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Medical/biological study (observational study)

Natural killer cell activity decreases in workers occupationally exposed to extremely low frequency magnetic fields exceeding 1 microT.

Published in: Int J Immunopathol Pharmacol 2009; 22 (4): 1059-1066

Aim of study (acc. to author)

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.
The study was performed to confirm previous results with a larger study group (see Gobba et al. 2009).
Background/further details: Individual extremely low frequency magnetic field exposure of all participants (121 workers; 65 men and 56 women) was measured during two consecutive work-shifts using personal dosimeters and environmental, non-occupational exposure was also monitored. Workers were classified as low exposed (62 subjects, TWA ≤ 0,2 µT), medium exposed (35 subjects; 0.21-0.99 µT) and higher exposed workers (24 subjects; TWA ≥ 1 µT).

Endpoint

Exposure

Exposure Parameters
Exposure 1:
  • unspecified
Exposure duration: low exposure group: 12.9 +/- 7.3 years; medium exposure group: 10.0 +/- 6.6 years; high exposure group: 12.0 +/- 8.8 years
Exposure 1
Main characteristics
Frequency
  • unspecified
Type
Exposure duration low exposure group: 12.9 +/- 7.3 years; medium exposure group: 10.0 +/- 6.6 years; high exposure group: 12.0 +/- 8.8 years
Exposure setup
Exposure source
Additional info exposure measurement: continuous for 8 h/day on 2 days occupational exposure and 16 h/d domestic exposure
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.2 µT average over time measured and calculated - maximum value for the low exposure group
magnetic flux density 0.21 µT average over time measured and calculated - minimum value for the medium exposure group
magnetic flux density 0.99 µT average over time measured and calculated - maximum value for the medium exposure group
magnetic flux density 1 µT average over time measured and calculated - minimum value for the higher exposure group
Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

In higher exposed workers (exceeding 1 µT) natural killer cell activity was significantly reduced compared to low exposure group. In the medium exposure group a decrease was also observed, but the difference was not significant.
In conclusion, the data suggest that occupational exposure to extremely low frequency magnetic fields, at least at TWA levels exceeding 1 µT, may induce a decrease in natural killer cell activity in peripheral blood lymphocytes.
Study character:

Study funded by

  • Istituto Superiore per la Prevenzione e la Sicurezza del Lavoro (ISPESL; National Institute for Occupational Safety and Prevention), Italy

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