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Hydrogen Fluoride

 

HYDROFLUORIC ACID(a)

7664-39-3

Hazard Summary-Created in April 1992; Revised in January 2000

    Hydrogen fluoride is used in the production of aluminum and chlorofluorocarbons, and in the glass etching and chemical industries.  Acute (short-term) inhalation exposure to gaseous hydrogen fluoride can cause severe respiratory damage in humans, including severe irritation and pulmonary edema.  Severe ocular irritation and dermal burns may occur following eye or skin exposure in humans.  Chronic (long-term) exposure of humans to fluoride at low levels has a beneficial effect of dental cavity prevention and may also be useful for the treatment of osteoporosis.  Exposure to higher levels of fluoride through drinking water may cause dental fluorosis or mottling, while very high exposures through drinking water or air can result in skeletal fluorosis in humans.  The only developmental effect observed from fluoride exposure in humans is dental fluorosis which can occur in a child's teeth when a mother receives high levels of fluoride during pregnancy.  EPA has not classified hydrogen fluoride for carcinogenicity.

Please Note: The main sources of information for this fact sheet are EPA's Health Issue Assessment for Hydrogen Fluoride and related compounds and the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for Fluorides, Hydrogen Fluoride, and Fluorine. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Uses

  • Hydrogen fluoride is used in the glass etching, electronic, and chemical industries. (7)
  • Hydrogen fluoride is predominantly used in the production of aluminum and chlorofluorocarbons (CFCs). Hydrogen fluoride is also used for separating uranium isotopes, as a catalyst in the petroleum industry, and in stainless steel pickling. (1,2,4)
  • Fluoride is sometimes added to public drinking water supplies, and is used in a number of dental products. (1,2)

Sources and Potential Exposure

  • The majority of exposure to fluoride occurs through the consumption of fluoridated drinking water and food. (1)
  • Individuals are most likely to be exposed to hydrogen fluoride by inhalation or dermal contact in the workplace. (1,2)
  • Individuals may also be exposed to hydrogen fluoride and other fluorides in the ambient environment from emissions from industrial processes and coal combustion, as well as from natural sources that include volcanic activity and dust from weathering fluoride-containing rocks and soils. (2)
  • Fluoride is also a component of cigarette smoke. (2)

Assessing Personal Exposure

  • Urine samples can be analyzed to determine whether or not exposure to fluorides has occurred. However, this test cannot distinguish among exposures to different fluorine compounds. (1)

Health Hazard Information

Acute Effects:
  • Acute inhalation exposure to gaseous hydrogen fluoride can cause severe respiratory damage in humans, including severe irritation and pulmonary edema.  Irritation of the eyes, nose, and upper and lower respiratory tract, lacrimation, sore throat, cough, chest tightness, and wheezing have been reported. (2-4,8)
  • Severe ocular irritation and dermal burns may occur following eye or skin exposure in humans. (1-3,5,8)
  • Convulsions and cardiac arrhythmias and death from cardiac or respiratory failure may occur in humans from ingestion of high doses of fluorides. (1,2)
  • Damage to the lungs, liver, and kidneys has been observed in animals acutely exposed to hydrogen fluoride by inhalation. (1,2)
  • Acute animal tests in rats, mice, guinea pigs, and monkeys have demonstrated hydrogen fluoride to have moderate to high acute toxicity from inhalation exposure.(6)
Chronic Effects (Noncancer):
  • Chronic exposure to fluoride through drinking water has been observed to cause dental fluorosis or mottling (staining or pitting of teeth) in humans.  At higher intakes through oral or inhalation exposure, skeletal fluorosis (i.e., an accumulation of fluoride in the skeletal tissues associated with pathological bone formation) has been noted in humans. (1,2)
  • Chronic inhalation exposure of humans to hydrogen fluoride has resulted in irritation and congestion of the nose, throat, and bronchi at low levels. (2,7)
  • Increased bone density has been reported among workers chronically exposed to fluorides (including hydrogen fluoride) via inhalation. (7)
  • Damage to the liver, kidneys, and lungs has been observed in animals chronically exposed to hydrogen fluoride by inhalation. (2)
  • At high concentrations, chronic oral fluoride exposure has been reported to result in adverse pulmonary effects, renal injury, thyroid injury, anemia, hypersensitivity, and dermatological reactions in humans. (2)
  • Chronic oral exposure to fluoride at low levels has a beneficial effect of dental cavity prevention. Fluoride has also been used for the treatment of osteoporosis. (2)
  • EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for hydrogen fluoride.
  • The California Environmental Protection Agency (CalEPA) has calculated a chronic inhalation reference exposure level (REL) of 0.03 milligrams per cubic meter (mg/m3) for hydrogen fluoride based on effects on bone density in humans.  The CalEPA reference exposure level is a concentration at or below which adverse health effects are not likely to occur.  It is not a direct estimator of risk but rather a reference point to gauge the potential effects.  At lifetime exposures increasivngly greater than the reference exposure level, the potential for adverse health effects increases. (7)
Reproductive/Developmental Effects:
  • Fluoride has been observed to cross the placenta in humans.  Dental fluorosis can occur in a child's teeth when the mother receives high levels of fluoride during pregnancy. (2)
  • In some animal studies, oral exposure to fluoride has caused impaired reproduction and malformation of fetal bones and teeth. (1,2)
  • Inhalation of hydrogen fluoride resulted in degenerative testicular changes in male dogs. (7)
  • Menstrual irregularities have been observed in women occupationally exposed to fluoride; no differences were found in the numbers of pregnancies, miscarriages, or births. (2)
Cancer Risk:
  • Epidemiological studies have not demonstrated an association between fluoride in drinking water and an increased risk of cancer. (1,2)
  • Increased rates of cancer have been observed in workers involving possible fluoride exposure; however, these situations involved mixed exposures to several chemicals, and fluoride could not be specifically implicated as the cause of the cancers. (1,2)
  • EPA has not classified hydrogen fluoride with respect to potential carcinogenicity.

