Association between extremely low-frequency electromagnetic fields occupations and amyotrophic lateral sclerosis: a meta-analysis

Occupational Exposure to Nonionizing Radiation and Risk for Malignancy in Young Adults

INTRODUCTION

Nonionizing radiation (NIR) is considered "possibly carcinogenic to humans," and therefore, exposure of young military personnel raises concerns regarding increased risk for cancer. The aim of our study was to compare the cancer incidence in exposed and nonexposed populations in order to gain better understanding of their risk.

MATERIALS AND METHODS

A longitudinal retrospective cohort study, between 2009 and 2018, was conducted. Israel Defense Forces (IDF) aerial defense units service members, with NIR exposure (range of 2-300 GHz, below the International Commission of Non-Ionizing Radiation Protection guidelines), were compared with a similar sociodemographic group of service members without NIR exposure. Both groups were followed for cancer incidence (all-cause and specific malignancies). Kaplan-Meier analysis of cancer-free survival and univariate and multivariable logistic regressions for possible confounders and risk factors were performed. This analysis was repeated on a matched 1:1 control group.

RESULTS

Exposure and comparison groups included 3,825 and 11,049 individuals, respectively. Forty-one cases diagnosed with cancer were identified during the follow-up time (mean 4.8 [±2.7] years), 13 (0.34%) of which were reported in the exposure group, and 28 (0.25%) were reported in the comparison group. The odds ratio (OR) for cancer incidence in the exposure vs. control groups was 1.34 (95%CI, 0.70-2.60), P-value = 0.3807. The results remained unchanged after adjustment for sex, age at enrollment, service length, socioeconomic status, and military occupation (adjOR = 1.38 [95%CI, 0.67-2.82], P = 0.3818).

CONCLUSIONS

Our study did not find an increased short-term risk for cancer in young adults exposed to NIR radiation as compared with unexposed young adults.

50 Hz Magnetic Field Exposure Inhibited Spontaneous Movement of Zebrafish Larvae through ROS-Mediated syn2a Expression

Extremely low frequency electromagnetic field (ELF-EMF) exists widely in public and occupational environments. However, its potential adverse effects and the underlying mechanism on nervous system, especially behavior are still poorly understood. In this study, zebrafish embryos (including a transfected synapsin IIa (syn2a) overexpression plasmid) at 3 h post-fertilization (hpf) were exposed to a 50-Hz magnetic field (MF) with a series of intensities (100, 200, 400 and 800 μT, respectively) for 1 h or 24 h every day for 5 days. Results showed that, although MF exposure did not affect the basic development parameters including hatching rate, mortality and malformation rate, yet MF at 200 μT could significantly induce spontaneous movement (SM) hypoactivity in zebrafish larvae. Histological examination presented morphological abnormalities of the brain such as condensed cell nucleus and cytoplasm, increased intercellular space. Moreover, exposure to MF at 200 μT inhibited syn2a transcription and expression, and increased reactive oxygen species (ROS) level as well. Overexpression of syn2a could effectively rescue MF-induced SM hypoactivity in zebrafish. Pretreatment with N-acetyl-L-cysteine (NAC) could not only recover syn2a protein expression which was weakened by MF exposure, but also abolish MF-induced SM hypoactivity. However, syn2a overexpression did not affect MF-increased ROS. Taken together, the findings suggested that exposure to a 50-Hz MF inhibited spontaneous movement of zebrafish larvae via ROS-mediated syn2a expression in a nonlinear manner.

Mesenchymal stem cell therapy in amyotrophic lateral sclerosis (ALS) patients: A comprehensive review of disease information and future perspectives

Amyotrophic lateral sclerosis (ALS) is a rare deadly progressive neurological disease that primarily affects the upper and lower motor neurons with an annual incidence rate of 0.6 to 3.8 per 100,000 people. Weakening and gradual atrophy of the voluntary muscles are the first signs of the disease onset affecting all aspects of patients' lives, including eating, speaking, moving, and even breathing. Only 5-10% of patients have a familial type of the disease and show an autosomal dominant pattern, but the cause of the disease is unknown in the remaining 90% of patients (Sporadic ALS). However, in both types of disease, the patient's survival is 2 to 5 years from the disease onset. Some clinical and molecular biomarkers, magnetic resonance imaging (MRI), blood or urine test, muscle biopsy, and genetic testing are complementary methods for disease diagnosis. Unfortunately, with the exception of Riluzole, the only medically approved drug for the management of this disease, there is still no definitive cure for it. In this regard, the use of mesenchymal stem cells (MSCs) for the treatment or management of the disease has been common in preclinical and clinical studies for many years. MSCs are multipotent cells having immunoregulatory, anti-inflammatory, and differentiation ability that makes them a good candidate for this purpose. This review article aims to discuss multiple aspects of ALS disease and focus on MSCs' role in disease management based on performed clinical trials.

Primary lateral sclerosis

Like motor neuron diseases (MNDs) refer to a constellation of primarily sporadic neurodegenerative diseases characterized by a progressive loss of upper and/or lower motor neurons. Primary lateral sclerosis (PLS) is considered a neurodegenerative disorder that is characterized by a gradually progressive course affecting the central motor systems, designated by the phrase "upper motor neurons." Despite significant development in neuroimaging, neurophysiology, and molecular biology, there is a growing consensus that PLS is of unknown etiology. Currently there is no disease-modifying treatment for PLS, or prospective randomized trials being carried out, partly due to the rarity of the disease and lack of significant understanding of the underlying pathophysiology. Consequently, the approach to treatment remains largely symptomatic. In this chapter we provide an overview of primary lateral sclerosis including clinical and electrodiagnostic considerations, differential diagnosis, updates in genetics and pathophysiology, and future directions for research.

Open Questions on the Electromagnetic Field Contribution to the Risk of Neurodegenerative Diseases

This work presents the current state of knowledge about the possible contributory influence of the electromagnetic field on the occurrence of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease, amyotrophic lateral sclerosis, and multiple sclerosis. Up-to-date literature indicates both favourable and adverse effects of electromagnetic exposure on human health, making it difficult to come to valid and unambiguous conclusions. The epidemiological data analysis from the World Health Organization statistics shows a substantial rise in neurological mortality compared with rises in total populations in developed countries over a mere 15-year period. The largest of the analysed countries produced odds ratios of >100%. The contribution of electromagnetic exposure to the incidence of neurodegenerative diseases is still undoubtedly open to discussion, and it requires further in-depth research to assess the action mechanism of electromagnetic fields in neurodegenerative diseases. The limitations of research published hitherto and the problem of drawing unequivocal conclusions are also in focus.

New evidence on the association of occupation with amyotrophic lateral sclerosis: A register-based case-control study in Finland

Objectives

Amyotrophic lateral sclerosis (ALS) is a serious neurodegenerative disease that usually leads to death within a few years from diagnosis. The risk factors for ALS are still largely unknown. However, it is assumed that environmental factors play a role in disease onset. Occupation is suggested as a potential risk factor, but findings are inconsistent. The aim of this study was to assess the association of occupation with ALS in Finland. Register data were used to avoid recall bias and to obtain a large enough sample to detect the potential associations.

