Pooled analysis of recent studies on magnetic fields and childhood leukaemia.
BACKGROUND
Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000.


METHODS
Seven studies with a total of 10,865 cases and 12,853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences.


RESULTS
In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1-0.2 μT, 0.2-0.3 μT and ≥0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81-1.41), 1.16 (0.69-1.93) and 1.44 (0.88-2.36), respectively. Without the most influential study from Brazil, the odds ratios increased somewhat. An increasing trend was also suggested by a nonparametric analysis conducted using a generalised additive model.


CONCLUSIONS
Our results are in line with previous pooled analyses showing an association between magnetic fields and childhood leukaemia. Overall, the association is weaker in the most recently conducted studies, but these studies are small and lack methodological improvements needed to resolve the apparent association. We conclude that recent studies on magnetic fields and childhood leukaemia do not alter the previous assessment that magnetic fields are possibly carcinogenic.
Kheifets
L
L
Department of Epidemiology, UCLA School of Public Health, 650 Charles Young Drive, Los Angeles, CA 90095, USA. kheifets@ucla.edu
Ahlbom
A
A
Crespi
C M
CM
Draper
G
G
Hagihara
J
J
Lowenthal
R M
RM
Mezei
G
G
Oksuzyan
S
S
Schüz
J
J
Swanson
J
J
Tittarelli
A
A
Vinceti
M
M
Wunsch Filho
V
V
D002648:Child; D002675:Child, Preschool; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects; D005260:Female; D006801:Humans; D007953:Leukemia, Radiation-Induced / Q000453:epidemiology*; D008297:Male; D012306:Risk