Biomedical subjects

M Zmyślony

Publications and source records attributed to M Zmyślony.

18 recordsLinked to original sources

PubMed2001

Protective effect of melatonin against in vitro iron ions and 7 mT 50 Hz magnetic field-induced DNA damage in rat lymphocytes.

We have previously shown that simultaneous exposure of rat lymphocytes to iron ions and 50Hz magnetic field (MF) caused an increase in the number of cells with DNA strand breaks. Although the mechanism of MF-induced DNA damage is not known, we suppose that it involves free radicals. In the present study, to confirm our hypothesis, we have examined the effect of melatonin, an established free radicals scavenger, on DNA damage in rat peripheral blood lymphocytes exposed in vitro to iron ions and 50Hz MF. The alkaline comet assay was chosen for the assessment of DNA damage. During pre-incubation, part of the cell samples were supplemented with melatonin (0.5 or 1.0mM). The experiments were performed on the cell samples incubated for 3h in Helmholtz coils at 7mT 50Hz MF. During MF exposure, some samples were treated with ferrous chloride (FeCl2, 10microg/ml), while the rest served as controls. A significant increase in the number of cells with DNA damage was found only after simultaneous exposure of lymphocytes to FeCl2 and 7mT 50Hz MF, compared to the control samples or those incubated with FeCl2 alone. However, when the cells were treated with melatonin and then exposed to iron ions and 50Hz MF, the number of damaged cells was significantly reduced, and the effect depended on the concentration of melatonin. The reduction reached about 50% at 0.5mM and about 100% at 1.0mM. Our results indicate that melatonin provides protection against DNA damage in rat lymphocytes exposed in vitro to iron ions and 50Hz MF (7mT). Therefore, it can be suggested that free radicals may be involved in 50Hz magnetic field and iron ions-induced DNA damage in rat blood lymphocytes. The future experimental studies, in vitro and in vivo, should provide an answer to the question concerning the role of melatonin in the free radical processes in the power frequency magnetic field.

Animals↗

PubMed2001

[Exposure to VHF and UHF electromagnetic fields among workers employed in radio and TV broadcast centers. I. Assessment of exposure].

Nowadays, radio and television have become one of the areas of the human technical activity that develops most rapidly. Also ultra-short waves of VHF (30-300 MHz) and UHF (0.3-3 GHz) bands have proved to be the most important carriers of radio and TV-programs. In Poland, a network of radio and TV broadcast centers (RTCN) with high (over 200 m) masts was set up in the 1960s and 1970s. These centers concentrate the majority of stations broadcasting national and local programs (for areas within the RTCN range). At present, the RTCN established several decades ago are equally important. The assessment of the exposure to electromagnetic fields among workers of multi-program broadcast stations is complicated and feasible only to a certain degree of approximation because of changing conditions of exposure in individual stations during their long history, resulting from the changing numbers and types of transmitters installed. In this work, the method of retrospective estimation of exposure dose is described, and the results of the assessment carried out at three kinds of typical RTCN are discussed. The results of the analysis indicate that the workers of RTCN are exposed primarily to electromagnetic fields of VHF and UHF bands, but this exposure may be considered as admissible, hence it should not exert an adverse effect on the workers' health.

Electromagnetic Fields↗

PubMed2000

DNA damage in rat lymphocytes treated in vitro with iron cations and exposed to 7 mT magnetic fields (static or 50 Hz).

