UN/NA Number Reference
DOT Class 2.3 Toxic Gas placard

UN 2188: Arsine

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 2188 is assigned the proper shipping name Arsine in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 2.3 Toxic Gas material. Required label(s): 2.3, 2.1.

Packing group indicates the degree of danger within a hazard class: PG I is high danger, PG II medium, PG III low. The proper shipping name, hazard class, UN number, and packing group together form the basic shipping description that must appear on shipping papers and, where required, on the package and placard.

Emergency Response (ERG Guide 119)

Hazards: TOXIC. May be fatal if inhaled or absorbed through skin. Flammable. Vapors heavier than air.

Fire: Small: dry chemical or CO2. Large: water spray or fog. Fight from maximum distance.

Spill: Do not touch. Stop leak if safe. Use water spray to reduce vapor.

Chemical and Physical Properties

Arsine appears as a chemical warfare blood agent. It is a colorless gas with a disagreeable garlic odor. Flammable. Heavier than air. Flame easily flashes back to the source of leak. Extremely toxic by inhalation. Confirmed human carcinogen. Under prolonged exposure to fire or heat containers may rupture violently and rocket. Rate of onset: Immediate to 24 hours Persistence: Minutes to hours Odor threshold: 0.5 ppm Source/use/other hazard: Used in electronics industry; reacts with H2O (don't use H2O in fire).

CAS Number: 7784-42-1
Molecular Formula: AsH3
Molecular Weight: 77.946 g/mol
Color / Form: Colorless gas
Odor: Disagreeable garlic odor
Boiling Point: -80.4 F
Melting Point: -179 °F (EPA, 1998)
Flash Point: Flammable gas
Specific Gravity: 1.689 (sinks in water)
Vapor Pressure: greater than 1 atm
Vapor Density: 2.66 to 2.695
Water Solubility: 20 cc/100 cc
pH: Aqueous solutions are neutral

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1 lb
EPCRA TPQ (40 CFR 355)
100 lb
OSHA PEL
TWA 0.05 ppm (0.2 mg/m 3 )
NIOSH REL
Ca C 0.002 mg/m 3 [15-minute]
IDLH
Ca [3 ppm]

A release of this material at or above its CERCLA reportable quantity (1 lb) requires immediate notification to the National Response Center at 800-424-8802.

Special Provisions

49 CFR 172.102 special provision codes for this entry: 1. These codes modify the general requirements (packaging, quantity limits, exceptions) for this specific material. Look up each code in 49 CFR 172.102 for the full text.

Need the full interactive record? Open UN 2188 in the SpillNerd lookup tool for the live database entry with placard graphics, GHS pictograms, full segregation tables, and synonym search. For another material, use the UN number and chemical lookup.

Reference data compiled from the DOT Hazardous Materials Table (49 CFR 172.101), the 2024 Emergency Response Guidebook, and public chemical databases (PubChem, NIOSH, EPA). Always verify the correct shipping description against the current regulation and the manufacturer's SDS Section 14 before shipping.