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Formic Acid Safety Data

Formic acid has the chemical formula HCOOH or CH2O2 and it's molecular representation is shown at right.

  molecular representation of formic acid

Emergency Assistance...   CHEMTREC   1-800-424-9300   or   202-483-7616

Occupational Safety and Health Guidelines for Formic Acid

The information contained in these guidelines has been gathered from many sources, some of these sources are in areas covered by different legislation and so there may be differences to your local ordinances. You should establish exactly what these ordinances are rather than relying on this document, which has been generalised for the use of beekeepers.

Formic Acid is dangerous by inhalation, skin contact or ingestion. It is corrosive to all body tissues.


Formic acid is also known as... Hydrogen carboxylic acid, methanoic acid, aminic acid, formylic acid, Bilorin, Collo-didax, Formira, Formisotin.

Formic acid is a clear colourless, fuming liquid with a strongly pungent, characteristic odour. The usual commercial product is a solution of around 90% formic acid in water. But for beekeeping use, various dilutions are used.

The odour threshold concentration for formic acid is 49 parts per million (ppm) in air.

Molecular weight... 46.03

Boiling point... (@ 760 mm Hg) = 101 ° C

Specific gravity (water = 1) = 1.22 @ 20 ° C (glacial)

Vapour density... (Air = 1) = 1.6 (glacial)

Melting point... 8.4 degrees C (glacial)

Vapour pressure...@ 20 ° C = 35 mm Hg (Also quoted as 40 mm Hg in some documents)

Miscible in water in all proportions also miscible with alcohol, ether, acetone, benzene, and glycerol.

Evaporation rate... (butyl acetate = 1) = 2.1

Contact between formic acid and strong oxidizers, alkaline materials, or strong caustic agents should be avoided. Contact with concentrated sulphuric acid causes the formation of carbon monoxide. Explosion risk in contact with hydrogen peroxide or furfuryl alcohol.

Glacial formic acid will slowly decompose at room temperatures resulting in increased pressure if containers are sealed or unvented.

Flash point... ~68 ° C (closed cup)(Also quoted as 50°C (90%))
Auto ignition temperature... 539 ° C (glacial)
Flammable limits in air (by volume)... Lower = 18%, upper = 57%

For small fires use dry chemical, carbon dioxide, water spray, or regular foam extinguishers. Use water spray, fog, or regular foam to fight large fires involving formic acid.

Fires involving formic acid should be fought upwind from the maximum distance possible. Keep unnecessary people away, isolate the hazard area and deny entry. Emergency personnel should stay out of low areas and ventilate closed spaces before entering. Containers of formic acid may explode in the heat of the fire and should be moved from the fire area if it is possible to do so safely. If this is not possible, cool fire exposed containers from the sides with water until well after the fire is out. Stay away from the ends of containers. Fire fighters should wear a full set of protective clothing and self-contained breathing apparatus with full face piece, operated in pressure demand mode, when fighting fires involving formic acid.

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for formic acid of 5 ppm (9 mg/m3) as a TWA for up to a 10 hour workday and a 40 hour workweek.

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned formic acid a threshold limit value (TLV) of 5 ppm (9.4 mg/m3) as a TWA for a normal 8 hour workday and a 40 hour workweek and a short term exposure limit (STEL) of 10 ppm (19 mg/m3) for periods not to exceed 15 minutes. Exposures at the STEL concentration should not be repeated more than four times a day and should be separated by intervals of at least 60 minutes [ACGIH 1994, p. 22].

Effects on Humans... Formic acid is dangerously irritating to the skin, eyes, and mucous membranes and may also be toxic to the kidneys. Workers exposed to formic acid in a textile plant complained of nausea at an average formic acid concentration of 15 ppm [NLM 1992]. Atmospheric concentrations as low as 32 mg/l may be corrosive; however, a dilute solution of 10% formic acid apparently is not corrosive [Clayton and Clayton 1982]. Acute, overexposure to formic acid causes corrosion of the skin, eyes, and mucous membrane of the mouth, throat, and esophagus and may be associated with complications such as cardiovascular collapse and ischemic damage to the heart, liver and kidneys, swelling of the airway, and respiratory distress. Ingesting causes ulceration of the gastrointestinal tract, which results in perforation and peritonitis and late scarring of structures of the gastrointestinal tract which, in turn, produces obstructions that require surgical repair [Gosselin 1984]. A worker splashed in the face with formic acid developed respiratory distress and difficulty in swallowing, and died within 6 hours [Hathaway et al. 1991]. Other reports indicate that splashes of formic acid in the eye have caused permanent clouding of the cornea, with loss of visual acuity. In one case, the injury required removal of the affected eye [Grant 1986]. Chronic absorption of formic acid may cause damage to the kidneys, which is indicated by albuminuria and hematuria [NLM 1992]. Chronic skin contact may cause sensitization dermatitis, particularly in workers previously sensitized to formaldehyde [NLM 1992].