The present study was undertaken to verify a hypothesis that exposure of the cells to static or 50 Hz magnetic fields (MF) and simultaneous treatment with a known oxidant, ferrous chloride, may affect the oxidative deterioration of DNA molecules. The comet assay was chosen for the assessment of DNA damage. The experiments were performed on isolated rat lymphocytes incubated for 3h in Helmholtz coils at 7 mT static or 50 Hz MF. During MF exposure, part of the cell samples were incubated with 0.01 microM H(2)O(2) and another one with 10 microg/ml FeCl(2,) the rest serving as controls. Lymphocyte exposure to MF at 7 mT did not increase the number of cells with DNA damage in the comet assay. Incubation of lymphocytes with 10 microg/ml FeCl(2) did not produce a detectable damage of DNA either. However, when the FeCl(2)-incubated lymphocytes were simultaneously exposed to 7 mT MF, the number of damaged cells was significantly increased and reached about 20% for static MF and 15% for power frequency MF. In the control samples about 97% of the cells did not have any DNA damage. It is not possible at present to offer a reasonable explanation for the findings of this investigation - the high increase in the number of lymphocytes showing symptoms of DNA damage in the comet assay, following simultaneous exposure to the combination of two non-cytotoxic factors -10 microg/ml FeCl(2) and 7 mT MF. In view of the obtained results we can only hypothesise that under the influence of simultaneous exposure to FeCl(2) and static or 50 Hz MF, the number of reactive oxygen species generated by iron cations may increase substantially. Further studies will be necessary to confirm this hypothesis and define the biological significance of the observed effect.

Animals↗

PubMed2000

[The role of melatonin in the molecular mechanism of weak, static and extremely low frequency (50 Hz) magnetic fields (ELF)].

Melatonin is a neurohormone produced by the pineal gland. It has been recently found that it is also an antioxidant and a free radical scavenger. Melatonin was documented to be a direct trap of hydroxyl and peroxyl radicals. Therefore, this hormone could protect cells, tissues and organs against oxidative (free radicals) damage (DNA, protein, lipids). It has been suggested that noxious effects of ELF exposure (cancer or immunological disturbances) could be due to increased the concentration of free radicals induced by magnetic field. This is also leading to a hypothesis that melatonin suppression (by electromagnetic fields) in humans may increase the probability of mutagenic and carcinogenic risks. The future experiments, in vitro and in vivo, should provide an answer to the question on what is the real role of melatonin in the molecular (free radicals) mechanisms of weak magnetic fields.

Humans↗

PubMed2000

[Cellular radio systems. Problems faced in assessing exposure to electromagnetic fields].

Over twenty years of its existence, cellular radio systems have become one of the major sources of human exposure to electromagnetic field (EMF) of high frequency. With the increasing number of cellular phones, the interest in health effects of exposure to EMF emitted by them continues to grow. At present, there is a general opinion that thermal effect (change of electromagnetic energy into thermal energy) is an essential mechanism of possible biological effects. The majority of world standards for exposure to EMF are based on this effect. The author presents Polish standards and those of the International Commission on Nonionizing Radiation Protection (ICNIRP) for EMF of frequencies used in cellular radio systems, both basic that limits SAR (Specific Absorption Rate), and derived that limits the power density, as well as intensity of electric and magnetic fields. Attention was also turned to the problems concerning the application of cellular phones and those resulting from the character of the field emitted by them to which their users are exposed. Bearing in mind the results of the laboratory analyses of SAR values occurring in the user's head, and measurements of power density in the vicinity of the base station antennas, it can be stated that, in view of binding and recommended standards, cellular phones do not present any hazard to their users (private or professional). However, it should be stressed that standards adopted protect the user's head against the thermal effect, whereas the question on whether they also protect against non-thermal effects still remains without answer.

Electromagnetic Fields↗

PubMed2000

[Occupational exposure to electromagnetic fields and its health effects in electric energy workers].

Power frequency (50 to 60 Hz) electromagnetic fields (EMF) are briefly characterised, EMF sources occurring in the electromagnetic industry are discussed, and methods for and problems involved in the evaluation of individual occupational EMF exposure are also presented. The results of certain cohort industrial and case-referent studies indicate slightly enhanced risk of brain cancer and leukaemia in the group under study. The meta-analysis of the results obtained from numerous studies, published recently, showed a relative risk (RR) of 1.1-1.3 for leukaemia, and of 1.1-1.2 for brain cancer. Only a few studies demonstrate a dose-effect relationship for malignant neoplasms which decreases the power of the hypothesis on the cause-effect relationship. Among health effects of EMF exposure in electric utility workers, other than malignant neoplasms, an increased risk of certain diseases of the circulatory and neurological systems has been reported. The difficulty in the assessment of individual exposure is the main problem in evaluating the relationship between EMF exposure and adverse health effects in electric utility workers. We hope to investigate this further.

