To study the possible effects of occupational extremely low frequency magnetic field exposure on natural killer cell cytotoxic activity in peripheral blood cells of workers engaged in different occupational activities not involving any exposure to chemical/physical factors.
Individual extremely low frequency magnetic field exposure of all participants (22 men, 30 women) was measured during three consecutive work-shifts using personal dosimeters and environmental, non-occupational exposure was also monitored. Workers were classified as low exposed (26 subjects, TWA ≤ 0.2 µT) and higher exposed workers (26 subjects; TWA > 0.2 µT).
In higher exposed workers, a trend to reduced natural killer cell activity was found compared to low exposed, but the difference was not significant. A significant reduction in natural killer cell activity was observed in a subgroup of highest exposed workers (12 subjects; TWA >1 µT) compared to the low exposed.
In conclusion, the data suggest that occupational exposure to extremely low frequency magnetic field, at least at TWA levels exceeding 1 µT may induce a reduction of natural killer cell activity in peripheral blood lymphocytes.