Average annual dose - hdbk11300211

DOE-HDBK-1130-98

Several things can happen when a cell is exposed to ionizing radiation. The following

are possible effects of radiation on cells.

a. There is no damage

b. Cells repair the damage and operate normally

1) The body of most cells is made up primarily of water. When ionizing radiation

hits a cell, it is most likely to interact with the water in the cell. One of the

byproducts of radiation-induced ionization of water is hydrogen peroxide.

Hydrogen peroxide can damage cell atomic structures.

2) Ionizing radiation can also hit the nucleus of the cell. The nucleus contains the

vital parts of the cell, such as chromosomes. The chromosomes determine cell

function. When chromosomes duplicate themselves, the chromosomes transfer

their information to new cells. Radiation may cause a change in the

chromosome that does not affect the cell.

3) Damage to chromosomes and other cell structures can be repaired. In fact,

our bodies repair a very large number of chromosome breaks every day

(References 7 and 10).

3. Average annual dose

The average annual total effective dose equivalent to the general population from

naturally occurring and manmade sources is about 360 mrem.

c. Cells are damaged and operate abnormally

1) Cell damage may not be repaired or may be incompletely repaired. In that

case, the cell may not be able to function properly.

2) It is possible that a chromosome in the cell nucleus could be damaged but not

be repaired correctly. If the cell continues to reproduce, this is called a

mutation and may result in cancer.

d. Cells die as a result of the damage

At any given moment, thousands of our cells die and are replaced by normal

functioning cells. However, the radiation damage to a cell may be so extensive that

the cell dies prematurely.