Exposure to hydrofluoric acid can result in skin burns or other injuries, depending on which body part was exposed to it.
Injuries usually occur when hydrofluoric acid comes in contact with the skin.
Symptoms vary depending on which body part is exposed and may include pain (sometimes described as burning) at the site of the exposure.
If hydrofluoric acid comes in contact with the skin, is ingested, or is inhaled, it may affect the whole body.
To diagnose an injury due to hydrofluoric acid exposure, doctors ask questions about potential exposure to the acid, do a physical examination, and may take x-rays or do electrocardiography or endoscopy.
Hydrofluoric acid is commonly used in many industrial processes, including oil refining, silicon and glass etching, refrigerant production, and aluminum metal production. Hydrofluoric acid is also used as a brick and stone cleaner, rust remover, and wheel cleaner. Most exposure to hydrofluoric acid occurs in the workplace.
Hydrofluoric acid is a weak acid that can penetrate the skin and move into the underlying tissues and damage them.
Usually, injuries due to exposure occur when hydrofluoric acid comes in contact with the skin. Injury can also result when the acid comes in contact with the eyes, is ingested, or is inhaled. Workers may accidentally ingest hydrofluoric acid if it is stored in unmarked containers, such as water bottles. This type of exposure is not common. Outside the workplace, the acid may be ingested when a person attempts self-harm or a young child ingests it out of curiosity.
Symptoms of Hydrofluoric Acid Exposure
Symptoms of hydrofluoric acid exposure vary depending on which body part was exposed to the acid and the concentration of the acid in the solution (whether dilute or concentrated). Pain may occur immediately or develop several hours later.
After the skin is exposed, pain is typically the first symptom and may occur before redness, swelling, blisters, or grayish white patches on the skin (signs of a chemical burn) develop. Pain is often more severe than expected based on how much of the skin is affected. If the fingers and nail beds are burned, the nails may remain intact, and pain may be severe even though the nails and skin may look normal or near-normal.
When hydrofluoric acid is inhaled, the most common symptoms are pain in upper airway, chest pain (described as burning), cough, and shortness of breath. People may also report a burning sensation where the skin contacted the acid, nausea, vomiting, and headache. The throat may be red and swollen, and people may wheeze or make crackling sounds when they breathe. The tiny muscles in the airway's walls may tighten (contract) involuntarily (called bronchospasm), making breathing difficult. When exposure is greater, the lungs may fill with fluid, and people may cough up blood or develop acute hypoxemic respiratory failure (adult respiratory distress syndrome), which may be fatal.
Ingesting a dilute solution of hydrofluoric acid may cause the mouth and throat to become red and swollen. Ingesting a small amount of hydrofluoric acid may cause no symptoms. If a concentrated solution is ingested, the stomach is irritated and bleeds, and the lungs may be affected as when hydrofluoric acid is inhaled.
Contact with the eyes may occur when hydrofluoric acid splashes into the eyes. If the acid is diluted, the eyes may be painful and red, and the conjunctiva (the membrane that lines the eyelid and covers the white of the eye) may bulge. Symptoms may not occur until hours after the exposure. If the acid is more concentrated, symptoms occur more rapidly. The cornea may degenerate, and the eyeball may rupture.
When hydrofluoric acid comes in contact with the skin, is ingested, or is inhaled, it may affect the whole body, causing an excess of fluoride in the body (fluoride toxicity). Contact with eyes does not have the same effect. Body-wide effects occur more rapidly when the acid is ingested. Fluoride toxicity can cause a low level of calcium, a low level of magnesium, abnormal heart rhythms, and low blood pressure.
Diagnosis of Hydrofluoric Acid Exposure
A doctor's evaluation
Blood tests
To diagnose an injury due to hydrofluoric acid exposure, doctors ask questions about possible exposure to the acid during the last 24 hours and do a physical examination. They ask about the following:
How the acid came in contact with the body
How long it was in contact with body
Whether the acid was dilute or more concentrated
What other chemicals were also present
Whether personal protective equipment (PPE) was being used
Doctors also ask about drugs and disorders that increase the risk of low levels of calcium or magnesium.
