Hydrofluoric Acid Burns

Excerpt

Hydrofluoric acid was discovered in 1771 by Swedish pharmaceutical chemist Carl Wilhelm Scheele when he was investigating the mineral called fluorite (Calcium fluoride). Hydrogen fluoride (HF) has several synonyms: Hydrofluoric acid, Fluoric acid, Hydrofluoride, Fluorine monohydride, Fluorane. Hydrofluoric (HF) acid is an extremely powerful inorganic acid and a vigorous dehydrating agent that is used in many industrial branches including production of aluminum, stainless steel and hydrofluorocarbons, glass etching, stevedoring and transportation industries, inorganic and organic chemical manufacturing, mineral processing, petroleum oil refineries, fire extinguishers manufacturing, steel mills, cleaning HVAC systems, and as the precursor to all fluorine compands in the pharmaceutical industry. Consumer products containing hydrofluoric acid include rust removers, detergents, marble, brick and stone cleaning, toilet bowl clearners, insecticides, automobile wheel cleaners and air conditioner cleaners.

Hydrofluoric acid is comprised of a diatomic compound of hydrogen and fluoride atoms as a gas, while in the liquid state it has strong hydrogen bonds between the chains forming a polymeric compound. Anhydrous hydrofluoric acid and hydrofluoric acid in aqueous solutions range in appearance from colorless to slightly tinted based upon the concentration and impurities. It has a boiling point of 20 degrees celcius (68 degrees fahrenheit) at 760 mmHg, vapour density greater than air and readily dissolves in water that when diluted (exothermal reaction) is visibly indistinguishable from water. Hydrofluoric acid has a disagreeable, pungent odor at concentrations of 0.04 ppm which is way below the OSHA PEL (Permissible Exposure Limit) of 3 ppm and is extremely corrosive and has the ability to dissovle a number of materials especially oxides.

The Major source of production of hydrofluoric acid is by treating fluorite with concentrated sulfuric acid at temperatues of 265 degrees fahrenheit to produce hydrofluic acid and calcium sulfate. Alternate production is a by-product in the production of phosphoric acid from the mineral apatite. Hydrofluoric acid is also produced by the release from industrial and welding processes and environmental activities such as volcanoes. HF production exceeds one million tons world wide by a number of manufactors and is transported and stored under high pressure as a highly concentrated liquid. In the United States of America, the Department of Transportation Hazard Label and National Fire Protection Assocation (NFPA) 704 lists the health value of 4 (can be lethal), flammability value of 0 (will not burn under typical fire conditions), instability value of 2 (readily undergoes violent chamical changes at elevated temperatures and pressures) and special value of W with line through (reacts violently or exposevely with water). Domestic concentrations of hydrofluoric acid is typically around 0.5% with industrial concentrations approaching 100%.

Primary health consequences including dermal burns, eye injury, acute respiratory symptoms, gastrointestinal symptoms and cardiac abnormalities can occur from direct skin / eye contact, ingestion of solutions or inhalation of fumes and vapors with unintentional and intentional exposures. Unintentional exposure of hydrofluoric acid in and out of the workplace include inappropriate operations, mechanical failure of equipment, explosions of containers and tanks containing HF, during traffic incidents with leakage of HF, inadequate protective equipment and children accidentally exposed through ingestion of domestic cleaners. Intentional cases of ingestion, with suicidal and homicidal intent, of hydrofluoric acid have been documented.

Hydrofluoric acid is highly toxic and damaging to humans due to the “double danger” properties of the corrisive nature of the hydrogen ions and toxic effect due to the ability of fluoride ions to penetrate into deep tissue causing liquefactive necrosis and release of cellular products. Hydrofluoric acid burns present with a unique concern for systemic fluoride toxicity including cardiovascular, pulmonary, renal and neuromuscular symptoms, electrolyte imbalance and enzyme inhibition which can lead to cardiac arrhythmias and death. Chronic symptoms may occur or persist for months after HF ingestion or respiratory exposure.