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Chlorine dioxide

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

CAS number: 10049–04–4

NIOSH REL: 0.1 ppm (0.3 mg/m3) TWA, 0.3 ppm (0.9 mg/m3) STEL

Current OSHA PEL: 0.1 ppm (0.3 mg/m3) TWA

1989 OSHA PEL: 0.1 ppm (0.3 mg/m3) TWA, 0.3 ppm (0.9 mg/m3) STEL

1993-1994 ACGIH TLV: 0.1 ppm (0.28 mg/m3) TWA, 0.3 ppm (0.83 mg/m3) STEL

Description of Substance: Yellow to red gas or a red-brown liquid (below 52 F) with an unpleasant odor similar to chlorine and nitric acid.

LEL: . . Unknown

Original (SCP) IDLH: 10 ppm

Basis for original (SCP): IDLH AIHA [1958] reported that rats exposed repeatedly to about 10 ppm for 4 hours daily died, whereas those exposed to about 0.1 ppm, 5 hours daily for 10 weeks, showed no detectable effects [Dalhamn 1957]. AIHA [1958] also reported that animals survived 2-hour exposures to 20 ppm, though some species exhibited symptoms [Gloemme and Lundgren 1957]. Elkins [1950] stated that 5 ppm is definitely irritating and 2 cases of illness (1 fatal) resulted from exposure to less than 19 ppm. AIHA [1958] reported that delayed deaths occur in animals after single exposures to 150 to 200 ppm for less than 1 hour [Gloemme and Lundgren 1957]. Based on the data cited above, an IDLH of 10 ppm is chosen.

Short-term exposure guidelines None developed


Lethal concentration data:






Adjusted 0.5-hr




Rat Dalhamn 1957 ----- 260 2 hr 416 ppm (1.6) 42 ppm

Lethal dose data:







Adjusted LD

Derived value
Rat Abdel-Rahman et al. 1982 oral 292 ----- 729 ppm 73 ppm

Human data: It has been reported that 5 ppm is definitely irritating and that 19 ppm caused the death of one worker inside a tank (time of exposure was not specified) [Elkins 1950].

Revised IDLH: 5 ppm

Basis for revised IDLH: The revised IDLH is 5 ppm based on acute inhalation toxicity data in humans [Elkins 1950].


1. Abdel-Rahman MS, Gerges SE, Alliger H [1982]. Toxicity of alcide. J Appl Toxicol 2(3):160-164.

2. AIHA [1958]. Chlorine dioxide. In: Hygienic guide series. Am Ind Hyg Assoc J 19:261-262.

3. Dalhamn T [1957]. Chlorine dioxide: toxicity in animal experiments and industrial risks. AMA Arch Ind Health 15(2):101-107.

4. Elkins HB [1950]. Chlorine dioxide, ClO2. In: The chemistry of industrial toxicology. New York, NY: John Wiley & Sons, Inc., pp. 87-88.

5. Gloemme J, Lundgren KD [1957]. Health hazards from chlorine dioxide. AMA Arch Ind Health 16:169-176.