TO BE OR NOT TO XRAY,,,THAT IS THE QUESTION

[Leo @ MIA]

HHE Number HETA-2003-0206-3067

Title Health hazard evaluation summary report: HETA-2003-0206-3067,
evaluation of radiation exposure to TSA baggage screeners,
Transportation Security Administration, Washington, DC

Author Achutan-C; Mueller-C

Abstract 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 (ìR/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.

Keywords Region-3; X-ray-equipment; X-ray-absorption; Ionizing-
radiation; Radiation-exposure; Airport-personnel; Work-practices;
Humans

State DC; OH




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