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

adioactive material in an accident. The most serious U.S. nuclear power plant accident
occurred at Three Mile Island Unit 2 (TMI) in 1979. The accident at TMI was the worst
case scenario of a nuclear power plant accident, namely, a loss of coolant, resulting in the
partial meltdown of the reactor core and release of radioactive material into the
atmosphere. Although the reactor core at TMI was damaged by excessive heat, the
mishap resulted in only very small releases of radioactivity into the surrounding
environment. Environmental samples of air, water, milk, vegetation, soil, and foodstuffs
at TMI showed that most of the radiation was contained, and that those isotopes released
had no physical or health effects on individuals or the environment.
More extensive releases at TMI did not occur primarily because of the containment
structure. Containment structures have been included in U.S. reactor designs since the
early stages of commercial power plants. They are meant to prevent the release of
radioactive material to the area surrounding the power plant if an accident occurs. In
contrast, in the reactor accident at Chernobyl in 1986, which was the costliest industrial
and environmental accident ever, there was no containment structure. The reactor core at
Chernobyl continued to release radioactive material—mainly xenon-133, iodine-131,
and, to a lesser extent, cesium-137, strontium-90, and plutonium-239—into the
atmosphere for 2 weeks after the accident occurred due to graphite fires that could not be
extinguished.
Environmental Exposure Pathways
There are three main routes of exposure by which the health of people are affected by
radioactive material:
• Inhalation of radioactive material (e.g., breathing the plume).
• Ingestion of radioactive material (e.g., through food contamination).
• External exposure (e.g., from ground contamination).
Figure 6.2 illustrates one way in which children could be harmed by radiation in the
aftermath of a terrorist attack involving radioactive material. In this example, I-131 is
used because it is the isotope for which there is the most evidence of its environmental
exposure pathway—namely, the grass-cow-milk pathway—and because it is one of the
few isotopes for which there is a specific radioprotective agent. However, the likelihood
of an RDD using I-131 is extremely low because of its short half-life (a few weeks). I-
131 will be released if there is a nuclear yield after an attack using an IND, and it may be
released after a terrorist attack on a nuclear power plant if the attack results in an
environmental release of radioactive material.
In contrast, strontium-90, which also follows the grass-cow-milk pathway, is of lesser
concern because it does not become airborne as easily as the iodines and thus is less
likely to travel as far as the radioiodines. However, strontium-90 has a much longer halflife
(30 years), and although there is less concern, it will last for decades.
In contrast to radioiodine, most radioisotopes do not have a stable isotopic form that is
biologically important and for which the radioactive form can cause biological damage
via normal metabolic pathways. The element of each isotope has different biological,
199