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In our previous studies, we demonstrated that 20 h pre-exposure of SH-SY5Y human neuroblastoma cells to 1950 MHz, UMTS signal, at specific absorption rate of 0.3 and 1.25 W/kg, was able to reduce the oxidative DNA damage induced by a subsequent treatment with menadione in the alkaline comet assay while not inducing genotoxicity per se. In this study, the same cell model was used to test the same experimental conditions by setting different radiofrequency exposure duration and timing along the 72 h culture period. The results obtained in at least three independent experiments indicate that shorter exposure durations than 20 h, that is, 10, 3, and 1 h per day for 3 days, were still capable to exert the protective effect while not inducing DNA damage per se. In addition, to provide some hints into the mechanisms underpinning the observed phenomenon, thioredoxin-1, heat shock transcription factor 1, heat shock protein 70, and poly [ADP-ribose] polymerase 1, as key molecular players involved in the cellular stress response, were tested following 3 h of radiofrequency exposure in western blot and qRT-PCR experiments. No effect resulted from molecular analysis under the experimental conditions adopted., (© 2024 The Author(s). Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.)

Background: Over the last decades, great concern has been raised about possible adverse effects to human health due to exposures to radiofrequency electromagnetic fields (RF-EMF, 100 kHz - 300 GHz) emitted by wireless communication technologies. In 2011 the International Agency for Research on Cancer classified RF-EMF as possibly carcinogenic to humans, highlighting that the evidence was weak and far from conclusive. Updated systematic reviews of the scientific literature on this topic are lacking, especially for mechanistic studies., Objectives: To perform a systematic review of the scientific literature on genotoxic effects induced by RF-EMF in in vitro experimental models. The overall aim is to assess the confidence and level of evidence of the induced effects in mammalian cell cultures., Methods: Full details regarding the eligibility criteria, information sources, and methods developed to assess risk of bias in the included study, are reported in our published protocol (Romeo et al. 2021). The databases NCBI PubMed, Web of Science, and EMF-Portal were used as information sources (last searched on 31st December 2022). In developing the systematic review, we followed the guidelines provided by the National Toxicology Program-Office of Health Assessment and Translation (NTP-OHAT), adapted to the evaluation of in vitro studies. A narrative synthesis of the body of evidence was performed by tabulating data classified according to meaningful groups (endpoints) and sub-groups (exposure parameters). This report, abstract included, conforms to the PRISMA 2020 (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines., Results: Out of 7750 unique records identified, 159 articles were eligible for inclusion. From the extracted data, we identified 1111 experiments (defined as independent specific combinations of diverse biological and electromagnetic parameters). The large majority (80%) of experiments reviewed did not show statistically significant genotoxic effects of RF-EMF exposures, and most "positive" studies were rated as of moderate to low quality, with negative ratings in the key bias domains. A qualitative evidence appraisal was conducted at the endpoint level, and then integrated across endpoints., Discussion: To the best of our knowledge, this is the first systematic review of the scientific literature on genotoxic effects in mammalian cell cultures in relation to RF-EMF exposure, which confirms and strengthens conclusions from previous syntheses of this specific topic thanks to the use of transparently reported methods, pre-defined inclusion criteria, and formal assessment of susceptibility to bias. Limitations of the evidence included the frequent reporting of findings in graphical display only, and the large heterogeneity of experimental data, which precluded a meta-analysis., Conclusions: In the assessment restricted to studies reporting a significant effect of the exposure on the outcome, we reached an overall assessment of "low" confidence in the evidence that RF-EMF induce genotoxic effects in mammalian cells. However, 80% of experiments reviewed showed no effect of RF exposure on the large majority of endpoints, especially the irreversible ones, independently of the exposure features, level, and duration (moderate evidence of no effect). Therefore, we conclude that the analysis of the papers included in this review, although only qualitative, suggests that RF exposure does not increase the occurrence of genotoxic effects in vitro., Framework and Funding: This systematic review addresses one of the evidence streams considered in a larger systematic review of the scientific literature on the potential carcinogenicity of RF-EMF, performed by scientists from several Italian public research agencies. The project is supported by the Italian Workers' Compensation Authority (INAIL) in the framework of the CRA with the Istituto Superiore di Sanità "BRiC 2018/06 - Scientific evidence on the carcinogenicity of electromagnetic fields"., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

This study aims to investigate the cellular effects of radiofrequency exposure, 1950 MHz, long-term evolution (LTE) signal, administered alone and in combination with mitomycin-C (MMC), a well-known cytotoxic agent. Chinese hamster lung fibroblast (V79) cells were exposed/sham exposed in a waveguide-based system under strictly controlled conditions of both electromagnetic and environmental parameters, at specific absorption rate (SAR) of 0.3 and 1.25 W/kg. Chromosomal damage (micronuclei formation), oxidative stress (reactive oxygen species [ROS] formation), and cell cycle progression were analyzed after exposure and coexposure. No differences between exposed samples and sham-controls were detected following radiofrequency exposure alone, for all the experimental conditions tested and biological endpoints investigated. When radiofrequency exposure was followed by MMC treatment, 3 h pre-exposure did not modify MMC-induced micronuclei. Pre-exposure of 20 h at 0.3 W/kg did not modify the number of micronuclei induced by MMC, while 1.25 W/kg resulted in a significant reduction of MMC-induced damage. Absence of effects was also detected when CW was used, at both SAR levels. MMC-induced ROS formation resulted significantly decreased at both SAR levels investigated, while cell proliferation and cell cycle progression were not affected by coexposures. The results here reported provide no evidence of direct effects of 1950 MHz, LTE signal. Moreover, they further support our previous findings on the capability of radiofrequency pre-exposure to induce protection from a subsequent toxic treatment, and the key role of the modulated signals and the experimental conditions adopted in eliciting the effect., (© 2023 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.)

The evolution of emerging technologies that use Radio Frequency Electromagnetic Field (RF-EMF) has increased the interest of the scientific community and society regarding the possible adverse effects on human health and the environment. This article provides NextGEM's vision to assure safety for EU citizens when employing existing and future EMF-based telecommunication technologies. This is accomplished by generating relevant knowledge that ascertains appropriate prevention and control/actuation actions regarding RF-EMF exposure in residential, public, and occupational settings. Fulfilling this vision, NextGEM commits to the need for a healthy living and working environment under safe RF-EMF exposure conditions that can be trusted by people and be in line with the regulations and laws developed by public authorities. NextGEM provides a framework for generating health-relevant scientific knowledge and data on new scenarios of exposure to RF-EMF in multiple frequency bands and developing and validating tools for evidence-based risk assessment. Finally, NextGEM's Innovation and Knowledge Hub (NIKH) will offer a standardized way for European regulatory authorities and the scientific community to store and assess project outcomes and provide access to findable, accessible, interoperable, and reusable (FAIR) data.

