International Commission on Radiological Protection
Pregnancy and medical radiation.
Ann ICRP. 2000;30(1):iii-viii, 1-43.
Abstract/Text
Thousands of pregnant patients and radiation workers are exposed to ionising radiation each year. Lack of knowledge is responsible for great anxiety and probably unnecessary termination of pregnancies. For many patients, the exposure is appropriate, while for others the exposure may be inappropriate, placing the unborn child at increased risk. Prenatal doses from most properly done diagnostic procedures present no measurably increased risk of prenatal death, malformation, or impairment of mental development over the background incidence of these entities. Higher doses, such as those involved in therapeutic procedures, can result in significant fetal harm. The pregnant patient or worker has a right to know the magnitude and type of potential radiation effects that might result from in utero exposure. Almost always, if a diagnostic radiology examination is medically indicated, the risk to the mother of not doing the procedure is greater than is the risk of potential harm to the fetus. Most nuclear medicine procedures do not cause large fetal doses. However, some radiopharmaceuticals that are used in nuclear medicine can pose significant fetal risks. It is important to ascertain whether a female patient is pregnant prior to radiotherapy. In pregnant patients, cancers that are remote from the pelvis usually can be heated with radiotherapy. This however requires careful planning. Cancers in the pelvis cannot be adequately treated during pregnancy without severe or lethal consequences for the fetus. The basis for the control of the occupational exposure of women who are not pregnant is the same as that for men. However, if a woman is, or may be, pregnant, additional controls have to be considered to protect the unborn child. In many countries, radiation exposure of pregnant females in biomedical research is not specifically prohibited. However, their involvement in such research is very rare and should be discouraged. Termination of pregnancy is an individual decision affected by many factors. Fetal doses below 100 mGy should not be considered a reason for terminating a pregnancy. At fetal doses above this level, informed decisions should be made based upon individual circumstances.
E J Hall
Scientific view of low-level radiation risks.
Radiographics. 1991 May;11(3):509-18. doi: 10.1148/radiographics.11.3.1852943.
Abstract/Text
The average number of diagnostic x-ray procedures per year in the United States equals the total population and results in an annual collective effective dose equivalent of about 9 million person-rem. Possible deleterious effects include (a) genetic consequences, the risks of which can be assessed only from animal studies; (b) carcinogenesis, which can be assessed from survivors of nuclear bombings and patients exposed for medical reasons; and (c) effects on the developing embryo or fetus. For stochastic endpoints such as cancer and genetic anomalies, it is estimated that the current practice of radiology in the United States increases spontaneous frequency by less than 1%. No single procedure is likely to produce harm to the conceptus, but an accumulation of procedures in a pregnant woman could be hazardous during the sensitive period of 8-15 weeks after conception, with microcephaly and mental retardation the most likely deleterious effects. The balance of risk versus benefit in diagnostic radiology is heavily weighted toward benefit, but the risks are there, and constant efforts are needed to reduce radiation doses to the minimum necessary.
C Streffer, R Shore, G Konermann, A Meadows, P Uma Devi, J Preston Withers, L-E Holm, J Stather, K Mabuchi, H R
Biological effects after prenatal irradiation (embryo and fetus). A report of the International Commission on Radiological Protection.
Ann ICRP. 2003;33(1-2):5-206.
Abstract/Text
In its 1990 recommendations, the ICRP considered the radiation risks after exposure during prenatal development. This report is a critical review of new experimental animal data on biological effects and evaluations of human studies after prenatal radiation published since the 1990 recommendations.Thus, the report discusses the effects after radiation exposure during pre-implantation, organogenesis, and fetogenesis. The aetiology of long-term effects on brain development is discussed, as well as evidence from studies in man on the effects of in-utero radiation exposure on neurological and mental processes. Animal studies of carcinogenic risk from in-utero radiation and the epidemiology of childhood cancer are discussed, and the carcinogenic risk to man from in-utero radiation is assessed. Open questions and needs for future research are elaborated. The report reiterates that the mammalian embryo and fetus are highly radiosensitive. The nature and sensitivity of induced biological effects depend upon dose and developmental stage at irradiation. The various effects, as studied in experimental systems and in man, are discussed in detail. It is concluded that the findings in the report strengthen and supplement the 1990 recommendations of the ICRP.
