The collection of biological materials is increasing in popularity in museums. Materials, such as bodily tissue and blood, are used and stored for scientific research, like DNA. The samples are stored in stainless steel vats, called cryovats, which contain liquid nitrogen. When cooled at temperatures below -150°Celsius, the liquid nitrogen turns into a frigid vapor that keeps the tissue frozen. There are different hazards for these collections, depending on the physical state of the specimen:
- Before the tissue is frozen, the specimens may contain pathogens that are potentially infectious.
- After the tissue is frozen, the liquid nitrogen in which it is stored may cause freezer burn, and if leaking will deplete oxygen supply.
Before freezing: Unless a specimen is marked, it is difficult to detect hazards without analytical testing. Research the specimen history for any risk of pathogen exposure.
After freezing: Monitor collection areas to detect leaks in the nitrogen supply and regulate the amount of nitrogen flowing into the vats.
Before freezing: Symptoms will vary depending upon the type of disease.
After freezing: If a nitrogen leak occurs, nitrogen levels may exceed oxygen levels. Any workers in the collection area during this time are at risk of passing out due to depleted oxygen levels. Symptoms from low oxygen levels include:
- Shortness of breath
All laboratories that work with biological material should follow safety guidelines outlined by biosafety level 2 procedures, including:
- Supply appropriate personal protective equipment (PPE) including disposable gloves, eye goggles, and lab coat.
- Equip laboratory with lockable doors and monitored access.
- Post biohazard signage on the entrance to the laboratory when agents that pose a potential risk are in use.
- Install working surfaces that are impervious to water so that infected residues can not leak into the surface
- Use workbench liners that are easily disposable after use as biohazard waste
- Use an approved decontaminant to clean work surfaces
- Use biosafety cabinets (class II) for work with potentially infectious agents
- Require that employees wash hands before leaving the work environment
- Dispose of sharps in proper receptacles
- No eating, drinking, applying cosmetics, handling of contact lenses, or allowing pets in the lab
More information on biosafety level 2 criteria may be found on the Center for Disease Control and Prevention’s website in the book Biosafety in Microbiological and Biomedical Laboratories (BMBL), 5th Edition [
The following guidelines will help protect staff working in frozen tissue storage areas where liquid nitrogen is in use:
- Wear protective cryo-gloves, cryo-aprons, and eye goggles in case of splashing nitrogen and to prevent freezer burn.
- Install a ventilation system in the storage area that runs continuously
- Install an oxygen monitor in the storage area that will immediately sound an alarm in the event of low oxygen levels.
- Install windows flanking one whole wall of the storage room so those working in an adjacent room would be able to see if anyone in the storage area becomes unconscious.
In 2001 the American Museum of Natural History opened its newest research collection, the Ambrose Monell Cryo Collection for Molecular and Microbial Research. The collection serves as an accessible repository of frozen tissue specimens representing DNA of a wide range of species, collected and maintained under rigorously controlled conditions. The AMNH constructed a state-of-the-art facility to house the collection that includes proper safety protocols to protect staff members when working with the cryovats and specimens.
An on-line article from Science World, “Frozen in Time: A Museum Biologist Keeps Animal Tissues Frozen for Years”, explains a visit to the AMCC’s frozen tissue lab.
The Harvard-Smithsonian Center for Astrophysics website offers information on general safety precautions for cryogenic liquids.
Because this is a growing field, there is limited information on frozen tissue storage in museums. Further information on working with biological materials may be found on websites for other types of institutions and research centers.
The University of Newcastle-upon-Tyne lists guidelines on “Safe Work with Human and Animal Tissues” on their website.
The Institutional Animal Care and Use Committee offers guidelines on “Occupational Hazards Associated with the Care and use of Laboratory Animals”.
The Common Access to Biological Resources and Information (CABRI) website offers information on “Safe Handling of Liquid Nitrogen”.