We have a lot to be concerned about. Some people say small amounts of radiation are good for you while others say there is no amount of radiation that is safe. So why can’t someone make it easy to decide when or if you should worry about radiation exposure? That is exactly what we’re going to do here—help by providing the facts. If you want additional information on why there is disagreement about the effects of low-level radiation, we have provided this in the section titled "Controversy."
Let’s Begin Radiation specialists use the unit “rem” (or sievert) to describe the amount of radiation dose someone received. We are going to use that unit throughout the sections. Without getting into technical specifics about that unit, it is enough to know that it indicates a measure of how much radiation energy is absorbed in our body. And, as we will see in other sections, the total energy that is absorbed and its effectiveness in causing change is the basis for determining whether health effects may result.
We’ll get into some detail later, but for a baseline—
1 rem received in a short period or over a long period is safe—we don’t expect observable health effects. 10 rem received in a short period or over a long period is safe—we don’t expect immediate observable health effects, although your chances of getting cancer might be very slightly increased. 100 rem received in a short time can cause observable health effects from which your body will likely recover, and 100 rem received in a short time or over many years will increase your chances of getting cancer. 1,000 rem in a short or long period of time will cause immediately observable health effects and is likely to cause death.
Safe or Not?
Why do some people say all radiation exposure is bad and others say it can be okay? Even the scientific community differs on the answer to the question of low radiation doses and health effects. Radiation can cause biological changes in cells when they are outside the human body, and these can be seen in a laboratory even when the dose is small. However, these changes are not seen or cannot be related to health effects in humans. The fact that changes can occur may make some people believe all radiation is bad and the fact that this is not related to human health effects may make others believe it is safe at low levels. The human health effects that have been observed have been when individuals or groups have received larger doses of radiation (more than 50 rem) from events like those due to military uses of nuclear weapons, accidents, and uses of radiation in medicine for therapy.
