Contaminated liquid nitrogen vapour as a risk factor in pathogen transfer.

Area of Science:

• Cryobiology
• Microbiology
• Biobanking

Background:

• Particulate matter, including pathogenic organisms, accumulates in liquid nitrogen storage.
• Viability of these organisms can be preserved by immersion in liquid nitrogen.
• Current sealing and sterilization methods reduce but do not eliminate contamination risks.

Purpose of the Study:

• To demonstrate the release of contaminants from liquid nitrogen during cooling processes.
• To assess the risk of sample and facility contamination from vapor-phase storage.
• To highlight the potential for cross-contamination between storage sites.

Main Methods:

• Utilized fungal spores and organic crystals as model contaminants.
• Simulated the cooling of programmable freezers and dry shippers using liquid nitrogen vapor.
• Observed particle release during the cooling process.

Main Results:

• Contained particles are released into the environment when liquid nitrogen vapor cools equipment.
• Storage in the vapor phase above liquid nitrogen poses a significant risk of sample and facility contamination.
• Cross-contamination between local and international sites is a potential consequence.

Conclusions:

• Vapor-phase storage above liquid nitrogen is not risk-free for sample integrity.
• The release of contaminants presents a risk of cross-contamination with serious implications for clinical and agricultural applications.
• This unquantified risk should be incorporated into risk analyses for reproductive material storage protocols.