p-Dichlorobenzene

CAS number: 106–46–7

NIOSH REL: None established; NIOSH considers p-dichlorobenzene to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].

Current OSHA PEL: 75 ppm (450 mg/m³) TWA

1989 OSHA PEL: 75 ppm (450 mg/m³) TWA, 110 ppm (675 mg/m³) STEL

1993-1994 ACGIH TLV: 10 ppm (60 mg/m³) TWA, A3

Description of Substance: Colorless or white crystalline solid with a mothball-like odor.

LEL:. . 2.5% (10% LEL, 2,500 ppm)

Original (SCP) IDLH: 1,000 ppm

Basis for original (SCP) IDLH: No useful data on acute inhalation toxicity are available on which to base the IDLH for p-dichlorobenzene. The chosen IDLH, therefore, is based on an analogy with o-dichlorobenzene, which has an IDLH of 1,000 ppm.

Short-term exposure guidelines: None developed

ACUTE TOXICITY DATA

Lethal dose data:

Species	Reference	Route	LD50 (mg/kg)	LDLo (mg/kg)	Adjusted LD	Derived Value
Rat Human Mouse Rat G. pig Rat Rabbit	Ben-Dyke et al. 1970 Deichmann and Gerarde 1969 Domenjos 1946 Hollingsworth et al. 1956 Hollingsworth et al. 1956 Varshavskaya 1967 Yakkyoku 1978	oral oral oral oral oral oral oral	500 ----- 2,950 ----- ----- 2,512 2,830	----- 857 ----- 4,000 2,800 ----- -----	573 ppm 982 ppm 3,380 ppm 4,583 ppm 3,208 ppm 2,878 ppm 3,242 ppm	57 ppm 98 ppm 338 ppm 458 ppm 321 ppm 288 ppm 324 ppm

Other animal data: No adverse effects were noted in a workplace averaging 105 ppm (range 50 to 170 ppm), but painful irritation of the eyes and nose was found at 80 to 160 ppm, and breathing was difficult at concentrations greater than 160 ppm [Hollingsworth et al. 1956]. In another workplace, workers exposed to 17 to 500 ppm reported severe eye irritation [Dow 1978].

Other human data: None relevant for use in determining the revised IDLH.

Revised IDLH: 150 ppm Basis for revised IDLH: The revised IDLH for p-dichlorobenzene is 150 ppm based on acute inhalation toxicity data in workers [Dow 1978; Hollingsworth et al. 1956]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for p-dichlorobenzene at any detectable concentration.]

REFERENCES:

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

2. Deichmann WB, Gerarde HW [1969]. Dichlorobenzene, ortho and para (PDB, dichlorocide). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., pp. 210-211.

3. Spencer EY [1973]. Guide to the chemicals used in crop protection. London, Ontario, Canada: Research Institute, University of Western Ontario Sub Post Office, p. 183.

4. Dow Chemical Company [1978]. Preliminary study into the environmental fate of PARADOW blocks, May 17, 1973. TSCA 8(d) submission 8DHQ-0978-0299. EPA, Washington, D.C. [From ACGIH [1991]. p-Dichlorobenzene. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 410-416.]

5. Hollingsworth RL, Rowe VK, Oyen F, Hoyle HR, Spencer HC [1956]. Toxicity of paradichlorobenzene. AMA Arch Ind Health 14:138-147.

6. Varshavskaya SP [1967]. The hygienic standardization of mono- and dichlorobenzenes in reservoir waters. Nauch Tr Aspir Ordinatorov Pervyi Mosk Med Inst, pp. 175-177 (in Russian). [From ACGIH [1991]. p-Dichlorobenzene. In: Documentation of the threshold limit values and biological exposure indices. 6th ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 410-416.]

7. Yakkyoku (Pharmacy) [1978]; 29:453-457 (in Japanese).