Pediatric Terrorism and Disaster Preparedness: A ... - PHE Home

To assess radiation dose, a researcher counts the radiation-induced chromosomal
abnormalities in peripheral blood lymphocytes. The classic method is a standard genetic
karyotype, which takes about 3 days but offers a good dose estimate. This approach
counts the aberrations on a chromosome smear, especially aberrations involving two or
more centromeres (dicentrics). The number of chromosomal abnormalities correlates
directly with radiation dose (see Appendix E of the AFRRI Handbook, available at
www.afrri.usuhs.mil).
Radiation-induced skin injury. Skin changes after radiation exposure offer a rough
estimate of minimum dose, given that skin changes do not develop below about 3 Gy.
Radiation-induced skin injury takes 10–14 days to appear and may resemble a skin burn.
“Burns” that appear earlier may not be from radiation but rather from thermal or chemical
exposure associated with the event. The severity of the burn increases with increasing
dose.
Overall Dose Assessment
All of the above signs, symptoms, and tests can be used to provide an estimate of dose
(Table 6.6). Dose assessment is an ongoing process that should include the techniques
described above, as well as others recommended by experts. Close attention to dosimetric
clues will eventually lead to a reasonably accurate estimate of dose. As the saying goes
among health physicists, “Eventually the patient will tell you the dose.”
Medical Diagnosis: External Contamination
Background
External contamination with radionuclides can occur in the same settings and situations
that cause internal contamination. Any person who simply passes through a contaminated
area without appropriate personal protective equipment (PPE), as well as any person who
is injured in a contaminated area, will become externally contaminated. Civilians,
emergency responders, and military personnel can encounter radionuclides both in
peacetime and while waging the war on terrorism. Accidents in medical, industrial,
institutional, military, and nuclear research and nuclear power settings can cause external
contamination, as could an RDD (e.g., dirty bomb) or nuclear detonation. The largest
amount of fallout is on the surface of the ground, so children and crawling infants are
particularly prone to pick up this material on their bare skin.
Contaminated materials present as solid particulate matter or liquids that are on the
ground or exposed surfaces. Health physicists have described these contaminants as
“radioactive dirt” that can be washed off skin and hair. Radionuclides can be deposited
on the skin and into body orifices during the immediate event or afterward through
contact with contaminated surfaces or liquids. Liquids that contain radioactive materials
can readily penetrate body orifices and non-protective clothing, allowing contamination
of other external areas or internal contamination by absorption or ingestion. However, up
to 95% of contamination is on the outer clothing and shoes. The body surfaces most
likely to be contaminated include the hands, face, lower legs, and oral and nasal cavities.
167