May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 1335–87–1

NIOSH REL: 0.2 mg/m3 TWA [skin]

Current OSHA PEL: 0.2 mg/m3 TWA [skin]

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 0.2 mg/m3 TWA [skin]

Description of Substance: White to light-yellow solid with an aromatic odor.

LEL:. . Noncombustible Solid

Original (SCP) IDLH: 2 mg/m3

Basis for original (SCP) IDLH: Although AIHA [1966] stated that “IDLHs for the chloronaphthalenes are probably unattainable,” an IDLH of 2 mg/m3 for hexachloronaphthalene has been chosen for this draft technical standard. The chosen IDLH is based on the industrial exposure cited by ACGIH [1971] in which fatal cases of hepatic injury occurred in a plant where air concentrations of mixed pentachloronaphthalenes and hexachloronaphthalenes ranged from 1 to 2 mg/m3 [Elkins 1959].

Short-term exposure guidelines: None developed


Animal data: Repeated exposure of rats to 8.9 mg/m3 of a mixture of hexachloronaphthalene and pentachloronaphthalene for up to 4.5 months produced jaundice and was fatal; minor liver injury still occurred at 1.16 mg/m3 [Drinker et al. 1937]. Hexachloronaphthalene has been shown to be more toxic than pentachloronaphthalene in ingestion studies with calves [Bell 1958]. Total doses of hexachloronaphthalene ranging from 5 to 23 mg/kg were given orally in mineral oil over 10 days and lacrimation, salivation, nasal discharge, depression, and anorexia occurred by the 5th day [Bell 1958].

Human data: It has been reported that fatal cases of hepatic injury have occurred from chronic exposures in a plant where air concentrations of mixed pentachloronaphthalenes and hexachloronaphthalenes ranged from 1 to 2 mg/m3 [Elkins 1959].

Revised IDLH: 2 mg/m3 [Unchanged]

Basis for revised IDLH: Based on chronic inhalation toxicity data in humans [Elkins 1959] and animals [Bell 1958, Drinker 1937], the original IDLH for hexachloronaphthalene (2 mg/m3) is not being revised at this time.



1. ACGIH [1971]. Hexachloronaphthalene. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 125.

2. AIHA [1966]. Chloronaphthalenes. In: Hygienic guide series. Am Ind Hyg Assoc J 27:89.

3. Bell WB [1958]. The relative toxicity of the chlorinated naphthalenes in experimentally produced bovine hyperkeratosis (x-disease). Vet Med 48:135-140.

4. Drinker CK, Warren MF, Bennett GA [1937]. The problem of possible systemic effects from certain chlorinated hydrocarbons. J Ind Hyg Toxicol 19(7):283-299.

5. Elkins HB [1959]. The chemistry of industrial toxicology. 2nd ed. New York, NY: John B. Wiley & Sons, Inc., pp. 151-152.

Page last reviewed: December 4, 2014