Methods

This case-control study included ALS cases that occurred between 1980 and 2015 in Finland (n = 4,781). ALS cases were identified from the causes of death register. For each ALS case, six controls were selected matched for sex and birth-year. The date of death of the ALS case was set as index date. Information on occupation was obtained from Statistics Finland for all subjects. The focus was on the longest-held occupation on 2-digit level (70 groups). The association of occupation with ALS was analyzed using conditional logistic regression.

Results

Compared to “clerical work and other office work,” the risk of ALS was increased in “packing and wrapping work” (OR 1.53, 95% CI 1.08–2.17), “laundering, dry cleaning and pressing work” (OR 1.83, 95% CI 1.08–3.08), and “travel service work” (OR 8.75, CI 2.76–27.74). A decreased risk was found in “planning, administrative and research work in the technical fields” (OR 0.69, 95% CI 0.48–0.98). Of the significant associations identified, only “travel service work” was significant after FDR multiple testing correction.

Conclusions

This study identified occupations in which the risk of ALS was increased. Further studies are needed to pinpoint the potential exposures in these occupations that may trigger the disease.

Field exposure to 50 Hz significantly affects wild‑type and unfolded p53 expression in NB69 neuroblastoma cells

Previous studies have shown that intermittent exposure to a 50 Hz, 100 µT sinusoidal magnetic field (MF) promotes proliferation of human neuroblastoma cells, NB69. This effect is mediated by activation of the epidermal growth factor receptor through a free radical-dependent activation of the p38 pathway. The present study investigated the possibility that the oxidative stress-sensitive protein p53 is a potential target of the MF, and that field exposure can affect the protein expression. To that end, NB69 cells were exposed to short intervals of 30 to 120 min to the aforementioned MF parameters. Two specific anti-p53 antibodies that allow discrimination between the wild and unfolded forms of p53 were used to study the expression and cellular distribution of both isoforms of the protein. The expression of the antiapoptotic protein Bcl-2, whose regulation is mediated by p53, was also analyzed. The obtained results revealed that MF exposure induced increases in p53 gene expression and in protein expression of the wild-type form of p53. Field exposure also caused overexpression of the unfolded form of p53, together with changes in the nuclear/cytoplasmic distribution of both forms of the protein. The expression of protein Bcl-2 was also significantly increased in response to the MF. As a whole, these results indicated that the MF is capable of interacting with the function, distribution and conformation of protein p53. Such interactions could be involved in previously reported MF effects on NB69 proliferation promotion.

Motor neuron disease risk and magnetic field exposures

BACKGROUND

Many studies have investigated magnetic field exposure and the risks of motor neuron disease (MND). Meta-analyses have found positive associations but a causal relationship has not been established.

AIMS

To investigate the risks of MND and occupational exposure to magnetic fields in a large UK cohort.

METHODS

Mortality of 37 986 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1987-2018. Employees were first employed in the period 1942-82 and were still in employment on the 1 November, 1987. Detailed calculations enabled estimates to be made of magnetic field exposures. Observed deaths were compared with expected numbers based on mortality rates for the general population of England and Wales and Poisson regression was used to calculate rate ratios (relative risks) for categories of lifetime, lagged (distant) and lugged (recent) magnetic field exposure.

RESULTS

Mortality from MND in the total cohort was similar to national rates (observed 69, expected 71.3, SMR 97, 95% CI 76-122). There were no statistically significant trends of risks increasing with lifetime, recent or distant magnetic field exposure, although positive associations were observed for some categories of recent exposure.

CONCLUSIONS

The study did not find that the cohort had elevated risks of MND as a consequence of occupational lifetime exposure to magnetic fields, although a possible role for recent exposures could usefully be investigated in other datasets.

Occupational Exposure to Extremely Low-Frequency Magnetic Fields and Risk of Amyotrophic Lateral Sclerosis: Results of a Feasibility Study for a Pooled Analysis of Original Data

Previous meta-analyses have suggested an increased risk of amyotrophic lateral sclerosis (ALS) associated with occupational exposure to extremely low-frequency magnetic fields (ELF-MF). However, results should be interpreted with caution since studies were methodologically heterogeneous. Here, we assessed the feasibility of a pooling study to harmonize and re-analyze available original data. A systematic literature search was conducted. Published epidemiological studies were identified in PubMed and EMF-Portal from literature databases' inception dates until January 2019. The characteristics of all studies were described, including exposure metrics, exposure categories, and confounders. A survey among the principal investigators (PI) was carried out to assess their willingness to provide their original data. The statistical power of a pooling study was evaluated. We identified 15 articles published between 1997 and 2019. Studies differed in terms of outcome, study population, exposure assessment, and exposure metrics. Most studies assessed ELF-MF as average magnetic flux density per working day; however, exposure categories varied widely. The pattern of adjustment for confounders was heterogeneous between studies, with age, sex, and socioeconomic status being most frequent. Eight PI expressed their willingness to provide original data. A relative risk of ≥1.14 for ALS and occupational exposure to ELF-MF can be detected with a power of more than 80% in a pooled study. The pooling of original data is recommended and could contribute to a better understanding of ELF-MF in the etiology of ALS based on a large database and reduced heterogeneity due to a standardized analysis protocol with harmonized exposure metrics and exposure categories. Bioelectromagnetics. © 2021 Bioelectromagnetics Society.

Associations of Occupational Exposures to Electric Shocks and Extremely Low-Frequency Magnetic Fields With Motor Neurone Disease

In a New Zealand population-based case-control study we assessed associations with occupational exposure to electric shocks, extremely low-frequency magnetic fields (ELF-MF) and motor neurone disease using job-exposure matrices to assess exposure. Participants were recruited between 2013 and 2016. Associations with ever/never, duration, and cumulative exposure were assessed using logistic regression adjusted for age, sex, ethnicity, socioeconomic status, education, smoking, alcohol consumption, sports, head or spine injury, and solvents, and was mutually adjusted for the other exposure. All analyses were repeated stratified by sex. An elevated risk was observed for having ever worked in a job with potential for electric shocks (odds ratio (OR) = 1.35, 95% confidence interval (CI): 0.98, 1.86), with the strongest association for the highest level of exposure (OR = 2.01, 95% CI: 1.31, 3.09). Analysis by duration suggested a nonlinear association: Risk was increased for both short duration (<3 years; OR = 4.69, 95% CI: 2.25, 9.77) and long duration (>24 years; OR = 1.88; 95% CI: 1.05, 3.36) in a job with high level of electric shock exposure, with less pronounced associations for intermediate durations. No association with ELF-MF was found. Our findings provide support for an association between occupational exposure to electric shocks and motor neurone disease but did not show associations with exposure to work-related ELF-MF.

The role of magnetic fields in neurodegenerative diseases

The term neurodegenerative diseases include a long list of diseases affecting the nervous system that are characterized by the degeneration of different neurological structures. Among them, Alzheimer disease (AD), Parkinson disease (PD), and amyotrophic lateral sclerosis (ALS) are the most representative ones. The vast majority of cases are sporadic and results from the interaction of genes and environmental factors in genetically predisposed individuals. Among environmental conditions, electromagnetic field exposure has begun to be assessed as a potential risk factor for neurodegeneration. In this review, we discuss the existing literature regarding electromagnetic fields and neurodegenerative diseases. Epidemiological studies in AD, PD, and ALS have shown discordant results; thus, a clear correlation between electromagnetic exposure and neurodegeneration has not been demonstrated. In addition, we discuss the role of electromagnetic radiation as a potential non-invasive therapeutic strategy for some neurodegenerative diseases, particularly for PD and AD.

