Teratogenic effects of static magnetic field on mouse fetuses

Survey of Delivery Outcomes for Employees at MR Imaging Facilities in Japan Based on Information Recorded in the Maternal and Child Health Handbook

The effect of maternal occupational non-ionizing radiation (NIR) exposure from MRI on premature birth and low birth weight delivery was analyzed based on questionnaire survey (263 employees, 443 births). Although the highest occurrence rates of both outcomes were observed in the group whose NIR exposure occurred only before pregnancy, no statistical significance was detected.

No Meta-Analytic Evidence for Risks due to Prenatal MRI in Animal Models

BACKGROUND

Magnetic resonance imaging (MRI) is a powerful, non-invasive tool for both clinical practice and research. Though the safety of MRI has been endorsed by many professional societies and government bodies, some concerns have remained about potential risk from prenatal MRI. Case-control animal studies of MRI scanning during gestation and effects on offspring are the most direct test available for potential risks. Herein, we provide a meta-analysis of extant animal studies of prenatal MRI examining reproductive and offspring outcomes.

METHODS

Relevant articles were identified through PubMed search and citation searching of known articles and review papers. Eighteen relevant studies were identified with case-control designs of prenatal scanning conducted in vivo with mammalian species using MRI-relevant field strength. Standardized mean difference effect sizes were analyzed across k=81 outcomes assessed across n=649 unexposed dams, n=622 exposed dams, n=3031 unexposed offspring, n=3378 exposed offspring, using a multi-level meta-analysis approach that clustered effect sizes within publication.

RESULTS

The meta-analysis indicated no significant evidence for an effect of prenatal MRI (SMD=0.17, 95% CI=[-0.19,0.54], t=0.94, p=.35) across outcomes. Similarly, no effects were observed when separately examining the four most commonly assessed outcomes: birth weight, litter size, fetal viability, and physical malformations (p>.05).

CONCLUSIONS

Case-control mammalian animal studies indicate no significant known risks of prenatal MRI to reproductive outcomes or offspring development. This is largely mirrored in human research, though the lack of randomized case-control designs limits direct comparison. The current findings provide additional support to the prevailing consensus that prenatal MRI poses no known risk to offspring.

Effects of Moderate to High Static Magnetic Fields on Reproduction

With the wide application of magnetic resonance imaging in hospitals and permanent magnets in household items, people have increased exposure to various types of static magnetic fields (SMFs) with moderate and high intensities, which has caused a considerable amount of public concern. Studies have shown that some aspects of gametogenesis and early embryonic development can be significantly affected by SMFs, while others have shown no effects. This review summarizes the experimental results of moderate to high-intensity SMFs (1 mT-16.7 T) on the reproductive development of different model animals, and we find that the effects of SMFs are variable depending on experimental conditions. In general, the effects of inhomogeneous SMFs seem to be more significant compared to that of homogeneous SMFs, which is likely due to magnetic forces generated by the magnetic field gradient. Moreover, some electromagnetic fields may have induced bioeffects because of nonnegligible gradient and heat effect, which are much reduced in superconducting magnets. We hope this review can provide a starting point for more in-depth analysis of various SMFs on reproduction, which is indispensable for evaluating the safety and potential applications of SMFs on living organisms in the future. © 2022 Bioelectromagnetics Society.

The Influence of Vitamin E and Omega-3 Fatty Acids on Reproductive Health Indices Among Male Workers Exposed to Electromagnetic Fields

The present study aims to investigate the effects of using the supplementation of vitamin E and Omega 3 fatty acids on reproductive indices among workers in an automobile parts manufacturing plant. The effect of exposure to electromagnetic fields on certain sex hormones and sperm parameters will also be assessed. The participants were deployed into four groups as per the double-blind block randomization method. Semen parameters and sex hormones of the participants were analyzed before and after 3-month consumption of supplements. The level of workers’ exposure to low-frequency magnetic and electrical fields was measured through the recommendation of National Institute for Occupational Safety and Health. Univariate analysis of variance indicated that exposure to electric fields had a statistically significant effect on sperm count, morphology, and motility. The simultaneous consumption of vitamin E + Omega 3 had a statistically significant effect on sperm morphology and motility.