Brain Neoplasms↗

PubMed1999

[The evaluation of the exposure of seamstresses to electromagnetic fields, emitted by sewing machines].

The authors present the results of the first phase of the studies on the risk of pregnancy complications in semesters and on their work environment with special reference to electromagnetic fields (EMF) emitted by various types of industrial sewing machines. EMF measurements were taken in the surrounding of 464 sewing machines used in five sewing works in the region of Lodź. The results obtained provided evidence that semesters++ working with industrial sewing machines were exposed to EMF of 60 Hz. Thirteen types of machines were identified. Having based on the statistical analysis (analysis of variance) it was found that individual types of sewing machines emit substantially different EMFs. Depending on the level of EMF emitted at a given workpost, all the machines were classified into three groups: those with weak (O A/m-1.5 A/m); medium (2 A/m-4 A/m); and strong (9 A/m-16 A/m) emissions.

Electromagnetic Fields↗

PubMed1998

[The role of free radicals in mechanisms of biological function exposed to weak, constant and net magnetic fields].

For many years biological effect of magnetic fields has been the subject of great interest. Based on the current body of knowledge, many specialists suggest that it may play some role in the process of embryogenesis and teratogenesis; disturb the functioning of the central nervous and immunological systems; and effect cellular growth and differentiation, particularly in terms of carcinogenesis. However, sufficient evidence collaborating the assumption of health hazard arising from general exposure to magnetic field has not as yet been provided. At present, very intensive studies have been carried out in order to elucidate the mechanism of the effect of magnetic fields both in terms of physical and biological aspects. The authors present the most recognised hypotheses among those suggested in this area. They devote more attention to the hypothesis on a possible effect of weak magnetic fields, namely those observed in the occupational and commmunal environments, on free radicals which play a key role in a number of processes occurring in live organisms. The results of in vitro studies which confirm that such a mechanism does exist in simple biological systems are also discussed. The effect of this mechanism on the whole organism is still unknown. The future experimental, particularly in vivo, studies should provide a final answer to the question whether the effects observed are only transient ones or whether they play a decisive role in the mechanism of magnetic fields affecting human organism.

Animals↗

PubMed1998

[Exposure to electromagnetic fields with frequencies of 50 Hz and changes in the circulatory system in workers at electrical power stations].

Bearing in mind a great diffusion of electromagnetic fields (EMF) with power-line frequency (in Poland-50 Hz) both in the occupational and communal environments, it is not surprising that possible health effects related to this exposure evoke much interest. Electromagnetic fields may affect the circulatory and nervous systems because of theoretical probability that electric impulses, generated by external electric and magnetic fields, may disturb their functions. For this reason we have decided to evaluate the functioning of the circulatory system in persons occupationally exposed to power-line frequency electromagnetic fields by employing the most up-to-date methods facilitating the in-depth diagnosis of the circulatory system and neurovegetative mechanisms. The work presented focused on the evaluation of electrocardiographic changes. The study covered 63 workers of the transforming and distributing stations, aged 22-67 years (median 39 +/- 10), employed under exposure for 2-43 years (median 15 +/- 10). The control group consisted of 42 workers of radio link stations, aged 23-65 years (median 30 +/- 14), employed in the similar system but not exposed to EMF, with employment duration of 1-42 years (median 13 +/- 4). All persons were subject to general medical examinations, resting ECG, and 24 h Holter monitoring. In addition, the level of exposure in individual workplaces was estimated following the measurements of the intensity of electric and magnetic fields. In workers of electromagnetic stations an increased risk for electrocardiographic disturbances was revealed. Under conditions of exposure to electric fields, observed in stations where workers were employed, the risk was increased by 10%.

Adult↗

PubMed1997

[Evaluation of selected functional circulation parameters of workers from various occupational groups exposed to electromagnetic fields of high frequency. III. 24-h monitoring of arterial blood pressure (ABP)].

