# NIOSH Pocket Guide to Chemical Hazards
Oxalic acid | CAS 144-62-7
HOOCCOOH • 2H2O | RTECS RO2450000
Synonyms & Trade Names Ethanedioic acid, Oxalic acid (aqueous), Oxalic acid dihydrate | DOT ID & Guide
Exposure Limits | NIOSH REL: TWA 1 mg/m3 ST 2 mg/m3
OSHA PEL†: TWA 1 mg/m3
IDLH 500 mg/m3 | Conversion
Physical Description Colorless, odorless powder or granular solid. [Note: The anhydrous form (COOH)2 is an odorless, white solid.]
MW: 126.1 | BP: Sublimes | MLT: 215°F (Sublimes) | Sol: 14%
VP: <0.001 mmHg | IP: ? |  | Sp.Gr: 1.90
Fl.P: ? | UEL: ? | LEL: ? |
Combustible Solid
Incompatibilities & Reactivities Strong oxidizers, silver compounds, strong alkalis, chlorites [Note: Gives off water of crystallization at 215°F and begins to sublime.]
Measurement Methods None available
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: Daily Provide: Eyewash | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush promptly Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations NIOSH/OSHA Up to 25 mg/m3: (APF = 25) Any supplied-air respirator operated in a continuous-flow mode£/(APF = 25) Any powered, air-purifying respirator with a dust and mist filter£ Up to 50 mg/m3: (APF = 50) Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter/(APF = 50) Any self-contained breathing apparatus with a full facepiece/(APF = 50) Any supplied-air respirator with a full facepiece Up to 500 mg/m3: (APF = 2000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode Emergency or planned entry into unknown concentrations or IDLH conditions: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode/(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus Escape: (APF = 50) Any air-purifying, full-facepiece respirator with a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, mucous membrane; eye burns; localized pain, cyanosis; shock, collapse, convulsions; kidney damage
Target Organs Eyes, skin, respiratory system, kidneys
See also: INTRODUCTION