Implantable cardioverter defibrillator and 50-Hz electric and magnetic fields exposure in the workplace.

PURPOSE: The operation of implantable cardioverter defibrillators (ICD) can be disrupted by exposure to electromagnetic fields (EMF). In the workplace, some workers can be exposed to EMF higher than in daily life. We present an approach aimed at assessing fitness for work in this type of situation, based on in situ case studies in the absence of clinical and in vivo studies. METHODS: A risk assessment protocol was developed to measure the 50-Hz electric and magnetic fields in the various places where the worker is likely to be present. These measures are taken in the worker's presence, while monitoring the ICD operation. RESULTS: All cases of implanted ICD workers in EDF, the French electricity company (around 130,000 employees), and potentially exposed to high electric and/or magnetic fields, between 2004 and 2009 are presented. These three cases involved different work circumstances, with exposure to 50-Hz electric and/or magnetic fields. No interference of the ICD was observed. CONCLUSIONS: This information provides the basis for the occupational physician to make a decision about fitness for work. This procedure can be extended to other medical implants and to electromagnetic fields frequencies other than 50-Hz.

Methodology of a study on the French population exposure to 50 Hz magnetic fields.

The characterisation of population exposure to a 50-Hz magnetic field (MF) is important for assessing health effects of electromagnetic fields. With the aim of estimating and characterising the exposure of the French population to 50-Hz MFs, two representative samples of the population were made. A random selection method based on the distribution of households in different regions of France was used. The samples were carried out starting from a random polling of telephone numbers of households (listed, unlisted fixed phones and cell phones only). A total of 95,362 telephone numbers were dialed to have 2148 volunteers (1060 children and 1088 adults). They all agreed to carrying an EMDEX II meter, measuring and recording MFs, and to filling out a timetable for a 24-hour period. In this article, the methodology of the sample selection and the collection of all necessary information for the realisation of this study are presented.

Is melatonin the hormonal missing link between magnetic field effects and human diseases?

The disruption of melatonin secretion has been largely studied since it could provide the missing link between the exposure to 50/60-Hz electric and magnetic fields (EMF) and the occurrence of possible health effects as the "melatonin hypothesis". We analysed the current experimental data from animal (rodents) where contradictory results have been observed, and from human studies conducted with volunteers or with workers in various conditions of exposure, biological endpoints and metrics. In humans, even in long lasting exposures, the overall results of these studies do not support the "melatonin hypothesis". It is unlikely that malignancies or mood disorders reported by people exposed to 50/60-Hz EMF could be related to the disruption of the melatonin levels.

Evaluation of the nocturnal levels of urinary biogenic amines in men exposed overnight to 50-Hz magnetic field.

The aim of this study was to determine whether exposure to magnetic fields might affect human health and to look for possible effects of acute exposure (9 hours) to 50-Hz magnetic fields (10 microT) on the urinary concentration of biogenic amines. Thirty-two young men (20-30 years old) were divided into two groups (sham-exposed and exposed group) of 12 to 16 subjects each. All subjects participated in two 24-hour experiments to evaluate the effects of both continuous and intermittent exposure to magnetic fields. The subjects were exposed to the magnetic field from 2300 to 0800, while lying down. Total urine (from 2300 to 0800) was collected at 0800. The results (expressed as a ratio of biogenic amine excretion to creatinine excretion (nmol/mmol)) did not differ significantly between sham-exposed and exposed men for any of the parameters measured: adrenaline, noradrenaline, dopamine, dihydroxyphenylalanine, 3,4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid. These results suggest that nocturnal exposure to either continuous or intermittent 50-Hz magnetic fields of 10 microT does not affect, at least under our experimental conditions, the nocturnal excretion of biogenic amines in healthy young men.

[Effects of 50 to 60 Hz and of 20 to 50 kHz magnetic fields on the operation of implanted cardiac pacemakers]. / Effets des champs magnétiques de 50 et 60 Hz et de 20 à 50 kHz sur le fonctionnement des cardiostimulateurs implantés.