C B Jankowski
Radiation and pregnancy. Putting the risks in proportion.
Am J Nurs. 1986 Mar;86(3):260-5.
Abstract/Text
M De Santis, E Di Gianantonio, G Straface, A F Cavaliere, A Caruso, F Schiavon, R Berletti, M Clementi
Ionizing radiations in pregnancy and teratogenesis: a review of literature.
Reprod Toxicol. 2005 Sep-Oct;20(3):323-9. doi: 10.1016/j.reprotox.2005.04.004.
Abstract/Text
The present paper is a review of the data available in the literature concerning the prenatal exposure to radiation evaluating the reported teratogenic effect. We have particularly focused on the fetal effects of maternal ionising radiation exposure, both diagnostic and occupational, particularly in terms of congenital anomalies and birth weight. Ionising radiation represents a possible teratogen for the fetus, but this risk has been found to be dependent on the dosage and the effects correlatable to the gestational age at exposure. Recently, of particularly note is the fact that maternal thyroid exposure to diagnostic radiation has been associated with a slight reduction in the birth weight. Inadvertent exposure from diagnostic procedures in pregnancy doesn't usually increase the natural risk of congenital anomalies but creates a considerable state of maternal anxiety. Diagnostic radiological procedures should be avoided in pregnant women unless the information cannot be obtained by other techniques.
日本産科婦人科学会・日本産婦人科医会編：妊娠中の放射線被曝の胎児への影響について尋ねられたら？ 産婦人科診療ガイドライン産科編 2023、p62-64.
R L Brent
Utilization of developmental basic science principles in the evaluation of reproductive risks from pre- and postconception environmental radiation exposures.
Teratology. 1999 Apr;59(4):182-204. doi: 10.1002/(SICI)1096-9926(199904)59:4<182::AID-TERA2>3.0.CO;2-H.
Abstract/Text
The subject of the reproductive toxicity of various forms of radiation can be anxiety provoking to the public on two accounts, since reproductive failure engenders an unusual level of guilt and anger in the affected families, and radiation effects are misunderstood and feared by the public. Reproductive problems include an array of genetic and acquired diseases affecting parents and their offspring. Many of these problems are associated with the risk of being induced by preconception and/or postconception exposures to environmental agents. For the various forms of radiation, namely, ionizing radiation, ultrasound, low-frequency electromagnetic fields (EMF), and microwaves, the potential for producing reproductive effects varies considerably with the form of "radiation" and, of course, the dose. Whether the exposure occurs preconceptionally or postconceptionally is another major consideration. In evaluating the actual reproductive risks, we rely on accurate dosimetry and information obtained in epidemiological studies and animal studies. Epidemiological studies must demonstrate consistency of the reproductive finding, and animal studies should be designed to add to the findings of the epidemiological studies. Most importantly, the conclusions must not contradict the basic principles of teratology, genetics, and reproductive biology, and they should be biologically plausible. But frequently important basic science principles are ignored in the evaluation process. Yet developmental basic science principles can be instrumental in refuting or supporting the concern about possible risks. Although there is some overlap with regard to the preconception and intrauterine effects of ionizing radiation, there are significant differences. Preconception effects are mainly stochastic effects, while intrauterine effects are mainly deterministic effects. The stochastic genetic risks are lower than the deterministic risks at equivalent exposures. Thus, it is frequently difficult to demonstrate the occurrence of stochastic effects in populations that have received low preconception exposures to ionizing radiation. The reproductive effects from preconception and intrauterine exposures to electromagnetic fields (low-frequency EMF, video display terminals, microwaves) and ultrasound represent much different problems, since the main effects of microwaves and ultrasound occur because of their hyperthermic effects at high exposures. Low-frequency EMF does not have the capacity to produce hyperthermia, and none of these forms of nonionizing radiation has the specificity to damage the DNA comparable to the specificity of ionizing radiation. Not only do they not have targeted mutagenic effects at the usual exposures that populations receive, they are not cytotoxic at these exposure levels as well. From the viewpoint of biological plausibility, these other forms of radiation are much less likely to have the potential for producing reproductive toxicity at the usual population exposures.