In the last years, radiofrequency (RF) has demonstrated that it can reduce DNA damage induced by a subsequent treatment with chemical or physical agents in different cell types, resembling the adaptive response, a phenomenon well documented in radiobiology. Such an effect has also been reported by other authors both in vitro and in vivo, and plausible hypotheses have been formulated, spanning from the perturbation of the cell redox status, to DNA repair mechanisms, and stress response machinery, as possible cellular mechanisms activated by RF pre-exposure. These mechanisms may underpin the observed phenomenon, and require deeper investigations. The present study aimed to determine whether autophagy contributes to RF-induced adaptive response. To this purpose, SH-SY5Y human neuroblastoma cells were exposed for 20 h to 1950 MHz, UMTS signal, and then treated with menadione. The results obtained indicated a reduction in menadione-induced DNA damage, assessed by applying the comet assay. Such a reduction was negated when autophagy was inhibited by bafilomycin A1 and E64d. Moreover, CRISPR SH-SY5Y cell lines defective for ATG7 or ATG5 genes did not show an adaptive response. These findings suggest the involvement of autophagy in the RF-induced adaptive response in human neuroblastoma cells; although, further investigation is required to extend such observation at the molecular level.

In the last decades, experimental studies have been carried out to investigate the effects of radiofrequency (RF, 100 kHz-300 GHz) electromagnetic fields (EMF) exposure on the apoptotic process. As evidence-based critical evaluation of RF and apoptosis in vitro is lacking, we performed a scoping literature review with the aim of systematically mapping the research performed in this area and identifying gaps in knowledge. Eligible for inclusion were in vitro studies assessing apoptosis in mammalian cells exposed to RF-EMF, which met basic quality criteria (sham control, at least three independent experiments, appropriate dosimetry analysis and temperature monitoring). We conducted a systematic literature review and charted data in order to overview the main characteristics of included studies. From the 4362 papers retrieved with our search strategy, 121 were pertinent but, among them, only 42 met basic quality criteria. We pooled data with respect to exposure (frequency, exposure level and duration) and biological parameters (cell type, endpoint), and highlighted some qualitative trends with respect to the detection of significant effect of RF-EMF on the apoptotic process. We provided a qualitative picture of the evidence accumulated so far, and highlighted that the quality of experimental methodology still needs to be highly improved.

Magnetic resonance imaging (MRI) is one of the most-used diagnostic imaging methods worldwide. There are ∼50,000 MRI scanners worldwide each of which involves a minimum of five workers from different disciplines who spend their working days around MRI scanners. This review analyzes the state of the art of literature about the several aspects of the occupational exposure to electromagnetic fields (EMF) in MRI: regulations, literature studies on biological effects, and health surveillance are addressed here in detail, along with a summary of the main approaches for exposure assessment. The original research papers published from 2013 to 2021 in international peer-reviewed journals, in the English language, are analyzed, together with documents published by legislative bodies. The key points for each topic are identified and described together with useful tips for precise safeguarding of MRI operators, in terms of exposure assessment, studies on biological effects, and health surveillance., (© 2021. International Federation for Medical and Biological Engineering.)

In previous studies we demonstrated that radiofrequency (RF) electromagnetic fields (EMF) is able to reduce DNA damage induced by a subsequent treatment with genotoxic agents, resembling the adaptive response, a phenomenon well known in radiobiology. In this study we report on the capability of the culture medium from SH-SY5Y neuroblastoma cells exposed to 1950 MHz to elicit, in recipient non-exposed cells, a reduction of menadione-induced DNA damage (P < 0.05; comet assay), indicating the capability of non-ionizing radiation to elicit a bystander effect. A comparable reduction was also detected in cultures directly exposed to the same EMF conditions (P < 0.05), confirming the adaptive response. In the same exposure conditions, we also evidenced an increase of heat shock protein 70 (hsp70) in culture medium of cells exposed to RF with respect to sham exposed ones (P < 0.05; western blot analysis), while no differences were detected in the intracellular content of hsp70. On the whole, our results evidence a protective effect of RF against menadione-induced DNA damage in directly and non-directly exposed cells, and suggest hsp70 pathway to be investigated as one of the potential candidate underpinning the interaction between RF exposure and biological systems., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: Exposure to radiofrequency electromagnetic fields (RF-EMF, 100 kHz - 300 GHz) emitted by wireless communication technologies is pervasive and ubiquitous. Concern has been raised about possible adverse effects to human health. In 2011 the International Agency for Research on Cancer has classified RF-EMF as possibly carcinogenic to humans, highlighting that the evidence is weak and far from conclusive. Updated systematic reviews of the scientific literature on this topic are lacking, especially for mechanistic studies., Objectives: To develop a protocol for a systematic review of experimental studies investigating genotoxic effects induced by RF-EMF in in vitro cellular models. Genotoxicity is one of the key-biological indicators of carcinogenicity, and the most common characteristics of established carcinogens. The predefined procedures for conducting the systematic review are outlined below., Methods: We will follow the guidelines developed by the National Toxicology Program-Office of Health Assessment and Translation (NTP-OHAT), adapted to the evaluation of in vitro studies., Eligibility Criteria: We will include experimental in vitro studies addressing the relationship between controlled exposures to RF-EMF and genotoxicity in mammalian cells only. Eligibility for inclusion will be further restricted to peer reviewed articles reporting findings from primary studies., Information Sources: We will search the scientific literature databases NCBI PubMed, Web of Science, and EMF-Portal. No filter on publication date will be applied. Only studies published in English will be considered. The reference lists of the included papers and available reviews will be screened for unidentified relevant papers. References will be managed through Endnote X9 software., Data Extraction and Synthesis of Results: Data from included papers will be extracted according to predefined forms. Heterogeneity within the available evidence will determine the type of evidence synthesis that is appropriate. Findings will be summarized in tables, graphical displays and in a narrative synthesis of the available evidences. A meta-analysis will be carried out if subgroups of studies homogeneous in terms of exposure characteristics, endpoint, and cell types will be identified., Risk of Bias: The internal validity of included studies will be assessed using the NTP-OHAT Risk of Bias Rating Tool for animal studies, adapted to in vitro studies. This stage of the process will be managed through the Health Assessment Workspace Collaborative (HAWC)., Evidence Appraisal: To rate confidence in the body of evidence, we will use the OHAT GRADE-based approach for animal studies., Framework and Funding: This protocol concerns one of the evidence streams considered in a larger systematic review of the scientific literature on the potential carcinogenicity of RF-EMF, performed by scientists from several Italian public research agencies. The project is supported by the Italian Workers' Compensation Authority (INAIL) in the framework of the CRA with the Istituto Superiore di Sanità "BRiC 2018/06 - Scientific evidence on the carcinogenicity of radiofrequency electromagnetic fields"., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The last decades have seen a huge increase in applications and devices using and emitting non-ionizing radiation, otherwise referred to as "electromagnetic fields" (EMF) [...].

