dry ice pellets medawareness

What is dry ice and how does it work?

Dry ice is a solid form of carbon dioxide, primarily used as a cooling agent where sub-zero refrigeration is not available. Unlike water ice, dry ice does not melt but vaporizes from a solid to a gas in a phase-changing process known as sublimation. Dry ice is also colder than water ice, at −78.5 °C (−109.3 °F). When dry ice is exposed to air, this solid form of carbon dioxide turns into gaseous carbon dioxide, which keeps your contents, whether its ice cream, frozen food or Varicella vaccines, frozen.

Is  transporting vaccines with dry ice safe for use in the vaccine cold-chain?

Using dry ice in the vaccine cold-chain is a mixed bag. Some health departments approve of transporting vaccines with dry ice while others restrict it. For example, the CDC approves the use of dry ice for transporting Varivax. Merck however, the makers of Varivax, just recently banned the use of dry ice in their shipping containers. Why isn’t there a ban on dry ice across the board?

What are the hazards of using dry ice in the vaccine cold-chain?

Other than causing frostbite from mishandling, and destroying vaccines through mis-packaging, dry ice can kill. Transporting vaccines with dry ice in a non-ventilated vehicle can lead to carbon dioxide poisoning. As the dry ice sublimates, becoming gaseous, it will displace all of the vital air in the car with a high concentration of carbon dioxide. The symptoms of CO2 poisoning include:

  • deep or labored breathing
  • muscle twitching
  • increased blood pressure
  • headache
  • increased pulse rate
  • loss of judgment
  • unconsciousness (occurs in under a minute when CO2 concentration rises about 10%)
  • and even death

Transporting vaccines with dry ice should be banned. Portable freezers, like those made by Roemer Industries Inc., make transporting Varicella vaccines safe and easy.

Image credit: Wikipedia