Measurements were performed on 240 children (117 girls) between 9 and 16 years of age, and 123 elderly people (60 women), aged 61 years or more. The electric current of 50 Hz was linearly increased from 1 µA, and children and elderly people were asked to press a button at the first sensation to interrupt the current flow. Measurements were repeated six times.
Exposure duration: until first perception of the current
|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.|
|cf. remarks||-||-||-||-||I > 1 µA|
The results of the the children and elderly people were compared to the population of adult men and women between 16 and 60 years of age (publication 10184).
Children showed gender-related differences in electric current perception, with girls (median=236 µA) being more sensitive to electric currents than boys (median=257 µA). The perception thresholds of girls did not differ significantly from those of adult women. In contrast, the values for boys and men differed significantly: the perception thresholds of boys were well below those of men.The results of elderly people did not exhibit significant differences to the results of adult men and women.
With these results from different groups of the general population, a common probability distribution in regard to sensitivity to electric currents was generated: The 50 Hz electric current perception median value for adult men and women amounted to 273 µT. The inclusion of children and elderly people lead to a median value of 268 µT.
Deriving touch current limits for children from adult male data by the reduction factor 2 turns out to be not justified as they are considerably too high if compared with the values derived from data of the overall general population. The new data indicate the need for a review of the existing limits.