At what radiation exposure does the risk of congenital anomalies increase significantly between 2-8 weeks of gestation?

The risk of congenital anomalies associated with radiation exposure during the critical period of organogenesis (2-8 weeks of gestation) becomes significantly increased at a threshold of approximately 15-20 Rads. This is because the developing embryo and fetus are particularly sensitive to radiation during this time, when the foundational structures of the body, such as the organs and limbs, are forming.

At 20 Rads, the potential for harmful effects including congenital anomalies rises significantly. Research indicates that exposure to this level of radiation can lead to various developmental issues, given that the embryonic cells are rapidly dividing and differentiating. The effects of radiation vary depending on timing, dose, and type of exposure, but the consensus in the literature supports that exposure approaches or exceeding this threshold greatly heightens the risk of adverse developmental outcomes.

Thus, the correct answer reflects the well-documented understanding of radiation exposure risks during specific gestational periods, particularly when evaluating fetal development during crucial phases of organ formation.