UNLABELLED: The effect of 50 Hz and 60 Hz (frequencies of current distribution) and 20 kHz to 50 kHz (frequencies of induction cooktop) magnetic interference on implanted pacemakers have been assessed with the present generation of device technology. Sixty patients implanted in 1998 and 1999 with dual chamber pacemakers from 9 different manufacturers were monitored with telemetry while passing through, and standing between a system of two coils. They generated a 50 Hz or a 60 Hz magnetic field at 50 microT. Then, patients used a cooktop at different power. The recordings were made with the standard setting of "medically correct" sensing parameters chosen for the patients. Then pacemakers were reprogrammed to the unipolar mode, with the highest atrial (A) and ventricular (V) sensitivity that did not induce muscular inhibition while moving. Between each exposure (50 Hz, 60 Hz or 20 kHz to 50 kHz), the pacemaker programmation was controlled. At the end of the tests, pacemakers will be reprogrammed with the standard setting. The medical observer being blind to the existence or not of the magnetic field. No pacemaker was influenced by the vicinity of the magnetic field at medically correct settings. At unipolar high sensitivity, no inhibition nor reprogramming was observed. Transient reversion to interference mode was observed in 6 cases, 3 transient acceleration due to atrial detection of the interference, and one T wave detection by the ventricular lead. All were observed with the 60 Hz, and only 3 with the 50 Hz magnetic field. One device (Biotronik) shifted out of its special program (hysteresis research) during the tests with the induction cooktop, but it maintained its standard program, and the event could not be repeated despite further testing. CONCLUSION: Actual pacemakers do not present any electromagnetic interference with 50 Hz and 60 Hz or induction cooktop frequency working. They are insensitive with medically correct settings. Unusual high sensitivity leads only to noise reversion mode, or transient ventricular tracking.

[ A registry of ischaemic cardiopathies among active workers at Electricité de France-Gaz de France. Program development and first results]. / Un registre des cardiopathies ischémiques chez les salariés en activité d'EDF et Gaz de France. Mise en place et premiers résultats.

BACKGROUND: The social security department of the French national electric and gas company has established an ischemic heart disease register among a population of about 140 000 employees based on sick leaves as well as deaths recorded with their medical cause. METHODS: History of the illness, medical tests and treatments were known retrospectively from the consulting physicians of the company. Acute coronary events recorded were: inaugural angina pectoris, myocardial infarction, sudden coronary death and fortuitous discovery of coronary disease. RESULTS: A first study conducted on employees during the 1993-1995 period showed infarction incidence age rates similar to those estimated from the French MONICA registers for France as a whole. Regional discrepancies were observed for myocardial infarction rates: Nord-Pas de Calais, Champagne-Ardennes, Lorraine, Franche-Comté and Limousin were at the most elevated risk (SIR=131, 155, 169, 125 and 178 resp). Large variations according to socio-economic status were observed. CONCLUSION: This register will permit studies on the links between socio-economic status at different professional career points and the occurrence of ischemic heart disease and the evaluation of the impact of psychosocial factors such as previous depressive disorders.

Absence of the effects of 50 Hz magnetic fields on the progression of acute myeloid leukaemia in rats.

PURPOSE: As the most recent epidemiological studies provide no definite conclusions about the effects of 50/60 Hz magnetic fields (MFs) on the incidence of leukaemia in humans, animal models in a well-controlled environment are useful for evaluating the possibility of an association between MFs and leukaemia. The present study was designed to determine whether 50 Hz magnetic fields can alter the progression of leukaemia. MATERIALS AND METHODS: A well-characterized model of transplantable acute myeloid leukaemia in rats was used for the first time. This model is closely related to human acute myeloid leukaemia, the type most frequently reported in epidemiological studies of adults. After leukaemic cell implantation, rats were exposed to a sinusoidal 50 Hz MF of 100 microT for 18 h a day, 7 days a week, throughout leukaemia progression. The parameters investigated were: survival time, body weight, haematologic parameters, infiltration of blood, bone marrow, spleen and liver by leukaemic cells. RESULTS: The results showed no significant changes (p > 0.05) in leukaemic MF-exposed versus unexposed rats for any of the parameters involved in leukaemia progression. CONCLUSION: These data do not support the hypothesis that 50 Hz magnetic fields influence leukaemia progression in humans.