In previous investigations, we demonstrated that pre-exposure of different cell cultures to radiofrequency fields can reduce the damage induced by genotoxic agents, an effect resembling the so-called adaptive response. In this study, we pre-exposed human peripheral blood lymphocytes and Chinese hamster lung fibroblast cell line to 1950 MHz, UMTS (Universal Mobile Telecommunication System) signal, for 20 h, and then treated cultures with Mitomycin-C. After confirming the induction of an adaptive response in terms of the reduction of micronuclei formation, we observed that such a response was negated by treatments with 3-aminobenzamide. Since 3-aminobenzamide is an inhibitor of poly (ADP-ribose) polymerase enzyme, which is involved in DNA repair, these results support the possible involvement of DNA repair mechanisms in radiofrequency-induced adaptive response.

This study aims to assess whether a 1950 MHz radiofrequency (RF) electromagnetic field could protect human neuroblastoma SH-SY5Y cells against a subsequent treatment with menadione, a chemical agent inducing DNA damage via reactive oxygen species formation. Cells were pre-exposed for 20 h to specific absorption rate of either 0.3 or 1.25 W/kg, and 3 h after the end of the exposure, they were treated with 10 µM menadione (MD) for 1 h. No differences were observed between sham- and RF-exposed samples. A statistically significant reduction in menadione-induced DNA damage was detected in cells pre-exposed to either 0.3 or 1.25 W/kg (P < 0.05). Moreover, our analyses of gene expression revealed that the pre-exposure to RF almost inhibited the dramatic loss of glutathione peroxidase-based antioxidant scavenging efficiency that was induced by MD, and in parallel strongly enhanced the gene expression of catalase-based antioxidant protection. In addition, RF abolished the MD-dependent down-regulation of oxoguanine DNA glycosylase, which is a critical DNA repairing enzyme. Overall, our findings suggested that RF pre-exposure reduced menadione-dependent DNA oxidative damage, most probably by enhancing antioxidant scavenging efficiency and restoring DNA repair capability. Our results provided some insights into the molecular mechanisms underlying the RF-induced adaptive response in human neuroblastoma cells challenged with menadione.

The purpose of this review is to make a contribution to build a comprehensive knowledge of the main aspects related to the occupational exposure to electromagnetic fields (EMFs) in magnetic resonance imaging (MRI) environments. Information has been obtained from original research papers published in international peer-reviewed journals in the English language and from documents published by governmental bodies and authorities. An overview of the occupational exposure scenarios to static magnetic fields, motion-induced, time-varying magnetic fields, and gradient and radiofrequency fields is provided, together with a summary of the relevant regulation for limiting exposure. A particular emphasis is on reviewing the main EMF exposure assessment approaches found in the literature. Exposure assessment is carried out either by measuring the unperturbed magnetic fields in the MRI rooms, or by personal monitoring campaigns, or by the use of numerical methods. A general lack of standardization of the procedures and technologies adopted for exposure assessment has emerged, which makes it difficult to perform a direct comparison of results from different studies carried out by applying different assessment strategies. In conclusion, exposure assessment approaches based on data collection and numerical models need to be better defined in order to respond to specific research questions. That would provide for a more complete characterization of the exposure patterns and for identification of the factors determining the exposure variability. Graphical abstract Main approaches adopted in the literature to perform occupational exposure assessment to electromagnetic fields (EMFs) in magnetic resonance imaging (MRI) environments. SMF: static magnetic field; GMF: gradient magnetic fields; RF: radio-frequencies.

Reversible electroporation is used to increase the uptake of chemotherapeutic drugs in local tumor treatment (electrochemotherapy) by applying the pulsing protocol (8 rectangular pulses, 1000 V/cm, 100 µs) standardized in the framework of the European Standard Operating Procedure on Electrochemotherapy multicenter trial. Currently, new electrochemotherapy strategies are under development to extend its applicability to tumors with different histology. Electrical parameters and drug type are critical factors. A possible approach is to test pulse parameters different from European Standard Operating Procedure on Electrochemotherapy but with comparable electroporation yield (European Standard Operating Procedure on Electrochemotherapy-equivalent protocols). Moreover, the use of non-toxic drugs combined with electroporation represents the new frontier for electrochemotherapy applications; calcium electroporation has been recently proposed as a simple tool for anticancer therapy. In vitro investigations facilitate the optimization of electrical parameters and drugs for in vivo and clinical testing. In this optimization study, new pulsing protocols have been tested by increasing the pulse number and reducing the electric field with respect to the standard. European Standard Operating Procedure on Electrochemotherapy-equivalent protocols have been identified in HL-60 and A431 cancer cell models, and a higher sensitivity in terms of electroporation yield has been recorded in HL-60 cells. Moreover, cell killing efficacy of European Standard Operating Procedure on Electrochemotherapy-equivalent protocols has been demonstrated in the presence of increasing calcium concentrations on both cell lines. Equivalent European Standard Operating Procedure on Electrochemotherapy protocols can be used to optimize the therapeutic effects in the clinic, where different regions of the same cancer tissue, with different electrical properties, might result in a differential electroporation yield of the standard protocol over the same tissue, or, eventually, in an override of the operational limits of the instrument. Moreover, using calcium can help overcome the drawbacks of standard drugs (side effects, high costs, difficult handling, preparation, and storage procedures). These results support the possibility of new treatment options in both standard electrochemotherapy and calcium electroporation, with clear advantages in the clinic.