Assessment of sexual hormones in foundry workers exposed to heat stress and electromagnetic fields

The presence of hazardous agents in workplaces has raised concerns regarding their possible impacts on male reproductive system. The present study investigated the individual and combined effects of exposure to heat stress and electromagnetic fields with low-frequency characteristics on the levels of sex hormones in two foundry sections (Aluminum and Cast Iron) of an automobile parts manufacturing plant. The level of workers' exposure (n = 110) to each of the mentioned stressors, was measured through standard methods and for each person and the time-weighted average (TWA) of exposure was calculated. The participants of each sections were classified into separate exposure groups based on the 33rd and 66th percentile of the level of to heat stress and electromagnetic fields exposure. In order to determine serum sex hormones, blood samples were taken from all participants between 7-9 am and then the blood samples were analyzed by ELISA method. In total of two sections, the lowest mean testosterone levels was observed in the third exposure group of the electromagnetic fields (magnetic field>1.40 μT; electric field >0.42 V/m), however, the mean difference in testosterone levels between the three different groups of exposure wasn't statistically significant (P > 0.05). According to the results of Logistic Regression, the electric field had the greatest effect on testosterone levels as the main male hormone. Drawing a definitive conclusion regarding the effects of each harmful physical hazards is difficult due to the existence of psychological stressors and other environmental stressors such as chemical pollution, ergonomic hazards and other physical stressors.

Maternal occupational exposure to chemicals in the textile factory during pregnancy is associated with a higher risk of polydactyly in the offspring

Background: The number of children with polydactyly seen in our clinic is increasing. In addition to genetic factors, an influence of environmental effects during pregnancy is becoming increasingly apparent; however, epidemiological data on these effects are lacking.Methods: This hospital-based, case-control study enrolled 143 patients with polydactyly and 286 control patients with no genetic diseases, to evaluate the association between maternal exposure to a textile factory environment during pregnancy and the likelihood of giving birth to a child with polydactyly.Results: Maternal exposure to a textile factory environment during pregnancy was associated with an increased risk of giving birth to a child with polydactyly (exposure to textile factory environment: unadjusted odds ratio (OR) = 3.31, 95% confidence interval (CI) = 1.75-6.27, p = .0002; work seniority of exposed occupation: unadjusted OR 1.28, 95% CI = 1.13-1.47, p = .0002). Covariate screening indicated that certain risk factors (family monthly income per capita, mother's emotional state during pregnancy, colporrhagia, passive smoking, smoking, and history of consanguineous marriage) were potential confounding factors. After adjusting for these variables, the OR of exposure to a textile factory environment remained significant (exposure to textile factory environment: adjusted OR = 3.08, 95% CI = 1.32-7.19, p = .0094; work seniority of exposed occupation: adjusted OR = 1.58, 95% CI = 1.20-2.08, p = .0010). The risk of polydactyly increased with the number of years of employment.Conclusions: Maternal exposure to a textile factory environment appears to be a risk factor for polydactyly in newborns.

Relationship between exposure to Extremely Low-Frequency (ELF) magnetic field and the level of some reproductive hormones among power plant workers

BACKGROUND AND AIMS

Today, human beings are exposed to the ELF magnetic field of electrical equipment and power lines, which can damage Leydig cells and alter the secretion of reproductive hormones. The purpose of this study was to investigate the relationship between exposure to ELF magnetic field and the level of some reproductive hormones in male power plant workers.

MATERIALS AND METHODS

The present cross-sectional study was carried out among all male employees of different units of the selected power plant around Tehran, Iran. All participants were asked to complete demographic data sheets and General Health questionnaire, on condition of consent and meeting the inclusion criteria. Time-weighted average (TWA) exposure to magnetic field of 122 men was measured by IEEE Std C95.3.1 method using TES 1393 Gauss meter. Based on the exposure level, subjects were divided into three groups. Serum Levels of Free Testosterone, Luteinizing Hormone (LH), and Follicle stimulating hormone (FSH) in participants were determined. Data analysis was performed using ANOVA, Kruskal-Wallis tests, and the relationships between variables were assessed by linear regression and correlation using SPSS v.25 software.

