Additionally, the workers lived in houses that were close to substations and high voltage power lines. Thus, they had long histories (1-20 years) of long-term exposure to extremely low frequency magnetic fields. Blood samples were taken hourly from 20:00 to 08:00 the next morning. Cortisol concentrations and patterns were compared to age-matched, unexposed control subjects (n=15) whose exposure level was ten times lower.
Exposure duration: continuous for up to 20 years
|Exposure duration||continuous for up to 20 years|
|magnetic flux density||0.1 µT||minimum||measured||-||weekly geometric mean (individual exposure)|
|magnetic flux density||2.6 µT||maximum||measured||-||weekly geometric mean (individual exposure)|
|magnetic flux density||0.72 µT||mean||calculated||-||of 15 workers|
|magnetic flux density||0.82 µT||mean||calculated||-||arithmetic means of the residential exposure|
|magnetic flux density||0.64 µT||mean||calculated||-||arithmetic means of the daytime exposure|
The comparison of the control group and the exposure groups (0.1-0.3 μT (n = 5) and > 0.3 μT (n = 9)) revealed a significant effect of field intensity on the cortisol secretory pattern. The data suggest that chronic exposure to extremely low frequency magnetic fields alters the serum cortisol levels with a statistically significant decline in the peak-time (06:00–08:00) cortisol levels even at the lower intensity of exposure, although the general secretory pattern of cortisol was unaffected.