Amyotrophic Lateral Sclerosis: A Neurodegenerative Motor Neuron Disease With Ocular Involvement

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that causes degeneration of the lower and upper motor neurons and is the most prevalent motor neuron disease. This disease is characterized by muscle weakness, stiffness, and hyperreflexia. Patients survive for a short period from the onset of the disease. Most cases are sporadic, with only 10% of the cases being genetic. Many genes are now known to be involved in familial ALS cases, including some of the sporadic cases. It has also been observed that, in addition to genetic factors, there are numerous molecular mechanisms involved in these pathologies, such as excitotoxicity, mitochondrial disorders, alterations in axonal transport, oxidative stress, accumulation of misfolded proteins, and neuroinflammation. This pathology affects the motor neurons, the spinal cord, the cerebellum, and the brain, but recently, it has been shown that it also affects the visual system. This impact occurs not only at the level of the oculomotor system but also at the retinal level, which is why the retina is being proposed as a possible biomarker of this pathology. The current review discusses the main aspects mentioned above related to ALS, such as the main genes involved, the most important molecular mechanisms that affect this pathology, its ocular involvement, and the possible usefulness of the retina as a biomarker.

Residential distance from high-voltage overhead power lines and risk of Alzheimer's dementia and Parkinson's disease: a population-based case-control study in a metropolitan area of Northern Italy

Background

The association between the extremely low-frequency magnetic field generated by overhead power lines and neurodegenerative disease is still a matter of debate.

Methods

A population-based case-control study was carried out on the residents in the Milan metropolitan area between 2011 and 2016 to evaluate the possible association between exposure to extremely low-frequency magnetic fields generated by high-voltage overhead power lines and Alzheimer's dementia and Parkinson's disease. A statistical analysis was performed on cases and controls matched by sex, year of birth and municipality of residence (with a case to controls ratio of 1 : 4) using conditional logistic regression models adjusted for socio-economic deprivation and distance from the major road network as potential confounders.

Results

Odds ratios for residents <50 m from the source of exposure compared with residents at ≥600 m turned out to be 1.11 (95% confidence interval: 0.95–1.30) for Alzheimer's dementia and 1.09 (95% confidence interval: 0.92–1.30) for Parkinson's disease.

Conclusions

The finding of a weak association between exposure to the extremely low-frequency magnetic field and neurodegenerative diseases suggests the continuation of research on this topic. Moreover, the low consistency between the results of the already existing studies emphasises the importance of increasingly refined study designs.

Residential exposure to ultra high frequency electromagnetic fields emitted by Global System for Mobile (GSM) antennas and amyotrophic lateral sclerosis incidence: A geo-epidemiological population-based study

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease of unknown etiology. Mobile communication antennas have increased over the last few decades. Consequently, there has been a steady increase in environmental exposure to ultra high frequency electromagnetic fields (UHF-EMFs) emitted by Global System for Mobile (GSM) communication antennas, which raises concerns about possible health risks in the general population. We aimed to evaluate the relationship between residential exposure to UHF-EMFs generated by GSM antennas and the risk of ALS in general population. A geo-epidemiological population-based study was performed in Limousin (France). ALS incident cases were identified through a register (FRALim, 2000-2012 period). A model to estimate UHF-EMF exposure was developed based on the distance and the power of GSM antennas. Exposure to multiple emissions from multiple directions was considered. A non-cumulative and a cumulative model were established. A geographic information system integrated the raster model of exposure, and the residential distribution of observed and expected cases. A generalized linear model was performed to test the association. Overall, 312 ALS cases were included. We estimated exposures below 1.72 V/m in urban areas and below 1.23 V/m in rural areas for 90% of the population. A gradient effect between UHF-EMF exposure and ALS incidence was apparent with a statistically significant trend. A significant increased risk of ALS was observed between the non-exposure category and the highest exposure category, with a relative risk of 1.78 (95% CI: 1.28-2.48) in the non-cumulative model and 1.83 (95% CI: 1.32-2.54) in the cumulative model. Our results suggest a possible association between residential UHF-EMF exposure and ALS. Ecological studies are a means of generating hypotheses. Further studies are needed to clarify the potential role of EMFs on neurodegeneration.

Extremely low frequency magnetic field induces human neuronal differentiation through NMDA receptor activation

Magnetic fields with different frequency and intensity parameters exhibit a wide range of effects on different biological models. Extremely low frequency magnetic field (ELF MF) exposure is known to augment or even initiate neuronal differentiation in several in vitro and in vivo models. This effect holds potential for clinical translation into treatment of neurodegenerative conditions such as autism, Parkinson's disease and dementia by promoting neurogenesis, non-invasively. However, the lack of information on underlying mechanisms hinders further investigation into this phenomenon. Here, we examine involvement of glutamatergic Ca²⁺ channel, N-methyl-D-aspartate (NMDA) receptors in the process of human neuronal differentiation under ELF MF exposure. We show that human neural progenitor cells (hNPCs) differentiate more efficiently under ELF MF exposure in vitro, as demonstrated by the abundance of neuronal markers. Furthermore, they exhibit higher intracellular Ca²⁺ levels as evidenced by c-fos expression and more elongated mature neurites. We were able to neutralize these effects by blocking NMDA receptors with memantine. As a result, we hypothesize that the effects of ELF MF exposure on neuronal differentiation originate from the effects on NMDA receptors, which sequentially triggers Ca²⁺-dependent cascades that lead to differentiation. Our findings identify NMDA receptors as a new key player in this field that will aid further research in the pursuit of effect mechanisms of ELF MFs.

Risk Factors and Emerging Therapies in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal progressive neurodegenerative disease characterized by a permanent degeneration of both upper and lower motor neurons. Many different genes and pathophysiological processes contribute to this disease, however its exact cause remains unclear. Therefore, it is necessary to understand this heterogeneity to find effective treatments. In this review, we focus on selected environmental and genetic risk factors predisposing to ALS and highlight emerging treatments in ALS therapy. Of numerous defective genes associated with ALS, we focus on four principal genes that have been identified as definite causes of ALS: the SOD1 gene, C9orf72, TDP-43, as well as the recently identified TBK1. We also provide up-to-date information on selected environmental factors that have historically been considered as key players in ALS development and pathogenesis. In parallel to our survey of known risk factors, we also discuss emerging ALS stem cell therapies and experimental medicines currently undergoing phase II and III clinical trials.