Symptoms of acute exposure include redness, swelling, blistering of the skin and mucous membranes of the mouth and throat, eye irritation, nausea, vomiting, diarrhea, difficulty in swallowing, difficulty in breathing, headache, dizziness, blood in the urine, decreased or absence of urine production, and unconsciousness. Signs of shock and impending cardiovascular collapse including clammy skin, a weak and rapid pulse, shallow breathing.

Symptoms of chronic exposure may include kidney damage, dermatitis, and skin sensitisation.

Emergency medical procedures... Remove an incapacitated worker from further exposure and implement first aid, give artificial respiration if required. If ingestion has occurred do not induce vomiting, give several glasses of water. In cases of skin contact, remove contaminated clothing, flush with water for 15 minutes. In cases of eye contact, flush with water for at least 15 minutes while lifting the eyelids. I any of the above cases seek immediate medical attention.

Workers who may be exposed to chemical hazards should be monitored in a systematic program of medical surveillance that is intended to prevent occupational injury and disease. The program should include education of employers and workers about work-related hazards, early detection of adverse health effects, and referral of workers for diagnosis and treatment. The occurrence of disease or other work-related adverse health effects should prompt immediate re-evaluation of primary preventive measures.

Personal Hygiene... If formic acid contacts the skin, workers should flush the affected areas immediately with plenty of water, followed by washing with soap and water.

Clothing contaminated with formic acid should be removed immediately, and provisions should be made for the safe removal of the chemical from the clothing. Persons laundering the clothes should be informed of the hazardous properties of formic acid, particularly its potential for causing severe irritation.

Workers should thoroughly wash hands, forearms, and face with soap and water before eating, using tobacco products, using toilet facilities, applying cosmetics, or taking medication.

Do not eat, drink, use tobacco products, apply cosmetics, or take medication in areas where formic acid or a solution containing formic acid is handled, processed, or stored.

Formic acid should be stored in a cool, dry, well ventilated area... In tightly sealed containers that are labeled in accordance local hazard requirements. Containers of formic acid should be protected from physical damage and ignition sources, and should be stored separately from strong oxidizers, alkaline materials, strong caustic agents, concentrated sulphuric acid, hydrogen peroxide, and furfuryl alcohol.

In the event of a spill or leak involving formic acid, persons not wearing protective equipment and clothing should be restricted from contaminated areas until clean-up has been completed. The following steps should be undertaken following a spill or leak:

  1. Notify safety personnel.
  2. Remove all sources of heat and ignition.
  3. Ventilate the area of the spill or leak.
  4. Do not touch the spilled material; stop the leak if it is possible to do so without risk.
  5. For small liquid spills, take up with vermiculite, dry sand, earth or other noncombustible absorbent material and place into closed containers for later disposal.

Employers are not required to report the amount of formic acid emitted or released from their facility annually unless the amount exceeds 5,000 pounds (USA).

Employers should institute a complete respiratory protection program, including respirator selection and evaluation of the worker's ability to perform the work while wearing a respirator. Regular training of personnel, respirator fit testing and regular respirator maintenance, inspection, and cleaning must be implemented.

Personal protective clothing and other protective equipment must be used and maintained to be effective in preventing skin contact with formic acid. The selection of gloves, sleeves and coverall suits should be based on the extent of the worker's potential exposure to formic acid. The resistance of various materials to permeation by formic acid is tabled below...

MaterialBreakthrough time (hr)MaterialBreakthrough time (hr)
Butyl Rubber>8Saranex>8
Polyvinyl Chloride>4Natural RubberCaution, 1 to 4
Nitrile RubberCaution, 1 to 4VitonCaution, 1 to 4
4H (PE/EVAL)Caution, 1 to 4PolyethyleneNot recommended
Polyvinyl AlcoholNot recommended 

Users should consult the best available performance data and manufacturers' recommendations... Significant differences have been demonstrated in the chemical resistance of similar materials such as butyl, produced by different manufacturers. In addition, the chemical resistance of a mixture may be significantly different from that of any of it's components.

Chemical resistant clothing should be periodically evaluated to determine its effectiveness in preventing dermal contact. Safety showers and eye wash stations should be located close to operations that involve formic acid.

Splash proof chemical safety goggles or face shields (200 mm - 300 mm or longer) should be worn during any operation in which this caustic substance may be splashed into the eyes.

As well as wearing protective outer protection (e.g., aprons, encapsulating suits), workers should wear coveralls, or similar full body suits that are laundered each day. Employers should provide lockers to store work and street clothing separately. Employers should collect work clothing at the end of each work shift and provide for its laundering. Laundry personnel should be informed about the potential hazards of handling contaminated clothing and instructed about measures to minimise their own health risks.

Protective clothing should be kept free of oil and grease and should be inspected and maintained regularly to preserve its effectiveness. Users should be aware that protective clothing may interfere with the body's normal heat dissipation, especially during hot weather or during work in hot or poorly ventilated areas.

Dave Cushman.

Page created 25/10/2002

Page updated 12/12/2022

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