Magnetic field desensitizes 5-HT(1B) receptor in brain: pharmacological and functional studies.

It was previously suggested that exposure to magnetic fields (MFs) could generate dysfunction of the CNS. The physiological manifestations described lead us to postulate that these symptoms might be related to a dysfunction of the serotonergic system and particularly of the 5-HT(1B) receptors. Accordingly, MFs could modify the conformation of these receptors altering their functional activities. In rat brain membrane preparations, we showed that the affinity constant of 5-HT for 5-HT(1B) receptors was modified under exposure to MFs since K(d) varied from 4.7+/-0.5 to 12+/-3 nM in control and exposed (2.5 mT) membranes, respectively. This effect was intensity-dependent (the sigmoidal dose-response curve was characterized by an EI(50) of 662+/-69 microT and a maximal increase of 321+/-13% of the control K(d)), reversible, temperature-dependent and specific to the 5-HT(1B) receptors. Similar results have also been obtained with the human 5-HT(1B) receptors. In parallel assays, the functional activity of 5-HT(1B) receptors was investigated. The capacity of a 5-HT(1B) agonist to inhibit the cAMP production was reduced by 37% (53.7+/-3.5% to 33.7+/-4.1%) following exposure to MFs and the cellular activity of the receptors (inhibition of the synaptosomal release of 5-HT) also was markedly reduced (66.5+/-3.2% to 28.5+/-4.2%). These results clearly show that in in vitro assays, MF specifically interacts with 5-HT(1B) receptors, inducing structural changes of the protein that result in a functional desensitization of the receptors. Thus, in vivo, exposure to MFs may lead to physiological changes, particularly in the field of mood disorders where the 5-HT system is strongly involved.

Assessment of the effects of nocturnal exposure to 50-Hz magnetic fields on the human circadian system. A comprehensive study of biochemical variables.

The proposed laboratory investigation was designed to evaluate the effects of acute exposure to both continuous and intermittent magnetic fields (MFs) (50 Hz-10 microT) on the circadian rhythm of clinical chemistry variables in humans: electrolytes (magnesium, calcium, phosphorus, sodium, potassium, and chloride), enzymes (amylase, lipase, aldolase, gamma glutamyl-transferase [GGT], lactate dehydrogenase [LDH], aspartate aminotransferase [ASAT], and alkaline phosphatase [ALP]), lipids (cholesterol, high-density lipoprotein [HDL], apolipoprotein A1 [ApoA1], and ApoB), proteins (total proteins and albumin), nitrogen substances (uric acid, urea, and creatinine), iron, glycemia, and transferrin. Young volunteers (32 subjects; 16 exposed and 16 sham exposed) were selected according to the screening criteria. Each subject participated in two sessions held within a 4-week period. In the first session, one group of volunteers (16 subjects) was exposed to a continuous MF and then, in the second session, to an intermittent MF. The second group (16 subjects) served as a control for both sessions. At each session, blood samples were collected at 3 h intervals from 11:00 to 20:00 and hourly from 22:00 to 08:00. The results indicate that both continuous and intermittent 50-Hz linearly polarized MFs of 10 microT intensity have no effects on the circadian rhythms or on the levels of the variables studied here.

Absenteeism and mortality of workers exposed to electromagnetic fields in the French Electricity Company.

The objective of this study was to describe the health status of electricity workers exposed to electromagnetic fields during their job. Two groups of exposed workers were studied from 1978 to 1993: the live line workers (n = 121) and the substation workers (n = 232.7) of the French Electricity Company (EDF). A control group was randomly selected from all the company non-management male employees; one control for each exposed subject was matched for the first year of employment. Absenteeism indices and mortality rates were computed and compared in the exposed and control groups. The absence rates were 1.98% in the substation workers and 2.5% in the control group (p < 0.001) and 2.7% in the live-line workers and 2.8% in the control group (NS). No effect of the length of exposure was found. However the medical causes of sickness absence were different: exposed employees had less psychiatric and respiratory diseases but more accidents at work than their control group. Relative risks of accidents at work were 1.2 95% confidence interval (CI) = 1.08-1.33[ for substation workers and 3.22 (CI = 1.78-5.88) for live line workers. EDF electromagnetic field exposed workers seemed not to be affected by any specific health problems except for an excess of accidents at work.