Associations of Electric Shock and Extremely Low-Frequency Magnetic Field Exposure With the Risk of Amyotrophic Lateral Sclerosis

We explored the associations of occupational exposure to extremely low-frequency magnetic fields (ELF-MF) and electric shocks with the risk of amyotrophic lateral sclerosis (ALS) in a pooled case-control study (European Multidisciplinary ALS Network Identification to Cure Motor Neurone Degeneration (Euro-MOTOR)) of data from 3 European countries. ALS patients and population-based controls were recruited in Ireland, Italy, and the Netherlands between 2010 and 2015. Lifetime occupational and lifestyle histories were obtained using structured questionnaires. We applied previously developed job exposure matrices assigning exposure levels to ELF-MF and potential for electric shocks. Odds ratios and 95% confidence intervals were estimated by means of logistic regression for exposure to either ELF-MF or electric shocks, adjusted for age, sex, study center, education, smoking, and alcohol consumption and for the respective other exposure. Complete occupational histories and information on confounding variables were available for 1,323 clinically confirmed ALS cases and 2,704 controls. Both ever having had exposure to ELF-MF above the background level (odds ratio = 1.16, 95% confidence interval: 1.01, 1.33) and ever having had potential exposure above background for electric shocks (odds ratio = 1.23, 95% confidence interval: 1.05, 1.43) were associated with ALS. Adjustment for the respective other exposure resulted in similar risk estimates. Heterogeneity in risks across study centers was significant for both exposures. Our findings support possible independent associations of occupational exposure to ELF-MF and electric shocks with the risk of ALS.

Are rises in Electro-Magnetic Field in the human environment, interacting with multiple environmental pollutions, the tripping point for increases in neurological deaths in the Western World?

Whilst humans evolved in the earth's Electro-Magnetic-Field (EMF) and sun-light, both being essential to life but too much sun and we burn. What happens if background EMF rise to critical levels, coinciding with increasing environmental pollutants? Two of the authors can look back over 50 clinical years and appreciate the profound changes in human morbidity across a range of disparate conditions - autoimmune diseases, asthma, earlier cancer incidence and reduced male sperm counts. In particular have been increased autism, dyslexia, Attention Deficit Hyperactivity Disorder and neurological diseases, such as Amyotrophic Lateral Sclerosis, Multiple Sclerosis, Parkinson's Disease, Early Onset Dementia, Multiple System Atrophy and Progressive Supranuclear Palsy. What might have caused these changes-whilst genetic factors are taken as given, multiple environmental pollutants are associated with neurological disease although the mechanisms are unclear. The pace of increased neurological deaths far exceeds any Gompertzian explanation - that because people are living longer they are more likely to develop more age-related problems such as neurological disease. Using WHO global mortality categories of Neurological Disease Deaths (NDD) and Alzheimer's and Dementia deaths (Alz), updated June 2018, together they constitute Total Neurological Mortality (TNM), to calculate mortality rates per million for people aged 55-74 and for the over-75's in twenty-one Western countries. Recent increases in American people aged over-75's rose 49% from 1989 to 2015 but US neurological deaths increased five-fold. In 1989 based on Age-Standardised-Deaths-Rates America USA was 17th at 324 pm but rising to 539 pm became second highest. Different environmental/occupational factors have been found to be associated with neuro-degenerative diseases, including background EMF. We briefly explore how levels of EMF interact upon the human body, which can be described as a natural antennae and provide new evidence that builds upon earlier research to propose the following hypothesis. Based upon recent and new evidence we hypothesise that a major contribution for the relative sudden upsurge in neurological morbidity in the Western world (1989-2015), is because of increased background EMF that has become the tipping point-impacting upon any genetic predisposition, increasing multiple-interactive pollutants, such as rises in petro-chemicals, hormone disrupting chemicals, industrial, agricultural and domestic chemicals. The unprecedented neurological death rates, all within just twenty-five years, demand a re-examination of long-term EMF safety related to the increasing background EMF on human health. We do not wish to 'stop the modern world', only make it safer.

Occupational Exposures and Neurodegenerative Diseases-A Systematic Literature Review and Meta-Analyses

Objectives: To carry out an integrated and stratified meta-analysis on occupational exposure to electromagnetic fields (EMFs), metals and pesticides and its effects on amyotrophic lateral sclerosis (ALS) and Parkinson's and Alzheimer's disease, and investigate the possibility of publication bias. Methods: In the current study, we updated our recently published meta-analyses on occupational exposures in relation to ALS, Alzheimer's and Parkinson's disease. Based on 66 original publications of good scientific epidemiological standard, according to the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines, we analysed subgroups by carrying out stratified meta-analyses on publication year, statistical precision of the relative risk (RR) estimates, inspection of the funnel plots and test of bias. Results: Based on 19 studies the weighted RR for occupational exposure to EMFs was 1.26 (95% confidence interval (CI) 1.07⁻1.50) for ALS, 1.33 (95% CI 1.07⁻1.64) for Alzheimer's disease and 1.02 (95% CI 0.83⁻1.26) for Parkinson's disease. Thirty-one studies concerned occupational exposure to pesticides and the weighted RR was 1.35 (95% CI 1.02⁻1.79) for ALS, 1.50 (95% CI 0.98⁻2.29) for Alzheimer's disease and 1.66 (95% CI 1.42⁻1.94) for Parkinson's disease. Finally, 14 studies concerned occupational exposure to metals and only exposure to lead (five studies) involved an elevated risk for ALS or Parkinson's disease and the weighted RR was 1.57 (95% CI 1.11⁻2.20). The weighted RR for all the non-lead exposures was 0.97 (95% CI 0.88⁻1.06). Conclusions: Exposure to pesticides increased the risk of getting the mentioned neurodegenerative diseases by at least 50%. Exposure to lead was only studied for ALS and Parkinson's disease and involved 50% increased risk. Occupational exposure to EMFs seemed to involve some 10% increase in risk for ALS and Alzheimer's disease only.

Amyotrophic Lateral Sclerosis and Occupational Exposures: A Systematic Literature Review and Meta-Analyses

Objectives: We conducted a systematic literature review to identify studies fulfilling good scientific epidemiological standards for use in meta-analyses of occupational risk factors for amyotrophic lateral sclerosis (ALS). Methods: We identified 79 original publications on associations between work and ALS. The MOOSE (Meta-analysis Of Observational Studies in Epidemiology) and GRADE (Grading of Recommendations, Assessment, Development and Evaluations) guidelines were used to ensure high scientific quality, and reliable protocols were applied to classify the articles. Thirty-seven articles fulfilled good scientific standards, while 42 were methodologically deficient and thus were excluded from our meta-analyses. Results: The weighted relative risks for the various occupational exposures were respectively; 1.29 (95% confidence interval (CI): 0.97–1.72; six articles) for heavy physical work, 3.98 (95% CI: 2.04–7.77; three articles) for professional sports, 1.45 (95% CI: 1.07–1.96; six articles) for metals, 1.19 (95% CI: 1.07–1.33; 10 articles) for chemicals, 1.18 (95% CI: 1.07–1.31; 16 articles) for electromagnetic fields or working with electricity, and 1.18 (95% CI: 1.05–1.34; four articles) for working as a nurse or physician. Conclusions: Meta-analyses based only on epidemiologic publications of good scientific quality show that the risk of ALS is statistically significantly elevated for occupational exposures to excessive physical work, chemicals (especially pesticides), metals (especially lead), and possibly also to electromagnetic fields and health care work. These results are not explained by publication bias.

