Protection, Limited -- What Radiation Pills Can and Can't Do

Rarely in the history of radiation has there been so much interest in it by the public. You can't go very far in the U.S. today without hearing something about so-called "dirty bombs" or a discussion over some country's ominous nuclear plans.

Unfortunately, there is a great deal of misunderstanding about radiation. One area receiving a great deal of current attention among emergency responders is the topic of self-protection from radiation incidents--specifically oral prophylaxis, more commonly referred to as "radiation pills."

This article is intended as a brief explanation of the various types of radiation, their characteristics and the agents that protect you against them.

Radiation: A Background

In order to understand the abilities and weaknesses of radiation pills, it is important to understand the types and origins of, and dangers posed by, radiation.

There are two major types of radiation: ionizing and non-ionizing. Ionizing radiation has enough energy to pull electrons away from their atoms, creating ions. This is the potentially dangerous type of radiation people most commonly think of when they think radiation. Non-ionizing radiation has enough energy to move atoms within a molecule, but not enough to ionize them.

These types of radiation occupy opposite ends of the same electromagnetic spectrum. Non-ionizing radiation includes the low-frequency, radio, microwave and infrared portions of the spectrum, visible light, and extends into the ultraviolet range. Ionizing radiation is higher-frequency and has extremely high energy: Each instance of ionization releases approximately 33 electron volts to be absorbed by surrounding materials. Basically, this deposits a large amount of energy into a small area. This is enough to disrupt chemical bonds and can be harmful to living tissue.

There are three main kinds of ionizing radiation: alpha, beta and gamma. These have different penetration and ionization characteristics. X-rays fall into the gamma category, but are less penetrating. Neutron radiation is considered part of this ionizing category as well; for more, see Types of Ionizing Radiation.

Sources of non-ionizing radiation are all around us: The sun, which provides solar radiation; portable radios and microwaves, which create radio-frequency radiation; and stoves that give off thermal radiation are all examples.

There are only a few sources of ionizing radiation. Some is received from space; it also comes from natural sources like soil, water and vegetation. There are radioactive substances in the 50-pound bag of salt in your garage, in the marble of your countertop, in the Fiestaware plate on that countertop, and even in the bananas on the plate!

None of these things will harm you--the strength and duration of dosage aren't high enough. For radiation to hurt you, one of two things must happen: 1) You must come near a high exposure-rate source of radiation for a short period of time (acute exposure), or 2) You must come near a low exposure-rate source of radiation and stay near it for a long time--i.e., years (chronic exposure).

The most common way for the second scenario to occur is for a radioactive substance to lodge in your body. Your body ignores the fact that an item is radioactive and simply deals with it like any other chemical substance. Many radioactive substances are simply excreted from the body over time. Some, however, chemically mimic other non-radioactive chemicals and become bound to or stored in an organ.

This allows a radioactive product that would otherwise not be injurious to become an issue. For instance, radioactive radium-223 is an alpha emitter. With external exposure, alpha radiation normally doesn't penetrate the skin. However, if it's swallowed or inhaled, radium--chemically similar to calcium--is readily stored in the blood-forming bones where it lodges. Nestled there, it continues to irradiate radiosensitive newly forming blood cells as they pass, damaging them.