Magnetic resonance imaging (MRI) has evolved rapidly over the past few decades as one of the most flexible tools in medical research and diagnostic imaging. MRI facilities are important sources of multiple exposure to electromagnetic fields for both patients and health-care staff, due to the presence of electromagnetic fields of multiple frequency ranges, different temporal variations, and field strengths. Due to the increasing use and technological advancements of MRI systems, clearer insights into exposure assessment and a better understanding of possible harmful effects due to long-term exposures are highly needed. In the present exploratory study, exposure assessment and biomonitoring of MRI workers at the Radio-diagnostics Unit of the National Cancer Institute of Naples "Pascale Foundation" (Naples, Italy) have been carried out. In particular, exposure to the MRI static magnetic field (SMF) has been evaluated by means of personal monitoring, while an application tool has been developed to provide an estimate of motion-induced, time-varying electric fields. Measurement results have highlighted a high day-to-day and worker-to-worker variability of the exposure to the SMF, which strongly depends on the characteristics of the environment and on personal behaviors, and the developed application tool can be adopted as an easy-to-use tool for rapid and qualitative evaluation of motion-induced, time-varying electric field exposure. Regarding biomonitoring, the 24 workers of the Radio-diagnostics Unit were enrolled to evaluate both spontaneous and mitomycin C-induced chromosomal fragility in human peripheral blood lymphocytes, by means of the cytokinesis-block micronucleus assay. The study subjects were 12 MRI workers, representative of different professional categories, as the exposed group, and 12 workers with no MRI exposure history, as the reference group. The results show a high worker-to-worker variability for both field exposure assessment and biomonitoring, as well as several critical issues and practicalities to be faced with in this type of investigations. The procedures for risk assessment and biomonitoring proposed here can be used to inform future research in this field, which will require a refinement of exposure assessment methods and an enlargement of the number of subjects enrolled in the biomonitoring study to gain robust statistics and reliable results.

It has been shown that magnetic fields in the extremely low frequency range (ELF-MF) can act as a stressor in various in vivo or in vitro systems, at flux density levels below those inducing excitation of nerve and muscle cells, which are setting the limits used by most generally accepted exposure guidelines, such as the ones published by the International Commission on Non-Ionizing Radiation Protection. In response to a variety of physiological and environmental factors, including heat, cells activate an ancient signaling pathway leading to the transient expression of heat shock proteins (HSPs), which exhibit sophisticated protection mechanisms. A number of studies suggest that also ELF-MF exposure can activate the cellular stress response and cause increased HSPs expression, both on the mRNA and the protein levels. In this review, we provide some of the presently available data on cellular responses, especially regarding HSP expression, due to single and combined exposure to ELF-MF and heat, with the aim to compare the induced effects and to detect possible common modes of action. Some evidence suggest that MF and heat can act as costressors inducing a kind of thermotolerance in cell cultures and in organisms. The MF exposure might produce a potentiated or synergistic biological response such as an increase in HSPs expression, in combination with a well-defined stress, and in turn exert beneficial effects during certain circumstances.

In this study, the effect of radiofrequency (RF) exposure to 1950 MHz, Universal Mobile Telecommunication System signal, was investigated in Chinese hamster lung fibroblast cell line (V79). Genotoxic and cytotoxic effects of 20-h exposure at specific absorption rate (SAR) values from 0.15 W/kg to 1.25 W/kg were measured by means of cytokinesis-block micronucleus (MN) assay. Exposure was carried out blinded under strictly controlled conditions of dosimetry and temperature. The effect of RF exposure alone at four SAR values was tested, that is, 0.15, 0.3, 0.6, and 1.25 W/kg. A statistically significant increase in MN frequency was found in cultures exposed to 0.15 and 0.3 W/kg (P < 0.05) compared to sham-exposed ones, in the absence of cytotoxicity. SAR values of 0.6 and 1.25 W/kg did not exert any effect. Moreover, to evaluate the ability of RF to exert protective effects with respect to a chemical mutagen, cell cultures were also pre-exposed for 20 h at 0.3 or 1.25 W/kg, and then treated with 500 ng/ml of mitomycin-C (MMC). A significant reduction in the frequency of MN was detected in cultures pre-exposed to 1.25 W/kg compared to cultures treated with MMC alone (P < 0.05), indicating induction of adaptive response. Such a decrease was not induced by pre-exposure at 0.3 W/kg SAR. Taken together, our results indicated that V79 is a sensitive cell model to evidence either adverse or beneficial effects of RF exposure, depending on experimental conditions applied. Bioelectromagnetics. 38:245-254, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)

Possible hazardous effects of radiofrequency electromagnetic fields (RF-EMF) at low exposure levels are controversially discussed due to inconsistent study findings. Therefore, the main focus of the present study is to detect if any statistical association exists between RF-EMF and cellular responses, considering cell proliferation and apoptosis endpoints separately and with both combined as a group of "cellular life" to increase the statistical power of the analysis. We searched for publications regarding RF-EMF in vitro studies in the PubMed database for the period 1995-2014 and extracted the data to the relevant parameters, such as cell culture type, frequency, exposure duration, SAR, and five exposure-related quality criteria. These parameters were used for an association study with the experimental outcome in terms of the defined endpoints. We identified 104 published articles, from which 483 different experiments were extracted and analyzed. Cellular responses after exposure to RF-EMF were significantly associated to cell lines rather than to primary cells. No other experimental parameter was significantly associated with cellular responses. A highly significant negative association with exposure condition-quality and cellular responses was detected, showing that the more the quality criteria requirements were satisfied, the smaller the number of detected cellular responses. According to our knowledge, this is the first systematic analysis of specific RF-EMF bio-effects in association to exposure quality, highlighting the need for more stringent quality procedures for the exposure conditions.

The last decades have seen increased interest toward possible adverse effects arising from exposure to intense static magnetic fields. This concern is mainly due to the wider and wider applications of such fields in industry and clinical practice; among them, Magnetic Resonance Imaging (MRI) facilities are the main sources of exposure to static magnetic fields for both general public (patients) and workers. In recent investigations, exposures to static magnetic fields have been demonstrated to elicit, in different cell models, both permanent and transient modifications in cellular endpoints critical for the carcinogenesis process. The World Health Organization has therefore recommended in vitro investigations as important research need, to be carried out under strictly controlled exposure conditions. Here we report on the absence of effects on cell viability, reactive oxygen species levels and DNA integrity in MRC-5 human foetal lung fibroblasts exposed to 370 mT magnetic induction level, under different exposure regimens. Exposures have been performed by using an experimental apparatus designed and realized for operating with the static magnetic field generated by permanent magnets, and confined in a magnetic circuit, to allow cell cultures exposure in absence of confounding factors like heating or electric field components.

The impact of pulse repetition rate (PRR) in modulating electroporation (EP) induced by nanosecond pulsed electric fields (nsPEFs) in mammalian cells was approached here by performing both biological and numerical analysis. Plasma membrane permeabilization and viability of Jurkat cells were analyzed after exposure to 500, 1.3 MV/m, 40 ns PEFs with variable PRR (2-30 Hz). A finite-element model was used to investigate EP dynamics in a single cell under the same pulsing conditions, by looking at the time course of transmembrane voltage and pore density on the ns time scale. The biological observations showed an increased EP and reduced viability of the exposed cells at lower PRR in the considered range. The numerical analysis resulted in different dynamics of plasma membrane response when ns pulses were delivered with different PRR, consistently with a phenomenon of electrodesensitization recently hypothesized by another research group.

