Immediately Dangerous to Life or Health Concentrations (IDLH)
Chromic acid and chromates
CAS number: 1333–82–0 (CrO3)
NIOSH REL: 0.001 mg Cr(VI)/m3 TWA; NIOSH considers chromic acid and chromates to be potential occupational carcinogens as defined by the OSHA carcinogen policy [29 CFR 1990].
Current OSHA PEL: 0.1 mg CrO3/m3 CEILING
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: Water soluble: 0.05 mg CrO3/m3 TWA;
Certain water insoluble: 0.05 mg CrO3/m3 TWA, A1
Description of Substance: Varies
Original (SCP) IDLH: 30 mg/m3 (as CrO3)
Basis for original (SCP) IDLH: Very little quantitative data are available concerning the acute toxicity produced by the inhalation of chromic acid and chromates. AIHA  reported that both the short exposure tolerance to chromic acid and the atmospheric concentration immediately dangerous to life are unknown. The chosen IDLH is based on the statements by ILO  that "a man exposed for several days to concentrations of chromic acid mist of about 20 to 30 mg/m3 experienced cough, headache, dyspnea, and substernal pain; the signs persisted for 2 weeks. Another man working on the same process was similarly but less severely affected." No other useful data are available on which to base the IDLH.
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA
Lethal dose data:
Gad et al. 1986
113 mg Cr(VI)/m3
11 mg Cr(VI)/m3
Chi J Prev Med 1980
Kobayashi et al. 1976
462 mg Cr(VI)/m3
291 mg Cr(VI)/m3
46 mg Cr(VI)/m3
29 mg Cr(VI)/m3
Human data: A worker exposed for several days to concentrations of chromic acid mist of about 20 to 30 mg/m3 (equivalent to about 10 to 15 mg Cr(VI)/m3) experienced cough, headache, dyspnea, and substernal pain; the signs persisted for 2 weeks [ILO 1971]. Another man working on the same process was similarly but less severely affected [ILO 1971]. The fatal oral dose of chromium has been reported to be 1 to 3 grams [Seiler et al. 1988]. [Note: An oral dose of 1 to 3 grams is equivalent to a 70-kg worker being exposed to 667 to 2,000 mg Cr(VI)/m3 for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]
|Revised IDLH: 15 mg Cr(VI)/m3 [Unchanged]
Basis for revised IDLH: Based on toxicity data in humans [ILO 1971; Seiler et al. 1988], the original IDLH for chromic acid and chromates is not being revised at this time. However, instead of 30 mg/m3 (as CrO3), the IDLH is being expressed as its equivalent, 15 mg Cr(VI)/m3. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for chromic acid and chromates at concentrations above 0.001 mg Cr(IV)/m3.]
1. AIHA . Chromic acid. In: Hygienic guide series. Am Ind Hyg Assoc Q 17:233-234.
2. Chi J Prev Med ; 14:86-88 (in Chinese).
3. Gad SC, et al. . Acute toxicity of four chromate salts, Proceedings of the Chromium Symposium, pp. 43-58. In: DHHS/ATSDR Toxicological Profile for Chromium (Draft), p. 51.
4. ILO . Chromium, alloys, compounds. In: Encyclopaedia of occupational health and safety. 2nd ed. Vol. I (A-K). Geneva, Switzerland: International Labour Office, pp. 295-297.
5. Kobayashi H, Kamiya N, Hiraga K . Toxicological studies on chromium: acute toxicities of chromium trioxide. Annual Report of Tokyo Metropolitan Research Laboratory of Public Health 27:119-123 (in Japanese).
6. Seiler HG, Sigel H, Sigel A, eds. . Handbook on the toxicity
of inorganic compounds. New York, NY: Marcel Dekker, Inc., p. 247.
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