Hydrofluoric acid (HF) is not just a corrosive, it is a potentially deadly poison with latent effects that may not manifest for up to 24 hours after the exposure, depending on the concentration of the acid and the duration of exposure.
HF readily penetrates the skin, causing deep tissue layer destruction. Severity and rapidity of onset of signs and symptoms depends on the concentration, duration of exposure, and penetrability of the exposed tissue. Pain may be delayed.
CONCENTRATIONS LESS THAN 20% - Erythema and pain may be delayed up to 24 hours, often not reported until tissue damage is extreme. In one study, 7% HF produced symptoms in 1 to several hours, 12% HF in less than one hour, and 14.5% HF immediately.
CONCENTRATIONS 20 TO 50% - Erythema and pain may be delayed from 1 to 8 hours, and is often not reported until tissue damage is extreme.
CONCENTRATIONS GREATER THAN 50% - Produces immediate burning, erythema, and tissue damage.
Systemic fluoride toxicity may result from ingestion, inhalation, or extensive dermal burns. Hypocalcemia, hypomagnesemia, hyperkalemia (potassium), pulmonary edema, metabolic acidosis, ventricular arrhythmias, and death are possible.
Eye exposure may result in severe ocular damage with concentrations greater than 0.5%. Fume exposure commonly causes eye irritation and can also cause ocular injury. Signs and symptoms may be delayed.
Ingestion may result in vomiting and abdominal pain; painful necrotic lesions, hemorrhagic gastritis, and pancreatitis have been reported after significant exposure.
Inhalation of hydrofluoric acid vapors may cause severe throat irritation, cough, dyspnea, cyanosis, lung injury and pulmonary edema resulting in death.
HF should always be handled in a fume hood. PPE should include a long-sleeved acid resistant apron and a face shield in addition to the usual lab coat and safety glasses.
Gloves must be chosen to be resistant to HF but also be compatible with the process: Heavy 6 mil nitrile, butyl or neoprene gloves worn over nitrile examination gloves are preferred, but may inhibit manual dexterity to a point of interfering with the work and endangering the laboratorian. In this case, double gloving with nitrile examination gloves is recommended while keeping alert to any wetness on the outer glove- in which case the outer glove should be changed immediately.