A S Dekaban
Abnormalities in children exposed to x-radiation during various stages of gestation: tentative timetable of radiation injury to the human fetus. I.
J Nucl Med. 1968 Sep;9(9):471-7.
Abstract/Text
Medical radiation exposure of pregnant and potentially pregnant women. Report No. 54., Vol. Washington: NCRP, 1977.
Committee Opinion No. 723: Guidelines for Diagnostic Imaging During Pregnancy and Lactation.
Obstet Gynecol. 2017 Oct;130(4):e210-e216. doi: 10.1097/AOG.0000000000002355.
Abstract/Text
Imaging studies are important adjuncts in the diagnostic evaluation of acute and chronic conditions. However, confusion about the safety of these modalities for pregnant and lactating women and their infants often results in unnecessary avoidance of useful diagnostic tests or the unnecessary interruption of breastfeeding. Ultrasonography and magnetic resonance imaging are not associated with risk and are the imaging techniques of choice for the pregnant patient, but they should be used prudently and only when use is expected to answer a relevant clinical question or otherwise provide medical benefit to the patient. With few exceptions, radiation exposure through radiography, computed tomography scan, or nuclear medicine imaging techniques is at a dose much lower than the exposure associated with fetal harm. If these techniques are necessary in addition to ultrasonography or magnetic resonance imaging or are more readily available for the diagnosis in question, they should not be withheld from a pregnant patient. Breastfeeding should not be interrupted after gadolinium administration.
Wladimir Wertelecki
Malformations in a chornobyl-impacted region.
Pediatrics. 2010 Apr;125(4):e836-43. doi: 10.1542/peds.2009-2219. Epub 2010 Mar 22.
Abstract/Text
OBJECTIVE: One of the populations most exposed to chronic low-dose radiation from Chornobyl (Chernobyl in Russian) lives in Polissia, the region representing the northern half of Rivne Province (Oblast) in Ukraine. Here the patterns and population rates of malformations are reported and possible etiologic factors and regional contrasts are explored.
PATIENTS AND METHODS: Malformations, as defined by international standards, noted among all 96 438 births in Rivne between 2000 and 2006, were analyzed statistically. Contrasts of rates in Polissia compared with the rest of Rivne also were investigated.
RESULTS: The overall rate of neural tube defects in Rivne is among the highest in Europe (22.2 per 10,000 live births). The rates of conjoined twins and teratomas also seem to be elevated. In Polissia, the overall rates of neural tube defects are even higher (27.0 vs 18.3, respectively; odds ratio: 1.46 [95% confidence interval: 1.13-1.93]), and the rates of microcephaly and microphthalmia may also be elevated.
CONCLUSIONS: The malformation patterns observed suggest early disruptions of blastogenesis, manifesting as alterations of body axes, twinning, duplications, laterality, and midline formation. The results are sufficiently compelling to justify continuing and expanding this investigation of malformations in chronic low-dose radiation-impacted regions of Ukraine.
Kelsey Needham Dancause, Lyubov Yevtushok, Serhiy Lapchenko, Ihor Shumlyansky, Genadiy Shevchenko, Wladimir Wertelecki, Ralph M Garruto
Chronic radiation exposure in the Rivne-Polissia region of Ukraine: implications for birth defects.
Am J Hum Biol. 2010 Sep-Oct;22(5):667-74. doi: 10.1002/ajhb.21063.
