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Since the circulatory and nervous systems are composed of electrically excitable tissues, it is plausible that they can be stimulated by electromagnetic fields (EMF). No clinical studies have as yet been carried out to explain whether and how occupational exposure to 50 Hz EMF can influence the neurovegetative regulation of the cardiovascular function. The present project was undertaken to assess the autonomic function in workers occupationally exposed to 50 Hz EMF, by analyzing the heart rate variability.The study group comprised 63 workers of switchyard substations, aged 22-67 years (39.2 +/- 10.0 years), and the control group 42 workers of radio link stations, aged 20-68 years (40.7 +/- 9.2 years), employed at workposts free from EMF exposure. The age range and employment duration in both groups did not differ significantly. To assess the neurovegetative regulation of the cardiac function, heart rate variability (HRV) analysis was made based on 512 normal heart beats recorded at rest. The analysis, performed using fast Fourier transformation, concerned the time- and frequency-domain HRV parameters. Power spectrum in the very low (VLF), low (LF) and high (HF) frequency bands was determined.The relative risk of decreased HRV (STD R-R27 ms), calculated with use of a logistic regression model, was significantly higher in the exposed group than in controls (OR = 2.8). The VLF power spectrum was significantly higher in the exposed group and correlated with the exposure level. The percentage of subjects with dominant sympathetic function (LF/HF1) was significantly higher in the study group than in controls (65% vs. 47%).It was concluded that occupational exposure to 50 Hz EMF could influence the neurovegetative regulation of the cardiovascular system.

Objectives: In Poland, occupational exposure to cold microclimate is quite common (5.1 workers/1000 occupationally active people). Reports on health effects of this exposure are rather scarce. The aim of the study was to evaluate the physiological reaction in workers occupationally exposed to cold microclimate. Materials and Methods: Examinations were performed in a group of 102 workers (41 women and 61 men) employed at cold storage units. The mean age in the group was 39.1 ± 9.9 years and the duration of employment under conditions of cold environment was over 12 years. The study population was divided into four groups, according to microclimate conditions (group I, ambient temperature -26°C; group II, 10-14°C; group III, 18-20°C, control group; and group IV, 0-10°C). The workers underwent the following procedures: general medical examinations, cold pressor test, ambulatory blood pressure monitoring, and heart rate variability (HRV) analysis (time- and frequency-domain parameters). Results: The results were adjusted for confounding factors (age, smoking and drinking habits). The analysis of HRV parameters did not reveal any significant differences between the study groups. However, systolic and diastolic blood pressure (BP) in the daytime and at night was significantly higher in group IV compared to group II. Mean heart rate (HR) in the daytime and at night and the BP and HR day/night ratio did not differ between the groups. The analysis of BP by gender revealed that in women, systolic BP during the day and at night was significantly higher in group IV than in group II. In the group of workers with hypertension (18 men and 5 women), men reacted to the cold pressor test either by increased or decreased BP while all the women reacted by the increased BP. Conclusions: Our findings indicated that in workers exposed to cold microclimate, the physiological reaction was dependent on gender and ambient temperature. Women seemed to be more sensitive to cold stress than men. However, this finding must be further investigated.

Research findings indicate that the use of mobile phones may lead to a number of symptoms such as headache, impaired concentration and memory, fatigue. In Poland this problem has not as yet been addressed by scientific studies.The present project was undertaken to investigate whether the symptoms of ill health reported by young people may be associated with the use of mobile phone.A survey using a self-reported questionnaire was conducted among randomly selected university students in Lodz, Central Poland. The questionnaire was designed specifically for this study and contained items on health condition and complaints as well as on frequency of mobile phone use. The number of questionnaires necessary for the study was assessed using the simple random sample method. Out of the 160 copies distributed among the students, 140 (87.5%) were completed. Eventually, 117 questionnaires were subject to analysis; the data from respondents who reported health problems (neck trauma in a car accident, chronic sinusitis and arterial hypertension) were excluded. The following statistical methods were used to analyse questionnaire data: t-Student test for equal and unequal variances or F-Snedecor test for comparing parameters in two study groups, Fisher exact test for comparing frequency, and single and multiple logistic regression models for quantitative risk assessment of negative health outcomes in relation to exposure level and with control for confounders. The subjects were 61 (52.1%) males and 56 females (47.9%).Most of the subjects (62%) assessed their health condition as good, 31% as very good and 7% as fair. 70% complained of headache and 20% of dizziness. Impaired concentration occurred in 56% of respondents. Facial dermatitis was reported by 11%. The most prevalent symptom related to mobile phone use was the thermal sensation within the auricle and behind/around the ear. This was reported by 33 subjects (28.2%). Out of 82 subjects who complained of headache, only 8 (6.8%) related this symptom to mobile phone use. Only 10 subjects of 65 reporting impaired concentration thought it could be associated with their using a mobile phone. The symptoms and health complaints reported by the respondents in no case were the reason for a medical check-up or taking any medication.The large number of young people complaining of headache and impaired concentration calls for further research to investigate the underlying reasons. It cannot be excluded that one of them may be exposure to EMF emitted by mobile phone. The explanation should be sought through further experimental and epidemiologic studies.

