Extremely Low‐Frequency Magnetic Fields and the Risk of Childhood B‐Lineage Acute Lymphoblastic Leukemia in a City With High Incidence of Leukemia and Elevated Exposure to ELF Magnetic Fields

Abstract

It is important to study the relationship between extremely low-frequency magnetic fields (ELF-MFs) and childhood leukemia, particularly in locations with a high incidence of this neoplasm in children and an elevated exposure to ELF-MF, such as Mexico City. The aim was to investigate the association between ELF-MF exposure and the risk of B-lineage acute lymphoblastic leukemia (B-ALL). A case-control study was conducted in Mexico City during the period from 2010 to 2011. Residential 24-h ELF-MF measurements were obtained for 290 incident BALL patients and 407 controls, aged less than 16 years. Controls were frequency-matched by sex, age (±18 months), and health institution. The adjusted odds ratios (aOR) and 95% confidence intervals (CIs) were calculated. ELF-MF exposure at <0.2 μT was used to define the reference group. ELF-MF exposure at ≥0.3 μT was observed in 11.3% of the controls. Different ELF-MF intensity cutoff values were used to define the highest exposure category; the highest exposure category for each cutoff value was associated with an increased risk of BALL compared with the corresponding lower exposure categories. The aORs were as follows: ≥0.2 μT = 1.26 (95% CI: 0.84-1.89); ≥0.3 μT = 1.53 (95% CI: 0.95-2.48); ≥0.4 μT = 1.87 (95% CI: 1.04-3.35); ≥0.5 μT = 1.80 (95% CI 0.95-3.44); ≥0.6 μT = 2.32 (95% CI: 1.10-4.93). ELF-MF exposure as a continuous variable (per 0.2 μT intervals) was associated with BALL risk (aOR = 1.06; 95% CI: 1.01-1.12). In the present study, the proportion of children exposed to ≥0.3 μT is among the highest reported worldwide. Additionally, an ELF-MF exposure ≥0.4 μT may be associated with the risk of BALL .

Exposure to magnetic fields and childhood leukemia: a systematic review and meta-analysis of case-control and cohort studies

“…The data extraction involved the following data: authors, journal name, year of publication, country, objective of the study, socio-demographic data (type of population, sex ratio and average age), sample size, design, outcomes, type of electromagnetic field (frequency and magnetic flux density), moment of magnetic field exposure (date, time of the day, season), method used to assess the magnetic field exposure, distance between the child's home and overhead power lines, characteristics of the power lines, leukemia subtype, moving house history, conclusion, presence of conflicts of interest and funding. We have contacted Dr Jirik and Dr Núñez-Enríquez to have all the information necessary for the extraction of the data of their studies [26,27].…”

“…Based on the World Bank Income classification [61], all the European studies and the studies conducted in the USA, Canada, Japan and New Zealand come from high income countries. Some studies have been conducted in upper middle income countries: the studies performed in Mexico [27,48], Brazil [32] and Malaysia [49]. Finally, the studies by Feizi and Arabi [47], Sohrabi et al [51] and Tabrizi and Hosseini [57] have been conducted in Iran, a lower middle income country.…”

“…Our systematic review indicates that less children from high income countries have been exposed to residential magnetic fields above 0.4 µT than children from lower income countries. Only 0.3% of children from high income countries have been exposed to ELF-MF higher than 0.4 µT [4-6, 26, 31, 46, 50, 54, 55, 59] whereas 11.6% of children from lower income countries [27,47,48] have been exposed to ELF-MF above 0.4 µT.…”

“…After a sensitivity analysis that restricted the global meta-analysis to children under the age of 15 by removing seven studies [2,4,25,27,37,46,59], the estimated pooled OR for the relation between ELF-MF and childhood leukemia was 1.13 (95% CI 0.92-1.39; p=0.23). The study by Verkasalo et al [25] is a cohort study and the exclusion of this study did not substantially affect the association between ELF-MF and childhood leukemia (pooled OR=1.26; 95% CI 1.06-1.49; p=0.01).…”

“…Living between 200 and 3: Exposure to magnetic fields higher than 0.4 µT increased the risk of developing childhood leukemia (all leukemia subtypes were combined in this analysis). Two studies performed in Mexico are included in this meta-analysis but one is based exclusively on Down syndrome (DS) children [48] and the other one has excluded DS children [27]. The exclusion of the study by Mejia-Arangure et al [48] based only on DS children did not change the association between magnetic fields higher than 0.4 µT and childhood leukemia (pooled OR=1.37; 95% CI 1.02-1.83; p=0.04).…”