Abstract/Text
OBJECTIVES: The health effects of chronic low-dose radiation exposure remains a controversial question. Monitoring after the Chernobyl nuclear accident in Ukraine suggested that chronic low-dose radiation exposure was not linked to cancer mortality among the general population. However, elevated rates of birth defects in contaminated compared to uncontaminated regions suggest that exposure to radiation in utero might impact development and that chronic radiation exposure might represent an underestimated risk to human health.
METHODS: We sought to determine current radiation exposure routes in Rivne-Polissia, a region of Ukraine contaminated by the Chernobyl accident. This represents a first step toward comprehensive studies of the effects of chronic radiation exposure on human health. We designed and administered a dietary and activity survey to 344 women in Polissia. We assessed types and sources of food consumed, types of outdoor activities, and alcohol intake.
RESULTS: Alcohol intake was low and alone does not account for the observed high rates of birth defects. Wild foods, especially mushrooms and berries, and locally produced foods, especially milk related, were major radiation exposure routes. Additionally, women were exposed to radiation through inhalation while burning grasses and potato vines in fields, and wood for cooking and heating.
CONCLUSIONS: Twenty four years after the Chernobyl accident, women continue to be chronically exposed to low-dose radiation at levels exceeding current recommendations. This might contribute (especially synergistically with alcohol consumption and micronutrient deficiencies) to higher prevalence of birth defects in areas of Ukraine with high levels of radiation contamination compared to uncontaminated areas.
(c) 2010 Wiley-Liss, Inc.
United Nations Information Service Vienna：東電福島事故後の 10 年： 放射線関連のがん発生率上昇は みられないと予測される（https://www.unscear.org/docs/publications/2020/PR_Japanese_PDF.pdf）.
W J Schull
Brain damage among individuals exposed prenatally to ionizing radiation: a 1993 review.
Stem Cells. 1997;15 Suppl 2:129-33. doi: 10.1002/stem.5530150719.
Abstract/Text
Mental retardation as a result of prenatal exposure to ionizing radiation is not a common phenomenon when compared to the incidence of cancer, but it has nevertheless been well-documented. This article describes results from studies of individuals who were exposed prenatally to radiation in Hiroshima and Nagasaki. The critical time of exposure, when the most significant damage was done, was during the 8th-15th week of gestation, with a lesser effect at 16-25 weeks. Individuals in the study were assessed by measurement of an intelligence quotient and by examination of school performance. Studies show that the period of 8-15 weeks of gestation coincides with a key time for neuronal cell migration in the developing brain. There is continuing investigation of the mechanism of this migration and how it might be disrupted by ionizing radiation.
J N Yamazaki, W J Schull
Perinatal loss and neurological abnormalities among children of the atomic bomb. Nagasaki and Hiroshima revisited, 1949 to 1989.
JAMA. 1990 Aug 1;264(5):605-9.
Abstract/Text
Studies of the survivors of the atomic bombing of Hiroshima and Nagasaki who were exposed to ionizing radiation in utero have demonstrated a significant increase in perinatal loss and the vulnerability of the developing fetal brain to injury. These studies have also helped to define the stages in the development of the human brain that are particularly susceptible to radiation-related damage. Exposure at critical junctures in development increases the risk of mental retardation, small head size, subsequent seizures, and poor performance on conventional tests of intelligence and in school. The most critical period, 8 through 15 weeks after fertilization, corresponds to that time in development when neuronal production increases and migration of immature neurons to their cortical sites of function occurs. The epidemiologic data are, however, too sparse to settle unequivocally the nature of the dose-response function and, in particular, whether there is or is not a threshold to damage. If a threshold does exist, it appears to be in the 0.10- to 0.20-Gy fetal-dose range in this vulnerable gestational period.
R W Miller
Discussion: severe mental retardation and cancer among atomic bomb survivors exposed in utero.