A meta-analysis on residential exposure to magnetic fields and the risk of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is caused by the gradual degeneration and death of motor neurons, with mostly unknown etiology. Some risk factors have been suggested for this disease including extremely low frequency magnetic fields (ELF-MF) exposure. This meta-analysis assesses the association of residential exposure to ELF-MF with the risk of ALS. Five studies have addressed the risk of ALS in relation to overhead power lines. A pooled relative risk (RR) of 0.71 [95% confidence interval (CI): 0.48, 1.07] for the most exposed population group (either <200 m distance from high voltage power lines or >0.1 μT) was found. Little heterogeneity (I2=0.00%, p=0.67) and indication for publication bias (PBegg’s test=0.22; PEgger’s test=0.19) was seen. Overall, we found no evidence for an association between residential exposure to ELF-MF and the risk of ALS, although the number of exposed cases is low.

The increasing importance of environmental conditions in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common neurodegenerative disease affecting motor neurons (MNs). Although a small percentage of ALS has a familial origin, the vast majority of cases are sporadic in which genetic factors and environment interact with each other leading to disease onset in genetically predisposed individuals. In the current model of the disease, each individual has a determined genetic load, some degree of cell degeneration related to age and several risky environmental exposures. In this scenario, MN degeneration would occur when the sum of these factors reach a certain threshold. To date, an extensive list of environmental factors has been associated to ALS, including different categories, such as exposure to heavy metals and other toxicants, cyanotoxins or infectious agents. In addition, in recent years, lifestyle and other demographic parameters are gaining relevance in the genesis of the disease. Among them, physical activity, nutrition, body mass index, cardiovascular risk factors, autoimmune diseases and cancer are some of the conditions which have been related to the disease. In this review, we will discuss the potential mechanisms of environmental conditions in motor neuron degeneration. Understanding the role of each one of these factors as well as their interactions appears as a crucial step in order to develop new preventive, diagnostic and therapeutic approaches for ALS patients.

Olfactory memory is enhanced in mice exposed to extremely low-frequency electromagnetic fields via Wnt/β-catenin dependent modulation of subventricular zone neurogenesis

Exposure to extremely low-frequency electromagnetic fields (ELFEF) influences the expression of key target genes controlling adult neurogenesis and modulates hippocampus-dependent memory. Here, we assayed whether ELFEF stimulation affects olfactory memory by modulating neurogenesis in the subventricular zone (SVZ) of the lateral ventricle, and investigated the underlying molecular mechanisms. We found that 30 days after the completion of an ELFEF stimulation protocol (1 mT; 50 Hz; 3.5 h/day for 12 days), mice showed enhanced olfactory memory and increased SVZ neurogenesis. These effects were associated with upregulated expression of mRNAs encoding for key regulators of adult neurogenesis and were mainly dependent on the activation of the Wnt pathway. Indeed, ELFEF stimulation increased Wnt3 mRNA expression and nuclear localization of its downstream target β-catenin. Conversely, inhibition of Wnt3 by Dkk-1 prevented ELFEF-induced upregulation of neurogenic genes and abolished ELFEF’s effects on olfactory memory. Collectively, our findings suggest that ELFEF stimulation increases olfactory memory via enhanced Wnt/β-catenin signaling in the SVZ and point to ELFEF as a promising tool for enhancing SVZ neurogenesis and olfactory function.

Occupational exposure to extremely low-frequency magnetic fields and risk for central nervous system disease: an update of a Danish cohort study among utility workers

PURPOSE

Evidence of whether exposure to extremely low-frequency magnetic fields (ELF-MF) is related to central nervous system diseases is inconsistent. This study updates a previous study of the incidence of such diseases in a large cohort of Danish utility workers by almost doubling the period of follow-up.

METHODS

We investigated the risks for dementia, motor neurone disease, Parkinson disease, multiple sclerosis and epilepsy among 32,006 men employed at the 99 utility companies that supplied Denmark with electricity during the period 1900-1993. Cases were identified in the Danish National Patient Registry and the cohort was followed during 1982-2010. Exposure was estimated from a job-exposure matrix based on company records of job title and area of work and cohort members were allocated to one of three categories (<0.1, 0.1-0.99 and ≥1.0 µT).

RESULTS

For dementia, multiple sclerosis and epilepsy the incidence rate ratios (IRR) were close to unity, but higher for motor neurone disease [IRR 1.24, 95% confidence interval (CI) 0.86-1.79] and lower for Parkinson disease (IRR 0.81, 95% CI 0.67-0.97) among workers exposed to ≥0.1 µT compared with the Danish population. For the highest level of exposure (≥1.0 µT), IRRs of 1.44, 1.78, 1.40 and 1.34 were observed for dementia, motor neurone disease, multiple sclerosis and epilepsy, respectively.

CONCLUSIONS

We observed elevated risks of dementia, motor neurone disease, multiple sclerosis and epilepsy and lower risks of Parkinson disease in relation to exposure to ELF-MF in a large cohort of utility employees.

Magnetic fields exposure from high-voltage power lines and risk of amyotrophic lateral sclerosis in two Italian populations

The aetiology of amyotrophic lateral sclerosis (ALS), a rare and extremely severe neurodegenerative disease, has been associated with magnetic fields exposure. However, evidence for such a relation in the general population is weak, although the previous null results might also be due to exposure misclassification, or a relationship might exist only for selected subgroups. To test such a hypothesis we carried out a population-based case-control study in two Northern and Southern Italy regions, including 703 ALS cases newly diagnosed from 1998 to 2011 and 2737 controls randomly selected from the residents in the study provinces. Overall, we found that a residence near high-voltage power lines, within the corridors yielding a magnetic fields of ≥0.1 μT, was not associated with an excess disease risk, nor did we identify a dose-response relationship after splitting the exposed corridor according to the 0.1, 0.2 and 0.4 μT cut-points of exposure. These results were confirmed taking into account age at onset, period of diagnosis, sex, geographical area, and length of exposure. Overall, despite the residual possibility of unmeasured confounding or small susceptible subgroups not identified in our study, these results appear to confirm that the exposure to magnetic fields from power lines occurring in the general population is not associated with increased ALS risk.

Amyotrophic lateral sclerosis and environmental factors

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that affects central and peripheral motor neuron cells. Its etiology is unknown, although a relationship between genetic background and environmental factors may play a major role in triggering the neurodegeneration. In this review, we analyze the role of environmental factors in ALS: heavy metals, electromagnetic fields and electric shocks, pesticides, β-N-methylamino-L-alanine, physical activity and the controversial role of sports. The literature on the single issues is analyzed in an attempt to clarify, as clearly as possible, whether each risk factor significantly contributes to the disease pathogenesis. After summarizing conflicting observations and data, the authors provide a final synthetic statement.