Physical Properties

  • The chemical formula for hydrogen fluoride is HF, and its molecular weight is 20.01 g/mol. (1,5)
  • Hydrogen fluoride is a colorless gas that is very soluble in water. (1,2,5)
  • Hydrogen fluoride has a sharp, pungent, irritating odor; the odor threshold is 0.042 parts per million (ppm). (1,2,9)
  • Anhydrous hydrogen fluoride is one of the strongest acids known. (2)
  • The vapor pressure for hydrogen fluoride is 912 mm Hg at 25 °C. (2)


Conversion Factors:
To convert concentrations in air (at 25 °C) from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45). For hydrogen fluoride: 1 ppm = 0.82 mg/m3.

Health Data from Inhalation Exposure

AIHA ERPG--American Industrial Hygiene Association's emergency response planning guidelines.  ERPG 1 is the maximum airborne concentration below which it is believed nearly all individuals could be exposed up to one hour without experiencing other than mild transient adverse health effects or perceiving a clearly defined objectionable odor; ERPG 2 is the maximum airborne concentration below which it is believed nearly all individuals could be exposed up to one hour without experiencing or developing irreversible or other serious health effects that could impair their abilities to take protective action.
ACGIH TLV ceiling--American Conference of Governmental and Industrial Hygienists' threshold limit value ceiling; the concentration of a substance that should not be exceeded during any part of the working exposure.
LC50 (Lethal Concentration50)--A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.
NIOSH REL--National Institute of Occupational Safety and Health's recommended exposure limit; NIOSH-recommended exposure limit for an 8- or 10-h time-weighted-average exposure and/or ceiling.
NIOSH IDLH -- NIOSH's immediately dangerous to life or health concentration; NIOSH recommended exposure limit to ensure that a worker can escape from an exposure condition that is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from the environment.
OSHA PEL--Occupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects averaged over a normal 8-h workday or a 40-h workweek.

The health and regulatory values cited in this factsheet were obtained in December 1999.
a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.
b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.  OSHA numbers are regulatory, whereas NIOSH, ACGIH, and AIHA numbers are advisory.
c This NOAEL is from the critical study used as the basis for the CalEPA chronic reference exposure level.

References

  1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Fluorides, Hydrogen Fluoride and Fluorine. U.S. Public Health Service, U.S. Department of Health and Human Services, Altanta, GA. 1993.
  2. U.S. Environmental Protection Agency. Health Issue Assessment: Summary Review of Health Effects Associated with Hydrogen Fluoride and Related Compounds. EPA/600/8-89/002F. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1989.
  3. U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
  4. M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.
  5. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.
  6. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.
  7. California Environmental Protection Agency (CalEPA). Technical Support Document for the Determination of Noncancer Chronic Reference Exposure Levels.  Draft for Public Comment.  Office of Environmental Health Hazard Assessment, Berkeley, CA.  1997.
  8. California Environmental Protection Agency (CalEPA). Technical Support Document for the Determination of Acute Reference Exposure Levels for Airborne Toxicants.  Scientific Review Panel Draft.  Office of Environmental Health Hazard Assessment, Berkeley, CA.  1998.
  9. J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Journal of Applied Toxicology, 3(6):272-290. 1983.
  10. American Conference of Governmental Industrial Hygienists (ACGIH). 1999 TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents. Biological Exposure Indices.  Cincinnati, OH.  1999.
  11. National Institute for Occupational Safety and Health (NIOSH).  Pocket Guide to Chemical Hazards.  U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention.  Cincinnati, OH.  1997.
  12. Occupational Safety and Health Administration (OSHA).  Occupational Safety and Health Standards, Toxic and Hazardous Substances. Code of Federal Regulations. 29 CFR 1910.1000.  1998.
  13. American Industrial Hygiene Association (AIHA). The AIHA 1998 Emergency Response Planning Guidelines and Workplace Environmental Exposure Level Guides Handbook. 1998.
a. * This fact sheet discusses the health effects of hydrogen fluoride but also presents information on related fluoride compounds. If the information presented is not specifically on hydrogen fluoride but on related compounds, it is discussed in the fact sheet as "fluoride." 

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