UN/NA Number Reference
DOT Class 6.1 Toxic Substance placard

UN 1558: Arsenic

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1558 is assigned the proper shipping name Arsenic 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 II. 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 152)

Hazards: TOXIC. Combustible. May be ignited by heat, sparks. Toxic fumes when burned.

Fire: Small: dry chemical, CO2, water spray. Large: water spray, fog.

Spill: Do not touch. Eliminate ignition sources. Ventilate area. Use water spray.

Chemical and Physical Properties

Arsenic appears as a grayish metallic solid that turns black upon exposure to air. Insoluble in water. Toxic by ingestion.

CAS Number: 7440-38-2
Molecular Formula: As
Molecular Weight: 74.92159 g/mol
Color / Form: IT EXISTS IN THREE ALLOTROPIC FORMS, THE YELLOW (ALPHA), BLACK (BETA) AND GREY (GAMMA) FORMS
Odor: ... Odorless ...
Boiling Point: 1135 F
Melting Point: 1135 °F (Sublimes) (NIOSH, 2024)
Autoignition: 180 °C
Specific Gravity: 5.727 (sinks in water)
Vapor Pressure: 0 mmHg (approx)
Water Solubility: Insoluble

Regulatory Data

CERCLA RQ (40 CFR 302.4)
1 lb
OSHA PEL
[1910.1018] TWA 0.010 mg/m 3
NIOSH REL
Ca C 0.002 mg/m 3 [15-minute]
IDLH
Ca [5 mg/m 3 (as As)]
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: IB8, IP2, IP4, T3, TP33. 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 1558 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.