Teratology. 1999 Apr;59(4):234-5. doi: 10.1002/(SICI)1096-9926(199904)59:4<234::AID-TERA8>3.0.CO;2-B.
Abstract/Text
When I was in medical school, Douglas Power Murphy, Professor of Obstetrics and Gynecology, told us of his inexpensive, simple study of "microcephaly" and mental retardation in newborn infants whose mothers had received therapeutic radiation early in pregnancy. His review of the literature and mail inquiry of other obstetrics centers in the United States revealed 14 published cases (Murphy, '28) and 16 unpublished (Goldstein and Murphy, '29). Here am I, 52 years later, still updating his findings.
W J Blot, R W Miller
Mental retardation following in utero exposure to the atomic bombs of Hiroshima and Nagasaki.
Radiology. 1973 Mar;106(3):617-9. doi: 10.1148/106.3.617.
Abstract/Text
M Otake, W J Schull, H Yoshimaru
A review of forty-five years study of Hiroshima and Nagasaki atomic bomb survivors. Brain damage among the prenatally exposed.
J Radiat Res. 1991 Mar;32 Suppl:249-64.
Abstract/Text
Significant effects on the developing brain of exposure to ionizing radiation are seen among those individuals exposed in the 8th through the 25th week after fertilization. These effects, particularly in the most sensitive period, 8-15 weeks after fertilization, manifest themselves as an increased frequency of severe mental retardation (SMR), a diminution in IQ score and in school performance, and an increase in the occurrence of seizures. Of 30 SMR cases, 18 (60%) had small heads. About 10% of the individuals with small head sizes observed among the in utero clinical sample were mentally retarded. When all of the cases of mental retardation are included in the analysis, a linear dose-response model fits the data adequately and no evidence of a threshold emerges; however, if the two probable nonradiation-related cases of Down's syndrome are excluded from the 19 SMR cases exposed 8-15 weeks after fertilization, the evidence of a threshold is stronger. The 95% lower bound of the threshold based on the new dosimetry system appears to be in the range of 0.12-0.23 Gy. In the 16-25 week period, the 95% lower bound of the threshold is 0.21 Gy both with and without inclusion of two probable nonradiation-related retarded cases. In a regression analysis of IQ scores and school performance data, a greater linearity is suggested with the new dosimetry (DS86) than with the old (T65DR), but the mean IQ score and the mean school performance of those exposed in utero to doses under 0.10 Gy are similar, and not statistically different from the means in the control group. The risk ratios for unprovoked seizures, following exposure during the 8th through the 15th week after fertilization, are 4.4 (90% confidence interval: 0.5-40.9) after 0.10-0.49 Gy and 24.9 (4.1-191.6) after 0.50 Gy or more when the mentally retarded are included and 4.4 (0.5-40.9) and 14.5 (0.4-199.6), respectively, when they are excluded.
J V Neel, W J Schull, A A Awa, C Satoh, H Kato, M Otake, Y Yoshimoto
The children of parents exposed to atomic bombs: estimates of the genetic doubling dose of radiation for humans.
Am J Hum Genet. 1990 Jun;46(6):1053-72.
Abstract/Text
The data collected in Hiroshima and Nagasaki during the past 40 years on the children of survivors of the atomic bombings and on the children of a suitable control population are analyzed on the basis of the newly revised estimates of radiation doses. No statistically significant effects emerge with respect to eight different indicators. Since, however, it may confidently be assumed some mutations were induced, we have taken the data at face value and calculated the minimal gametic doubling doses of acute radiation for the individual indicators at various probability levels. An effort has also been made to calculate the most probable doubling dose for the indicators combined. The latter value is between 1.7 and 2.2 Sv. It is suggested the appropriate figure for chronic radiation would be between 3.4 and 4.5 Sv. These estimates suggest humans are less sensitive to the genetic effects of radiation than has been assumed on the basis of past extrapolations from experiments with mice.