The problem of blood pressure regulation in persons occupationally exposed to electromagnetic fields (EMF) has not as yet been elucidated, and most data come from studies carried out long time ago (1960-70) in the former Soviet Union. Our study was aimed at verifying the Soviet data by means of modern methods. Together with traditional methods, a 24-h monitoring of arterial blood pressure (ABP) using a Medilog ABP kit (Oxford) were employed. Measurements were taken automatically every 0.5 h during daily activities and every 1 h during the night rest (about 41 measurements/day). The mean systolic and diastolic blood pressure and heart rate were calculated over day (BPSDOver, BPDOver, HROver), during daily activities (HPDD, BPSD, HRD) and during the night rest (BPSN, BPDN, HRN). The subjective and objective examinations were carried out as well as resting ECG and a 24-h Holter were performed (the results have been published earlier). The study covered male workers of middlewave broadcast stations (71), radioservice (40) and radio line stations (42). The subjects were aged 21-60 years and the duration of their work with devices generating high frequency EMF ranged between 1 and 42 years. The first group of workers was exposed to EFM at the frequency of 1 Mhz, the second at about 150 Mhz and the third group, not exposed, served as the control group. The study revealed that the mean arterial blood pressure and the day/night blood pressure variability indicator showed no significant differences between the groups, whereas the daily heart rate was significantly lower in the workers of middlewave broadcast stations in comparison with the controls despite similar type of work as far as physical effort and psychic burden are concerned, and similar non-occupational activities. The day/night heart rate variability indicator was significantly lower in the groups exposed. The decreased value of this indicator may suggest the occurrence of disorders in the neurovegetative regulation. In persons employed at radioservice stations a higher incidence of the increased arterial blood pressure, in comparison with the control group, was observed.

Adult↗

PubMed1997

[The present state of knowledge concerning the effect of electromagnetic fields of 50/60 Hz on the circulatory system and the autonomic nervous system].

Diseases of the circulatory system together with neoplastic diseases are recognised as the major health problem in the contemporary world. Their origin and aggravation may be related to the exposure to electromagnetic fields (EMFs) since theoretically, disorders in the functioning of the circulatory system are most likely due to electric impulses generated in it by external magnetic fields. The nervous system, including its autonomic part which regulates, among others, the functioning of the circulatory system, because of its electric nature is another system which may be disturbed by EMFs. From the 1960s, biological studies on the effects of power-line frequency EMFs have been carried out in many countries. In view of the applied study model, four main directions of these studies can be identified: in vitro and in vivo animal experiments, experimental studies on humans, clinical and epidemiological studies. Experimental studies on animals and humans have yielded ambiguous and very often contradictory results. Some of them indicate that EMF contributes to slowing down the cardiac rhythm and the stroke volume of the left ventricle, other results suggest their acceleration, and still other show no differences. The results of clinical studies performed in many countries in different groups of workers exposed to power-line frequency EMFs have not produced the evidence for drawing unequivocal conclusions. Again some studies reveal that those exposed show disorders in neurovegetative and blood pressure regulations (hypotension or hypertension) as well as in cardiac rhythm (bradycardia or tachycardia). Other studies do not confirm harmful effect of EMF on the circulatory system. Therefore, it is not feasible to find out, on the basis of these studies, whether and how chronic exposure to power-line frequency EMFs influences the functioning of the circulatory system, the more so as ECG standard recording has been to date the only diagnostic method, and according to the present state of knowledge it is not sufficient to assess the functioning of the circulatory system. Epidemiological studies play the most important role in the evaluation of health effects of the exposure to power-line frequency EMFs. These studies have been carried out for fifteen years, however, they do not consider the effect of chronic exposure to EMF of 50 Hz frequency on the circulatory system.

Animals↗

PubMed1997

[Electromagnetic poles and reproduction].

The authors review epidemiological data concerning the relationship between reproduction disorders and the exposure to electromagnetic fields (EMF) emitted by power lines, industrial power-charged devices, diagnostic and therapeutical appliances, video display terminals (VDTs) and electric household devices. The studies involved the analysis of the EMF effect on female and male reproduction, including the risk of spontaneous abortion, still birth and premature birth, low birth weight and congenital malformations as well as on the progeny gender proportion, among persons employed under the condition of EMF exposure. It was observed that the findings were frequently inconsistent, i.e. under the same conditions of EMF exposure some date indicated its negative effect on the reproduction process and some did not. No data confirming an acute effect of occupational exposure to EMF on the risk of spontaneous abortion, low birth weight, congenital malformations or other reproduction disorders were obtained, however, the negative effect of EMF cannot be explicitly excluded.

