Flying Frozen Tamales, Undeclared

Posted on 5/12/2023 by Roseanne Bottone and Roger Marks

When you ship frozen foods, you might assume that regulations for “hazardous materials” don't apply to your packages. A typical frozen steak is not flammable, after all, or explosive, corrosive, radioactive, or poisonous, and it’s not a type of regulated gas, oxidizer, or organic peroxide. 

Why, then, do frozen steaks, frozen tamales, and other frozen foods show up regularly on Hazmat Incident Reports filed with US DOT? 

Here's why: It’s common to pack frozen foods with dry ice to keep them cold during transportation. When shipped on an airplane or a vessel/cargo ship, dry ice is subject to regulation as a hazardous material (called “dangerous goods” internationally).  

In this article:

Why is Dry Ice a Hazardous Material (Sometimes)?

Dry ice can pose an acute health and safety hazard in transportation. Packages containing dry ice will not be accepted for transportation unless the shipper has followed specific requirements for packaging, labeling, shipping documents, etc. (as applicable).  

Dry ice does something unusual for a frozen solid; it “sublimates.” Instead of melting into liquid when the temperature rises, dry ice changes directly into a gas—carbon dioxide (CO2). 

CO2 is denser than oxygen and will displace the oxygen in an enclosed space. Below the deck of a cargo ship or inside of an airplane cargo hold, displacement of oxygen can push all breathable air out of reach and cause people to suffocate.

Flying Frozen Tamales, Undeclared

As dry ice sublimates, carbon dioxide gas can also build up inside of a package and cause it to rupture. To prevent this, shippers of dry ice must use a type of packaging that allows some "venting" of gas to relieve internal pressure.  

Dry ice also poses a safety hazard to package handlers and others in the supply chain: Direct contact with skin can cause painful (and in some cases severe) burns. 

Facts about dry ice as a hazardous material:

  • UN identification number: UN 1845
  • DOT Hazard Class: 9, "Miscellaneous"
  • Proper shipping name: Carbon dioxide, solid or Dry ice

“Carbon dioxide, solid or Dry ice” is listed on US DOT’s Hazmat Table (49 CFR 172.101) with the letters/symbols “A” and “W” shown in Column 1 to indicate the material is regulated by air and water only. 

That means that dry ice is regulated as a hazardous material only when it is shipped:

  • By air (i.e., on a cargo or passenger aircraft), or
  • By vessel (i.e., over the water on a cargo ship).

Shipments that travel by highway or rail only are not subject to regulation for hazardous materials. 

What regulations should be followed to ship with dry ice?

The Shipping Dry Ice Online Course goes into full detail on how to ship dry ice in compliance with US and international hazmat/dangerous regulations for air (IATA) and vessel (IMDG) shipments. 

dry ice shipping and hazmat regulations for frozen foods

What Hazmat Regulations to Ship with Dry Ice?

In most cases, shippers of hazardous materials (including dry ice) by air or vessel must follow the provisions in one of the following “international” regulatory codes: 

Don’t let the names of these regulations fool you—practically every major air carrier requires compliance with the IATA DGR—even if the shipment never leaves US airspace. The same is true for vessel operators/carriers, who are likely to require compliance with the IMDG Code. 

Requiring shippers to follow a standard set of regulations makes it easier for air and ocean carriers to operate internationally and move cargo between countries and continents with very different regulatory schemes in place. 

More: IATA and IMDG Dangerous Goods Training FAQ

Hazmat Incident Reports Involving Dry Ice

As the hazardous materials incident reports shared below show, that’s not always the case. Incidents involving dry ice in air transportation occur regularly and often involve non-hazardous cargo (like foods). These incidents can result in packages being removed from transportation and/or perishable goods being destroyed or returned to the shipper. 

Here's a taste of some recent hazmat incident reports involving frozen foods and dry ice discovered during transportation.

The following are excerpts from real hazardous materials Incident Reports submitted to US DOT on Form F 5800.1. DOT requires an incident report after any release of a hazardous material in transportation (including dry ice).

More about hazmat incident reporting.


“Responded to a package that was cold to the touch, upon inspecting the contents discovered several pounds of dry ice pellets cooling vanilla glaze

—April 2023 in Dallas, TX

“…discovered approximately 6 lbs. of dry ice pellets in bags cooling plant-based donuts.

—March 2023 in Round Rock, TX

"During handling, the characteristic rattle sound produced by dry ice was heard, responder opened package to find four pints of ice cream being cooled by ...dry ice."

—February 2023 in Londonderry, NH

"Two packages were cold to the touch and had heavy frost forming on them. Responder opened packages to reveal... dry ice cooling various pastries.

—January 2023 in Van Nuys, CA

"...discovered several pounds of dry ice cooling smashed avocados. There are no dangerous goods marks or labels on the box." 

—May 2022 in Louisville, KY


"Responded to a package that was forming frost on the exterior of the box...discovered undeclared dry ice cooling tamales.

—February 2022 in Portland, OR


dry ice is a class 9 hazardous material handle carefully

Hazmat Training to Ship Dry Ice

Lion's Shipping Dry Ice Online Course course is built for hazmat employees who perform pre-transportation job functions like packaging, marking, or preparing shipping papers for shipments containing dry ice. Anyone who encounters dry ice on the job will benefit from increased awareness of its unique hazards.

Tags: dangerous goods, dry ice, hazmat shipping, IATA, UN 1845

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