[Residence close to high-tension electric power lines and its association with leukemia in children].
BACKGROUND
There are different risk factors which have been related to the presence of leukemia in children. In the past years one of these factors has become relevant, the risk of living in an area near to high electric voltage lines, generators of electromagnetic fields of low frequency (EMF), which can cause development of leukemia in children.


OBJECTIVE
To learn whether living in an area close to EMF generator sources, electric transformers, high electric voltage distribution or transmission lines and electric substations, is a risk factor in the development of leukemia in children living in Mexico City.


METHODS
A projective study of case-control was accomplished. The cases were obtained from hospitals of the third level. The diagnosis of leukemia in its different varieties was confirmed through biopsy of bone marrow. The controls were selected in the same hospital from inpatients and outpatients with different problems, except neoplasia. A total sample of 81 cases and 77 controls was analyzed. The residence of the controls and cases were visited using a questionnaire coded with the different study variables. To diminish the memory bias in relation to EMF, the subjects were shown different pictures pointing out the different sources of exposures, which were asked. Having obtained the information, different odds ratios (OR) were calculated for the different associations, as well as the confidence intervals at 95% and an unconditioned logistic regression was accomplished to know the adjusted OR.


RESULTS
There were no differences between the cases and controls according to the relative who gave the information, the current age of children, the parents's age, the social class and the parent's occupation. It was found that all the generating sources of EMF, which were involved in the study, had and OR above 1. Being the highest, the ones living near the distribution or transmission wires of high voltage with an OR of 2.63 (1.26-5.36) and 2.5 (0.97-6.67) respectively. When the distance of exposure was controlled, the highest OR was for distribution lines (OR 2.12; 0.79-5.85). When the analysis was applied to persons who have moved from the residence, it was found that the OR was above 1 in all the associations, the highest being the distribution wires and with the distance the highest was the electric substations. Furthermore, the multivariate analysis showed that the risk continued only for the distribution wires.


CONCLUSIONS
The EMF exposure was found positive, however this is not very precise, that is why it is necessary to carry out other studies to confirm the existence of the association and correct possible biases which could appear during the research.
Fajardo-Gutiérrez
A
A
Unidad de Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, México, D.F.
Garduño-Espinosa
J
J
Yamamoto-Kimura
L
L
Hernández-Hernández
D M
DM
Gómez-Delgado
A
A
Mejía-Aranguré
M
M
Cartagena-Sandoval
A
A
Martínez-García
M C
MC
D016022:Case-Control Studies; D002648:Child; D016001:Confidence Intervals; D004574:Electromagnetic Fields / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D007938:Leukemia / Q000453:epidemiology / Q000209:etiology*; D008800:Mexico / Q000453:epidemiology; D016017:Odds Ratio; D011210:Power Plants; D015995:Prevalence; D012044:Regression Analysis; D012111:Residence Characteristics; D014505:Urban Population / Q000706:statistics & numerical data