EUROPAEM EMF Guideline 2016 for the prevention, diagnosis and treatment of EMF-related health problems and illnesses

Chronic diseases and illnesses associated with non-specific symptoms are on the rise. In addition to chronic stress in social and work environments, physical and chemical exposures at home, at work, and during leisure activities are causal or contributing environmental stressors that deserve attention by the general practitioner as well as by all other members of the health care community. It seems necessary now to take "new exposures" like electromagnetic fields (EMF) into account. Physicians are increasingly confronted with health problems from unidentified causes. Studies, empirical observations, and patient reports clearly indicate interactions between EMF exposure and health problems. Individual susceptibility and environmental factors are frequently neglected. New wireless technologies and applications have been introduced without any certainty about their health effects, raising new challenges for medicine and society. For instance, the issue of so-called non-thermal effects and potential long-term effects of low-dose exposure were scarcely investigated prior to the introduction of these technologies. Common electromagnetic field or EMF sources: Radio-frequency radiation (RF) (3 MHz to 300 GHz) is emitted from radio and TV broadcast antennas, Wi-Fi access points, routers, and clients (e.g. smartphones, tablets), cordless and mobile phones including their base stations, and Bluetooth devices. Extremely low frequency electric (ELF EF) and magnetic fields (ELF MF) (3 Hz to 3 kHz) are emitted from electrical wiring, lamps, and appliances. Very low frequency electric (VLF EF) and magnetic fields (VLF MF) (3 kHz to 3 MHz) are emitted, due to harmonic voltage and current distortions, from electrical wiring, lamps (e.g. compact fluorescent lamps), and electronic devices. On the one hand, there is strong evidence that long-term exposure to certain EMFs is a risk factor for diseases such as certain cancers, Alzheimer's disease, and male infertility. On the other hand, the emerging electromagnetic hypersensitivity (EHS) is more and more recognized by health authorities, disability administrators and case workers, politicians, as well as courts of law. We recommend treating EHS clinically as part of the group of chronic multisystem illnesses (CMI), but still recognizing that the underlying cause remains the environment. In the beginning, EHS symptoms occur only occasionally, but over time they may increase in frequency and severity. Common EHS symptoms include headaches, concentration difficulties, sleep problems, depression, a lack of energy, fatigue, and flu-like symptoms. A comprehensive medical history, which should include all symptoms and their occurrences in spatial and temporal terms and in the context of EMF exposures, is the key to making the diagnosis. The EMF exposure is usually assessed by EMF measurements at home and at work. Certain types of EMF exposure can be assessed by asking about common EMF sources. It is very important to take the individual susceptibility into account. The primary method of treatment should mainly focus on the prevention or reduction of EMF exposure, that is, reducing or eliminating all sources of high EMF exposure at home and at the workplace. The reduction of EMF exposure should also be extended to public spaces such as schools, hospitals, public transport, and libraries to enable persons with EHS an unhindered use (accessibility measure). If a detrimental EMF exposure is reduced sufficiently, the body has a chance to recover and EHS symptoms will be reduced or even disappear. Many examples have shown that such measures can prove effective. To increase the effectiveness of the treatment, the broad range of other environmental factors that contribute to the total body burden should also be addressed. Anything that supports homeostasis will increase a person's resilience against disease and thus against the adverse effects of EMF exposure. There is increasing evidence that EMF exposure has a major impact on the oxidative and nitrosative regulation capacity in affected individuals. This concept also may explain why the level of susceptibility to EMF can change and why the range of symptoms reported in the context of EMF exposures is so large. Based on our current understanding, a treatment approach that minimizes the adverse effects of peroxynitrite - as has been increasingly used in the treatment of multisystem illnesses - works best. This EMF Guideline gives an overview of the current knowledge regarding EMF-related health risks and provides recommendations for the diagnosis, treatment and accessibility measures of EHS to improve and restore individual health outcomes as well as for the development of strategies for prevention.

NADPH oxidase-produced superoxide mediated a 50-Hz magnetic field-induced epidermal growth factor receptor clustering

PURPOSE

A 50-Hz magnetic field (MF) was found to induce epidermal growth factor receptor (EGFR) clustering in our previous study. The aim of this work was to investigate the molecular mechanisms that mediated MF-induced EGFR clustering.

MATERIALS AND METHODS

Human amniotic epithelial (FL) cells were exposed to a 50-Hz MF. Total reactive oxygen species (ROS), cytoplasmic and mitochondrial superoxide production were detected by DCFH-DA, DHE and MitoSOX, respectively. EGFR clustering was analyzed using confocal microscopy after indirect immunofluorescence staining.

RESULTS

Results showed that exposing FL cells to MF at intensity higher than 0.2 mT for 15 min enhanced total ROS production. Additionally, enhanced total ROS and cytoplasmic superoxide production were observed after exposing cells to MF at 0.4 mT for 5, 15, or 30 min, while mitochondrial superoxide production for 15 or 30 min. Pretreatment with Nox inhibitor, DPI, effectively inhibited MF-induced cytoplasmic superoxide production and subsequent EGFR clustering while mitochondrial superoxide production was not affected.

CONCLUSIONS

Nox-produced superoxide mediated a 50-Hz magnetic field-induced EGFR clustering.

Occupational exposures and the risk of amyotrophic lateral sclerosis

OBJECTIVES

To examine the associations of specific occupations and occupational exposures with the risk of amyotrophic lateral sclerosis (ALS) in the Swedish population.

METHODS

A nested case-control study was conducted in Sweden. Patients with ALS diagnosed during 1991-2010 (n=5020) were identified from the National Patient Register and 5 controls per case (n=25 100) were randomly selected from the general Swedish population, individually matched to cases by birth year and sex. Occupational history was obtained from the Swedish censuses in 1970, 1980 and 1990. The Nordic Occupational Cancer Study Job Exposure Matrix was used to identify exposures related to individual occupations. Conditional logistic regression was used to estimate ORs and their 95% CIs.

RESULTS

Higher risk of ALS was associated with precision-tool manufacturing (OR 1.68, 95% CI 1.11 to 2.52) and glass, pottery and tile work (OR 1.76, 95% CI 1.03 to 3.00), whereas lower risk was associated with textile work (OR 0.44, 95% CI 0.21 to 0.91). None of the examined occupational exposures were associated with ALS risk overall. However, among individuals younger than 65 years of age, an association with a higher risk of ALS was found for formaldehyde (OR 1.29, 95% CI 1.00 to 1.65), and an association with a lower risk of ALS was found for methylene chloride (OR 0.49, 95% CI 0.26 to 0.93).

CONCLUSIONS

We identified several occupations and occupational exposures that may be associated with the risk of ALS in Sweden. Occupational history obtained from censuses every 10 years remains a limitation of the study.

Preliminary Results of National Amyotrophic Lateral Sclerosis (ALS) Registry Risk Factor Survey Data

BACKGROUND

The National ALS Registry is made up of two components to capture amyotrophic lateral sclerosis (ALS) cases: national administrative databases (Medicare, Medicaid, Veterans Health Administration and Veterans Benefits Administration) and self-identified cases captured by the Registry's web portal. This study describes self-reported characteristics of U.S. adults with ALS using the data collected by the National ALS Registry web portal risk factor surveys only from October 19, 2010 through December 31, 2013.

OBJECTIVE

To describe findings from the National ALS Registry's web portal risk factor surveys.

MEASUREMENTS

The prevalence of select risk factors among adults with ALS was determined by calculating the frequencies of select risk factors-smoking and alcohol (non, current and former) histories, military service and occupational history, and family history of neurodegenerative diseases such as ALS, Alzheimer's and/or Parkinson's.

RESULTS

Nearly half of survey respondents were ever smokers compared with nearly 41% of adults nationally. Most respondents were ever drinkers which is comparable to national estimates. The majority were light drinkers. Nearly one-quarter of survey respondents were veterans compared with roughly 9% of US adults nationally. Most respondents were retired or disabled. The industries in which respondents were employed for the longest time were Professional and Scientific and Technical Services. When family history of neurodegenerative diseases in first degree relatives was evaluated against our comparison group, the rates of ALS were similar, but were higher for Parkinson's disease, Alzheimer's disease and any neurodegenerative diseases.

