Provocation of electric hypersensitivity under everyday conditions.
OBJECTIVE
In most previous provocation studies subjects suffering from "electric hypersensitivity" have not been able to determine correctly whether or not they have been subjected to a sham or true provocation to magnetic or electric fields. However, an often-discussed weakness is that most of the earlier provocation studies have been performed in a laboratory situation, often with simulated fields, which may not be representative of conditions prevailing in the homes or workplaces of the patients. Criticism has also been put forth about neglect of the long latency period of symptoms. Therefore, a provocation study was performed in the homes or workplaces of the patients, where we also studied the symptoms and on-off answer 24 hours after the exposure.


METHODS
Fifteen subjects selected as having fast and distinct reactions from electric equipment were provoked on 4 occasions: mainly 2 true and 2 sham provocations. The intervals between exposure were a few or more days in order to provide the subjects with an opportunity to recover before the next provocation. A control group of healthy subjects with normal hearing and vision verified that the provocations were performed in a blind manner.


RESULTS
The patients suffering from "electric hypersensitivity" were no better than the control group in deciding whether or not they were exposed to electric and magnetic fields.


CONCLUSIONS
Exposure to electric and magnetic fields per se does not seem to be a sufficient cause of the symptoms experienced by this patient group.
Flodin
U
U
Department of Occupational and Environmental Medicine, Centre for Public Health Sciences, Linköping, Sweden. ulf.flodin@lio.se
Seneby
A
A
Tegenfeldt
C
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D003955:Diagnostic Tests, Routine / Q000379:methods; D004311:Double-Blind Method; D004560:Electricity / Q000009:adverse effects*; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D011336:Probability; D012016:Reference Values; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric