US Dept of Labor

Occupational Safety & Health AdministrationWe Can Help

Oxalic Acid

General Description

  • Synonyms: Oxalic acid dihydrate; Ethanedioic acid
  • OSHA IMIS Code Number: 1970
  • Chemical Abstracts Service (CAS) Registry Number: 144-62-7
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: RO2450000
  • NIOSH Pocket Guide to Chemical Hazards, Oxalic Acid: chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits

  • OSHA Permissible Exposure Limit (PEL):
  • American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 1 mg/m3 TWA; 2 mg/m3 STEL
  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL): 1 mg/m3 TWA; 2 mg/m3 STEL

Health Factors

  • NIOSH Immediately Dangerous To Life or Health Concentration (IDLH): 500 mg/m3
  • Potential Symptoms: Eye, mucous membrane, skin irritation; eye burns; local pain; cyanosis (blue lips, fingernails, skin); shock, collapse, convulsions; kidney damage; pulmonary edema (may be delayed); INGES: Sore throat, burning sensation, abdominal pain, vomiting; diarrhea and bloody stools; drowsiness; numbness of fingers and toes.
  • Health Effects: Irritation-Eyes, Nose, Throat, Skin---Marked (HE14); Lung edema (HE11); Acute systemic effects (HE4)
  • Affected Organs: Eyes, skin, respiratory system, kidneys
  • Notes:
    1. Oxalic acid is a normal minor metabolite of carbohydrates (e.g., fructose), glycine, and vitamin C, but it is produced in toxic amounts after ethylene glycol intoxication.
    2. Kidney dialysis patients may be particularly susceptible to oxalate-induced nephrotoxicity and neurotoxicity.
    3. Prolonged barbiturate sleeping time in rats treated with star fruit juice was attributed to its high oxalate content, indicating a possible inhibition of some drug-metabolizing cytochrome P-450s in the liver.
    4. Calcium oxalate crystals, which occur in certain plants, may cause irritant contact dermatitis in agricultural workers.
  • Literature Basis:
    • NIOSH Pocket Guide to Chemical Hazards: Oxalic Acid.
    • International Chemical Safety Cards (WHO/IPCS/ILO): Oxalic acid.
    • Chen, C.L., Chou, K.J., Wang, J.S., Yeh, J.H., Fang, H.C. and Chung, H.M.: Neurotoxic effects of carambola in rats: the role of oxalate. J. Formos. Med. Assoc. 101 (5): 337-441, 2002.
    • Pohanish, R.P. (editor): Oxalic Acid. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 2. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1763-1765.
    • Rofe, A.M., James, H.M., Bais, R., Edwards, J.B. and Conyers, R.A.: The production of (14C) oxalate during the metabolism of (14C) carbohydrates in isolated rat hepatocytes. Aust. J. Exp. Biol. Med. Sci. 58 (2): 103-116, 1980.
    • Salinas, M.L., Ogura, T. and Soffchi, L.: Irritant contact dermatitis caused by needle-like calcium oxalate crystals, raphides, in Agave tequilana among workers in tequila distilleries and agave plantations. Contact Dermatitis 44(2): 94-96, 2001.
    • Tse, K.C., et al.: Star fruit intoxication in uraemic patients: case series and review of the literature. Intern. Med. J. 33 (7): 314-316, 2003.
  • Date Last Revised: 10/28/2004

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • glass fiber filter (37-mm, open face)
  • maximum volume: 100 Liters
  • maximum flow rate: 1.0 L/min (TWA)
  • current analytical method: Ion Chromatography; IC
  • method reference: OSHA Analytical Method (PV2115)
  • method classification: Partially Validated
Wipe Sampling Method:
  • glass fiber filter (37-mm)
  • analytical solvent: Deionized water

** All Trademarks are the property of their respective owners.

Search Chemical Sampling Information

Index

By Name

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

By CAS Number
collage image - OSHA Salt Lake Technical Center

*Accessibility Assistance: Contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300 for assistance accessing PDF materials.

All other documents, that are not PDF materials or formatted for the web, are available as Microsoft Office® formats and videos and are noted accordingly. If additional assistance is needed with reading, reviewing or accessing these documents or any figures and illustrations, please also contact OSHA's Directorate of Technical Support and Emergency Management at (202) 693-2300.

**eBooks - EPUB is the most common format for e-Books. If you use a Sony Reader, a Nook, or an iPad you can download the EPUB file format. If you use a Kindle, you can download the MOBI file format.

Back to Top

Thank You for Visiting Our Website

You are exiting the Department of Labor's Web server.

The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Users must request such authorization from the sponsor of the linked Web site. Thank you for visiting our site. Please click the button below to continue.

Close