Hydroquinone

CAS number: 123–31–9

NIOSH REL: 2 mg/m³ 15-minute CEILING

Current OSHA PEL: 2 mg/m³ TWA

1989 OSHA PEL: Same as current PEL

1993-1994 ACGIH TLV: 2 mg/m³ TWA

Description of Substance: Light-tan, light-gray, or colorless crystals.

LEL:. . Unknown

Original (SCP) IDLH*: Unknown [*Note: "Effective" IDLH = 200 mg/m³ -- see discussion below.]

Basis for original (SCP) IDLH: No acute inhalation toxicity data are available on which to base an IDLH for hydroquinone. For this draft technical standard, therefore, the respirators have been selected on the basis of the assigned protection factor afforded by each device up to 100 ´ the OSHA PEL of 2 mg/m³ (i.e., 200 mg/m³); only the "most highly reliable" respirators are permitted for use in concentrations exceeding 200 mg/m³. This concentration is not likely to be attained in industry.

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
Mammal Mouse Rabbit Rat G. pig Dog Cat	Kazpuchina 1979 Korolev et al. 1973 Takahashi 1975 Woodward et al. 1949 Woodward et al. 1949 Woodward et al. 1949 Woodward et al. 1949	oral oral oral oral oral oral oral	490 245 200 320 550 200 70	----- ----- ----- ----- ----- ----- -----	3,430 mg/m3 1,715 mg/m3 1,400 mg/m3 2,240 mg/m3 3,850 mg/m3 1,400 mg/m3 490 mg/m3	343 mg/m3 172 mg/m3 140 mg/m3 224 mg/m3 385 mg/m3 140 mg/m3 49 mg/m3

Human data: It has been reported that 5 to 12 grams is the lethal oral dose [Zeidman and Deutel 1945]. [Note: An oral dose of 5 to 12 grams is equivalent to a worker being exposed to 3,333 to 8,000 mg/m³ for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]

Revised IDLH: 50 mg/m3 Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for hydroquinone. Therefore, the revised IDLH for hydroquinone is 50 mg/m3 based on acute oral toxicity data in humans [Zeidman and Deutel 1945] and animals [Woodward et al. 1949].

REFERENCES:

1. Kazpuchina EA [1979]. Estimation of the acute limit of the effect of benzene and its metabolites. Toksikol Nov Prom Khim Vesh 15:136-139 (in Russian).

2. Korolev AA, Abinder AA, et al. [1973]. Hygienic and toxicologic features of products of phenol destruction in ozone treatment of water. Gig Sanit 38(8):6-10 (in Russian).

3. Takahashi A [1975]. Problems of hygiene maintenance for food coming into contact with rubber and plastics products. Nippon Gomu Kyokaishi 48(9):537 [Translated by Inglis EA [1976]. Int Polymer Sci Tech 3(1):T/93-T/105.]

4. Woodward G, Hagan EC, Radomski JL [1949]. Toxicity of hydroquinone for laboratory animals. Fed Proc 8:348.

5. Zeidman I, Deutel R [1945]. Poisoning by hydroquinone and monomethyl-paraaminophenol sulfate: report of 2 cases with autopsy findings. Am J Med Sci 210:328-333.