The determinants of Canadian children's personal exposures to magnetic fields

Abstract

Study of the health effects of magnetic fields often depends on identifying determinants and hence indicators of personal exposure. This study identified determinants of children's exposure to magnetic fields and constructed a prediction model for them. For 632 children participating in a case-control study of childhood leukemia, we made direct measures of exposure over 48 h using a portable device, together with observations on candidate determinants. A child's age and sex, the proportion of time spent in the home, and their parents' education or income were very weak predictors of (logged) mean 48 h magnetic field (R(2) < 1%). More important were province (R(2) = 8.0%) and type of residence (R(2) = 11.3%). Low temperatures at the time of measurement were associated with high fields (about 20% increase for each 10 degrees C below 14, R(2) = 4.9%). Several visible attributes of wiring around residences predicted exposure, mostly captured in the Wertheimer-Leeper wire code (R(2) = 13.5%). Stationary 24 h measurement in the bedroom (R(2) = 63.3%) and spot measurements outside the house (R(2) = 40.7%) predicted personal exposures best. Adding other minor predictors increased only slightly variance explained by 24 h stationary (R(2) = 66.2%) and spot (R(2) = 46.8%) measurements. Without spot or stationary measurements, the best model was much less powerful (R(2) = 29.0%). We conclude that spot measurements outside the residence provide a moderately effective basis for estimating exposure for children living there, but do not perform as well as 24 h stationary measurements in the child's bedroom. Although several other easily-observed variables were associated with personal exposure, they were weak determinants, either individually or in combination.

Correlation of year-to-year magnetic field exposure metrics among children in a leukemia survival study

“…Regional differences in exposure have also been found among Canadian children (Deadman et al, 1999;Armstrong et al, 2001 ).…”

“…Our results suggest that factors intrinsic to the home influence childhood magnetic field exposures. Armstrong et al (2001 ) found the type of residence (e.g., single family home versus apartment ) to be a strong predictor of childhood exposure. Kavet et al (1999 ), focusing on homes located away from power lines, found that the presence of ground currents, the number of service drops on the same transformer serving the home, and increasing age of the home predicted higher residential magnetic fields.…”

Use of short-term measurements for assessing temporal variability of residential ELF magnetic field exposure

“…Rankin et al (2002) reported a Spearman correlation of 0.74 between point-in-time MF measurements and personal exposures, but the personal exposure measurement was limited to exposure in the home. Studies on the correlation of spot measurements with total 24 h personal exposure have shown correlations from 0.37 to 0.77 for timeweighted average exposure (Armstrong et al, 2001;Eskelinen et al, 2002) and from 0.41 to 0.74 for threshold-type exposure metrics (Eskelinen et al, 2002). It is of interest that, in the present data, the correlations with total 24 h exposure are not generally lower than those with the 12 h spent at home.…”

Environmental Electromagnetic Field and Female Fertility

“…To elucidate the mechanisms underlying the acceleration of cell damage (Armstrong et al 2001;Chun et al 1996), in the present study, the earlier step of cell damage on the cellular membrane integrity, mitochondrial features, appearance of apoptotic bodies, nucleus condensation, and lipid droplet accumulation is investigated with EM and TUNEL assay. Each of these end points showed a parallel correlation with apoptosis when the animals exposed to EMF for long time.…”