Aim: This study was designed to investigate the cytotoxicity of multiwalled carbon nanotube buckypaper (BP) in stimulated human peripheral blood lymphocytes. Materials & methods & results: BP treatment led to a delay in the cell growth, as proven by a minor increase in the cell number over time relative to that seen in untreated cells, assessed by trypan blue, resazurin and neutral red assays. The analysis of cell-cycle profile, by propidium iodide staining, indicated that BP treatment blocked cell-cycle progression by arresting cells at the G0/G1 phase. Moreover, increased apoptosis was also recorded by Annexin V-fluorescein isothiocyanate/propidium iodide staining., Conclusion: The results presented here demonstrate an inhibitor effect of BP on cell growth that was likely through cytostatic and cytotoxic events.

The aim of this preliminary investigation was to assess whether human peripheral blood lymphocytes which have been pre-exposed to non-ionizing radiofrequency fields exhibit an adaptive response (AR) by resisting the induction of genetic damage from subsequent exposure to ionizing radiation. Peripheral blood lymphocytes from four healthy donors were stimulated with phytohemagglutinin for 24 h and then exposed for 20 h to 1950 MHz radiofrequency fields (RF, adaptive dose, AD) at an average specific absorption rate of 0.3 W/kg. At 48 h, the cells were subjected to a challenge dose (CD) of 1.0 or 1.5 Gy X-irradiation (XR, challenge dose, CD). After a 72 h total culture period, cells were collected to examine the incidence of micronuclei (MN). There was a significant decrease in the number of MN in lymphocytes exposed to RF + XR (AD + CD) as compared with those subjected to XR alone (CD). These observations thus suggested a RF-induced AR and induction of resistance to subsequent damage from XR. There was variability between the donors in RF-induced AR. The data reported in our earlier investigations also indicated a similar induction of AR in human blood lymphocytes that had been pre-exposed to RF (AD) and subsequently treated with a chemical mutagen, mitomycin C (CD). Since XR and mitomycin-C induce different kinds of lesions in cellular DNA, further studies are required to understand the mechanism(s) involved in the RF-induced adaptive response.

In this study, rat pheochromocytoma (PC12) cells were exposed, as a model of neuron-like cells, to 1950 MHz radiofrequency (RF) radiation with a signal used by the 3G wireless technology of the Universal Mobile Telecommunications System (UMTS) to assess possible adverse effects. RF exposure for 24 h at a specific absorption rate (SAR) of 10 W/kg was carried out in a waveguide system under accurately controlled environmental and dosimetric parameters. DNA integrity, cell viability, and apoptosis were investigated as cellular endpoints relevant for carcinogenesis and other diseases of the central nervous system. Very sensitive biological assays were employed to assess the effects immediately after RF exposure and 24 h later, as demonstrated by the cellular response elicited in PC12 cells using positive control treatments provided for each assay. In our experimental conditions, 24 h of RF exposure at a carrier frequency and modulation scheme typical of a UMTS signal was not able to elicit any effect in the selected cellular endpoints in undifferentiated PC12 cells, despite the application of a higher SAR value than those applied in the majority of the studies reported in the literature., (Copyright © 2012 Wiley Periodicals, Inc.)

The induction of an adaptive response (AR) was examined in human peripheral blood lymphocytes exposed to non-ionizing radiofrequency fields (RF). Cells from nine healthy human volunteers were stimulated for 24h with phytohaemagglutinin and then exposed for 20h to an adaptive dose (AD) of a 1950MHz RF UMTS (universal mobile telecommunication system) signal used for mobile communications, at different specific absorption rates (SAR) of 1.25, 0.6, 0.3, and 0.15W/kg. This was followed by treatment of the cells at 48h with a challenge dose (CD) of 100ng/ml mitomycin C (MMC). Lymphocytes were collected at the end of the 72h total culture period. The cytokinesis-block method was used to record the frequency of micronuclei (MN) as genotoxicity end-point. When lymphocytes from six donors were pre-exposed to RF at 0.3W/kg SAR and then treated with MMC, these cells showed a significant reduction in the frequency of MN, compared with the cells treated with MMC alone; this result is indicative of induction of AR. The results from our earlier study indicated that lymphocytes that were stimulated for 24h, exposed for 20h to a 900MHz RF GSM (global system for mobile communication) signal at 1.25W/kg SAR and then treated with 100ng/ml MMC, also exhibited AR. These overall data suggest that the induction of AR depends on RF frequency, type of the signal and SAR. Further characterization of RF-induced AR is in progress., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Comet assay is one of the most popular tests for the detection of DNA damage at single cell level. In this study, an algorithm for comet assay analysis has been proposed, aiming to minimize user interaction and providing reproducible measurements. The algorithm comprises two-steps: (a) comet identification via Gaussian pre-filtering and morphological operators; (b) comet segmentation via fuzzy clustering. The algorithm has been evaluated using comet images from human leukocytes treated with a commonly used DNA damaging agent. A comparison of the proposed approach with a commercial system has been performed. Results show that fuzzy segmentation can increase overall sensitivity, giving benefits in bio-monitoring studies where weak genotoxic effects are expected.

Purpose: To investigate the influence of cell cycle on the adaptive response (AR) induced by the exposure of human blood lymphocytes to radiofrequency fields (RF)., Materials and Methods: Human peripheral blood lymphocytes in G(0)-, G(1)- or S-phase of the cell cycle were exposed for 20 hours to an adaptive dose (AD) of 900 MHz RF at an average specific absorption rate of 1.25 W/kg and then treated with a challenge dose (CD) of 100 ng/ml mitomycin C (MMC). Un-exposed and sham-exposed controls as well as cells treated with MMC alone were included in the study. The incidence of micronuclei (MN) was evaluated to determine the induction of AR., Results: The results indicated that the cells which were exposed to AD of RF in G(0)- and G(1)-phase of the cell cycle did not exhibit AR while such a response was observed when the cells were exposed to AD of RF in S-phase of the cell cycle., Conclusions: These results confirmed the observations reported in our previous investigation where AR was observed in human blood lymphocytes exposed to AD of RF in S-phase of the cell cycle and further suggested that the timing of AD exposure of RF is important to elicit AR.

