Answer to Question #1167 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
Why is the embryo most vulnerable to ionizing radiation between one and three months?
The embryo (stage of pregnancy up to about six weeks post conception) and the fetus (the stage of pregnancy from six weeks onward) will be most sensitive to exposure to ionizing radiation exposure when the cells are dividing rapidly and are the least specialized. These factors are at play during the first three months of pregnancy. In addition, it is during this time that the organs are being formed. Injury to a few cells at this stage poses more of a risk than injury at a later stage. Detailed information on prenatal radiation exposures can be found on the US Nuclear Regulatory Commission website under Regulatory Guide 8.13.
Genevieve S. Roessler, PhD