Health hazard evaluation summary report: HETA-2003-0206-3067, evaluation of radiation exposure to TSA baggage screeners, Transportation Security Administration, Washington, DC.
Between November 2002 and March 2003, the National Institute for Occupational Safety and Health (NIOSH) received three health hazard evaluation (HHE) requests from Transportation Security Administration (TSA) employees at the Cincinnati, Honolulu, and Baltimore airports. The employees expressed concerns about a variety of potential exposures including diesel exhaust, dirt, dust, noise, and hazardous items found in baggage. In addition, a concern common to all three requests was exposure to x-rays from carry-on baggage and checked baggage screening machines. On March 26, 2003, TSA management submitted a separate request for NIOSH "to perform an independent study to determine the levels of radiation emissions from the various TSA screening equipment, and whether routine use of dosimetry is warranted." In May 2003, the following 12 airports were selected for study: Logan International (BOS); Baltimore-Washington International (BWI); Cincinnati/Northern Kentucky International (CVG); Los Angeles International (LAX); T.F. Green Municipal (PVD); Palm Beach International (PBI); Chicago O'Hare International (ORD); Harrisburg International (MDT); Honolulu International (HNL); McCarren International (LAS); Miami International (MIA); and Philadelphia International (PHL). The objectives of the NIOSH HHE were as follows: (1) assess the work practices, procedures, and training provided to TSA baggage screeners who operated machines that generate x-rays and (2) characterize TSA baggage screeners' radiation exposures and determine if routine monitoring with radiation dosimeters is warranted. Basic characterizations of work practices, spot measurements for radiation, and employee interviews were completed between August 2003 and February 2004. Monthly radiation measurements were obtained from personal dosimeters issued to TSA baggage screeners between March and August 2004. During the basic characterization phase, we observed poor work practices such as employees reaching into the Explosive Detection System (EDS) machines to clear bag jams and employees covering up the emergency stop buttons. We inspected and measured radiation exposure rates for 281 EDS machines. We observed that EDS machines at several airports exhibited a flaw that could be a source of unnecessary radiation exposure to TSA baggage screeners operating these machines. Radiation could leak out of the main gantry housing the computer-aided tomography (CAT) scanner through gaps between the entrance and exit baggage conveyors that appeared because the conveyor belt tunnels on most standalone units were not bolted to the gantry. Workers who frequently have to push odd-sized baggage up the entrance conveyor of the standalone machines are potentially exposed to the radiation present in the gap between the gantry and conveyor belt tunnel. We recommended taking six machines offline because the potential exposures to workers from these machines were equal to or greater than 500 microRoentgen per hour (uR/hour), the Food and Drug Administration's Performance Standard for cabinet x-ray systems. Occupational radiation measurements over a 6-month period from 854 TSA employees included 4024 results from dosimeters worn on the chest (as an estimate of exposure received by the whole body) and 3944 results from dosimeters worn on the wrist. Approximately 89% of the occupational whole body exposures and 88% of the occupational exposures to the wrist were below 1 millirem (mrem). None of the participants' doses in this evaluation exceeded the Occupational Safety and Health Administration (OSHA) permissible exposure limit of 1250 mrem per calendar quarter for individuals present in a restricted area (an area where access is controlled by the employer for purposes of protecting individuals from exposure to radiation or radioactive materials). Furthermore, no doses exceeded 25% of the OSHA quarterly limit which would require employee monitoring. The median estimated 12-month cumulative occupational whole body dose during the period of observation was zero at four of six airports. The highest median estimated 12-month cumulative occupational doses (whole body and wrist) occurred at LAX (14.7 and 15.5 mrem); the other airport with a non-zero median estimated 12-month cumulative dose was BOS (0.4 mrem each for whole body and wrist). Doses for only two out of 854 individuals exceeded the 500 mrem/year estimated cumulative occupational dose, which is the monitoring threshold of the National Radiation Council, and only 13 exceeded an estimated cumulative whole body or wrist dose of 100 mrem/year, which is the monitoring threshold of the Department of Energy. However, because the sample of airports may not be representative, and the study participants were volunteers, these results may not generalize to the entire TSA workforce. Given the strengths and weaknesses of this study, the need for a routine radiation dosimetry program for TSA screeners can neither be justified nor refuted at this time. Approximately 90% of the doses that screeners received were below 1 mrem, but some doses were at levels that warrant further action. Therefore, additional monthly or quarterly dosimetry targeted at specific airports for at least a year may be useful to evaluate the high doses reported in this evaluation. The number of airports and the specific airports for this targeted monitoring are left to the discretion of the TSA. Selection criteria could include airport size, machine type, and orientation of machines (in-line versus standalone). It is recommended that the dosimetry program be managed by a health or medical physicist. To address weaknesses of this study, we also recommend that TSA make participation in the dosimetry program mandatory.