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Chemical Sampling Information (CSI)
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General Description

Synonyms: Formic acid (85-95% in aqueous solution); Hydrogen carboxylic acid; Methanoic acid

OSHA IMIS Code Number: 1310

Chemical Abstracts Service (CAS) Registry Number: 64-18-6

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: LQ4900000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 1779 153

NIOSH Pocket Guide to Chemical Hazards, Formic acid: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

OSHA Permissible Exposure Limit (PEL):

General Industry: 29 CFR 1910.1000 Table Z-1 -- 5 ppm, 9 mg/m3 TWA

Construction Industry: 29 CFR 1926.55 Appendix A -- 5 ppm, 9 mg/m3 TWA

Maritime: 29 CFR 1915.1000 Table Z-Shipyards -- 5 ppm, 9 mg/m3 TWA

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 5 ppm, 9.4 mg/m3 TWA; 10 ppm, 19 mg/m3 STEL

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 5 ppm, 9 mg/m3 TWA

Health Factors

NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 30 ppm

Potential Symptoms: Irritation of eyes, skin, throat; skin burns, blisters, dermatitis; lacrimation; rhinorrhea; cough, dyspnea; nausea; eye redness, pain, burns, blurred vision; pulmonary edema; metabolic acidosis; unconsciousness; INGES. ACUTE: Burning sensation, sore throat, abdominal pain, cramps, vomiting, diarrhea

Health Effects: Irritation-Eyes, Nose, Throat, Skin---Marked (HE14); Mutagen (HE2)

Affected Organs: Eyes, skin, respiratory system


  1. Formic acid is permitted by the FDA for direct addition to food as a flavoring substance or adjuvant (21 CFR 172.515).
  2. Formic acid is a metabolite of methanol, formaldehyde and methyl formate, and can build up to toxic levels when the ability of 10-formyl tetrahydrofolate synthetase to metabolize it to carbon dioxide and water is greatly exceeded.
  3. Occupational exposures that are within exposure limits may be difficult to monitor by measuring formic acid in urine because of its natural occurrence in urine.
  4. A case of systemic intoxication, including metabolic acidosis, hemolysis, and hemoglobinuria, following a skin burn with undiluted formic acid has been reported.

Literature Basis:

  • NIOSH Pocket Guide to Chemical Hazards: Formic acid.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Formic acid.
  • Barceloux, D.G., et al.: American Academy of Clinical Toxicology practice guidelines on the treatment of methanol poisoning. J. Toxicol. Clin. Toxicol. 40(4): 415-446, 2002.
  • Berode, M., Sethre, T., Läubli, T. and Savolainen, H.: Urinary methanol and formic acid as indicators of occupational exposure to methyl formate. Int. Arch. Occup. Environ. Health 73(6): 410-414, 2000.
  • d'Alessandro, A., Osterloh, J.D., Chuwers, P., Quinlan, P.J., Kelly, T.J. and Becker, C.E.: Formate in serum and urine after controlled methanol exposure at the threshold limit value. Environ. Health Perspect. 102(2): 178-181, 1994.
  • Pohanish, R.P. (editor): Formic Acid. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1186-1188.
  • Sigurdsson, J., Bjornsson, A. and Gudmundsson, S.T.: Formic acid burn-local and systemic effects. Report of a case. Burns Incl. Therm. Inj. 9(5): 358-361, 1983.

Date Last Revised: 10/19/2006

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Charcoal Tube (400/200 mg sections, 20/40 mesh)
    analytical solvent: 0.0015 M B4O7-2
    maximum volume: 48 Liters
    maximum flow rate: 0.2 L/min
    current analytical method: Ion Chromatography; IC
    method reference: OSHA Manual of Analytical Methods (OSHA ID-186SG)
    method classification: Partially Validated
    note: Samples requesting formic acid must be shipped to the laboratory ASAP and kept cold.

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