Aluminium Phosphide Poisoning (Celphos): The Poison With No Antidote

Aluminium phosphide — sold as Celphos, Quickphos, or simply “rice tablet” — is a grain fumigant and one of the most lethal poisons encountered in Indian practice. It is heavily examined in forensic medicine because it has no antidote, a characteristic autopsy picture and enormous medicolegal significance.

At a glance

Mechanism

The tablet is stable while dry. On contact with water or gastric hydrochloric acid it releases phosphine, which blocks cytochrome c oxidase and halts oxidative phosphorylation. Cells with the highest energy demand fail first, and the myocardium fails hardest — hence profound, catecholamine-resistant cardiogenic shock. Phosphine also generates reactive oxygen species and depletes cellular antioxidant defences, producing widespread cell membrane injury.

Clinical features

• Early: vomiting, severe epigastric pain, retrosternal burning, restlessness, a garlic or decaying-fish odour on the breath.
• Cardiovascular: profound hypotension unresponsive to fluids and vasopressors, arrhythmias, myocarditis, ECG changes ranging from ST-T abnormalities to complete heart block.
• Metabolic: severe metabolic acidosis, hypomagnesaemia, hypoglycaemia or hyperglycaemia, adrenal insufficiency.
• Respiratory: ARDS, pulmonary oedema.
• Later: hepatic and renal failure in those who survive the first day.

Death is usually within 12 to 24 hours from circulatory collapse. Reported mortality is high — the outcome is largely determined by the amount ingested and how fresh the tablet was.

Diagnosis

Largely clinical, supported by the history and the characteristic odour. The silver nitrate paper test on gastric aspirate or exhaled breath turns black in the presence of phosphine and is a simple bedside confirmation.

Management

1. Ventilate the room and protect staff — phosphine is exhaled and released from vomitus.
2. Gastric decontamination is traditionally done with potassium permanganate solution (1:10,000), which oxidises phosphine, and/or coconut oil, which is thought to retard gas release. Activated charcoal may be given. Practice varies and evidence is weak; follow your unit’s protocol.
3. Aggressive haemodynamic support: intravenous fluids guided by filling status, vasopressors, and inotropes. Invasive monitoring is helpful because the shock is cardiogenic rather than distributive.
4. Correct acidosis with sodium bicarbonate; correct magnesium and glucose.
5. Intra-aortic balloon counterpulsation and other mechanical support have been used in specialist centres for refractory shock.
6. Intensive care for ARDS, arrhythmia and organ failure.

Forensic points

Autopsy findings are non-specific but include congestion of viscera, a garlicky smell on opening the body cavities, and gastric mucosal congestion or erosion. Preserve stomach contents and viscera in saturated saline — not in formalin or rectified spirit — for chemical analysis.

Last-minute checklist

• Phosphine is the poison; the tablet is only its container.
• Cytochrome c oxidase inhibition, like cyanide, but with myocardial failure dominating.
• Shock is refractory. No antidote exists.
• Silver nitrate paper test turns black.
• Preserve viscera in saturated saline for analysis.

Frequently asked questions

Why is there no antidote to aluminium phosphide?

Phosphine binds mitochondrial enzymes and causes widespread oxidative injury within minutes; by the time a patient reaches hospital the damage is already distributed across organs. Nothing available reverses that, so care is supportive.

Why does an old tablet cause milder poisoning?

Aluminium phosphide reacts with atmospheric moisture over time, so a tablet exposed to air has already released much of its phosphine and contains less available poison.

Why must viscera be preserved in saturated saline?

Formalin and rectified spirit interfere with the chemical detection of phosphine and other volatile poisons. Saturated saline preserves the sample without destroying the analyte.

References

• Reddy KSN, Murty OP. The Essentials of Forensic Medicine and Toxicology.
• Parikh CK. Textbook of Medical Jurisprudence, Forensic Medicine and Toxicology.
• Institutional critical care protocol for aluminium phosphide ingestion.