I. Use of Material

Due to the volatile nature of certain chemical forms of radioiodine (e.g., sodium iodide (NaI), Bolton Hunter reagent), charcoal filtration of the airstream is required to minimize the release of radioiodine to the environment. Such filtration may be accomplished by one of the following methods:

• Use a fume hood equipped with a charcoal filter. A list of these currently-approved hoods is on file in the RSO.
• Use a charcoal filtered "mini-hood" within or vented to an existing chemical hood. This arrangement may require a site visit by the RSO for approval.
• Perform the iodination procedure in a closed system utilizing a charcoal vent trap within an existing chemical fume hood.

The PH must inform the RSO in writing regarding which type of filtration will be employed and the location (i.e., building and room number) where the iodination procedures will be performed. If the procedures will be carried out in a lab not currently listed on a PH's permit, an A-4, Application For Radionuclide Laboratory Approval, form must be submitted to the RSO. In addition, if the iodination will take place in another PH's laboratory, written approval must be obtained from that PH and provided to the RSO.

Studies have shown that release of volatile radioiodine is most often associated with the initial opening of sealed vials of radioiodine and during the iodination reaction itself. Although additional releases during other phases of the procedure (e.g., column separation) are thought to be minimal, it is recommended that such procedures be carried out in a standard chemical fume hood (i.e., not necessarily charcoal-filtered). In addition, the volatile radioiodine stock vial should be stored in a hood (not necessarily charcoal-filtered) when not being used. If the iodinations will be carried out in the RSO hood (i.e., CL 916), the stock vial will be kept at the RSO.

In addition to the volatility problem, contamination control is a primary concern associated with iodination procedures. Some specific precautions for iodinators to follow in order to limit the spread of contamination include:

• Verify that the fume hood is operating properly.
• Wear appropriate protective attire (e.g., lab coat, protective eyewear).
• Use a spill tray lined with absorbent paper.
• "Double glove" (i.e., wear two disposable gloves on each hand) and change the outer gloves frequently.
• Monitor your hands frequently during the iodination procedure with a portable survey instrument utilizing a NaI probe. Be careful not to contaminate the instrument #9;
• Wash hands after iodinating

Due to the increased likelihood of contamination associated with iodinations as well as the fact that iodinations are frequently carried out in a single location by more than one PH, direct radiation and contamination (wipe) surveys must be performed and documented after each iodination. Results of these surveys, along with other pertinent information, must be immediately recorded on an Iodination Check List form. If the iodination is performed at the RSO facility (CL 916), the form must be kept on file at the RSO. However, if the iodination is performed in another lab, the form must be filed in the PH's Radionuclide Inventory and Survey Book.

If an individual has no prior experience iodinating, a minimum of three iodinations must be performed in the presence of an authorized iodinator or a member of the RSO staff. Assuming no major problems are observed during the supervised iodinations, the individual will be allowed to iodinate independently.

Routine thyroid bioassays are required for all persons who handle volatile forms of radioiodine. Before the first iodination by an individual, he/she must schedule a baseline thyroid bioassay with the RSO. Following each iodination, a bioassay must be performed between 24 and 72 hours after the iodination.