Intense nanosecond pulsed electric fields (nsPEFs) interact with cellular membranes and intracellular structures. Investigating how cells respond to nanosecond pulses is essential for a) development of biomedical applications of nsPEFs, including cancer therapy, and b) better understanding of the mechanisms underlying such bioelectrical effects. In this work, we explored relatively mild exposure conditions to provide insight into weak, reversible effects, laying a foundation for a better understanding of the interaction mechanisms and kinetics underlying nsPEF bio-effects. In particular, we report changes in the nucleus of Jurkat cells (human lymphoblastoid T cells) exposed to single pulses of 60 ns duration and 1.0, 1.5 and 2.5 MV/m amplitudes, which do not affect cell growth and viability. A dose-dependent reduction in alkaline comet-assayed DNA migration is observed immediately after nsPEF exposure, accompanied by permeabilization of the plasma membrane (YO-PRO-1 uptake). Comet assay profiles return to normal within 60 minutes after pulse delivery at the highest pulse amplitude tested, indicating that our exposure protocol affects the nucleus, modifying DNA electrophoretic migration patterns.

The single-cell gel electrophoresis (SCGE) or comet assay is a simple and sensitive method for quantitatively measuring DNA breakage and repair in individual cells. It can be applied to proliferating and non-proliferating cells and cells of those tissues, which are the first contact sites for mutagenic/carcinogenic substances. In this technique, cells are embedded in agarose, lysed, subjected to electrophoresis, and stained with a fluorescent DNA-binding dye. Cells with increased DNA damage display increased DNA migration from the nucleus toward the anode, which resembles the shape of a comet. The migration is observed by fluorescence microscopy after staining with a fluorescent DNA-binding dye, and the intensity of the comet tail reflects the number of DNA breaks. The assay is performed in almost all eukaryotic cells and has applications in many fields, including genetic toxicology, biomonitoring, ecotoxicology, medical, and nutritional research. The assay is a very sensitive tool to investigate the effect of carbon nanotubes on DNA of human cells in vitro. This chapter describes a procedure to perform the comet assay, in its alkaline version, on cell cultures treated with carbon nanotubes.

The aim of this study was to investigate DNA damage in human dermal fibroblasts from a healthy subject and from a subject affected by Turner's syndrome that were exposed for 24 h to radiofrequency (RF) radiation at 900 MHz. The RF-radiation exposure was carried out alone or in combination with 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a well-known environmental mutagen and carcinogen produced during the chlorination of drinking water. Turner's syndrome fibroblasts were also exposed for a shorter time (1 h). A signal similar to that emitted by Global System for Mobile Communications (GSM) mobile phones was used at a specific absorption rate of 1 W/kg under strictly controlled conditions of temperature and dosimetry. To evaluate DNA damage after RF-radiation exposure alone, the alkaline comet assay and the cytokinesis-block micronucleus assay were used. In the combined-exposure experiments, MX was given at a concentration of 25 microM for 1 h immediately after the RF-radiation exposure, and the effects were evaluated by the alkaline comet assay. The results revealed no genotoxic and cytotoxic effects from RF radiation alone in either cell line. As expected, MX treatment induced an increase in DNA migration in the comet assay, but no enhancement of the MX-induced DNA damage was observed in the cells exposed to RF radiation.

In the present study the third generation wireless technology of the Universal Mobile Telecommunication System (UMTS) signal was investigated for the induction of genotoxic effects in human leukocytes. Peripheral blood from six healthy donors was used and, for each donor, intermittent exposures (6 min RF on, 2 h RF off) at the frequency of 1950 MHz were conducted at a specific absorption rate of 2.2 W/kg. The exposures were performed in a transverse electro magnetic (TEM) cell hosted in an incubator under strictly controlled conditions of temperature and dosimetry. Following long duration intermittent RF exposures (from 24 to 68 h) in different stages of the cell cycle, micronucleus formation was evaluated by applying the cytokinesis block micronucleus assay, which also provides information on cell division kinetics. Primary DNA damage (strand breaks/alkali labile sites) was also investigated following 24 h of intermittent RF exposures, by applying the alkaline single cell gel electrophoresis (SCG)/comet assay. Positive controls were included by treating cell cultures with Mitomycin-C and methylmethanesulfonate for micronucleus and comet assays, respectively. The results obtained indicate that intermittent exposures of human lymphocytes in different stages of cell cycle do not induce either an increase in micronucleated cells, or change in cell cycle kinetics; moreover, 24 h intermittent exposures also fail to affect DNA structure of human leukocytes soon after the exposures, likely indicating that repairable DNA damage was not induced., ((c) 2007 Wiley-Liss, Inc.)

The single-wall carbon nanotubes (SWCNTs) are one of the new materials ofemerging technologies. They are becoming increasingly studied for the possibleapplications in electronics, optics and biology. In particular, very promising fields ofapplication are the development of optical biosensors and the intracellular drug delivery.Nevertheless, there is a paucity of information on their toxicological properties and onpotential human health risk. In the present study the SWCNTs were investigated for thepossible induction of toxicity in human blood cells. Cell growth, viability, apoptosis andmetabolic activity were evaluated in proliferating human peripheral blood lymphocytes. Inun-stimulated human leukocytes primary DNA damage was also evaluated. SWCNTsconcentrations ranging from 1 to 50 μg/ml were tested, and treatment duration varied from6 to 72 h, in accordance with the biological target investigated. A statistically significantdecrease in cell growth was found in cells treated with the highest concentrations (25 and50 μg/ml). Such decrease was not associated to cell death or apoptosis, but it wasdemonstrated to be related to a decrease in metabolic activity, as assessed by resazurinassay. Moreover, treatments of 6 h with SWCNTs concentrations of 1, 5 and 10 μg/mlfailed to induce primary DNA damage on the entire human leukocytes population.

Emerging technologies are considering the possible use of Terahertz radiation in different fields ranging from telecommunications to biology and biomedicine. The study of the potential effects of Terahertz radiation on biological systems is therefore an important issue in order to safely develop a variety of applications. This paper describes a pilot study devoted to determine if Terahertz radiation could induce genotoxic effects in human peripheral blood leukocytes. For this purpose, human whole blood samples from healthy donors were exposed for 20 min to Terahertz radiation. Since, to our knowledge, this is the first study devoted to the evaluation of possible genotoxic effects of such radiation, different electromagnetic conditions were considered. In particular, the frequencies of 120 and 130 GHz were chosen: the first one was tested at a specific absorption rate (SAR) of 0.4 mW g-1, while the second one was tested at SAR levels of 0.24, 1.4, and 2 mW g-1. Chromosomal damage was evaluated by means of the cytokinesis block micronucleus technique, which also gives information on cell cycle kinetics. Moreover, human whole blood samples exposed to 130 GHz at SAR levels of 1.4 and 2 mW g-1 were also tested for primary DNA damage by applying the alkaline comet assay immediately after exposure. The results obtained indicate that THz exposure, in the explored electromagnetic conditions, is not able to induce either genotoxicity or alteration of cell cycle kinetics in human blood cells from healthy subjects.