RESULTS

There was no significant statistical correlation between the level of ELF exposure and serum levels of free testosterone, LH, and FSH, (r = 0.158). Serum levels of LH decreased significantly with age and duration of work experience (P < .05, r = -.25, P = .005, r = -.203, P = .025).

CONCLUSION

There was no relationship between exposure to magnetic field in power plants and reproductive hormone levels, although it is impossible to make definitive comments without using more accurate methods to estimate male fertility.

The Effect of Prenatal Exposure to 2.4 GHz Radio Frequency on the Histology and Expression of the osteocalcin and RUNX2 Gene of the Forelimb in an NMRI Mouse

Introduction: Today the use of electromagnetic waves has dramatically increased in modern industrial societies. This study aimed to investigate the effect of prenatal exposure to 2.4 GHz wireless frequency on forelimb development in an NMRI mouse in vivo. Methods: A total of 21 female mice weighing 25-30 g were included in the present study. They were randomly assigned to 3 groups, namely control (n=7), sham (n=7), and experimental (n=7). After mating, the experimental group was exposed to 2.4 GHz radio frequency at a distance of 20-30 cm from the device, 4 h/d until the delivery. The sham group was placed at a distance of 20-30 cm from the device every day without exposure to electromagnetic waves, and the control group had a pregnancy period without any stress and electromagnetic wave exposure. After giving birth, the forelimbs were isolated from the infants and examined by stereological studies and RT-PCR for the evaluation of osteocalcin and RUNX2 gene expression. Results: Although, at first glance, there was no macroscopic teratogen effect in forelimbs in all groups, via a stereological method, we showed that bone and cartilage volume decreased in the experimental group compared to the other groups. We also found that the experimental group had lower expression of the osteocalcin and RUNX2 gene than the control and sham groups did. However, there were no significant differences between the control and sham groups in terms of bone and cartilage volume and gene expression. Conclusion: Although teratogen effect of prenatal exposure to 2.4 GHz radio frequency on forelimbs was not demonstrated macroscopically, further studies showed negative effects on the forelimb bone, cartilage volume, and gene expression.

Impact of cardiac magnetic resonance on endothelial function in type 2 diabetic patients

OBJECTIVES

Recent studies have shown that cardiac magnetic resonance (CMR) scanning is associated with cellular DNA damage. The aim of the present study was to assess the impact of CMR scanning on endothelial function in Chinese men with type 2 diabetes.

METHODS

A randomized, single-blind, parallel-group study was conducted in 60 Chinese men with type 2 diabetes treated with or without CMR (CMR and sham CMR group), and the changes of endothelial function before and after CMR were compared. High-resolution ultrasound was used to measure flow-mediated endothelium-dilation (FMD) of the brachial artery.

RESULTS

The FMD in CMR group at Day 1 after CMR was 3.60%, which was significantly lower than that (3.85%) in sham CMR group (p < 0.001). The levels of C-reactive protein (CRP), thiobarbituric acid-reactive substances (TBARS), tumor necrosis factor alpha (TNF-α) and interleukin-6(IL-6) in CMR group were significantly higher than those in sham CMR group at Day 1 (p < 0.001). But these characteristics did not differ between two groups at baseline, Day 2 and Day 3 (p > 0.05). Linear correlation and multiple regression analyses showed that CRP, TBARS, TNF-α and IL-6 were associated with FMD in the CMR group (p < 0.01).

CONCLUSIONS

The present data showed that CMR scanning can reversibly suppress endothelial function, probably through the increased production of oxygen-derived free radicals and inflammatory reactions in Chinese men with type 2 diabetes, indicating that CMR should be used with caution in order to avoid unnecessary damage to the endothelium.

CLINICAL TRIAL REGISTRATION URL

https://register.clinicaltrials.gov/, Unique Identifier: NCT02001753.

