Study type: Medical/biological study (experimental study)

Electric current perception study challenges electric safety limits med./bio.

By: Leitgeb N, Schroettner J
Published in: J Med Eng Technol 2002; 26 (4): 168-172
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Aim of study (acc. to author)

To study electric current perception in 708 adults aged between 16 and 60 years (349 men and 359 women).

Background/further details

The authors argue that knowledge about electric current perception suffers from a lack of women's data, small numbers of data on investigation of men and investigated samples non-representative for the general population.
The electric current of 50 Hz was linearly increased and interrupted by the volunteers at the first awareness of current flow. Measurements were repeated six times.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: until first perception of the current
  • I = 349 µA median value for men
  • I = 53 µA 0.5% value for men
  • I = 242 µA median value for women
  • I = 24 µA 0.5 % value for women

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Exposure duration until first perception of the current
Exposure setup
Exposure source
Setup conventional pregelled ECG Ag/AgCl electrodes with a contact area of 3.14 cm² and a center distance of 5.5 cm applied to the lateral side of the volunteer's forearm; current increased linearly; each measurement repeated 6 times with a 3 min. interval between measurements
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
cf. remarks - - - - I = 349 µA median value for men
cf. remarks - - - - I = 53 µA 0.5% value for men
cf. remarks - - - - I = 242 µA median value for women
cf. remarks - - - - I = 24 µA 0.5 % value for women

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • during exposure

Main outcome of study (acc. to author)

The data showed that the perception variability among the general population is 100-fold higher than estimated so far and that the currently used estimate of the threshold is more than 10-fold too high. For example, the perception threshold defined so far in respect to the mean 1086 µA., as well as to the 0.5% value 500 µA, is much too high. In fact, for men the new median amounts to 349 µA which is 3.1-fold lower and the 0.5% value to only 53 µA which is 9.4- fold lower than defined so far.
Besides this, it could be shown that there is an over-proportion of more sensitive women compared with men indicating the need for revision of the present assumptions on gender-specific differences in electrosensibility.
The authors conclude that the existing assumptions on safety limits and remaining safety factors need serious review. In any case, relaxation of safety requirements is not justified.

Study character:

Study funded by

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