The aim of this study was to investigate the induction of reactive oxygen species in murine L929 fibrosarcoma cells exposed to radiofrequency (RF) radiation at 900 MHz, with or without co-exposure to 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), a potent environmental carcinogen produced during chlorination of drinking water. Both continuous-wave and GSM mobile phone signals were applied for 10 or 30 min at specific absorption rates of 0.3 and 1 W/kg. Simultaneous sham exposures were performed for each exposure condition. MX treatment was performed at a subtoxic level of 500 microM, and the RF-field exposure was carried out during the first 10 or 30 min of the chemical treatment. The formation of reactive oxygen species was followed soon after the exposure and at different harvesting times until 1 h after RF-field treatment. The studied provided no indication that 900 MHz RF-field exposure, either alone or in combination with MX, induced formation of reactive oxygen species under any of the experimental conditions investigated. In contrast, exposure to MX resulted in a statistically significant increase in the formation of reactive oxygen species for all the treatment durations investigated, confirming that MX is an inductor of oxidative stress in L929 cells.

Human peripheral blood leukocytes from healthy volunteers have been employed to investigate the induction of genotoxic effects following 2 h exposure to 900 MHz radiofrequency radiation. The GSM signal has been studied at specific absorption rates (SAR) of 0.3 and 1 W/kg. The exposures were carried out in a waveguide system under strictly controlled conditions of both dosimetry and temperature. The same temperature conditions (37.0 +/- 0.1 degrees C) were realized in a second waveguide, employed to perform sham exposures. The induction of DNA damage was evaluated in leukocytes by applying the alkaline single cell gel electrophoresis (SCGE)/comet assay, while structural chromosome aberrations and sister chromatid exchanges were evaluated in lymphocytes stimulated with phytohemagglutinin. Alterations in kinetics of cell proliferation were determined by calculating the mitotic index. Positive controls were also provided by using methyl methanesulfonate (MMS) for comet assay and mitomycin-C (MMC), for chromosome aberration, or sister chromatid exchange tests. No statistically significant differences were detected in exposed samples in comparison with sham exposed ones for all the parameters investigated. On the contrary, the positive controls gave a statistically significant increase in DNA damage in all cases, as expected. Thus the results obtained in our experimental conditions do not support the hypothesis that 900 MHz radiofrequency field exposure induces DNA damage in human peripheral blood leukocytes in this range of SAR., (Copyright 2005 Wiley-Liss, Inc.)

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), the potent bacterial mutagen produced during chlorination of drinking water, was tested for the induction of oxidative stress in two murine cell lines: NIH 3T3 (fibroblasts) and L929 (fibrosarcoma cells). Following 1 h MX treatment at concentrations between 100 and 1000 microM, cellular stress conditions were monitored by measuring reactive oxygen species formation (ROS) and reduced glutathione levels (GSH). The kinetics of ROS formation and GSH depletion was investigated from 10 min to 1 h. MX caused detachment of cells at 1000 microM in L929 cells and at 300 microM in NIH 3T3 cells but the viability of the cells, measured by the trypan blue assay, decreased only by 20 and 7%, respectively, in 1h. MX increased ROS production in L929 cells in a dose-dependent manner, by 120% at 500 microM of MX in 1 h. The maximum ROS production was attained already in 10min. In NIH 3T3 cells, the ROS production was slightly, but not statistically significantly stimulated at 200 microM between 20 and 60 min. Concomitantly, MX decreased the intracellular content of GSH dose-dependently in both cell lines, by 48% in L929 cells at 500 microM of MX and 32% in NIH 3T3 cells at 200 microM of MX in one hour. The majority of this GSH depletion had occurred in 10 min. These findings indicate that MX induces oxidative stress in mammalian cells in vitro though the sensitivity of cells may differ for this effect.

In the present study, we investigated the induction of genotoxic effects in human peripheral blood lymphocytes after exposure to electromagnetic fields used in mobile communication systems (frequency 900 MHz). For this purpose, the incidence of micronuclei was evaluated by applying the cytokinesis-block micronucleus assay. Cytotoxicity was also investigated using the cytokinesis-block proliferation index. The experiments were performed on peripheral blood from 20 healthy donors, and several conditions were tested by varying the duration of exposure, the specific absorption rate (SAR), and the signal [continuous-wave (CW) or GSM (Global System of Mobile Communication) modulated signal]. The following exposures were carried out: (1) CW intermittent exposure (SAR = 1.6 W/kg) for 6 min followed by a 3-h pause (14 on/off cycles); (2) GSM signal, intermittent exposure as described in (1); (3) GSM signal, intermittent exposure as described in (1) 24 h before stimulation with phytohemagglutinin (8 on/off cycles); (4) GSM signal, intermittent exposure (SAR = 0.2 W/kg) 1 h per day for 3 days. The SARs were estimated numerically. No statistically significant differences were detected in any case in terms of either micronucleus frequency or cell cycle kinetics.

The aim of the present study is toinvestigate the genotoxic effect of THzradiation in human peripheral bloodlymphocytes following 20 minutes exposureto 1 mW average power Free Electron Laserradiation in the frequency range 120-140GHz. For this purpose 9 healthy donors wereemployed and cytokinesis block techniquewas applied to study micronucleusfrequency and cell proliferation. Theresults obtained indicate that all theelectromagnetic conditions adopted so far do not alter the investigated parameters,suggesting absence of direct chromosomaldamage and alteration of cell cyclekinetics (two tailed paired Student's test:p> 0.05 in all cases).

In the present study the effect of extremely low frequency pulsed magnetic fields (PMF) was evaluated in lymphocyte cultures from 12 subjects occupationally exposed to low doses of ionising radiations. The PMF signal characteristics were repetition frequency 50 Hz, triangular shape, rise time about 1.2 ms and peak intensity 2.5 mT. The cytokinesis-block technique was employed to evaluate genotoxicity and cytotoxicity in terms of micronucleus frequency and cell proliferation, respectively. When PMF-exposed cultures were compared with their respective controls, a slight but statistically significant increase was detected in both the biological parameters investigated ( p<0.05). The results obtained suggest a possible role of specific employments involving exposure to ionising radiation, in the risk associated with electromagnetic field exposure.

