Module 2 Biological Effects
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
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).
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
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.
Acute and Chronic Radiation Dose
Potential biological effects depend on how much and how
fast a radiation dose is received. Radiation doses can be
grouped into two categories: acute and chronic dose.