Endocrine functions in young men exposed for one night to a 50-Hz magnetic field. A circadian study of pituitary, thyroid and adrenocortical hormones.

In recent years, some epidemiologic studies have suggested that extremely low frequency magnetic and electric fields might affect human health, and, in particular, that the incidence of certain types of cancer, depression, and miscarriage might increase among individuals living or working in environments exposed to such fields. Work in our laboratory studies whether and how changes in the electromagnetic environment might affect human health. The study presented here was designed to look for possible effects of acute exposure to 50-Hz linearly polarized magnetic fields (10 microT) on the hormones of the hypothalamic-pituitary-thyroid and hypothalamic-pituitary-adrenal axes. Thirty-two young men (20-30 years old) were divided into two groups (sham-exposed or control group, and exposed group) of 16 subjects each. All subjects participated in two 24-hour experiments to evaluate the effects of both continuous and intermittent (one hour "off" and one hour "on" with the field switched "on" and "off" every 15 seconds) exposure to linearly polarized magnetic fields. The subjects were exposed to the magnetic field (generated by three Helmholtz coils per bed) from 2300 to 0800 while recumbent. Blood samples were collected during each session at 3 hour intervals from 1100 to 2000 and hourly from 2200 to 0800. Total urine was collected every 3 hours from 0800 to 2300 and then again at 0800. No significant differences were observed between sham-exposed and exposed men for any of the parameters measured: thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, triiodothyronine, thyroxine, free triiodothyronine, free thyroxine, thyroxine-binding globulin, cortisol, 17-hydroxycorticosteroids (17-OH-CS) and TBK. These results suggest that acute exposure to either continuous or intermittent 50-Hz linearly polarized magnetic fields of 10 microT does not affect, at least under our experimental conditions, these endocrine functions or their circadian rhythmicity in healthy young men.

Ventilation system, indoor air quality, and health outcomes in Parisian modern office workers.

A cross-sectional study was carried out to determine the effect on health of exposure to different types of ventilation, taking indoor environmental measurements (IEMs) of major contaminants and aeroallergens into account. Three buildings ventilated with heating, ventilating, and air conditioning (HVAC), fan coil units (FCUs), and natural ventilation were selected. One thousand one hundred forty-four workers answered health questionnaires. After adjusting for potential confounders, HVAC and FCU systems were related to a slightly higher risk of nonspecific symptoms (compared with natural ventilation), short-term throat irritation, work-related nasal discharge, nasal blockage on awakening, migraine, and usual coughing induced by cold air. Studying the potential effects of environmental contaminants and aeroallergens on health outcomes, taking the floor and type of ventilation into account, did not explain the observed excess of nonspecific symptoms.

Acute exposure to 50 Hz magnetic field does not affect hematologic or immunologic functions in healthy young men: a circadian study.

Some epidemiological studies report a relationship between magnetic field exposure and such human diseases as leukemia and immune system disturbances. The few published studies on animals do not demonstrate field exposure-related alterations in hematologic and immune systems. The data presented here are part of a broader study designed to investigate the possible effects of acute exposure to a 50 Hz linearly polarized magnetic field (10 microT) on hematologic and immunologic functions. Thirty-two young men (20-30 years old) were divided into two groups (control group i.e., sham-exposed. 16 subjects; exposed group, 16 subjects). All subjects participated in two 24 h experiments to evaluate the effects of both continuous and intermittent (1 h "off" and 1 h with the field switched "on" and "off" every 15 s) exposure to linearly polarized magnetic fields. The subjects were exposed to the magnetic field (generated by three Helmholtz coils per bed) from 23:00 to 08:00 while lying down. Blood samples were collected during each session at 3 h intervals from 11:00 to 20:00 and hourly from 22:00 to 08:00. No significant differences were observed between sham-exposed (control) and exposed men for hemoglobin concentration, hematocrit, red blood cells, platelets, total leukocytes, monocytes, lymphocytes, eosinophils, or neutrophils. Immunologic variables [CD3, CD4, CD8, natural killer (NK) cells and B cells] were unaltered. To our knowledge, this study is the first to document the effects of a 50 Hz magnetic field on the circadian rhythm of human hematologic and immune functions, and it suggests that acute exposure to either a continuous or an intermittent 50 Hz linearly polarized magnetic field of 10 microT, at least under the conditions of our experiment, does not affect either these function or their circadian rhythms in healthy young men.

