Alicja Bortkiewicz

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.

Subjective complaints of people living near mobile phone base stations in Poland

ObjectivesThe aim of our study was to assess the health conditions and subjective symptoms of the inhabitants living in the base stations vicinity and to analyse the relationship between the complaints and level of exposure to electromagnetic fields (EMF).Materials and MethodsOur study was performed in housing estates located in five regions of Łódź. The electric field measurements were performed in the buildings located closest to the azimuth of the antennas. Respondents were selected by trained interviewers using an uniform procedure. The number of the households to be examined was set at a minimum of 420. The questionnaire contained: demographic data, occupational and environmental exposure to EMF, health condition, subjective complaints. Results were adjusted for confounders (age, gender, EMF at the workplace and EMF emitted by household equipment) using multiple regression model.Results181 men and 319 women from 500 households were examined. Electric field above 0.8 V/m was recorded in 12% of flats. There was no significant correlation between electric field strength and the distance of examined flats from the base stations. To make possible comparison with relevant literature, we analysed also the frequency of the reported symptoms vs. the distance. Headache was declared by 57% people, most frequently (36.4%) living 100–150 m away from the base station compared to people living at longer distances (p = 0.013). 24.4% subjects, mostly living at a distance above 150 m, declared impaired memory. Difference was statistically significant in comparison with people living at other distances (p = 0.004).ConclusionsThe explanation why we did not find any correlation between the electric field strength and frequency of subjective symptoms but found a correlation between subjective symptoms and distance from base station needs further studies. Maybe new metrics of exposure assessment should be adopted for this purpose.

Dysregulation of Autonomic Control of Cardiac Function in Workers at am Broadcasting Stations (0.738–1.503 MHz)

Ninety-three adult males working at AM broadcasting stations (0.738–1.503 MHz) or radio line stations volunteered for cardiological examinations. The examinations included routine electrocardiogram (ECG) at rest, analysis of heart rate variability (HRV), Holter 24-h ECG, and 24-h ambulatory blood pressure (ABP). Results of cardiological examinations were correlated with individual exposure to EM fields (maximum exposure levels during working shift, daily exposure dose, and cumulative lifetime exposure). Of the 93 subjects qualified for the study, 71 (76.3%) experienced occupational RF exposure, while the remaining 22 (23.7%) had no history of regular EM exposure. ECG abnormalities or pathological changes were recorded quite frequently (50–70%) in both exposed and control populations. There was no correlation with exposure levels. We found measurable effects in the HRV and ABP parameters in the EM-exposed population, but none could be assigned clinical significance. The results suggest that exposure of wor...

Description of a large-scale study design to assess work-stress-disease associations for cardiovascular disease

We claim that a new level of studies is needed to answer a series of important questions about the expanding global chronic disease burden for cardiovascular disease (CVD) and for related conditions such as diabetes, metabolic syndrome, and obesity. These require a new study design structure, related to a new level of theory that goes beyond the current single-factor, a-theoretic epidemiological studies. This new platform for the design of large-scale Work/Stress/Disease studies would assess CVD-related disease mechanisms in a more general and dynamic form, based on the use of new tools for measuring autonomic functions in an occupational stress context and a new theory of disease causation. A sample outline is presented for such a study, based on Stress-Disequilibrium Theory (SDT) hypotheses, building on analytic tools developed for the assessment of stress-related exhaustion effects and chronic disease risks from Heart Rate Variability (HRV) research studies. The goal is to assess the associations between social organizational risks, particularly at work, and hypertension, metabolic syndrome, and diabetes II. The study design is multi-stage, spanning across several levels of disease-related de-regulation, and addressing co-morbidity of the conditions themselves. The study design is meant to span across a broad social population at all levels and would probably be multi-site, involving several countries, to yield the larger sample increased power for finding associations for work - physiological effects.

The risk of subjective symptoms in mobile phone users in Poland – An epidemiological study

ObjectivesTo assess the type and incidence of subjective symptoms related to the use of mobile phones in Polish users.Material and MethodsThe study was conducted in 2005 using a questionnaire survey. Although it has been quite a long time, up to now, no such data have been published for Poland. The questionnaire consisted of 53 questions concerning sex, age, education, general health, characteristics of a mobile phone (hand-held, loud-speaking unit) as well as the habits associated with its use (frequency and duration of calls, text messages, etc.) and complaints associated with using a mobile phone.ResultsAs many as 1800 questionnaires were sent. The response was obtained from 587 subjects aged 32.6±11.3 (48.9% women, 51.1% men); the age did not differ significantly between men and women. The subjects owned a cell phone for an average of 3 years. Majority of the respondents used the phone intensively, i.e. daily (74%) or almost daily (20%). Headaches were reported significantly more often by the people who talked frequently and long in comparison with other users (63.2% of the subjects, p = 0.0029), just like the symptoms of fatigue (45%, p = 0.013). Also, the feeling of warmth around the ear and directly to the auricle was reported significantly more frequently by the intensive mobile phone users, compared with other mobile phone users (47.3%, p = 0.00004 vs. 44.6%, p = 0.00063, respectively). Most symptoms appeared during or immediately after a call and disappeared within 2 h after the call. Continuous headache, persisting for longer than 6 h since the end of a call, was reported by 26% of the subjects.ConclusionsOur results show that the mobile phone users may experience subjective symptoms, the intensity of which depends on the intensity of use of mobile phones.

