NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Hydroquinone

CAS
123-31-9

C6H4(OH)2

RTECS
MX3500000
Synonyms & Trade Names

p-Benzenediol; 1,4-Benzenediol; Dihydroxybenzene; 1,4-Dihydroxybenzene; Quinol
DOT ID & Guide
2662 / 153

Exposure
Limits

NIOSH REL: C 2 mg/m3 [15-minute]
OSHA PEL: TWA 2 mg/m3
IDLH
50 mg/m3 See: 123319
Conversion
Physical Description
Light-tan, light-gray, or colorless crystals.
MW: 110.1
BP: 545°F
MLT: 338°F
Sol: 7%
VP: 0.00001 mmHg
IP: 7.95 eV

Sp.Gr: 1.33
Fl.P: 329°F (Molten)
UEL: ?
LEL: ?

Combustible Solid; dust cloud may explode if ignited in an enclosed area.
Incompatibilities & Reactivities

Strong oxidizers, alkalis
Measurement Methods
NIOSH 5004; OSHA PV2094
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet or contaminated
Change: Daily
Provide: Eyewash (>7%)
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Water flush
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
NIOSH/OSHA
Up to 50 mg/m3:
(APF = 25) Any powered air-purifying respirator with a high-efficiency particulate filter.
(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters.
(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece
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 an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters./Any appropriate escape-type, self-contained breathing apparatus
Important additional information about respirator selection
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
Irritation eyes: conjunctivitis; keratitis (inflammation of the cornea); central nervous system excitement; colored urine, nausea, dizziness, suffocation, rapid breathing; muscle twitching, delirium; collapse; skin irritation, sensitization, dermatitis
Target Organs
Eyes, skin, respiratory system, central nervous system
See also: INTRODUCTION   See ICSC CARD: 0166   See MEDICAL TESTS: 0120