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Optimization and Dose Reduction in Medical Imaging of the Pregnant Patient
Published in Lawrence T. Dauer, Bae P. Chu, Pat B. Zanzonico, Dose, Benefit, and Risk in Medical Imaging, 2018
Wesley E. Bolch, Matthew Maynard, William J. Godwin, Amy M. Geyer, Linda Kroger
A variety of radiogenic effects may arise following in utero exposure of the embryo/fetus including mental retardation, neurobehavioral effects, convulsive disorders, congenital malformations, fetal growth retardation, and embryonic death. Excellent and extensive reviews of both animal and human exposure data underlying our understanding of these effects may be found in both ICRP Publication 90 (ICRP 2003) and NCRP Report No. 174 (NCRP 2013). Their impact on the embryo or fetus is strongly dependent upon both the stage of development, the dose rate, and the dose received. During the preimplantation and presomite stages of development (<14 days post-conception), the cells of the embryo are pluripotential (stem cell in nature) and are highly sensitive to the lethal effects of ionizing radiation. However, if these cells survive, the resulting embryo/fetus will develop normally with no increased risk of anatomic malformation at birth. This early period is thus referred to as the all-or-none period. During the period 14–40 days post-conception, the embryo is undergoing the early stages of organogenesis, and this is a very vulnerable period for the production of major anatomic malformations. From 40 days post-conception until birth, the vulnerability of the fetus steadily declines with the exception of serious radiation effects to the central nervous system, gonads, and overall fetal growth if the dose is sufficiently high.
Environmental Ionizing Radiation
Published in Lorris G. Cockerham, Barbara S. Shane, Basic Environmental Toxicology, 2019
Lorris G. Cockerham, Michael B. Cockerham
Instead of lethality, morphological abnormalities are associated with irradiation during the middle stages of development. Irradiation-induced anomalies occurring during this time may result in death of the organism or abnormal development of one or more organ systems. Exposure during this period may result in gross malformations, growth retardation at term or as an adult, and structural neuropathology (Mettler and Moseley, 1985). In the human, most major organogenesis occurs during the first trimester of pregnancy, with embryonic death and congenital abnormalities resulting from irradiation exposure during this period (Robertson, 1989).
The Developmental Toxicity of Metals and Metalloids in Fish
Published in Michael C. Newman, Alan W. McIntosh, Metal Ecotoxicology, 2020
Among the most commonly observed end points in toxicity testing for effects of pollutants on fish embryos is successful hatch. Many factors could account for an embryo failing to hatch, embryonic death being a common cause, but grossly abnormal embryos also fail to hatch. In addition, there are embryos that often appear morphologically normal but do not hatch. These three conditions represent a progressive decrease in severity of effect of the toxicant. Studies that differentiate among these different states are more informative than those that merely report percentage hatch.
Evaluation of the developmental toxicity of solvents, metals, drugs, and industrial chemicals using a freshwater snail (Biomphalaria glabrata) assay
Published in Journal of Toxicology and Environmental Health, Part A, 2022
Rosângela Ribeiro de-Carvalho, Maria Regina Gomes-Carneiro, Barbara Rodrigues Geraldino, Gabrielle da Silveira Lopes, Francisco José Roma Paumgartten
In the field of experimental teratology, it is well-established that tests using nonmammalian species demonstrated that various environmental stressors markedly produced deranged embryo development leading to adverse outcomes including growth retardation, increased frequency of malformations, and embryonic death (Clarke Fraser 2010; Stockard 1907). Those investigators who pioneered experimental research in teratology postulated that non-mammalian vertebrates such as chicken, fish or amphibians (Clarke Fraser 2010; Stockard 1907; Wilson 1977) and invertebrates such as sea urchin were suitable test species for this type of study as these species not only allowed for direct access and exposure to the embryo but also to follow up normal or abnormal development within the eggs (Clarke Fraser 2010; Di Bernardo and Di Carlo 2017; Stockard 1907). Moreover, in the 19th and early 20th centuries, most teratologists postulated that uteri and placentae were virtually impregnable shelters that protected the mammalian embryo from environmental insults (Clarke Fraser 2010). As of the 1920/30s, however, this notion began to be undermined by results from experiments with pigs and rodents showing that micronutrient (vitamin) deficiencies, maternal exposure to ionizing radiation, trypan blue, alkylating agents and some other environmental factors resulted in adverse pregnancy outcomes such as embryofetal deaths and birth defects (Hale 1933, 1935; Warkany and Nelson 1940; Warkany and Schraffenberger 1944).