Module 2 Biological Effects
Delayed effects may result from either a single large
acute overexposure or from continuing low-level
chronic exposure. Cancer in its various forms is the
most important potential delayed effect of radiation
exposure. Other effects noted include cataracts,
life shortening and, for individuals exposed in the
womb, lower IQ test scores.
A heritable effect is a physical mutation or trait that is
passed on to offspring. In the case of heritable effects,
the parental individual has experienced damage to some
genetic material in the reproductive cells and has passed
the damaged genetic material onto offspring.
Heritable effects from radiation have never been
observed in humans but are considered possible. They
have been observed in studies of plants and animals.
Heritable effects have not been found in the 77,000
Japanese children born to the survivors of Hiroshima
and Nagasaki (these are children who were conceived
after the atom bomb -- i.e., heritable effects). Studies
have followed these children, their children, and their
Factors affecting biological damage due to exposure to
In general, the greater the dose, the greater the potential
for biological effects.
Dose rate (how fast)
The faster the dose is delivered, the less time the body
has to repair itself.
Type of radiation
For example, internally deposited alpha emitters are
more damaging than beta or gamma emitters for the
same energy deposited.
Area of the body that receives a dose