# NIOSH Pocket Guide to Chemical Hazards
Borates, tetra, sodium salts (Pentahydrate) | CAS 12179-04-3
Na2B4O7 • 5H2O | RTECS
Synonyms & Trade Names Borax pentahydrate, Sodium borate pentahydrate, Sodium tetraborate pentahydrate | DOT ID & Guide
Exposure Limits | NIOSH REL: TWA 1 mg/m3
OSHA PEL†: none
IDLH N.D. | Conversion
Physical Description Colorless or white, odorless crystals or free-flowing powder. [herbicide] [Note: Begins to lose water of hydration at 252°F.]
MW: 291.4 | BP: ? | MLT: 392°F | Sol: 3%
VP: 0 mmHg (approx) | IP: NA |  | Sp.Gr: 1.82
Fl.P: NA | UEL: NA | LEL: NA |
Noncombustible Solid
Incompatibilities & Reactivities None reported [However, see the reactivities & incompatibilities reported for the related substance Borax decahydrate above.]
Measurement Methods NIOSH 0500; OSHA ID125G
Personal Protection & Sanitation Skin: No recommendation Eyes: No recommendation Wash skin: Daily Remove: No recommendation Change: Daily | First Aid (See procedures) Eye: Irrigate immediately Skin: Soap wash Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations To be added later
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, upper respiratory system; dermatitis; epistaxis (nosebleed); cough, dyspnea (breathing difficulty)
Target Organs Eyes, skin, respiratory system
See also: INTRODUCTION