Swab Each Nostril Separately to Help Estimate Level of Internal (Lung) Contamination
In a mass casualty event, collecting and analyzing nasal swabs may not be feasible due to numbers of patients, transportation issues, and limited laboratory capacity
Swabs collected >1 hour after contamination may provide unreliable results
Remember that measuring radioactivity is not the same as measuring absorbed dose
Nasal swab samples can provide valuable information about inhaled radioactive material including
Identification of radioisotope and mode of isotope decay
A crude estimate of the amount of radioactivity deposited deep in the lung
The level of
radioactivity measured from nasal swabs (in units of Bq) can then be used to estimate the received deep in the lung (in units of dose of radiation rad, c Gy, rem, or Sv) How to collect nasal swabs
Use only one moist, clean, cotton-tipped applicator or nasal swab per nostril
Collect sample from anterior portion of the nose
Place each swab into its own container and label with name, date, time
Analyze each sample separately for radiation contamination
NOTE: Alpha-emitting radioisotopes will be masked by any water on the swab. Swabs must be allowed to dry fully before surveying for alpha emitters.
Radioactivity levels measured at the nostril are estimated to represent ~5% of the radioactivity inhaled into the deep lung
If inhaled particles are 0.2 - 5 microns in diameter, measured radioactivity from nasal swabs is estimated to be ~1-10% of lung contamination
If inhaled particles are 1-5 microns in diameter, measured radioactivity from nasal swabs is estimated to be ~5-10% of lung contamination
Significant over- or underestimation of radioactivity levels may occur depending on particle size, shape, chemistry, physical stability, individual inhalation patterns and underlying physical health
Parameters affecting actual dose to lung include isotope solubility, particle size and mode of radioactive decay
Distribution of inhaled radioactive material throughout the broncho-pulmonary system is not likely to be homogeneous
≥ 10-fold discrepancy in radioactivity levels between left and right nostril suggests
Contamination by other means, as by patient's hands or from surrounding facial contamination
Deviated septum, other anatomical obstruction
Factors limiting utility of nasal radioactivity to estimate lung dose
Obligate mouth breather
Swabs collected post-decontamination (i.e., after a person showers, blows nose, or wipes contamination from nose)
Swabs collected > 1 hour after contamination are unreliable due to normal mucociliary clearance
> 30 minutes after suspected contamination: uncertain value
> 45-60 minutes after suspected contamination: probably not reliable
Assume that when
external contamination has occurred, some victims may also be internally contaminated Using nasal swab information to manage patients, requires collaboration between health physics/radiation safety personnel and clinical subject matter experts
Need to consider possibility of multiple isotopes in radiological dispersal incident (e.g., "dirty bomb")
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