1. OSHA Occupational Chemical Database
  2. HYDROQUINONE (DIHYDROXYBENZENE)
Label abbreviations descriptions

HYDROQUINONE (DIHYDROXYBENZENE)†

Chemical Identification
Chemical Identification
CAS # 123-31-9
Formula
 

C₆H₆O₂
Synonyms
 

p-benzenediol; 1,4-benzenediol; dihydroxybenzene; 1,4-dihydroxybenzene; quinol
Physical Properties
Physical Properties
Physical description Light-tan, light-gray, or colorless crystals.
Boiling point 545°F Molecular weight 110.11
Freezing point/melting point 338°F Vapor pressure 4 mmHg at 302°F
Flash point 329°F Vapor density 3.81
Specific gravity 1.332 at 59°F Ionization potential 7.95 eV
Lower explosive limit (LEL) Upper explosive limit (UEL)
NFPA health rating 2 NFPA fire rating 1
NFPA reactivity rating 0 NFPA special instruction
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs
Monitoring Methods Used by OSHA
Monitoring Methods Used by OSHA
Analyte code (IMIS no.) 1490
Sampling group
Sampler/Sampling media XAD-7 (80/40 mg sections, 20/60 mesh) coated with 10% phosphoric acid [SKC 226-98]
Sampling time*
 

100 min
Sampling volume (TWA)*
 

20 L
Sampling flow rate (TWA)*
 

0.2 L/min
Sampling volume (STEL/Peak/C)*
 

 
Sampling flow rate (STEL/Peak/C)*
 

 
Analytical method instruments HPLC
Method reference OSHA PV2094 (partially validated)
Notes
 

 
Special requirements
 

 

* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Wipe Method
Wipe Method
Sampler/Sampling media
 

 
Bulk Method
Bulk Method
 

 
On-Site Screening Techniques
On-Site Screening Techniques
Device
Model/Type
Sampling information
(see manufacturer instructions)
Exposure Limits
Exposure Limits
OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA
 

2 mg/m³

 REL-TWA
 

 

 TLV-TWA
 

1 mg/m³ [2007]

 PEL-TWA
 

2 mg/m³
PEL-STEL
 

 

 REL-STEL
 

 

 TLV-STEL
 

 

 PEL-STEL
 

 
PEL-C
 

 

 REL-C
 

2 mg/m³ [15 minutes]

 TLV-C
 

 

 PEL-C
 

 
Skin notation
 

N

 Skin notation
 

N

 Skin notation
 

N

 Skin notation
 

N
Notes:
 

See 29 CFR 1910.1000 Table Z-1.

 Notes:
 

 

 Notes:
 

dermal sensitizer (DSEN)

 Notes:
 

 
Health factors:  See NIH-NLM PubChem. IDLH
 

50 mg/m³
Carcinogenic classifications: IARC-3, TLV-A3 Notes:
 

 
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:
 

 
Additional Resources and Literature References
Additional Resources and Literature References

NOAA: CAMEO Chemicals - Hydroquinone

NIOSH: Pocket Guide to Chemical Hazards - Hydroquinone

Literature References

 
  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Hydroquinone. See annual publication for most recent information.
  • International Chemical Safety Cards (WHO/IPCS/ILO): Hydroquinone.
  • DeCaprio, A.P.: The toxicology of hydroquinone - relevance to occupational and environmental exposure. Crit. Rev. Toxicol. 29(3): 283-330, 1999.
  • English, J.C. and Deisinger, P.J.: Metabolism and disposition of hydroquinone in Fischer 344 rats after oral or dermal administration. Food Chem. Toxicol. 43(3): 483-493, 2005.
  • Halder, R.M. and Richards, G.M.: Topical agents used in the management of hyperpigmentation. Skin Therapy Lett. 9(6): 1-3, 2004.
  • Pohanish, R.P. (editor): Hydroquinone. Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1293-1295.

Last Updated Date : 12/31/2020