The present study investigated, using in vitro experiments on human lymphocytes, whether exposure to a microwave frequency used for mobile communication, either unmodulated or in presence of phase only modulation, can cause modification of cell proliferation kinetics and/or genotoxic effects, by evaluating the cytokinesis block proliferation index and the micronucleus frequency. In the GSM 1800 mobile communication systems the field is both phase (Gaussian minimum shift keying, GMSK) and amplitude (time domain multiple access, TDMA) modulated. The present study investigated only the effects of phase modulation, and no amplitude modulation was applied. Human peripheral blood cultures were exposed to 1.748 GHz, either continuous wave (CW) or phase only modulated wave (GMSK), for 15 min. The maximum specific absorption rate (approximately 5 W/kg) was higher than that occurring in the head of mobile phone users; however, no changes were found in cell proliferation kinetics after exposure to either CW or GMSK fields. As far as genotoxicity is concerned, the micronucleus frequency result was not affected by CW exposure; however, a statistically significant micronucleus effect was found following exposure to phase modulated field. These results would suggest a genotoxic power of the phase modulation per se., (Copyright 2002 Wiley-Liss, Inc.)

In the present study micronucleus induction and cell proliferation in human peripheral blood lymphocytes cultured in vitro and exposed to 50 Hz sinusoidal magnetic fields for 72 h at different intensities (1.0, 0.75, 0.5, 0.25, and 0.05 mT rms) were investigated. The results obtained from 42 healthy donors aged between 26 and 54 y indicate that, for the field intensities tested, no genotoxic effects were found, as assessed by the cytokinesis-block micronucleus assay. On the contrary, cell proliferation, evaluated by the cytokinesis-block proliferation index, was slightly affected by the field at the intensities tested.

The genotoxic activity of the pesticides gliphosate, vinclozolin and DPX-E9636 was studied in in vitro cultures of bovine lymphocytes, using chromosome aberration (CA) and sister chromatid exchange (SCE) frequencies as genetic end-points and a variation of glucose 6-phosphate dehydrogenase (G6PD) enzyme activity as a marker of changes in the normal cell redox state. Results indicated a statistically significant increase of structural aberrations, sister chromatid exchanges and G6PD activity, suggesting that the pesticides tested induce either oxidative stress or a mutagenic effect in this species. The evaluation of both mitotic index and cell viability, after pesticide exposure, demonstrates a high cytotoxic effect which is always associated with the observed genotoxic effect.

We analyzed chromosome aberrations (CAs), sister chromatid exchanges (SCEs), mitotic index (MI), and glucose 6-phosphate dehydrogenase (G6PD) enzyme activity in human peripheral lymphocytes from three healthy donors exposed in vitro to different concentrations of gliphosate, vinclozolin, atrazine, and DPX-E9636. The pesticides gliphosate, vinclozolin, and atrazine have been studied in a broad range of genetic tests with predominantly conflicting or negative results, whereas little is known about the genotoxicity of DPX-E9636. In our experimental conditions, each chemical compound tested produced a dose-related increase in the percent of aberrant cells and an increase of SCE/cell. Furthermore, at the highest concentrations of vinclozolin, atrazine, and DPX-E9636, we observed a significant reduction of the mitotic index. The increase of G6PD activity in exposed lymphocyte cultures strongly indicated an induction of a pro-oxidant state of the cells as an initial response to pesticide exposure.

Peripheral blood lymphocytes from 15 subjects affected by Turner's syndrome (TS) and aged between 2 and 24 years (mean age 10.40 +/- 6.25) were tested to evaluate the spontaneous and Mitomycin-C-induced (MMC) micronucleus (MN) frequency. A group of 15 healthy subjects, in the same range of age (mean age 14.67 +/- 8.30), was also tested as control. As expected, statistically significant differences between spontaneous and MMC-induced MN were found either in TS and in healthy subjects. Unexpectedly, when the two groups of donors were compared, TS subjects showed a lower spontaneous and MMC-induced MN frequency, in comparison with healthy subjects. Cell proliferation kinetic and cytotoxicity were also measured applying the cytokinesis-block proliferation index (CBPI): the results show that MMC, at the employed concentration, does not induce cell cycle delay both in healthy and in TS donors. Whereas, when CBPI from TS and healthy donors were compared, a faster proliferation was found in TS patients in both untreated and MMC-treated cultures.

We exposed human peripheral blood lymphocyte cultures to 50 Hz pulsed magnetic fields (PMFs) in order to evaluate a possible genotoxic effect of such non-ionizing radiation. The genotoxic effect was evaluated in terms of both micronucleus (MN) induction and classical chromosomal aberrations (CA); the mitotic index (MI) was also calculated. Khalil and Qassem (1991) found chromosomal and chromatid breaks and mitotic delay in human lymphocytes exposed for 24, 48 and 72 h to a field with characteristics similar to those used in our laboratory. These data are in contrast with our results previously reported in terms of MN induction using the cytokinesis block method (Scarfi et al., 1991). In this study lymphocytes from five healthy human donors were examined with the above mentioned tests. No genotoxic effects and increased MI were found in exposed samples compared to the control ones, in agreement with our previous results.

The present study was carried out in order to set up a standardized quantitative assay for spontaneous micronuclei in bovine lymphocytes. For this purpose the cytokinesis-block micronucleus (MN) method, originally proposed by Fenech and Morley (1985) for human lymphocytes, was applied to peripheral blood lymphocytes of 20 healthy cows of Italian Friesian breed. The results demonstrate that the optimal concentration of cytochalasin B to obtain the highest frequency of binucleated cells (mean = 400.26 +/- 23.76/1000 cells scored) was 6 micrograms/ml. The baseline frequency of spontaneous MN formation in 500 binucleated cells was 12.3 +/- 4.1, i.e., 3 times higher than that reported in human lymphocytes (Fenech and Morley, 1985; Scarfi et al., 1991). The possible reason(s) for this difference (sensitivity to cytochalasin B, chromosome number, environmental genotoxic pollutants) is discussed.

Electromagnetic fields produce a variety of effects in several biological systems, including human peripheral blood lymphocytes. A great concern exists regarding possible carcinogenic effects in subjects exposed environmentally to such fields in the vicinity of power lines and electric domestic appliances. Using human lymphocytes from 33 healthy donors and a sensitive cytogenetic method, the cytokinesis-block micronucleus assay, we have demonstrated that the exposure to 50-Hz AC sinusoidal electric fields over a wide range of intensities (0.5-10 kV/m in air) does not increase the spontaneous frequency of micronuclei. Moreover, these fields did not affect the mitomycin-C-induced micronucleus formation, suggesting that they did not exert any synergistic or antagonistic effect.