Prenatal Radiation Exposure

DOE-HDBK-1130-98

Module 2 Biological Effects

Instructor's Notes

In general, the larger the area of the body that receives a

dose, the greater the biological effect.

Extremities are less sensitive than blood forming and

other critical organs. That is why the annual dose limit

for extremities is higher than for a whole body dose that

irradiates internal organs.

Cell sensitivity

The most sensitive cells are those that are rapidly

dividing. Examples include blood cells, hair follicles,

and the cells lin ing the gastrointestinal tract.

Individual sensitivity

Some individuals are more sensitive to environmental

factors such as ionizing radiation.

The developing embryo/fetus is the most sensitive, and

children are more sensitive than adults.

In general, the human body becomes relatively less

sensitive to ionizing radiation with increasing age. The

exception is that elderly people are more sensitive than

middle -aged adults due to the inability to repair damage

as quickly (less efficient cell repair mechanisms).

Prenatal Radiation Exposure

Although no effects were seen in Japanese children conceived

EO8 State the potential

after the atomic bomb, there were effects seen in some

effects associated with

children who were in the womb when exposed to the atomic

prenatal radiation dose.

bomb radiation at Hiroshima and Nagasaki. Some of these

children were born with a slightly smaller head size, lower

average birth weight, and increased incidence of mental

retardation. Some later showed lower IQ test scores and

slower scholastic development, smaller physical size, and

increased incidence of behavioral problems.

Sensitivity of the fetus

Embryo/fetal cells are rapidly dividing, which makes

them sensitive to many environmental factors including

ionizing radiation. The embryo/fetus is most

susceptible to developing adverse health effects if

exposed during the time period of 8 - 15 weeks after

conception.