Abortion, Spontaneous↗

PubMed1996

Heart rate variability in workers exposed to medium-frequency electromagnetic fields.

This study was undertaken to evaluate the neurovegetative regulation of the heart in workers occupationally exposed to medium frequency (MF) electromagnetic (EM) fields. The subjects were 71 workers of MF broadcast stations, aged 20-68 (mean 47.1) with the duration of work under exposure ranging from 2-40 years and 22 workers of radio link stations, aged 21-65 (mean 46.9) who were not exposed to MF EM fields. The distribution of age and work tenure in both groups did not differ significantly. Heart rate variability (HRV) was analysed basing on 512 normal heart evolutions registered in resting, from the body surface, using the Medea-HRV system. The analysis concerned time-domain and frequency-domain parameters of HRV using fast fourier transformation. Power spectrum in the low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency bands (LF and HF, respectively) was determined. Statistically insignificant differences found between exposed and non-exposed groups were found either in time- or in frequency-domain parameters of HRV. No correlation between the power spectrum and the subjects age was noted. Such a relationship, however, could be observed in the control group. In the study group a statistically significant negative correlation was found between the maximum intensity of EM fields and HF power spectrum. Thus it was concluded that occupational exposure to EM fields brings about impairments in the neurovegetative regulation of the cardiovascular function.

Adult↗

PubMed1996

[Evaluation of selected parameters of circulatory system function in various occupational groups exposed to high frequency electromagnetic fields. II. Electrocardiographic changes].

The effect of electromagnetic fields (EMF) on the circulatory and nervous systems has been the subject of great interest for many years, since electric impulses generated in these systems by outer electric and magnetic fields can theoretically disturb their functions. The only data on chronic effect of weak EMFs on the human body come from the studies carried out in the Soviet Union between the fifties and the seventies. In view of a growing number of persons exposed to EMF, there is an urgent need for verifying those data by means of modern diagnostic methods. That is the reason why our study of the EMF effect on the circulatory system has been initiated. It covered 71 workers at four AM broadcast stations, 40 workers at ten radio link stations and 42 workers at three radioservices. Workers' exposure to EMF was evaluated (see part I). Subjective and objective medical examinations were performed in all workers in order to assess their state of health, then resting electrocardiogram, Holter measurements, and high intensity ECG were taken, and variation in cardiac rhythm was analysed by a long-term recording of blood pressure. The results of the analysis of the questionnaire survey as well as the Holter and resting ECG examinations are presented. The study indicated that exposure to EMF in parameters found in AM broadcast station increased risk for electrographic disturbances (detected by means of resting ECG and a 24-hour Holter recording) by six times in comparison with that in radio link station workers not exposed to medium wave EMF. In radioservice workers this risk was twice as high as that in link station workers. It seems that in AM broadcast station workers, resting ECG should be complemented by a 24-hour Holter measurements, particularly, if workers complain of the circulatory system disturbances.

Adult↗

PubMed1996

Collection of occupational EMF exposure data in Poland. Concept of the structure and functioning.

An outline of the structure and operation principles of the database on EMF-producing devices used in Poland at frequencies ranging between 0.1 MHz and 300,000 MHz have been developed at the Nofer Institute of Occupational Medicine, Lodz. The primary objective of developing the EMF DATABASE is to ensure continuous and systematic collection of data on: quantities and types of devices and their specifications, EMF intensities produced, number of people exposed, exposure levels in absolute terms or according to specified criteria (gradation) or standards currently in force, etc. The EMF DATABASE structure is based on such a method of data collection which ensures that information searching is effected according to specified lists of parameters essential for a given main entry. The EMF DATABASE has been designed so as to ensure that it is possible to obtain as quickly as possible the desired information covering desired scope (for example cities, regions, whole country, field of application, device type, etc.). The information is presented in the form of a report, and the content of the report may differ, according to the requirements of the user. The structure of the EMF DATABASE is open to permit its extension. The DATABASE, therefore, provides the possibility of adding new data, and verifying the criteria adopted to assess exposures to EMFs. At the same time it constitutes a fundamental tool for the SYSTEM OF EMF EXPOSURE MINITORING, and a rich source of information about the subject. At the present stage of its development, the DATABASE structure and its functioning are being tested on a pilot scale. The paper presents the diagram of the DATABASE operation and some examples of information received in the form of reports.

