Encyclopedia of Environmental Health, Second Edition, Risk of Radiation Exposure to Children and Their Mothers

There is realistic concern about the impact of ionizing and nonionizing radiations on the health of children and their mothers. The magnitude and type of risks that are associated with radiation exposure to children and mothers must be determined to prevent the health consequences of such exposure. The developing organism is more sensitive to radiation and vulnerable to the development of radiation-induced pathology. Prenatal development, characterized by intensive cell proliferation, cell differentiation, and cell migration, is highly sensitive to radiation exposure. Therefore, exposure of embryos and fetuses to radiation is of immense concern for radiological protection and human health. Irradiation during gestation is associated with growth disorders, malformations, functional impairment, malignant diseases, and death. This risk of ionizing radiation is dependent on the developmental stage at exposure and radiation dose. An acute dose of ionizing radiation less than 0.05 Gray (Gy) does not affect the reproductive outcome of the population. However, ionizing radiation doses of 0.25 Gy or more that occur in the preimplantation stage of pregnancy can result in abortion, miscarriage, and stillbirth. At the most sensitive stage of development (2–7 weeks), the threshold exposure for birth defects, including microcephaly and orofacial clefts, was defined as 0.2 Gy. The threshold for deterministic effects increases after early organogenesis and also as the exposure is protracted. The threshold dose for severe mental retardation is 0.12–0.23 Gy between 8 and 15 weeks and approximately 0.21 Gy between weeks 16 and 25. Intrauterine exposure to ionizing radiations might affect the IQ of the child by approximately 30 IQ points per Gray exposure. Human epidemiological studies showed increased stillbirth trend, birth defects, thyroid cancer, and infant leukemia after the Chernobyl Nuclear Power accident in several European countries. Electromagnetic field (EMF) exposure less than 30 mT during pregnancy did not produce any abnormal clinical signs or significant changes. An approximate twofold increased risk of childhood leukemia for exposures greater than or equal to 0.4 mT has been observed. There is lack of good data to support the impact of other forms of nonionizing radiation such as radiofrequency radiation (RFR) on the children's and their mothers’ health. Although none of the radiation-associated diagnostic procedures in use today reach a dose of 0.05 Gy, radiological procedures should not be performed on pregnant women, and instead sonography or magnetic resonance imaging (MRI) should be used. However, the risk associated with EMF exposure is still a valid concern during MRI examinations in pregnant women.