The authors present some data on the effects of electromagnetic fields (EMF) generated by mobile phones on the nervous system. The main attention was paid to the usefulness of some neurophysiological methods, such as electroencephalography (EEG), multimodality evoked potentials (MEP), and event related potentials (ERP) in the evaluation of the bioelectrical activity of the brain. The majority of the cited articles underline the difficulties in the evaluation of adverse effects of EMF generated by mobile phones, which can result from their nonspecific influence on biological structures.

The problem of health effects of electromagnetic fields (EMF) emitted by cellular phone base stations evokes much interest in view of the fact that people living in their vicinity are fated to continuous exposure to EMF. None of the studies carried out throughout the world have revealed excessive values of standards adopted by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). A questionnaire was used as a study tool. The results of the questionnaire survey reveal that people living in the vicinity of base stations report various complaints mostly of the circulatory system, but also of sleep disturbances, irritability, depression, blurred vision, concentration difficulties, nausea, lack of appetite, headache and vertigo. The performed studies showed the relationship between the incidence of individual symptoms, the level of exposure, and the distance between a residential area and a base station. This association was observed in both groups of persons, those who linked their complaints with the presence of the base station and those who did not notice such a relation. Further studies, clinical and those based on questionnaires, are needed to explain the background of reported complaints.

The aim of the study was to evaluate the effect of electromagnetic fields (EMF) on the workers' circulatory system, and to find out to what extent the EMF frequency, short-term (maximum values) and chronic (daily and lifetime doses) exposures influence the type of the observed disorders. The gathered data will help to evaluate whether hygiene standards that limit maximum admissible EMF values (e.g., ICNIRP standards) protect against adverse effects of exposure. The study covered workers employed in transformer and distribution stations, medium wave transmitting stations, radio-service and radio and TV multichannel broadcasting stations. In all the cases, exposure levels were considerably lower than those set as admissible according to the ICNIRP standards. Nevertheless changes in the circulatory system and a significant relationship between blood pressure and neurovegetative regulation disorders and exposure parameters were observed. The frequency of changes in the circulatory system was significantly dependent not only on the maximum EMF value, but also on its dose, which indicates that the hygiene standards for EMF cannot be limited only to short-term exposure maximum values, but they should be supplemented with dose-related standards.

It is quite likely that non-visible electromagnetic fields (EMF) may affect melatonin production. Some studies confirmed this hypothesis and showed that extremely low EMF altered pineal function in animals and humans. Thus, it is reasonable to suppose that EMF emitted by cellular phones may also influence secretion of melatonin. The present study sought to evaluate possible effect of the exposure to EMF emitted by cellular phone on 6-hydroxymelatonin sulfate (6-OHMS) excretion, which reflects melatonin levels in blood.The examined group consisted of 9 healthy males aged 19-29 years. The experiment was performed under controlled conditions (the light intensity-50 lx till midnight and 0 lx during night). Each person was examined twice: on a day without exposure (control day, C-day) and on a day with continuous exposure (60 min. exposure from cellular phone, frequency 900 MHz, pulsed with 217 Hz, pulse with 576 micros, SAR 1.23 W/kg, E-day). From 7 p.m. to 8 p.m. they used a cellular phone. The subjects did not know which day was E-day, and which was C-day. From 8 p.m. till midnight the subjects listened to music and than they slept till 7 a.m. next day. Urine samples were collected at 7 p.m., at midnight, and at 7 a.m. in the same way in C-day as in E-day. Sample were frozen for later ELISA analysis of 6-OHMS. The 6-OHMS ELISA kit from Immuno-Biological Laboratories (Hamburg) was used for measurement of 6-OHMS. The data were analysed using Wilcoxon matched-pairs signed-ranks test for each subject and for the whole group. We compared 6-OHMS level on the E-day and on the C-day separately for 3 time-points - 7 p.m., midnight, 7 a.m.Mean 6-OHMS level in both experiments did not differ significantly for any of the respective time points. Circadian variations of 6-OHMS level were detected in all subjects.The results of our investigation has demonstrated that EMF emitted by cellular phones has no distinct influence on the melatonin level.

The present state of knowledge on the effects of exposure to medium frequency electromagnetic fields (MF EM) on the circulatory system derives mainly from the reports of Soviet studies of the 60s which indicated that in the exposed people such symptoms develop as heart rhythm disturbances, impaired conduction, decreased amplitude of ECG records and blood pressure changes (hypo-or hypertension)1,2,3,4,5. Although since these studies a considerable progress in ECG methodology has been made, their results have not as yet been verified using any objective methods. Therefore, we have undertaken the present study in order to evaluate the cardiovascular function in workers occupationally exposed to EM fields at different exposure levels and frequencies.