The effects of prenatal exposure to a 900-MHz electromagnetic field on the 21-day-old male rat heart

The growing spread of mobile phone use is raising concerns about the effect on human health of the electromagnetic field (EMF) these devices emit. The purpose of this study was to investigate the effects on rat pup heart tissue of prenatal exposure to a 900 megahertz (MHz) EMF. For this purpose, pregnant rats were divided into experimental and control groups. Experimental group rats were exposed to a 900 MHz EMF (1 h/d) on days 13-21 of pregnancy. Measurements were performed with rats inside the exposure box in order to determine the distribution of EMF intensity. Our measurements showed that pregnant experimental group rats were exposed to a mean electrical field intensity of 13.77 V/m inside the box (0.50 W/m(2)). This study continued with male rat pups obtained from both groups. Pups were sacrificed on postnatal day 21, and the heart tissues were extracted. Malondialdehyde, superoxide dismutase and catalase values were significantly higher in the experimental group rats, while glutathione values were lower. Light microscopy revealed irregularities in heart muscle fibers and apoptotic changes in the experimental group. Electron microscopy revealed crista loss and swelling in the mitochondria, degeneration in myofibrils and structural impairments in Z bands. Our study results suggest that exposure to EMF in the prenatal period causes oxidative stress and histopathological changes in male rat pup heart tissue.

Effects of pulsed electromagnetic field on differentiation of HUES-17 human embryonic stem cell line

Electromagnetic fields are considered to potentially affect embryonic development, but the mechanism is still unknown. In this study, human embryonic stem cell (hESC) line HUES-17 was applied to explore the mechanism of exposure on embryonic development to pulsed electromagnetic field (PEMF) for 400 pulses at different electric field intensities and the differentiation of HUES-17 cells was observed after PEMF exposure. The expression of alkaline phosphatase (AP), stage-specific embryonic antigen-3 (SSEA-3), SSEA-4 and the mRNA level and protein level of Oct4, Sox2 and Nanog in HUES-17 cells remained unchanged after PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m. Four hundred pulses PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m did not affect the differentiation of HUES-17 cells. The reason why electromagnetic fields affect embryonic development may be due to other mechanisms rather than affecting the differentiation of embryonic stem cells.

Impact of repetitive exposure to strong static magnetic fields on pregnancy and embryonic development of mice

PURPOSE

To evaluate possible risks of strong static magnetic fields for embryo implantation, gestation, organogenesis, and embryonic development.

MATERIALS AND METHODS

Pregnant mice were exposed for 75 minutes daily during the entire course of pregnancy at the bore entrance, representing the position of medical staff, and at the isocenter, representing the position of patients, of a 1.5 T and a 7 T human MRI scanner.

RESULTS

No effect of static magnetic field strength was observed with regard to pregnancy rate, duration of pregnancy, litter size, still births, malformations, sex distribution, or postpartum death of offspring. During the first 8 weeks postnatal, mice exposed in utero to a magnetic field strength of 1.5 T or stronger showed a slight delay in weight gain and in time to eye opening compared to controls.

CONCLUSION

Daily exposure to strong magnetic fields during pregnancy had no deleterious effect on offspring; however, a developmental retardation could be observed postnatally with regard to weight gain and eye opening.

Impact of cardiac magnetic resonance imaging on human lymphocyte DNA integrity

AIMS

Magnetic resonance (MR) imaging is widely used for diagnostic imaging in medicine as it is considered a safe alternative to ionizing radiation-based techniques. Recent reports on potential genotoxic effects of strong and fast switching electromagnetic gradients such as used in cardiac MR (CMR) have raised safety concerns. The aim of this study was to analyse DNA double-strand breaks (DSBs) in human blood lymphocytes before and after CMR examination.

METHODS AND RESULTS

In 20 prospectively enrolled patients, peripheral venous blood was drawn before and after 1.5 T CMR scanning. After density gradient cell separation of blood samples, DNA DSBs in lymphocytes were quantified using immunofluorescence microscopy and flow cytometric analysis. Wilcoxon signed-rank testing was used for statistical analysis. Immunofluorescence microscopic and flow cytometric analysis revealed a significant increase in median numbers of DNA DSBs in lymphocytes induced by routine 1.5 T CMR examination.

