UN/NA Number Reference
DOT Class 2.3 Toxic Gas placard

UN 1040: Ethylene oxide

49 CFR 172.101 Hazardous Materials Table·ERG 2024

DOT Classification and Shipping

UN 1040 is assigned the proper shipping name Ethylene oxide 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

Ethylene oxide appears as a clear colorless gas with an ethereal odor with a flash point below 0 °F. Liquid less dense than water. Vapors heavier than air. May polymerize exothermically if heated or contaminated. If the polymerization takes place inside a container, the container may rupture violently. Vapors very toxic. Vapors irritate the eyes, skin, and respiratory system. Prolonged skin contact may result in delayed burns. Used to make other chemicals, as a fumigant and industrial sterilant.

CAS Number: 75-21-8
Molecular Formula: C2H4O
Molecular Weight: 44.05 g/mol
Color / Form: Colorless ... gas at ordinary room temp and pressure; liquid below 12 °C
Odor: Sweet
Boiling Point: 51.3 F
Melting Point: -170.5 °F (EPA, 1998)
Flash Point: -0.4 to 0 F
Autoignition: 804 °F (USCG, 1999)
Specific Gravity: 0.8222 (floats on water)
Vapor Pressure: 1095 mmHg at 68 F
Vapor Density: 1.49 (heavier than air)
Water Solubility: Miscible
Log P: log Kow = -0.30

Regulatory Data

CERCLA RQ (40 CFR 302.4)
10 lb
EPCRA TPQ (40 CFR 355)
1000 lb
OSHA PEL
[1910.1047] TWA 1 ppm 5 ppm [15-minute Excursion]
NIOSH REL
Ca TWA 0.1 ppm (0.18 mg/m 3 ) C 5 ppm (9 mg/m 3 ) [10-min/day]
IDLH
Ca [800 ppm]
RCRA Waste Code(s)
[object Object], [object Object]

A release of this material at or above its CERCLA reportable quantity (10 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: 4, 342, T50, TP20. 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 1040 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.