Long-term effects on symptoms by reducing electric fields from visual display units.
OBJECTIVE
The purpose of the study was to see whether the results of an earlier study [ie, that skin symptoms were reduced by reducing electric fields from visual display units (VDU)] could be reproduced or not. In addition, an attempt was made to determine whether eye symptoms and symptoms from the nervous system could be reduced by reducing VDU electric fields.


METHODS
The study was designed as a controlled double-blind intervention. The electric fields were reduced by using electric-conducting screen filters. Forty-two persons completed the study while working at their ordinary job, first 1 week with no filter, then 3 months with an inactive filter and then 3 months with an active filter (or in reverse order). The inactive filters were identical to the active ones, except that their ground cables were replaced by empty plastic insulation. The inactive filters did not reduce the fields from the VDU. The fields were significantly lower with active filters than with inactive filters.


RESULTS
Most of the symptoms were statistically significantly less pronounced in the periods with the filters when compared with the period with no filter. This finding can be explained by visual effects and psychological effects. No statistically significant difference in symptom severeness was observed between the period with an inactive filter and the one with an active filter.


CONCLUSIONS
The study does not support the hypothesis that skin, eye, or nervous system symptoms can be reduced by reducing VDU electric fields.
Oftedal
G
G
SINTEF Unimed, Trondheim, Norway. gunnhild.oftedal@phys.ntnu.no
Nyvang
A
A
Moen
B E
BE
D000328:Adult; D002493:Central Nervous System Diseases / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D016288:Computer Terminals; D004311:Double-Blind Method; D004574:Electromagnetic Fields / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009664:Norway; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis* / Q000517:prevention & control*; D016272:Occupational Health; D011336:Probability; D011482:Protective Devices; D012016:Reference Values; D012871:Skin Diseases / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*; D018709:Statistics, Nonparametric; D014786:Vision Disorders / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control*