CONCLUSION

The present findings indicate that CMR should be used with caution and that similar restrictions may apply as for X-ray-based and nuclear imaging techniques in order to avoid unnecessary damage of DNA integrity with potential carcinogenic effect.

Effects of electromagnetic pulse on polydactyly of mouse fetuses

There is an increasing public concern regarding potential health impacts from electromagnetic radiation exposure. Embryonic development is sensitive to the external environment, and limb development is vital for life quality. To determine the effects of electromagnetic pulse (EMP) on polydactyly of mouse fetuses, pregnant mice were sham-exposed or exposed to EMP (400 kV/m with 400 pulses) from Days 7 to 10 of pregnancy (Day 0 = day of detection of vaginal plug). As a positive control, mice were treated with 5-bromodeoxyuridine on Days 9 and 10. On Days 11 or 18, the fetuses were isolated. Compared with the sham-exposed group, the group exposed to EMP had increased rates of polydactyly fetuses (5.1% vs. 0.6%, P < 0.05) and abnormal gene expression (22.2% vs. 2.8%, P < 0.05). Ectopic expression of Fgf4 was detected in the apical ectodermal ridge, whereas overexpression and ectopic expression of Shh were detected in the zone of polarizing activity of limbs in the EMP-exposed group and in the positive control group. However, expression of Gli3 decreased in mesenchyme cells in those two groups. The percentages of programmed cell death of limbs in EMP-exposed and positive control group were decreased (3.57% and 2.94%, respectively, P < 0.05, compared with 7.76% in sham-exposed group). In conclusion, polydactyly induced by EMP was accompanied by abnormal expression of the above-mentioned genes and decreased percentage of programmed cell death during limb development.

Whole body exposure to 2.4 GHz WIFI signals: effects on cognitive impairment in adult triple transgenic mouse models of Alzheimer's disease (3xTg-AD)

The present investigation aimed at evaluating the effects of long-term exposure to WIFI type radiofrequency (RF) signals (2.40 GHz), two hours per day during one month at a Specific Absorption Rate (SAR) of 1.60 W/kg. The effects of RF exposure were studied on wildtype mice and triple transgenic mice (3xTg-AD) destined to develop Alzheimer's-like cognitive impairment. Mice were divided into four groups: two sham groups (WT, TG; n=7) and two exposed groups (WTS, TGS; n=7). The cognitive interference task used in this study was designed from an analogous human cognitive interference task including the Flex field activity system test, the two-compartment box test and the Barnes maze test. Our data demonstrate for the first time that RF improves cognitive behavior of 3xTg-AD mice. We conclude that RF exposure may represent an effective memory-enhancing approach in Alzheimer's disease.

Exposure to static magnetic field delays induced preterm birth occurrence in mice

OBJECTIVE

The purpose of this study was to demonstrate that daily 40-minute whole body exposure to an inhomogeneous static magnetic field (SMF) prolongs induced preterm birth (PTB) in mice.

STUDY DESIGN

The murine model for PTB induction was performed by the administration of 25 μg/animal lipopolysaccharide (LPS) intraperitoneally. The applied SMF was an inhomogeneous gradient field with 2.8-476.7 millitesla peak-to-peak magnetic induction range by 10 mm lateral periodicity. During SMF exposure, mice were free to move in their cage.

RESULTS

The fetal development and the delivery were normal in animals that were exposed to SMF but not treated with LPS. SMF in these cases did not influence the term of delivery. In LPS-challenged animals, SMF exposure prolonged the time of PTB occurrence from 17.43 h (n = 7) to 21.93 h (n = 15) after the challenge (P < .05).

CONCLUSION

Exposure to inhomogeneous SMF may have a valuable effect in the prevention of PTB and may have clinical relevance to humans.

