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Neurophysiological effects of flickering light in patients with perceived electrical hypersensitivity
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. National Institute for Working Life, Umeå, Sweden.
Institute of the Human Brain, St Petersburg, Russia.
National Institute for Working Life, Umeå, Sweden.
Institute of the Human Brain, St Petersburg, Russia.
Show others and affiliations
1997 (English)In: Journal of Occupational and Environmental Medicine, ISSN 1076-2752, E-ISSN 1536-5948, Vol. 39, no 1, 15-22 p.Article in journal (Refereed) Published
Abstract [en]

An increasing number of people in Sweden are claiming that they are hypersensitive to electricity, These patients suffer from shin as well as neurological symptoms when they are near computer monitors, fluorescent tubes, or other electrical appliances, Provocation studies with electromagnetic fields emitted from these appliances have, with only one exception, all been negative, indicating that there are other factors in the office environment that can effect the autonomic and/or central nervous system resulting in the symptoms reported, Flickering light is one such factor and was therefore chosen as the exposure parameter in this study, Ten patients complaining of electrical hypersensitivity and the same number of healthy voluntary control subjects were exposed to amplitude-modulated light, The sensitivity of the brain to this type of visual stimulation was tested by means of objective electrophysiological methods such as electroretinography and visual evoked potential, A higher amplitude of brain cortical responses at all frequencies of stimulation was found when comparing patients with the control subjects, whereas no differences in retinal responses were revealed.

Place, publisher, year, edition, pages
Wolters Kluwer, 1997. Vol. 39, no 1, 15-22 p.
National Category
Environmental Health and Occupational Health
Identifiers
URN: urn:nbn:se:umu:diva-99018DOI: 10.1097/00043764-199701000-00006ISI: A1997WF86000004OAI: oai:DiVA.org:umu-99018DiVA: diva2:785266
Conference
7th International Congress of Psychophysiology, SEP, 1994, THESSALONIKI, GREECE
Projects
digitalisering@umu
Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
In thesis
1. Office work and physical factors: health aspects of electromagnetic fields and light
Open this publication in new window or tab >>Office work and physical factors: health aspects of electromagnetic fields and light
1997 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The overall aim of this thesis is to increase our knowledge of the physical environment of office workers with special focus on electromagnetic fields and to address the question of whether electromagnetic fields can directly or indirectly contribute to symptoms or discomfort among video display terminal ( VDT) workers. Furthermore, we have measured light modulation from various commonly used light sources in laboratory conditions and, as a second step, used modulated light as stimulus for provocation of neurophysiological responses in persons with perceived “electrical hypersensitivity” (EHS).During the last 20 years work-related illness among office workers has received increased attention. Changes in the physical environment, the introduction of VDTs and other electrical equipment and changes in light conditions have been discussed in this context. The basis for this thesis is the interdisciplinary Office Illness Project in Northern Sweden. Using a questionnaire completed by 4,943 office workers, 150 VDT workers with or without facial skin symptoms were selected for a case referent study of the electromagnetic fields in offices.When the measurements in the offices were performed in 1989, the general level of the 50 Hz magnetic fields in the offices was rather low, but in 5% of the offices the flux density exceeded 0.5 pT. At this level VDT monitors were shown to display detectable instability (jitter). Furthermore, the ability of test subjects (healthy volunteers) to detect jitter was shown to depend on both the amplitude and frequency characteristics of this instability. The study indicates that the instability of computer monitors and thereby the instability of the visual image of the VDT screen might be an increasing problem since it is known that the harmonic content of the general magnetic field in offices is on the rise.VDT monitors contributed to the magnetic field level at VDT workplaces in both extremely low and very low frequency ranges. However, the dominant source of electric fields in rooms was ungrounded electrical equipment, not VDT screens.High electric fields in the extremely low frequency range in the offices were associated with skin symptoms among VDT workers. The causal nature of this association cannot be determined since it may depend on undetected factors related to exposure. No associations were found, however, for any of the VDT-related electromagnetic fields and skin symptoms.Commonly used fluorescent tubes in our office environment have a degree of modulation of the light (flicker) that varies widely from less than 1% (fluorescent tubes with high frequency gear) up to nearly 100%. When persons with perceived EHS were exposed to flickering light, a higher amplitude of brain cortex responses were found at all tested frequencies compared with control subjects. These findings are of considerable interest, but further studies are required in order to establish a possible relationship between flickering light and discomfort/symptoms in persons with perceived EHS.

Place, publisher, year, edition, pages
Umeå: Umeå universitet och Arbetslivsinstitutet, 1997. 46 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 530
Keyword
Facial skin symptoms, office illness, electrical hypersensitivity, physical environment, flicker, jitter, neurophysiological effects
National Category
Environmental Health and Occupational Health
Identifiers
urn:nbn:se:umu:diva-96906 (URN)91-7191-386-6 (ISBN)
Public defence
1997-11-28, Stora föreläsningssalen, Arbetslivsinstitutet, Umeå, Umeå universitet, Umeå, 09:30
Supervisors
Projects
digitalisering@umu
Available from: 2015-02-02 Created: 2014-12-05 Last updated: 2015-04-10Bibliographically approved

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