Heart rate variability (HRV) analysis in radio and TV broadcasting stations workers.

ObjectivesThe aim of the study was to assess the mechanism of cardiovascular impairments in workers exposed to UHF-VHF radio frequency electromagnetic fields (EMF).Materials and MethodsHeart rate variability (HRV) was analysed using 512 normal heart beats registered at rest. The analysis concerned time-domain (STD R-R) and frequency-domain (VLF, LF, HF) parameters of HRV. Fifty nine workers (group I) with low-level and 12 workers (group II) with high-level exposure were examined. The mean age of the subjects was 47±9 years and 41±14 years, and mean exposure duration 19.1±8.8 years and 13±4 years, in groups I and II, respectively. The groups were divided according to: Emax, Edose, Emean for frequencies UHF, VHF and UHF+VHF: The control group consisted of 42 non-exposed subjects, aged 49±8 years. Statistical analysis comprised one-way analysis of variance, covariance analysis and logistic regression models.ResultsIn the exposed groups, the heart rate was higher than in the control one. Standard deviation of R-R intervals (STD R-R) was found to be significantly (p = 0.0285) lower in group I (42.5±24.7 ms) compared to the control group (62.9±53.5 ms). The risk of lowered STD R-R was significantly increased (OR = 2.37, p = 0.023) in group II. Both exposed groups presented significantly higher VLF and LF values than the control group (p = 0.005 and p = 0.0025, respectively). The EMF-exposed groups were characterised by the dominance of the sympathetic system (LF/HF 1.3±0.35).ConclusionsThe results indicate that exposure to radiofrequency EMF may affect the neurovegetative regulation.

Heart rate variability in workers exposed to carbon disulfide.

It is assumed that the cardiovascular impairments resulting from CS2 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 CS2 levels (0-10 mg/m3) and they concerned the VLF band. In workers under conditions of exposure to 10-18 mg/m3 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 CS2 concentrations (over 18 mg/m3). In view of our findings we concluded that occupational exposure to carbon disulfide may bring about an impaired neurovegetative regulation of the cardiovascular function.

Mobile phone use and risk for intracranial tumors and salivary gland tumors – A meta-analysis

Results of epidemiological studies on the association between use of mobile phone and brain cancer are ambiguous, as well as the results of 5 meta-analysis studies published to date. Since the last meta-analysis (2009), new case-control studies have been published, which theoretically could affect the conclusions on this relationship. Therefore, we decided to perform a new meta-analysis. We conducted a systematic review of multiple electronic data bases for relevant publications. The inclusion criteria were: original papers, case-control studies, published till the end of March 2014, measures of association (point estimates as odds ratio and confidence interval of the effect measured), data on individual exposure. Twenty four studies (26 846 cases, 50 013 controls) were included into the meta-analysis. A significantly higher risk of an intracranial tumor (all types) was noted for the period of mobile phone use over 10 years (odds ratio (OR) = 1.324, 95% confidence interval (CI): 1.028-1.704), and for the ipsilateral location (OR = 1.249, 95% CI: 1.022-1.526). The results support the hypothesis that long-term use of mobile phone increases risk of intracranial tumors, especially in the case of ipsilateral exposure. Further studies are needed to confirm this relationship. Int J Occup Med Environ Health 2017;30(1)27-43.

Changes in tympanic temperature during the exposure to electromagnetic fields emitted by mobile phone.

ObjectiveMobile phones generate microwave radiation which is absorbed by exposed tissue and converted into heat. It may cause detrimental health effects. The aim of the experiment was to check if exposure to EMF emitted by mobile phone influenced the tympanic temperature.Material and MethodsHuman volunteer study was performed on ten healthy young men, aged 22.1±4.7 years, examined three times: 1. on a day with 2×60 min of no exposure (sham day), 2. on a day with continuous, 60 min exposure and 60 min of no exposure, 3. on a day with intermittent exposure (4×15 min “on” and 4×15 min “off”). Exposure was generated by mobile phone (frequency 900 MHz, SAR 1.23 W/kg). The study was double-blind, performed under controlled conditions (at 24°C and 70% humidity). The tympanic temperature (Tty) was monitored every 10 sec by a thermistor probe placed close to the aural canal membrane in the ear opposite the one in contact with mobile phone (contralateral position). Multivariate repeated-measures analysis of variance was used to calculate the results.ResultsThe mean Tty in the whole group during continuous exposure was significantly higher than during sham exposure (p = 0.0001). During intermittent exposure the temperature was lower than during sham day (difference was up to 0.11°C). Within an hour after continuous exposure, Tty was higher by 0.03°C and after intermittent exposure Tty was lower by 0.18°C in comparison with sham day. Two hours after exposure Tty was significantly lower (p = 0.0001) than after sham exposure (0.06°C and 0.26°C respectively). The trends in Tty during experiment differed significantly in relation to exposure conditions (p < 0.05).ConclusionsThe results of this analysis indicate that the physiological response to EMF exposure from mobile phone was mostly related to type of exposure (continuous or intermittent).

Cardiovascular Disturbances in Workers Exposed to Carbon Disulfide

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.