Evaluation of testicular degeneration induced by low-frequency electromagnetic fields

The population exposure to electromagnetic fields (EMF) has been growing in recent decades. The generation, distribution and use of electric energy can generate low-frequency electromagnetic fields. The present study investigates the effects of EMF (60 Hz and 1 mT) on spermatogenesis of rats during different periods of maturation. Wistar rats were exposed to EMF from day 13 of gestation to postnatal day 21 or 90 in three daily applications of 30 min. Plasma testosterone concentration was not changed by EMF exposure; however, histopathological and histomorphometrical analyses of the testes showed testicular degeneration in a subset of animals exposed to EMF. The magnitude of the degenerative process varied between those individuals affected, indicating different individual sensitivity to EMF. The main alterations observed through transmission electron microscopy were highly electron-dense mitochondria with loss of their organization and cristae. Exposure to 60 Hz and 1 mT EMF can disturb spermatogenesis and may produce subfertility or infertility.

MR imaging in cases of antenatal suspected appendicitis--a meta-analysis

OBJECTIVE

Appendicitis is the most common surgical emergency in pregnancy. Acute appendicitis is often difficult to diagnose clinically, and concerns regarding antenatal CT imaging limit its use resulting in high false negative rates at laparotomy. MRI has recently been reported as a reasonable alternative to CT imaging in cases of suspected appendicitis. Our objective was to perform a meta-analysis of recently published data regarding the utility of MR imaging in cases of antenatal suspected acute appendicitis.

METHODS

We searched the PubMed database using keywords 'MRI', 'appendicitis', and 'pregnancy'. Five case series describing the role of MRI in cases of antenatal appendicitis were included. The sensitivity, specificity, positive, and negative predictive values were calculated.

RESULTS

Two hundred twenty-nine patients were included in the study. In the first analysis in which non-diagnostic scans were excluded, the sensitivity, specificity, positive and negative predictive values of MRI for diagnosing appendicitis were 95.0%, 99.9%, 90.4%, and 99.5%, respectively. In the second analysis, which included non-diagnostic scans, the sensitivity, specificity, positive and negative predictive values were 90.5%, 98.6%, 86.3%, and 99.0%, respectively

CONCLUSIONS

MR imaging may be useful in cases of suspected antenatal appendicitis. Data are still limited and larger prospective studies are necessary to confirm this finding.

Is the genotoxic effect of magnetic resonance negligible? Low persistence of micronucleus frequency in lymphocytes of individuals after cardiac scan

Magnetic resonance imaging is a diagnostic technique widely used in medicine and showing a growing impact in cardiology. Biological effects associated to magnetic resonance electromagnetic fields have received far little attention, but it cannot be ruled out that these fields can alter DNA structure. The present study aimed at to identify possible DNA damage induced by magnetic resonance scan in humans. Lymphocyte cultures from healthy subjects had been exposed into magnetic resonance device for different times and under different variable magnetic exposure in order to build dose-effect curves, using micronuclei induction as biological marker. Replicate cultures were also left for 24h at room temperature before stimulation, to verify possible damage recovery. Furthermore, micronuclei induction and recovery up to 120h have been also evaluated in circulating lymphocytes of individuals after cardiac scan. A dose-dependent increase of micronuclei frequency was observed in vitro. However after 24h, the frequency returns to control value when the exposure is within diagnostic dosage. After in vivo scan, a significant increase in micronuclei is found till 24h, after the frequencies slowly return to control value.

Prenatal imaging: ultrasonography and magnetic resonance imaging

The Eunice Kennedy Shriver National Institute of Child Health and Human Development held a workshop on September 18-19, 2006, to summarize the available evidence on the role and performance of current fetal imaging technology and to establish a research agenda. Ultrasonography is the imaging modality of choice for pregnancy evaluation due to its relatively low cost, real-time capability, safety, and operator comfort and experience. First-trimester ultrasonography extends the available window for fetal observation and raises the possibility of performing an early anatomic survey. Three-dimensional ultrasonography has the potential to expand the clinical application of ultrasonography by permitting local acquisition of volumes and remote review and interpretation at specialized centers. New advances allow performance of fetal magnetic resonance imaging (MRI) without maternal or fetal sedation, with improved characterization and prediction of prognosis of certain fetal central nervous system anomalies such as ventriculomegaly when compared with ultrasonography. Fewer data exist on the usefulness of fetal MRI for non-central nervous system anomalies.