- Contamination Control
The control of contamination is important in the prevention of the uptake and spread of radioactive material. The following precautions may be implemented during procedures to help control contamination:
- The use of a spill tray should be considered.
- Absorbent paper should be placed on lab benches and spill trays to limit the spread of contamination and aid in the clean-up of contaminated areas.
- Containers or instruments used in radioactive processes should be labeled with a radioactive symbol (e.g., radioactive tape).
- Radioactive material use should be confined as much as possible within designated areas of the lab (e.g., used in a hood).
- Laboratory surveys should be completed.
- Precautions should be made when chemicals may become volatilized (e.g., 35S amino acids in incubators, 3H water storage in freezers).
Personal Contamination (Internal and External)
- Disposable gloves must be utilized when handling any radioactive material. These gloves should be monitored periodically and changed frequently.
- Lab coats should be worn to protect clothing. They should be checked for contamination periodically and may be laundered without special precautions providing contamination is not present.
- Eating, drinking, smoking, storing consumables, and/or applying cosmetics is prohibited in labs.
- Mouth pipetting of radioactive material is prohibited. Mouth pipetting of non-radioactive material in radionuclide laboratories is strongly discouraged.
- Bioassays may be required for individuals utilizing large quantities of radioactive material and/or certain volatile radionuclides (e.g., 125I sodium iodide). The RSO may also require bioassays in the event of an accident involving personal contamination.
- Hands and clothing should be surveyed periodically during and after procedures involving the use of radioactive material. Such surveys may be in the form of a direct radiation survey with a portable survey instrument and/or a wipe survey.
- The RSO requires the use of fume hoods for procedures involving the generation of volatile radioactive material (e.g., when iodinating).
- Special filtration may be required depending on the chemical form used. Such requirements are generally specified in the PH's permit.
Control of External Exposure for High Energy Beta and Gamma Emitters (e.g., 32P, 22 Na, etc.)
- Exposure can be minimized by storing the radionuclide in the original shipping container well away from constantly occupied areas. Additional shielding is required if the exposure rate is greater than 2 mR/hr (or equivalent count rate) at 30 cm from the source.
- For new procedures, dry runs without the use of radioactive material are recommended to improve technique and minimize time of exposure. For extremely hazardous operations, dry runs under the supervision of the RSO may be required.
- Tongs or forceps should be used for the direct handling of unshielded vials containing more than a few microcuries of activity if long handling times are required (e.g., longer than a few seconds). Vessels containing millicurie quantities should rarely be handled directly with the fingers.
- A direct radiation survey may be required during and after procedures involving certain quantities of radioactivity.
- Iodination Procedures
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 Listform. 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.
- Radioactive Material in Animals
For acute in-vivo animal studies (i.e., animals sacrificed shortly after administration of the radioactive material), the PH is generally responsible for all radiation safety aspects of the procedure (e.g., post-procedure surveys, radwaste collection, etc.). The PH's permit will reflect any specific requirements or restrictions with regard to the study.
The requirements for chronic in-vivo animal studies which require the animal(s) to be housed in an "animal care facility" are more rigorous. These requirements are as follows:
- Following initial review and approval, an A-10, Precautions For Animals Containing Radioactive Materials, form will be prepared and signed by the RSO. Rules and restrictions will be specified on this form with several copies being forwarded to the PH.
- Once the animal(s) is/are administered the radioactive material, the remaining information on the A-10 form must be completed by the PH. This information generally includes:
- date and time of administration
- exposure rate at 10 centimeters and 1 meter (for gamma- and high energy beta- emitting radionuclides)
- number of animals/cage
- total activity/cage/day which would be found in any animal bedding if the radioactive material is excreted
- The PH should review Section II of the A-10 form to determine his/her responsibilities regarding routine care of the animal(s). Also, Section III of the form provides information regarding specific procedures which may be required (e.g., cage/area surveys, use of shoe covers, etc.).
- It should be noted that a new A-10 form must be affixed to each cage/pen as additional administrations of radioactive material are carried out. Additional forms will be provided by the RSO upon request. This form is valid for sixty days from the signed date on the form. After the unused forms have expired, they should be discarded and new ones should be obtained from the RSO. It should also be noted that these forms are approved specifically for the procedures which were initially reviewed and approved by the RSO. Therefore, any changes in the protocol (e.g., different radionuclide or amount administered) require an amendment, approval, and issuance of a new A-10 form by the RSO.
- When the animal(s) is/are transferred or removed from a cage and the contamination levels of the cage are found to be within acceptable limits, the completed A-10 form should be transferred to another cage along with the animal(s) or left in the animal care facility office if the animal(s) is/are either no longer radioactive or they are to be sacrificed.
- If a survey of the cage/pen is required per Section III of the A-10 form after the animal(s) is/are removed, the survey must be performed by the PH or his designee with the results recorded on an A-11, Contamination Survey For Animal Care Facilities, form. Once the survey is completed and contamination levels are within acceptable limits, the A-11 form should be attached to the A-10 form (from the cage/pen) and forwarded to the animal care facility office. The PH may be charged for the use of these cages until the animal care facility office receives the completed forms.
- If radioactivity is excreted by the animal(s), Section III of the A-10 form specifies how the excreta must be handled. In most cases, animal care personnel may dispose of the excreta. However, the PH has the following responsibilities regarding animal excreta which must be collected:
- The PH must provide the animal care facility with a solid radioactive waste disposal container, obtainable from the RSO, and a completed A-12, Log Sheet For Animal Bedding Contaminated With Radioactive Materials, form with the appropriate information completed.
- Once the disposal container is full or upon completion of the study (whichever comes first), the plastic liner must be sealed, the A-12 form placed on the container, and the container transported to the RSO by the PH or his/her designee. The RSO should be contacted prior to delivering the waste. If the animal care facility personnel are responsible for placing the contaminated bedding in the disposal container, the PH will be notified when the container is full and must remove it from the animal care facility within 48 hours of notification.
- The PH is responsible for the collection and transportation of contaminated animal excreta to the RSO if a metabolism cage is specifically required by the RSO to collect such excreta. If the PH requests the use of a metabolism cage but such cage is not required by the RSO, information will be provided on the A-10 form regarding the collection of excreta. In this situation, ultimate disposal of the contaminated excreta is still the responsibility of the PH.
Animals administered PET radiopharmaceuticals must have their cages posted with the A-10a, Precautions for Animals Containing PET Radiopharmaceuticals, form. This form may be removed and filed with the animal care center once the animal is deemed nonradioactive.