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

CAS number: 95–50–1

NIOSH REL: 50 ppm (300 mg/m3) CEILING

Current OSHA PEL: 50 ppm (300 mg/m3) CEILING

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 25 ppm (150 mg/m3) TWA, 50 ppm (301 mg/m3) STEL

Description of Substance: Colorless to pale-yellow liquid with a pleasant, aromatic odor.

LEL:. . 2.2% (10% LEL, 2,200 ppm)

Original (SCP) IDLH: 1,000 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by ACGIH [1971] that 1,000 ppm was fatal to guinea pigs after 20 hours [Browning 1953]. ACGIH [1971] also reported that Cameron et al. [1937] found liver damage in animals after exposure for a few hours at 50 to 800 ppm.

Short-term exposure guidelines: None developed


Lethal concentration data:

Species Reference LC50(ppm) LCLo(ppm) Time Adjusted 0.5-hrLC (CF) Derivedvalue
G. pigG. pig


Browning 1953Cameron et al. 1937

Hollingsworth et al. 1958





20 hr24 hr

7 hr

3,450 ppm (3.45)2,880 ppm (3.6)

1,970 ppm (2.4)

345 ppm288 ppm

197 ppm


Lethal dose data:

Species Reference Route LD50(mg/kg) LDLo(mg/kg) Adjusted LD Derived value
RatG. pig



Ben-Dyke et al. 1970Patty 1963

Thomson 1976/77

Yakkyoku 1981










573 ppm2,291 ppm

573 ppm

5,025 ppm

57 ppm229 ppm

57 ppm

503 ppm


Other animal data: RD50 (mouse), 182 ppm [DeCeaurriz et al. 1981].

Human data: Concentrations up to 100 ppm have been reported to have caused sporadic irritation of the eyes and respiratory tract [Elkins 1959].

Revised IDLH: 200 ppmBasis for revised IDLH: The revised IDLH for o-dichlorobenzene is 200 ppm based on acute inhalation toxicity data in animals [Hollingsworth et al. 1958]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 100 ppm.



1. ACGIH [1971]. o-Dichlorobenzene. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 76.

2. Ben-Dyke R, Sanderson DM, Noakes DN [1970]. Acute toxicity data for pesticides (1970). World Review of Pesticide Control 9:119-127.

3. Browning E [1953]. Toxicity of industrial organic solvents. New York, NY: Chemical Publishing Company, p. 190.

4. Cameron GR, Thomas JC, Ashmore SA, Buchan JL, Warren EH, Hughes AWM [1937]. The toxicity of certain chlorine derivatives of benzene, with special reference to o-dichlorobenzene. J Pathol Bacteriol 44(2):281-296.

5. DeCeaurriz JC, Micillino JC, Bonnet P, Guenier JP [1981]. Sensory irritation caused by various industrial airborne chemicals. Toxicol Lett 9(2):137-143.

6. Elkins HB [1959]. The chemistry of industrial toxicology. 2nd ed. New York, NY: John Wiley & Sons, Inc., p. 150.

7. Hollingsworth RL, Rowe VK, Oyen F, Torkelson TR, Adams EM [1958]. Toxicity of o-dichlorobenzene. AMA Arch Ind Health 17:180-187.

8. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1336.

9. Thomson WT [1976/77]. Agricultural chemicals. Fresno, CA: Thomas Publications, 3:32.

10. Yakkyoku (Pharmacy) [1981]; 32:471-474 (in Japanese).