UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 1553: Arsenic acid, liquid

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1553 is assigned the proper shipping name Arsenic acid, liquid in the U.S. DOT Hazardous Materials Table (49 CFR 172.101). It is classified as a Class 6.1 Toxic Substance material, Packing Group I. Required label(s): 6.1.

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 154)

Hazards: TOXIC. Corrosive. Non-combustible but may decompose producing toxic fumes when heated.

Fire: Use agent appropriate for surrounding fire. Cool containers.

Spill: Do not touch. Avoid inhalation. Use water spray to reduce fumes.

Chemical and Physical Properties

Arsenic acid, liquid appears as a clear colorless aqueous solution. Noncombustible. Corrosive to metals. Toxic by ingestion. Confirmed human carcinogen. Detrimental to the environment. Immediate steps should be taken to limit release.

CAS Number: 7778-39-4
Molecular Formula: AsH3O4
Molecular Weight: 141.943 g/mol
Color / Form: WHITE TRANSLUCENT CRYSTALS /HEMIHYDRATE/
Boiling Point: Boiling point (-H2O): 160 C /Hemihydrate/
Melting Point: 35 °C
Specific Gravity: 2.2 (sinks in water)
Vapor Pressure: Vapor pressure, kPa at 15Â C: 1.3
Water Solubility: Freely sol in alcohol, glycerol /Hemihydrate/
pH: WEAK ACIDIC PROPERTIES.

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1 lb
RCRA Waste Code(s)
[object Object]

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: T20, TP2, TP7, TP13, W31. 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 1553 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.