How to Send Extremely Perishable Items in the Mail With Dry Ice

Dry ice can preserve perishable food while in transit.

Dry ice is frozen carbon dioxide, frigidly cold at a temperatures between minus 70 and minus 109 degrees Fahrenheit. Because of dry ice's slow sublimation time -- about 5 lb. per 24 hours when kept in an insulated container -- it functions well as a shipping refrigerant for perishable food. Dry ice is not toxic in amounts sold to consumers, but it is dangerous, making safety precautions imperative. The low temperatures of frozen carbon dioxide can cause almost immediate frostbite and permanent damage to human tissue.

Things You'll Need

• Insulated cooler
• Insulated gloves
• Plastic wrap
• Shipping paper
• 2 corrugated cardboard boxes
• Expanded polystyrene container
• Polyethylene film

Instructions

1. Register for a dry ice shipping class if you intend to ship your package via airmail. The U.S. Department of Transportation and Air Transport Association require dry ice package preparers to receive training in proper packaging. Short online classes are available. Ground shipments of dry ice are not regulated.

2. Purchase dry ice as close as possible to your intended ship time. Do not handle dry ice directly. Use insulated gloves or tongs. Buy at least two pieces of dry ice. Purchase at least 5 lb. for every day (or fraction thereof) you expect your shipment to be in transit; 10 lb. per day is safest. Immediately place the dry ice in an insulated container.

3. Package the food to be shipped in sealed plastic and then place it in a corrugated cardboard container. Double-bag the food if it contains liquids. Set the container aside.

4. Divide your dry ice in half. Wrap each half in brown shipping paper or parchment paper. Place the first half at the bottom of an insulated container. FedEx recommends an expanded polystyrene container with walls between 1 1/2 inches and 3-inches thick. Place your food container on top of the first half of dry ice. Place the second half of dry ice on top of the food container. Place the lid on the insulated container. Do not seal the lid. Sublimating (melting) carbon dioxide must be able to escape or else the package could explode.

5. Place the insulated container inside a corrugated cardboard box. Address the package and label it with bold "Contains Dry Ice" warnings on all sides. Wrap the cardboard box in polyethylene film for added protection without the risk of a dangerous carbon dioxide buildup. Polyethylene film is a breathable material.

6. Bring the package to a freight service. Declare the nature of your package and ask the shipping company for a "Class 9" miscellaneous hazardous material label to affix to your package. These labels are required by federal law for all air and sea shipments. Choose priority overnight shipping unless financial or other limitations bar you from doing so.

References

• National Institutes of Health; Safety Alert-Shipping Dry Ice; Michael Gottesman; April 2006
• U.S. Department of Agriculture: Mail Order Food Safety
• FedEx: Packaging Pointers: Perishable Shipments
• Amherst College; Shipping and Packaging - Dry Ice; January 2010
• Appalachian State University: Shipping Non-Infectious Clinical Specimens