Hydrofluoric Acid Exposure

Hydrofluoric acid (HF) — used in glass etching, semiconductor manufacture, rust removers (domestic). Penetrates deep — calcium + magnesium chelation. Features: • Skin: severe deep pain disproportionate to visible erythema (can develop hours after exposure for dilute HF). • Eye: severe pain, corneal injury. • Inhalation: pulmonary oedema. • Ingestion: GI burns + systemic toxicity. Systemic toxicity (any significant exposure — even small skin area for high concentration): • Hypocalcaemia (severe; arrhythmia). • Hypomagnesaemia. • Hyperkalaemia. • Cardiac arrhythmia + arrest. • Refractory ventricular arrhythmia. Danger thresholds: • <20% concentration small area: usually local + delayed pain. • >50% any area: high systemic toxicity risk. • Body surface >1% with high concentration: significant systemic risk.