Parenatal Radiation Exposure

DOE-HDBK-1130-98

Module 2 Biological Effects

Instructor's Notes

Prenatal Radiation Exposure

Although no effects were seen in Japanese children

EO8 State the potential

conceived after the atomic bomb, there were effects seen in

effects associated with

some children who were in the womb when exposed to the

prenatal radiation dose.

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.

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.

Factors for potential effects associated with prenatal

exposures

Many chemical and physical (environmental) factors are

suspected of causing or known to have caused damage to

a fetus, especially early in the pregnancy. Radiation,

alcohol consumption, exposure to lead, and heat, such as

from hot tubs, are only a few such factors.

Current radiation protection standards and practices are based

on the premise that any radiation dose, no matter how small,

can result in health effects such as cancer. Further, it is

assumed that these effects are produced in direct proportion

to the dose received (i.e., doubling the radiation dose results in

a doubling of the risk of the effect). These two assumptions

lead to a dose-response relationship, often referred to as the

linear, no-threshold model, for limiting health effects at very

low radiation dose levels.