There is no specific test for fluoride toxicity, but doctors do blood tests to measure levels of calcium, magnesium, and fluoride.
If doctor suspect that the lungs contain fluid or if hydrofluoric acid was inhaled or ingested, a chest x-ray and other appropriate tests (such as pulse oximetry) are done. Doctors may also test lung function, although often after the person has recovered.
If the fingers are burned, x-rays are taken to check for bone damage.
If doctors suspect that the whole body has been affected, electrocardiography is done to check for abnormal heart rhythms.
If hydrofluoric acid was ingested, endoscopy may be done.
Prognosis for Hydrofluoric Acid Exposure
Prognosis depends on which body part was exposed to hydrofluoric acid.
If the skin is exposed, the exposure is mild, and diagnosis and treatment are prompt, prognosis is good. Burns usually heal over a period of several days to weeks, depending on their severity.
When hydrofluoric acid is inhaled, the prognosis depends on how concentrated the acid was and how long the exposure lasted. If the exposure was mild to moderate, symptoms may resolve on their own over a period of hours to days. If hydrofluoric acid exposure was more severe, the upper airway and/or lungs may remain irritated for months to years.
Ingesting dilute hydrofluoric acid may cause no symptoms or cause the digestive tract to become irritated. However, the irritation can be reversed. Ingesting concentrated hydrofluoric acid may lead to bleeding in the digestive tract or to fluoride toxicity. Either may be fatal.
If exposure of the eyes is mild, symptoms resolve over several days, If exposure is more severe, the cornea may be damaged, and chronic conjunctivitis, clouding of the cornea, glaucoma, or keratoconjunctivitis sicca (dryness of the cornea) may develop.
Prevention of Hydrofluoric Acid Exposure
Various organizations (such as the Occupational Safety and Health Administration [OSHA] and National Institute for Occupational Safety and Health [NIOSH]) provide recommendations for reducing the risk of exposure to hydrofluoric acid. They include
Providing workers with information about the hazards of hydrofluoric acid before they handle it
Limiting the time workers are exposed to hydrofluoric acid
Requiring workers to wear a properly functioning fume hood and appropriate personal protective equipment (PPE), such as goggles, disposable gloves, and an acid-resistant apron
Requiring workers to wear long pants, long sleeves, and closed-toe shoes
Equipping the work area with a safety shower and an eye wash station
Storing hydrofluoric acid correctly
Placing spill-response equipment (such as spill control pads) in all areas where hydrofluoric acid is used
Treatment of Hydrofluoric Acid Exposure
Various treatments depending on which body part was exposed
Prompt decontamination if applicable
Calcium and magnesium salts
Exposure of the skin to hydrofluoric acid
When the skin
If skin exposure was moderate or severe, the person is transferred to a burn center for possible surgery, including skin grafts, removal of dead tissue, and amputation.
Ingestion of hydrofluoric acid
If hydrofluoric acid is ingested, the stomach should sometimes be emptied with a tube inserted into the stomach through the mouth or nose as soon as possible. If emptying is delayed by more than an hour, it is unlikely to help and is therefore avoided.
Inhalation of hydrofluoric acid
If symptoms resemble those of adult respiratory distress syndrome (ARDS), treatments for ARDS may be used. Treatments include mechanical ventilation and proning (turning a person on their stomach).
Bodywide exposure to hydrofluoric acid
People with fluoride toxicity are admitted to an intensive care unit for tests and treatment.
Fluoride toxicity is treated with calcium and magnesium salts, given intravenously because these levels are low. Fluids are given intravenously, and drugs are given if needed to increase the low blood pressure caused by fluoride toxicity.
Hemodialysis may be done if people are stable. It can remove fluoride from the bloodstream.
Exposure of the eyes to hydrofluoric acid
If the eyes are exposed to hydrofluoric acid, doctors flush (irrigate) them with copious amounts of water as soon as possible. Irrigation is begun at a workplace eyewash station and is continued on the way to the hospital.
Consultation with ophthalmologists may be required.