It is assumed that the cardiovascular impairments resulting from CS 2 exposure may be associated with some functional disturbances within the autonomic nervous system. We adopted the heart rate variability (HRV) analysis to investigate the sympathetic and parasympathetic functions of the autonomic nervous system in workers exposed to carbon disulfide. The studies were performed on 152 workers, aged 24–66, with the period of exposure ranging from 5–38 years and 93 age-matched, non-exposed, healthy individuals as the control group. The HRV analysis concerned time-domain (AVG R–R, SD R–R, modal, median, minimum and maximum values) and frequency-domain indices (power spectrum in the very low-VLF, low-LF and high-HF frequency bands) calculated using the fast Fourier transformation. In the exposed group, neurovegetative regulation impairments could be observed. They were expressed as increased heart rate at rest, reduced power spectrum: total (TPS) and within HF, LF and VLF frequency bands as well as the absence of the physiological dependence of HRV parameters on age. These abnormalities could be found even in the group of workers exposed to the lowest CS 2 levels (0–10 mg/m 3 ) and they concerned the VLF band. In workers under conditions of exposure to 10–18 mg/m 3 the dysfunction of the autonomic control referred both to its sympathetic and parasympathetic part and was found to be more intense in workers exposed to the highest CS 2 concentrations (over 18 mg/m 3 ). In view of our findings we concluded that occupational exposure to carbon disulfide may bring about an impaired neurovegetative regulation of the cardiovascular function.

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.

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.

In previous studies we found measurable effects on variability of heart rate and on blood-pressure parameters of workers exposed to radiofrequency electromagnetic fields (EMF)compared with a control population, but none of the effects could be assigned clinical significance. In general, the obtained results strongly suggested that dysregulation of the autonomic control of the circulatory system was occurring. Therefore, it seemed logical that analysis of diurnal rhythms of blood pressure and heart rate, on the basis of data from 24 h recordings, might further support the above hypothesis.The aim of this study was to determine the course of diurnal rhythms of blood pressure and heart rate in a group of workers exposed to various intensities of radiofrequency electromagnetic fields.In the study we used 61 healthy workers (aged 30-50 years) who had been exposed to radiofrequency EMF of 0.738-1.503 Mhz and 42 healthy workers at radio-line stations (aged 28-49 years), who had not been exposed to EMF occupationally. The work patterns of these two groups were identical (12 h day working shift, 24 h interval, 12 h night shift and then 48 h rest). During the second day of the rest period 24 h ambulatory blood pressure (ABP) was recorded. For analysis of diurnal rhythms the group of exposed workers was divided into two subgroups: group A of 38 subjects exposed to low intensities of radiofrequency EMF (20-180 V/m) and group B of 23 subjects exposed to high intensities of radiofrequency EMF (200-550 V/m). Parameters of diurnal rhythms of blood pressure and heart rate (acrophase, amplitude and mean) were calculated by performing a least-square fit of a 24 h cosinor (single cosinor analysis) at P0.05.Healthy men aged 28-49 years, working on a pattern of 12-24-12-48 h, exhibited typical, well-preserved diurnal rhythms of blood pressure and heart rate with two maxima (at about 1400 and 1700-1800 h) and one minimum (at about 0200-0400 h). For workers exposed to radiofrequency EMF we noted a significant lowering of the amplitudes of rhythms of blood pressure and heart rate (P0.01) and a shift of the acrophase to an earlier time (1100-1200 h; P0.05). These changes were more pronounced among workers exposed to high intensities of radiofrequency EMF.Occupational exposure to radiofrequency EMF can result in changes of the diurnal rhythms of blood pressure and heart rate with lowering of their amplitudes and a shift of the acrophase. The clinical relevance of the present finding needs to be investigated in further studies.

According to literature data myocardial infarction was often the first noticeable effect of CS2 on the cardiovascular system. Therefore, a question arises whether earlier circulatory lesions are absent in CS2-exposed people, or they are present but are not detectable by the diagnostic methods used. The aim of our study has been to determine whether electrocardiological disturbances do occur in exposed people, and their association, if any, with the level of CS2 exposure. Modern diagnostic methods (resting and 24-h ECG, heart rate variability, late ventricular potential analysis, and long-term blood pressure monitoring) were used to answer this question. The examination comprised 177 male workers aged 24-66 years (44+/-12), employed under conditions of the exposure for 5-38 years (14+/-9), and 93 male workers non-exposed to CS2 aged 23-65 years (41+/-12). Results of our studies show that abnormalities in resting and/or 24-h ECG recordings occur significantly more frequently in people exposed to CS2 than in the controls. ECG abnormalities were found primarily among the workers with a long, over 20-year, period of exposure. The considerable coincidence between the questionnaire and ECG results was found (87% reported complaints were confirmed by ECG data). Therefore it seems that all CS2-exposed people reporting heart symptoms should be subjected to a detailed examination. The frequency of late ventricular potentials in CS2-exposed people was not higher than in the controls. It may indicate that the ECG disturbances observed in those people were associated with functional rather than organic changes. Results of long-term ABP monitoring did not show increased incidence of elevated blood pressure in the exposed group. As the levels of the risk factors of ischemic heart disease in the exposed and control groups were similar, it seems that exposure to CS2 was responsible for the significant changes in the circulatory system.