CONCLUSIONS

The National ALS Registry web portal, to our knowledge, is the largest, most geographically diverse collection of risk factor data about adults living with ALS. Various characteristics were consistent with other published studies on ALS risk factors and will allow researchers to generate hypotheses for future research.

Power Frequency Magnetic Fields Affect the p38 MAPK-Mediated Regulation of NB69 Cell Proliferation Implication of Free Radicals

The proliferative response of the neuroblastoma line NB69 to a 100 µT, 50 Hz magnetic field (MF) has been shown mediated by activation of the MAPK-ERK1/2 pathway. This work investigates the MF effect on the cell cycle of NB69, the participation of p38 and c-Jun N-terminal (JNK) kinases in the field-induced proliferative response and the potential involvement of reactive oxygen species (ROS) in the activation of the MAPK-ERK1/2 and -p38 signaling pathways. NB69 cultures were exposed to the 100 µT MF, either intermittently for 24, 42 or 63 h, or continuously for periods of 15 to 120 min, in the presence or absence of p38 or JNK inhibitors: SB203580 and SP600125, respectively. Antioxidant N-acetylcysteine (NAC) was used as ROS scavenger. Field exposure induced transient activation of p38, JNK and ERK1/2. The MF proliferative effect, which was mediated by changes in the cell cycle, was blocked by the p38 inhibitor, but not by the JNK inhibitor. NAC blocked the field effects on cell proliferation and p38 activation, but not those on ERK1/2 activation. The MF-induced proliferative effects are exerted through sequential upregulation of MAPK-p38 and -ERK1/2 activation, and they are likely mediated by a ROS-dependent activation of p38.

Exposure to a 50-Hz magnetic field induced mitochondrial permeability transition through the ROS/GSK-3β signaling pathway

PURPOSE

To investigate the biological effects of a 50-Hz magnetic field (MF) on mitochondrial permeability.

MATERIALS AND METHODS

Human amniotic epithelial cells were exposed to MF (50 Hz, 0.4 mT) for different durations. Mitochondrial permeability, mitochondrial membrane potential (ΔΨm), cytochrome c (Cyt-c) release and the related mechanisms were explored.

RESULTS

Exposure to the MF at 0.4 mT for 60 min transiently induced mitochondrial permeability transition (MPT) and Cyt-c release, although there was no significant effect on mitochondrial membrane potential (ΔΨm). Other than decreasing the total Bcl-2 associated X protein (Bax) level, MF exposure did not significantly affect the levels of Bax and B-cell lymphoma-2 (Bcl-2) in mitochondria. In addition, cells exposed to the MF showed increased intracellular reactive oxidative species (ROS) levels and glycogen synthase kinase-3β (GSK-3β) dephosphorylation at 9 serine residue (Ser(9)). Moreover, the MF-induced MPT was attenuated by ROS scavenger (N-acetyl-L-cysteine, NAC) or GSK-3β inhibitor, and NAC pretreatment prevented GSK-3β dephosphorylation (Ser(9)) caused by MF exposure.

CONCLUSION

MPT induced by MF exposure was mediated through the ROS/GSK-3β signaling pathway.

Epidemiology of amyotrophic lateral sclerosis: A review of literature

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease of motor neurons, resulting in worsening weakness of voluntary muscles until death occurs from respiratory failure. The incidence of ALS in European populations is two to three people per year per 100,000 of the general population. In Europe, crude prevalences range from 1.1/100,000 population in Yugoslavia to 8.2/100,000 in the Faroe Islands. Major advances have been made in our understanding of the genetic causes of ALS, whereas the contribution of environmental factors has been more difficult to assess and large-scale studies have not yet revealed a replicable, definitive environmental risk factor. The only established risk factors to date are older age, male gender and a family history of ALS. Median survival time from onset to death is usually 3 years from the first appearance of symptoms. Older age and bulbar onset are consistently reported to have poorer outcomes. However, there are conflicting data regarding gender, diagnostic delay and El Escorial criteria. The rate of symptom progression has been revealed to be an independent prognostic factor. Psychosocial factors and impaired cognitive function are negatively related to ALS outcome, while nutritional status and respiratory function are also related to ALS prognosis. The effect of enteral nutrition on survival is still unclear, although noninvasive positive pressure ventilation (NIPPV) has been found to improve survival. These findings have relevant implications for the design of future trials.

A comprehensive review of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease affecting motor neurons with an incidence of about 1/100,000. Most ALS cases are sporadic, but 5–10% of the cases are familial ALS. Both sporadic and familial ALS (FALS) are associated with degeneration of cortical and spinal motor neurons. The etiology of ALS remains unknown. However, mutations of superoxide dismutase 1 have been known as the most common cause of FALS. In this study, we provide a comprehensive review of ALS. We cover all aspects of the disease including epidemiology, comorbidities, environmental risk factor, molecular mechanism, genetic factors, symptoms, diagnostic, treatment, and even the available supplement and management of ALS. This will provide the reader with an advantage of receiving a broad range of information about the disease.

Low-frequency magnetic fields do not aggravate disease in mouse models of Alzheimer's disease and amyotrophic lateral sclerosis

Low-frequency magnetic fields (LF-MF) generated by power lines represent a potential environmental health risk and are classified as possibly carcinogenic by the World Health Organization. Epidemiological studies indicate that LF-MF might propagate neurodegenerative diseases like Alzheimer's disease (AD) or amyotrophic lateral sclerosis (ALS). We conducted a comprehensive analysis to determine whether long-term exposure to LF-MF (50 Hz, 1 mT) interferes with disease development in established mouse models for AD and ALS, namely APP23 mice and mice expressing mutant Cu/Zn-superoxide dismutase (SOD1), respectively. Exposure for 16 months did not aggravate learning deficit of APP23 mice. Likewise, disease onset and survival of SOD1(G85R) or SOD1(G93A) mice were not altered upon LF-MF exposure for ten or eight months, respectively. These results and an extended biochemical analysis of protein aggregation, glial activation and levels of toxic protein species suggests that LF-MF do not affect cellular processes involved in the pathogenesis of AD or ALS.

Risk factors for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease. It is typically fatal within 2-5 years of symptom onset. The incidence of ALS is largely uniform across most parts of the world, but an increasing ALS incidence during the last decades has been suggested. Although recent genetic studies have substantially improved our understanding of the causes of ALS, especially familial ALS, an important role of non-genetic factors in ALS is recognized and needs further study. In this review, we briefly discuss several major genetic contributors to ALS identified to date, followed by a more focused discussion on the most commonly examined non-genetic risk factors for ALS. We first review factors related to lifestyle choices, including smoking, intake of antioxidants, physical fitness, body mass index, and physical exercise, followed by factors related to occupational and environmental exposures, including electromagnetic fields, metals, pesticides, β-methylamino-L-alanine, and viral infection. Potential links between ALS and other medical conditions, including head trauma, metabolic diseases, cancer, and inflammatory diseases, are also discussed. Finally, we outline several future directions aiming to more efficiently examine the role of non-genetic risk factors in ALS.

