Risk To The Fetus From Ionizing Radiation

Risk To The Fetus From Ionizing Radiation
For some prenatal irradiation effects, there is epidemiological basis for the existence of threshold doses. For others, such as childhood cancer induction, the existence of a threshold is not clear-cut. Despite these uncertainties in the dose-effect relationship, some The risk of deleterious effects increases with increasing dose. The nature of this dependence, i.e. the shapes of the dose-response curves for humans in the low-dose range (under 50 rem), is controversial.

Broad generalizations based on fetal dose ranges may be made. There is no evidence supporting the increased incidence of any deleterious developmental effects on the fetus at diagnostic doses within this range. The additional risk of gross congenital malformations, mental retardation, intrauterine growth retardation and childhood cancer is believed to be low compared to to the baseline risk.

However, the lower limits (in terms of statistical confidence intervals around the mean) for threshold doses for some studies, especially those related to cancer induction, fall within this range. The lower limits (in terms of statistical confidence intervals) for threshold doses for effects such as mental retardation and diminished IQ and school performance fall within this range.

Overall, exposure at levels exceeding 10 rem could be expected to result in a dose-related increased risk for deleterious effects. For example, the lower limit (95% confidence interval) for the threshold for mental retardation is about 15 rem, which an expectation value of about 30 rem. Gestational age at the time of exposure , Menstrual history. History of previous pregnancies,

Including a history of congenital malformations Other potentially harmful environmental factors (malnutrition, smoking, alcohol / drugs, etc.) Maternal / paternal age, Calculation of fetal exposure using dose reconstruction techniques ,Attitude of the mother toward the pregnancy. In humans, the major deleterious effects on the fetus include fetal wastage (miscarriage), teratogenicity (birth defects), mental retardation, intrauterine growth retardation.