Computers↗

PubMed1996

[Evaluation of selected parameters of circulatory system function in various occupational groups of workers exposed to high frequency electromagnetic fields].

In various branches of the national economy there is a continuous increase in the use of devices producing electromagnetic fields (EMFs). Therefore, the number of persons exposed more or less to EMFs is still growing. Moreover, devices producing electromagnetic fields such as microwave ovens, cellular phones, microwave alarms etc. are now in common use. Both theoretical deliberations and laboratory studies indicate that electromagnetic fields affect the human body inducing a number of physical phenomena manifested by biological changes or even disorders in organic functions. Because of their electric character, the circulatory and nervous systems are particularly vulnerable to the EMF effect. Studies aimed at evaluating the circulatory system in persons exposed, in different degress, to EMF were initiated at the Nofer Institute of Occupational Medicine in 1993. To date, the studies have covered a group of workers employed at AM broadcast stations, radio link stations and radioservice. As were have obtained a quite an extensive material, it is our intention to present it in a series of publications. This one deals with the evaluation of exposure in the study group of workers. Evaluation methods and results of exposure to high frequency electromagnetic fields at workplaces under are study presented. No exposure to EMFs was found in workers at radio link stations. Therefore, they can serve as a control group in the studies of the EMF effect on the circulatory system. Exposure of radioservice and AM broadcast stations workers falls within allowable levels according to binding regulations, however, exposure of the latter was by several times higher than that of radioservice workers.

Blood Circulation↗

PubMed1991

Analysis of exposure to electromagnetic fields during professional use of radiotelephones.

An environmental survey on exposure to EM fields covered over 300 radiotelephone operating in the range of 300-344 MHz with input power of 5 W, used by 574 radiooperators and 48 radiomechanics employed in sanitary transport, power engineering, municipal traffic and coal mining. The intensity of EM fields was measured and timing of effective radiotelephone transmitter work was done. According to the Polish standards, it was found that 3% of the population examined were subject to excessive exposure, 6%--to conditionally admissible only and 17%--to admissible. Exposure assessment, made for extreme conditions based on literature, theoretical and experimental data, showed that in radiomechanics' necks, eyes and wrists there may occur SAR values: 10-15 W/kg, 1-1.5 W/kg and 1.8 W/kg, respectively.

Electromagnetic Fields↗

PubMedDate not supplied

Ambulatory ECG monitoring in workers exposed to electromagnetic fields.

The aim of this study was to evaluate the function of the circulatory system in workers occupationally exposed to medium frequency electromagnetic fields. The subjects were 71 workers at four AM broadcast stations [0.738-1.503 MHz] aged 20-68 (mean 46.9 +/- 13.1) years and 22 workers at radio link stations aged 23-67 (mean 48.2 +/- 17.4) years. Workers at AM broadcast stations experienced 2-40 (mean 18.6 +/- 12.1) years' exposure to electromagnetic fields (average daily exposure dose about 115 Vh m-1, maximum exposure levels during shift about 165 V m-1), workers at radio link stations had no history of regular exposure to electromagnetic fields. In all the subjects a general medical examination, resting ECG and 24 h Holter monitoring were performed. The work organization, work period structure, age, lifestyle, nutritional habits and health status in both groups remained fairly similar. The electrocardiographic abnormalities detected in the resting and/ or 24 h ECG were significantly more frequent (p = 0.006) in workers exposed to electromagnetic fields than in non-exposed subjects (75% versus 25%). A clear tendency for a higher number of rhythm disturbances (mostly ExV) was observed in AM broadcast station workers.

Adult↗