Children's Personal Exposure Measurements to Extremely Low Frequency Magnetic Fields in Italy

Abstract

Extremely low frequency magnetic fields (ELF-MFs) exposure is still a topic of concern due to their possible impact on children's health. Although epidemiological studies claimed an evidence of a possible association between ELF-MF above 0.4 μT and childhood leukemia, biological mechanisms able to support a causal relationship between ELF-MF and this disease were not found yet. To provide further knowledge about children's ELF-MF exposure correlated to children's daily activities, a measurement study was conducted in Milan (Italy). Eighty-six children were recruited, 52 of whom were specifically chosen with respect to the distance to power lines and built-in transformers to oversample potentially highly exposed children. Personal and bedroom measurements were performed for each child in two different seasons. The major outcomes of this study are: (1) median values over 24-h personal and bedroom measurements were <3 μT established by the Italian law as the quality target; (2) geometric mean values over 24-h bedroom measurements were mostly <0.4 μT; (3) seasonal variations did not significantly influence personal and bedroom measurements; (4) the highest average MF levels were mostly found at home during the day and outdoors; (5) no significant differences were found in the median and geometric mean values between personal and bedroom measurements, but were found in the arithmetic mean.

Keywords: children; exposure assessment; extremely low frequency magnetic fields (ELF-MF); personal measurement; power line; transformer.

Figure 1

Distribution of the median, geometric mean (geomean), and arithmetic mean (aritmean) of the magnetic field (μT) in the broadband frequency range (40–800 Hz) indicated as a box-plot for personal measurements for each group (PL, TRANSF, OTHER) in both summer and winter periods. The bars represent the 25th percentile, median, and 75th percentile values, while the whiskers are the minimum and 95th percentile values. The star represents the maximum value. The red dashed line is at 0.4 μT. The green dot-dash line at 3 μT is the 24-h median value established by Italian law [36] as the quality target. The distribution values are indicated in Appendix Table A1.

Figure 2

Distribution of the median, geometric mean, and arithmetic mean of the magnetic field (μT) in the broadband frequency range (40–800 Hz) indicated as a box-plot for bedroom measurements in both summer and winter periods for each group (PL, TRANSF, OTHER). The distribution values are indicated in Appendix Table A2.

Figure 3

Distribution of the median, geometric mean, and arithmetic mean of magnetic field (μT) in the harmonic frequency range (100–800 Hz) indicated as box-plots for personal measurements in both summer and winter periods and in each group (PL, TRANSF, OTHER). The distribution values are indicated in Appendix Table A3.

Figure 4

Distribution of the median, geometric mean, and arithmetic mean of magnetic field (μT) in the harmonic frequency range (100–800 Hz) indicated as box-plots for bedroom measurements in both summer and winter periods and in each group. The distribution values are indicated in Appendix Table A4.

Figure 5

Examples of exposure measurements. (a) Trend of the magnetic field (μT) measurements over time performed by a child within the OTHER group during the summer period, in which high exposure has been observed; (b) typical trend of magnetic field measurements over time of another child always belonging to the OTHER group performed in the summer period as well.

Figure 6

Distribution of median, geometric mean, and arithmetic mean of the magnetic field (μT) in different environments for each personal measurement day for each group and season in the broadband frequency range. (a) Distribution of the median of the magnetic field in different environments during the summer period; (b) Distribution of the median of the magnetic field in different environments during the winter period; (c) Distribution of the geometric mean of the magnetic field in different environments during the summer period; (d) Distribution of the geometric mean of the magnetic field in different environments during the winter period; (e) Distribution of the arithmetic mean of the magnetic field in different environments during the summer period; (f) Distribution of the arithmetic mean of the magnetic field in different environments during the winter period; Legend: hd + hn = at home during day and night; hd = at home during day; hn = at home during night; s = at school; o = outdoors. The distribution values are indicated in Appendix Table A5.

Figure 6

Distribution of median, geometric mean, and arithmetic mean of the magnetic field (μT) in different environments for each personal measurement day for each group and season in the broadband frequency range. (a) Distribution of the median of the magnetic field in different environments during the summer period; (b) Distribution of the median of the magnetic field in different environments during the winter period; (c) Distribution of the geometric mean of the magnetic field in different environments during the summer period; (d) Distribution of the geometric mean of the magnetic field in different environments during the winter period; (e) Distribution of the arithmetic mean of the magnetic field in different environments during the summer period; (f) Distribution of the arithmetic mean of the magnetic field in different environments during the winter period; Legend: hd + hn = at home during day and night; hd = at home during day; hn = at home during night; s = at school; o = outdoors. The distribution values are indicated in Appendix Table A5.