminum phosphide releases phosphine gas, which is the primary toxic agent causing cellular hypoxia through mitochondrial dysfunction and cytochrome C oxidase inhibition 5

Critical Toxicity Profile

• Ingestion of as little as 150-500 mg (approximately 0.5-1.5 tablets) can be fatal, with all exposures requiring ICU-level care 6, 3
• The mortality rate ranges from 18.6% to 59% depending on the series, making this one of the most lethal pesticide poisonings 2, 3
• Suicidal ingestion accounts for 97% of cases, though incidental inhalational exposures can occur in grain storage facilities 1, 2

Clinical Manifestations

Immediate symptoms (within minutes to hours):

• Nausea (79.4%), vomiting (76.5%), and abdominal pain (31.4%) are the most common presenting symptoms 2
• Refractory hypotension and cardiac failure are the hallmark features and primary cause of death 1, 5
• Severe metabolic acidosis develops rapidly (41.1% of patients) 2
• Electrocardiographic abnormalities including atrial fibrillation, ST elevation, and T-wave inversion may occur 4

Poor prognostic indicators:

• Higher tablet ingestion (>2 tablets) 2
• Severe metabolic acidosis (pH <7.2) 2, 3
• Presence of shock and hypotension refractory to dopamine 3
• Elevated liver function tests 2

Management Principles

There is no specific antidote for aluminum phosphide poisoning—management is entirely supportive. 1, 5

Immediate Interventions

• Early gastric lavage should be performed, though potassium permanganate solution (traditionally recommended) may not be universally available 4, 5
• Aggressive fluid resuscitation with crystalloid solutions and vasopressor support (norepinephrine) for refractory hypotension 1
• N-acetylcysteine administration may provide antioxidant support 1
• Magnesium sulfate is well-documented to reduce cardiac arrhythmias, though no uniform dosing protocol exists worldwide 4

Cardiovascular Support

• Calcium gluconate (100-200 mg/kg/dose) via slow infusion with ECG monitoring can be given for life-threatening arrhythmias 6
• Sodium bicarbonate (1-2 mEq/kg IV push) can be considered for severe acidosis, but should never be administered through the same IV line as calcium 6
• Prompt and adequate cardiovascular support is the core management strategy to maintain tissue perfusion until poison levels decrease 5

Respiratory Management

• Consider CPAP ventilation for patients with adequate consciousness and without contraindications 6
• Early intubation may be necessary for patients with altered mental status or respiratory failure 1

Critical Pitfalls to Avoid

• Phosphine gas released from aluminum phosphide is highly toxic to healthcare providers—ensure proper ventilation of treatment areas 6
• Avoid physical restraints without adequate sedation, as this worsens outcomes 6
• Monitor for rhabdomyolysis with serum creatinine kinase and potassium levels, treating with hydration and urine alkalinization if myoglobinuria develops 6

Important Distinction: Aluminum Compounds in Medicine

Do not confuse aluminum phosphide with aluminum-containing phosphate binders (aluminum hydroxide) used in chronic kidney disease:

• Aluminum hydroxide is used as a phosphate binder in CKD patients with serum phosphorus >7.0 mg/dL, but only for short-term therapy (≤4 weeks) due to neurotoxicity and osteomalacia risk 7
• Aluminum-containing phosphate binders should be reserved for refractory hyperphosphatemia when other agents fail 7
• Calcium citrate must be avoided when patients receive aluminum-based compounds, as citrate increases aluminum absorption and may precipitate acute toxicity 7

Aluminum Toxicity Management in CKD

• For serum aluminum levels 60-200 μg/L, administer deferoxamine (DFO) at 5 mg/kg with high-flux dialysis 6
• For serum aluminum levels >200 μg/L, do NOT give DFO due to neurotoxicity risk—instead perform intensive daily dialysis for 4-6 weeks 6
• DFO therapy carries a 91% mortality risk from mucormycosis in dialysis patients, necessitating reduced dosing and expanded treatment intervals 6

Public Health Considerations

• Aluminum phosphide tablets are freely available without restrictions in many developing countries including India, Iran, and Turkey, contributing to high poisoning rates 1, 2
• Withdrawal from the market and introduction of safer rodenticides is recommended in agricultural regions where access is unrestricted 2