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Introduction

Radiation Exposure

Will small radiation doses hurt me? No. Every day we live with radioactive materials around and inside our bodies as well as what is normally in our environment. However, a large dose of certain types of radiation could be harmful. That is the same answer I would give you if you asked if taking aspirin was harmful . . . yes, if you take enough of them. To put it briefly, in every medicine there is a little poison. If we use radiation safely, there are benefits. If we use radiation carelessly and high doses result, there are consequences.

Ionizing radiation can change the structure of the cells, sometimes creating potentially harmful effects that are more likely to cause changes in tissue. These changes can interfere with cellular processes so cells might not be able to divide or they might divide too much.

Although radiation has the potential to damage structures inside a cell, the structure of most concern is DNA (deoxyribonucleic acid). DNA contains the genetic information that allows each cell to function, grow, and reproduce. If DNA is damaged from radiation or some other agent (like toxic particles in smog), it has the capability to repair minor damage. However, if the damage can’t be repaired or is not repaired correctly, harmful effects may occur. These effects may or may not affect how we function on a day-to-day basis. If the cells are not very important to the operation of our body, it may not matter that they have been damaged or killed. However, if the cells are in critical organs (ones that keep us alive) and a large number of the cells have been damaged or killed, that organ might not be able to function normally.

If a cell is damaged by radiation or another toxin:

  • The cell might have some minor damage that is repaired.
  • The cell might have some minor damage that remains inactive until another agent interacts with the cell again.
  • The cell (if it is a reproductive cell like a sperm or egg cell) might have damage to the genetic code that doesn’t show up until future generations (your children, their children, etc.).
  • The cell might have damage that causes it to become cancerous.
  • The cell may simply stop functioning.
  • The cell may die.

Some effects may occur immediately (days or months) while others might take tens of years or even get passed to the next generation. Effects of interest for the person being exposed to radiation are called somatic effects and effects of interest that affect our children are called genetic effects. It is important to note here that, in addition to the possible interactions of radiation with a cell, there are other processes occurring in the body, causing thousands of cell-killing events every day. Some of these are due to normal metabolism and some are due to our contact with other toxins in our environment.

We know a lot about the interaction of radiation and the effects it can have on the human body. The effects depend on many factors, including the type of radiation and how we are exposed to that radiation and our own genetic makeup. We might be exposed from the outside (when we have an x ray) or from the inside (when we have radioactive materials inside of us), or from both. We might be exposed many times over a long period or we might be exposed once in a very short period. And we might be only partially exposed (like part of our leg during a knee x ray) or wholly exposed (like our whole body from exposure to daily natural background radiation). Also, some of us are more susceptible to radiation injury than others—we sunburn more easily, for example.

Before we begin, we need to briefly define what we mean when we say radiation “exposure” and radiation “dose.” When we say someone has been exposed to radiation, it simply means that the person interacted somehow with radiation—it’s like saying we were exposed to the sun, which means our body or a part of our body was out in the sun. Neither of those tells us how much of a dose we received—we were exposed to x rays or we were exposed to the sun, neither is an indication of dose. In the case of radiation, if we are exposed and some of the energy from the radiation stays in our body, that is radiation dose. Radiation dose is the energy deposited in our cells and tissues from exposure to radiation.