Magnetic fields and pineal function in humans: evaluation of nocturnal acute exposure to extremely low frequency magnetic fields on serum melatonin and urinary 6-sulfatoxymelatonin circadian rhythms.

Exposure to a 50/60-Hz electromagnetic field can decrease the nocturnal production of melatonin in rodents. Melatonin is considered to be a marker of circadian rhythms, and abnormalities in its secretion are associated with clinical disorders, including fatigue, sleep disruption, mood swings, impaired performance, and depression, which are consequences of desynchronisation. Interestingly, some epidemiological studies have been reported finding most of these clinical disorders in individuals living or working in an environment exposed to electromagnetic fields. This experiment was designed to look for the possible effects of acute exposure (9 hours) to 50-Hz linearly polarized magnetic fields (10 mu T) on the pineal function. Thirty-two young men (20-30 years old) were divided into two groups (control group, i.e., sham-exposed: 16 subjects; exposed group: 16 subjects). All subjects participated in two 24-hour experiments to evaluate the effects of both continuous and intermittent exposure to linearly polarized magnetic fields. They were synchronized with a diurnal activity from 08:00 to 23:00 and nocturnal rest. The experiment lasted two months (mid-February to mid-April). The subjects were exposed to the magnetic fields (generated by three Helmholtz coils per bed) from 23:00 to 08:00, while lying down. Blood samples were collected during each session at 3-hour intervals from 11:00 to 20:00 and hourly from 22:00 to 08:00. Total urine was collected every 3 hours from 08:00 to 23:00 and once during the night, from 23:00 to 08:00. The levels of serum melatonin and its metabolite in urine (6-sulfatoxymelatonin) in exposed men did not differ significantly from those in control (sham-exposed) subjects. This study shows that nocturnal acute exposure to either continuous or intermittent 50-Hz linearly polarized magnetic fields of 10 mu T does not affect melatonin secretion in humans.

Exploring the EMF-Melatonin Connection: A Review of the Possible Effects of 50/60-Hz Electric and Magnetic Fields on Melatonin Secretion.

This study analyzed the experimental data about the relationship between exposure to 50/60-Hz electric and magnetic fields (EMF) and melatonin secretion by the pineal gland. The authors report their results and discuss possible health consequences, in the light of epidemiologic data suggesting that breast neoplasms and depressive disorders might be related to EMF. The nocturnal peak of melatonin has been reported to be diminished, or time-shifted, or both, in rodents exposed to electric and/or magnetic fields. Current experimental data from primates and humans are insufficient to show that this change occurs in them. Epidemiologic studies of associations between EMF exposure and breast cancer and between EMF exposure and depressive disorders suggest that modifications of melatonin secretion could be a biologic signal of these effects. Nonetheless, changes in melatonin secretion cannot yet be considered a verified biologic explanation of any such association.

[Back pain at the French National Electricity and Gas Company]. / Les douleurs du rachis parmi les travailleurs d'Electricité de France et Gaz de France.

Frequency and severity of sickness absence due to back pain were studied among workers in the French National Electric and Gas Company. The results showed that the prevalence of back pain was less than 10% a year but the annual duration of absence that it involved was relatively important: 30 days in the average per disabled person. In a second part, the prevalence was studied according to individual and occupational variables. Differences according to occupational category are very important: between the occupations the most prone to absence, those of "switchboard operator", "mechanics driver" and "warehouseman" and the ones least exposed "managerial staff" and "skilled technician and upper management", the ratio for the prevalences was 10.