| Agent Name |
Hydrogen chloride |
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| Alternative Name |
Hydrochloric acid |
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| CAS Number |
7647-01-0 |
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| Formula |
Cl-H |
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| Major Category |
Toxic Gases & Vapors |
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| Synonyms |
Hydrochloric acid; Muriatic acid; [NIOSH]; Anhydrous hydrogen chloride; Anhydrous hydrochloric acid; HCl; Hydrochloride; [CHEMINFO] UN1050; UN1789; UN2186 |
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| Category |
Acids |
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| Description |
Colorless to slightly yellow gas with a pungent, irritating odor. [Note: Shipped as a liquefied compressed gas.] [NIOSH] |
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| Sources/Uses |
Sold as muriatic acid for a variety of household and construction purposes, e.g., scale remover; used to clean, pickle, and electroplate metal; also used in oil well activation, ore reduction, leather tanning, swimming pool cleaning, and refining of edible oils; [ACGIH] [ATSDR Medical Management] |
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| Comments |
Liquid causes second degree burns after contact for a few minutes; [CHRIS] Hydrogen chloride is highly corrosive; Muriatic acid (37% HCl) is highly corrosive; HCl solution < 30% is corrosive; [Quick CPC] Listed as one of "major irritant airborne toxicants"; [LaDou, p. 523] Possible frostbite from contact with liquid; [NIOSH] The following chemicals can release HCl when spilled in water: Acetyl chloride, Boron trichloride, Chloroacetyl chloride, Chromyl chloride, Dichloroacetyl chloride, Phosphorus trichloride, Phosphorus pentachloride, Phosphorus oxychloride, Titanium tetrachloride, Aluminum chloride, Chlorosulfonic acid, Silicon tetrachloride, CHLOROSILANES, Surfuryl chloride, Thionyl chloride, and metal alkyl and aryl halides. [ERG 2008] See the Process, "Toxic Gas from Spilling Chemical in Water." Hydrogen chloride is fibrogenic to the lungs in the context of an acute inhalation exposure complicated by bronchiolitis obliterans. |
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| Reference Link |
ATSDR Medical Management - Hydrogen chloride |
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| Exposure Assessment |
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| Skin Designation (ACGIH) |
No |
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| TIH |
Yes |
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| Ceiling (ACGIH) |
2 ppm |
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| PEL (OSHA) | Ceiling(OSHA) = 5 ppm |
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| MAK |
2 ppm |
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| IDLH (NIOSH) |
50 ppm |
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| Excerpts from Documentation for IDLHs |
Other human data: It has been reported that 50 to 100 ppm for 1 hour is barely tolerable and that 35 ppm causes irritation of the throat [Henderson and Haggard 1943]. It has also been reported that work is impossible at 50 to 100 ppm but is difficult but possible at 10 to 50 ppm [Flury and Zernik 1931]. |
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| Odor Threshold Low |
0.25 ppm |
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| Odor Threshold High |
10.06 ppm |
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| RD50 |
309 ppm |
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| Lethal Concentration |
LC50 (rats) = 3,124 ppm/1 hr |
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| Explanatory Notes |
Odor threshold from AIHA; The Guide from the Emergency Response Guidebook is for "Hydrogen chloride, anhydrous." |
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| Reference Link |
International Chemical Safety Cards (WHO/IPCS/ILO) |
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| Flammability (NFPA) |
0: will not burn |
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| Adverse Effects |
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| Toxic Pneumonitis |
Yes |
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| Fibrogenic |
Yes |
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| Dermatotoxin |
Skin Burns |
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| IARC Carcinogen |
Not Classifiable |
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| Links to Other NLM Databases |
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| Health Studies |
Human Health Effects from Hazardous Substances Data Bank: HYDROCHLORIC ACID
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