title: Retention efficacy and release of radioiodine in fume hoods.
abstract: Procedures to determine the release of hazardous gaseous substances including radioactive iodine are covered by different norms such as the European standard EN 14175 and the German national standard DIN 25466. The detection of sulphur hexafluoride (SF6) is required to comply with the prescribed methodology. The detection limit of this test is 4.5·10-7mol/m3in exhaust air. This detection limit would represent a very high activity in the region of 0.27 TBq/m3leading to an unacceptable risk. We therefore developed a test using a filter system, consisting of a combination of filters capable of separating various chemical forms of airborne radioiodine. Air samples were collected directly in front of the fume hood and in the laboratory beside two different fume hoods of a similar construction with a final activated carbon filter for retention of radioiodine. Particular attention was therefore paid to air samples taken after passage over the filters. Significant differences in the degree of retention of iodine were found between the two fume hoods investigated. In one test a malfunction of the fume hood was demonstrated. In this case 0.148 × 10-3% of the total released activity per m3air was found 1 cm in front of the hood sash. A remarkably high fraction of the activity released in the fume hood (1.3 × 10-3%/m3air) was measured after the activated carbon filter. In the ambient air, values of up to 8.6 × 10-6% pro m3laboratory air sampled were measured, despite a 6-8-fold air exchange. The selected procedure is a factor of 1011(Schomäcker et al., 2001) more sensitive than the standard recommended methods (EN 14175). The standard test prescribed by the DIN/EN failed to reveal any inadequacy in the protective function of the radionuclide hood with respect to radioiodine retention.
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Germany. Electronic address: klaus.schomaecker@uni-koeln.de.
authors.forename: K
authors.initials: K
authors.lastname: Schomäcker
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Fischer
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Zimmermanns
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Bregulla
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Sudbrock
authors.affiliation: Department of Nuclear Medicine, University Hospital Erlangen, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Prante
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Drzezga
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis*; D015386:Hazardous Substances / Q000032:analysis*; D007457:Iodine Radioisotopes / Q000032:analysis*; D057230:Limit of Detection; D014691:Ventilation / Q000295:instrumentation* / Q000379:methods
chemical_list: D000396:Air Pollutants, Radioactive; D015386:Hazardous Substances; D007457:Iodine Radioisotopes
keywords: DIN standards; Fume hood; Radioiodine; Radioiodine retention