Prenatal Radiation Exposure

DOE-HDBK-1130-98

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

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

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 lining 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).

D. Prenatal Radiation Exposure

Although no effects were seen in Japanese children conceived after the atomic bomb, there

were effects seen in some children who were in the womb when exposed to the atomic 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.