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Airborne Radioactive Materials

Contamination present in a room may create airborne radioactivity by simple movement of the air over the contamination, spreading it around in the air. Most radioisotopes will be picked up by air and spread through this mechanism. This is one more good reason to keep areas free of contamination.

Use of volatile forms of radionuclides, such as ¹²⁵I for iodinations or ³H-sodium borohydride may generate airborne radioactivity. Any chemical or physical form which readily volatilizes or evaporates into the air must be considered a potential airborne radioactivity risk.

Chemical reactions may generate radioactive gases or other airborne contaminants. An example is the labeling reaction for ³⁵S methionine, which generates a methyl mercaptan reaction which liberates HCl and ³⁵SO₂ gas. Airborne radioactivity has resulted in unnecessary intakes and area contamination in laboratories where the users were unaware of this risk and have not taken precautions to trap or contain the liberated ³⁵SO₂.

Heating or incubating may cause evaporation or chemical reactions which release radioactive materials into the air. Aerosols (tiny droplets or particles) are present with all materials, and pose an increased risk when handling stock solutions or other high concentrations of radionuclides. Use chemical fume hoods or biological safety cabinets for high activity, concentrated or potentially volatile radioactive materials manipulations.

Materials which have been frozen may release substantial quantities of aerosols or gaseous radioactive material when the containers are opened. There have been numerous incidents at MSU and other institutions where this has occurred and has caused significant contamination of work areas, equipment and clothing of the worker opening the containers.

Another cause of airborne radioactivity is media or solutions containing cells, bacteria or other living organisms. The living organisms metabolize the radioactive substrates and may produce radioactive gases or vapors as a byproduct.

When hazardous chemical forms of the radionuclides are used, such as radiolabeled carcinogens or toxins, increased risks are presented by the vapors, aerosols or gases present or generated in the use. In this case, the hazard present is not only radioactive, but may also pose airborne chemical risks.

In order to prevent uptake in these increased risk situations, fume hoods, biological safety cabinets or other containment must be used to protect the worker from uptake and internal deposition. Do not use clean benches (tissue culture hoods) for use of radioactive materials, or any other hazardous material. While the product is kept sterile by these hoods, the hazardous material present in the materials used are blown into the face of the worker, and into the room. Therefore, there is no protection for the worker.

In certain rare cases, respiratory protection may be necessary for certain radioisotope uses. However, respiratory protection should only be used when other means of control and containment do not provide enough protection. Respirators must be chosen carefully to ensure the proper fit and type of cartridge, and the use must be monitored carefully. For this reason, use of respirators for radioactive materials use must be pre-approved by the ORCBS, documented and monitored. Prior to using respirators for any reason, fit testing and medical monitoring are required.

If you are concerned that an intake has occurred, contact the ORCBS. Bioassays (urine samples) or other investigational methods may be employed to determine whether an intake has actually occurred and to recommend ways to avoid such undesirable situations in the future.

Disposal of Radioactive Waste

Radiation Safety Manual Table of Contents