EUROPAEM EMF Guideline 2015 for the prevention, diagnosis and treatment of EMF-related health problems and illnesses

Chronic diseases and illnesses associated with unspecific symptoms are on the rise. In addition to chronic stress in social and work environments, physical and chemical exposures at home, at work, and during leisure activities are causal or contributing environmental stressors that deserve attention by the general practitioner as well as by all other members of the health care community. It seems certainly necessary now to take "new exposures" like electromagnetic field (EMF) into account. Physicians are increasingly confronted with health problems from unidentified causes. Studies, empirical observations, and patient reports clearly indicate interactions between EMF exposure and health problems. Individual susceptibility and environmental factors are frequently neglected. New wireless technologies and applications have been introduced without any certainty about their health effects, raising new challenges for medicine and society. For instance, the issue of so-called non-thermal effects and potential long-term effects of low-dose exposure were scarcely investigated prior to the introduction of these technologies. Common EMF sources include Wi-Fi access points, routers and clients, cordless and mobile phones including their base stations, Bluetooth devices, ELF magnetic fields from net currents, ELF electric fields from electric lamps and wiring close to the bed and office desk. On the one hand, there is strong evidence that long-term-exposure to certain EMF exposures is a risk factor for diseases such as certain cancers, Alzheimer's disease and male infertility. On the other hand, the emerging electromagnetic hypersensitivity (EHS) is more and more recognized by health authorities, disability administrators and case workers, politicians, as well as courts of law. We recommend treating EHS clinically as part of the group of chronic multisystem illnesses (CMI) leading to a functional impairment (EHS), but still recognizing that the underlying cause remains the environment. In the beginning, EHS symptoms often occur only occasionally, but over time they may increase in frequency and severity. Common EHS symptoms include headaches, concentration difficulties, sleeping problems, depression, lack of energy, fatigue and flu-like symptoms. A comprehensive medical history, which should include all symptoms and their occurrences in spatial and temporal terms and in the context of EMF exposures, is the key to the diagnosis. The EMF exposure can be assessed by asking for typical sources like Wi-Fi access points, routers and clients, cordless and mobile phones and measurements at home and at work. It is very important to take the individual susceptibility into account. The primary method of treatment should mainly focus on the prevention or reduction of EMF exposure, that is, reducing or eliminating all sources of EMF at home and in the workplace. The reduction of EMF exposure should also be extended to public spaces such as schools, hospitals, public transport, and libraries to enable persons with EHS an unhindered use (accessibility measure). If a detrimental EMF exposure is reduced sufficiently, the body has a chance to recover and EHS symptoms will be reduced or even disappear. Many examples have shown that such measures can prove effective. Also the survival rate of children with leukemia depends on ELF magnetic field exposure at home. To increase the effectiveness of the treatment, the broad range of other environmental factors that contribute to the total body burden should also be addressed. Anything that supports a balanced homeostasis will increase a person's resilience against disease and thus against the adverse effects of EMF exposure. There is increasing evidence that EMF exposure has a major impact on the oxidative and nitrosative regulation capacity in affected individuals. This concept also may explain why the level of susceptibility to EMF can change and why the number of symptoms reported in the context of EMF exposures is so large. Based on our current understanding, a treatment approach that minimizes the adverse effects of peroxynitrite - as has been increasingly used in the treatment of multisystem disorders - works best. This EMF Guideline gives an overview of the current knowledge regarding EMF-related health risks and provides concepts for the diagnosis and treatment and accessibility measures of EHS to improve and restore individual health outcomes as well as for the development of strategies for prevention.

[Environmental factors in ALS]

ALS is likely to be a disorder of multifactorial origin. Among all the factors that may increase the risk of ALS, environmental ones are being studied for many years, but in the recent years, several advances have pointed to a new interest in their potential involvement in the disease process, especially for the cyanotoxin BMAA. Food containing BMAA has been found on Guam, a well-known focus of ALS/parkinsonism/dementia and high levels of BMAA have been identified into the brain of these patients. The BMAA cyanotoxin is potentially ubiquitous and have also been found into the food of patients who died from ALS both in Europe and USA. BMAA can be wrongly integrated into the protein structure during mRNA traduction, competing with serine. This may induce abnormal protein folding and a subsequent cell death. Heavy metals, such as lead or mercury may be directly toxic for neuronal cells. Several works have suggested an increased risk of ALS in individuals chronically exposed to these metals. Exposure to pesticides has been suggested to be linked to an increased risk of developing ALS. The mechanism of their toxicity is likely to be mediated by paraoxonases. These proteins are in charge of detoxifying the organism from toxins, and particularly organophosphates. To date, there are insufficient scientific data to suggest that exposure to electromagnetic fields may increase the risk of having ALS. We are particularly missing longitudinal cohorts to demonstrate that risk.

Exposure to environmental toxicants and pathogenesis of amyotrophic lateral sclerosis: state of the art and research perspectives

There is a broad scientific consensus that amyotrophic lateral sclerosis (ALS), a fatal neuromuscular disease, is caused by gene--environment interactions. In fact, given that only about 10% of all ALS diagnosis has a genetic basis, gene-environmental interaction may give account for the remaining percentage of cases. However, relatively little attention has been paid to environmental and lifestyle factors that may trigger the cascade of motor neuron degeneration leading to ALS, although exposure to chemicals--including lead and pesticides-agricultural environments, smoking, intense physical activity, trauma and electromagnetic fields have been associated with an increased risk of ALS. This review provides an overview of our current knowledge of potential toxic etiologies of ALS with emphasis on the role of cyanobacteria, heavy metals and pesticides as potential risk factors for developing ALS. We will summarize the most recent evidence from epidemiological studies and experimental findings from animal and cellular models, revealing that potential causal links between environmental toxicants and ALS pathogenesis have not been fully ascertained, thus justifying the need for further research.

Association between exposure to electromagnetic fields from high voltage transmission lines and neurobehavioral function in children

Background

Evidence for a possible causal relationship between exposure to electromagnetic fields (EMF) emitted by high voltage transmission (HVT) lines and neurobehavioral dysfunction in children is insufficient. The present study aims to investigate the association between EMF exposure from HVT lines and neurobehavioral function in children.

Methods

Two primary schools were chosen based on monitoring data of ambient electromagnetic radiation. A cross-sectional study with 437 children (9 to 13 years old) was conducted. Exposure to EMF from HVT lines was monitored at each school. Information was collected on possible confounders and relevant exposure predictors using standardized questionnaires. Neurobehavioral function in children was evaluated using established computerized neurobehavioral tests. Data was analyzed using multivariable regression models adjusted for relevant confounders.

Results

After controlling for potential confounding factors, multivariable regression revealed that children attending a school near 500 kV HVT lines had poorer performance on the computerized neurobehavioral tests for Visual Retention and Pursuit Aiming compared to children attending a school that was not in close proximity to HVT lines.

Conclusions

The results suggest long-term low-level exposure to EMF from HVT lines might have a negative impact on neurobehavioral function in children. However, because of differences in results only for two of four tests achieved statistical significance and potential limitations, more studies are needed to explore the effects of exposure to extremely low frequency EMF on neurobehavioral function and development in children.