W L Russell
Effect of the interval between irradiation and conception on mutation frequency in female mice.
Proc Natl Acad Sci U S A. 1965 Dec;54(6):1552-7.
Abstract/Text
Committee on biological effects of ionizing radiation Borer, Commission on life science, National research council: Health effects of exposure to low levels of ionizing radiation: BEIR V. Washington DC: National Academy Press, 1990.
R Doll, R Wakeford
Risk of childhood cancer from fetal irradiation.
Br J Radiol. 1997 Feb;70:130-9. doi: 10.1259/bjr.70.830.9135438.
Abstract/Text
The association between the low dose of ionizing radiation received by the fetus in utero from diagnostic radiography, particularly in the last trimester of pregnancy, and the subsequent risk of cancer in childhood provides direct evidence against the existence of a threshold dose below which no excess risk arises, and has led to changes in medical practice. Initially reported in 1956, a consistent association has been found in many case-control studies in different countries. The excess relative risk obtained from combining the results of these studies has high statistical significance and suggests that, in the past, a radiographic examination of the abdomen of a pregnant woman produced a proportional increase in risk of about 40%. A corresponding causal relationship is not universally accepted and this interpretation has been challenged on four grounds. On review, the evidence against bias and confounding as alternative explanations for the association is strong. Scrutiny of the objections to causality suggests that they are not, or may not be, valid. A causal explanation is supported by evidence indicating an appropriate dose-response relationship and by animal experiments. It is concluded that radiation doses of the order of 10 mGy received by the fetus in utero produce a consequent increase in the risk of childhood cancer. The excess absolute risk coefficient at this level of exposure is approximately 6% per gray, although the exact value of this risk coefficient remains uncertain.
Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, National Research Council, National Academy of Sciences: Health Risks from Exposure to Low Levels of Ionizing Radiation:BEIR VII Phase 2. Washington DC:National Academy Pr.
Nobuya Unno, Hisanori Minakami, Takahiko Kubo, Keiya Fujimori, Isamu Ishiwata, Hiroshi Terada, Shigeru Saito, Ichiro Yamaguchi, Naoki Kunugita, Akihito Nakai, Yasunori Yoshimura
Effect of the Fukushima nuclear power plant accident on radioiodine (¹³¹ I) content in human breast milk.
J Obstet Gynaecol Res. 2012 May;38(5):772-9. doi: 10.1111/j.1447-0756.2011.01810.x. Epub 2012 Apr 9.
Abstract/Text
BACKGROUND: Environmental pollution with radioiodine (iodine-131, (131) I) occurred after an accident at the Fukushima nuclear power plant (FNP) on March 11, 2011, in Japan. Whether environmental pollution with (131) I can contaminate human breast milk has not been documented.
METHODS: The (131) I content was determined in 126 breast milk samples from 119 volunteer lactating women residing within 250 km of the FNP, between April 24 and May 31, 2011. The degree of environmental pollution was determined based on the data released by the Japanese government.
RESULTS: An (131) I content of 210 Bq/kg in the tap water in Tokyo, which is located 230 km south of the FNP, on March 22 and of 3500 Bq/kg in spinach sampled in a city located 140 km southwest of the FNP on March 19 decreased over time to <21 Bq/kg on March 27 and 12 Bq/kg on April 26, respectively. Seven of the 23 women who were tested in April secreted a detectable level of (131) I in their breast milk. The concentrations of (131) I in the breast milk of the seven women were 2.3 Bq/kg (on April 24), and 2.2, 2.3, 2.3, 3.0, 3.5 and 8.0 (on April 25); the concentrations of (131) I in the tap water available for these seven women at the same time were estimated to be <1.3 Bq/kg. None of the remaining 96 women tested in May exhibited a detectable concentration of (131) I in their breast milk samples.
CONCLUSIONS: The contamination of breast milk with (131) I can occur even when only mild environmental (131) I pollution is present.
© 2012 The Authors. Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology.
