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Chemical Sampling Information (CSI)
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General Description

Synonyms: HCB; Perchlorobenzene; Pentachlorophenylchloride; Phenyl perchloryl

OSHA IMIS Code Number: 1376

Chemical Abstracts Service (CAS) Registry Number: 118-74-1

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: DA2975000

Department of Transportation Regulation Number (49 CFR 172.101) and Guide: 2729 152

Chemical Description and Physical Properties:

colorless to white solid in various forms
molecular weight: 284.76
vapor pressure: 0.001 Pa @ 20C
molecular formula: C6Cl6
boiling point: 323-326C
melting point: 231C

Exposure Limits

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV): 0.002 mg/m3 TWA; Skin; Appendix A3 - Confirmed Animal Carcinogen with Unknown Relevance to Humans

Health Factors

Carcinogenic Classification:

Environmental Protection Agency (EPA): Group B2, Probable Human Carcinogen

International Agency for Research on Cancer (IARC): Group 2B, Possibly carcinogenic to humans [122 KB PDF, 45 pages]

National Toxicology Program (NTP): Reasonably Anticipated to be a Human Carcinogen [152 KB PDF, 3 pages]

Potential Symptoms: INGES. ACUTE: Headache, nausea, vomiting; loss of sensory perception, numbness of hands and arms, partial paralysis of arms and legs, loss of muscle control; apprehension, excitement, tremors, convulsions, coma; INGES. CHRONIC (delayed symptoms): Porphyrinuria (red or dark urine); enlarged liver; goiter (enlarged thyroid); loss of appetite; photosensitivity, bullae (large blisters), severe mutilating scars, hyperpigmentation (darkening of skin), hirsutism (excessive hair); relatively painless arthritic changes, osteoporosis in hand bones, small hands; weakness, paresthesia, myotonia (temporary failure of muscle relaxation), cogwheeling (jerkiness of muscle contraction). In nursing infants: weakness, pink sores, convulsions, death.

Health Effects: Nervous System Disturbances (HE7); Chronic Toxicity---Liver, Thyroid, Skin, Developmental Toxicity, Death of Nursing Infants (HE3).

Affected Organs: CNS, liver, reproductive system (ovaries), thyroid, skin, bone


  1. OSHA does not have a PEL for hexachlorobenzene.
  2. Hexachlorobenzene is an OSHA Select Carcinogen.
  3. Infants and children may be more susceptible than adults to the neurotoxicity of hexachlorobenzene, and symptoms of toxicity may persist for more than 30 years.
  4. CYP3A4 is one of the cytochrome P450s that biotransform hexachlorobenzene to pentachlorophenol, which can be further metabolized to the reactive metabolite, tetrachlorohydroquinone. Most hexachlorobenzene, however, is slowly excreted unchanged in the feces over a period of years.
  5. EPA's oral reference dose (daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) for hexachlorobenzene is 0.0008 mg/kg/day.
  6. Hexachlorobenzene should not be confused with benzene hexachloride (hexachlorocyclohexane), the gamma isomer of which is known as the pesticide lindane.

Literature Basis:

  • Agency for Toxic Substances and Disease Registry (ATSDR): Toxicological profile for hexachlorobenzene. Atlanta: ATSDR, 2002, 357 pp.
  • EPA Air Toxics Website: Hexachlorobenzene. U.S. Environmental Protection Agency Technology Transfer Network.
  • Pohanish, R.P. (editor): Hexachlorobenzene. In, Sittig's Handbook of Toxic and Hazardous Chemicals and Carcinogens, Fourth Ed., Vol. 1. Norwich, NY: Noyes Publications, William Andrew Publishing, 2002, pp. 1234-1236.

Date Last Revised: 09/08/2005

Monitoring Methods used by OSHA

Primary Laboratory Sampling/Analytical Method (SLC1):

  • sampling media: Glass Fiber Filter (37 mm)
    analytical solvent: Toluene
    maximum volume: 480 Liters
    maximum flow rate: 2.0 L/min
    current analytical method: Gas Chromatography; GC/ECD
    method reference: OSHA Salt Lake Technical Center In-House File
    method classification: Not Validated

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