Social inequality and exposure to magnetic fields in the metropolitan region of São Paulo, Southeastern Brazil.
OBJECTIVE
To estimate the prevalence of exposure to magnetic fields generated by transmission lines (TL) and characterize the exposed population.


METHODS
Information about TL in the metropolitan region of São Paulo, Southeastern Brazil, was provided by the electricity companies and mapped out using geographic information system (GIS). Demographic and socioeconomic data were obtained from the 2000 Census and added to the GIS in another layer. Households and their inhabitants that were located at a distance from the TL that was sufficient to generate a magnetic field 0.3 microT (microteslas) were deemed to be exposed. The prevalence was estimated according to the area of the corridors of exposure along the TL. Two approaches were used to delimit the corridor width: one consisted of widths that were predefined by the TL voltage, and the other consisted of calculation of the magnetic field. The socioeconomic information on the exposed and non-exposed populations were compared by applying the two-proportion test (alpha= 5%).


RESULTS
In the corridors with predefined widths, the prevalence of exposure was 2.4%, and in the calculated corridors, the prevalence was 1.4%. Both methods indicated higher prevalence of exposure among the younger population, and among individuals with lower education and income levels (p < 0.001).


CONCLUSIONS
The prevalence of exposure to magnetic fields generated by TL in the metropolitan region of São Paulo was lower than what has been observed in other countries. The results indicate inequality in the exposure to magnetic fields in this urban area, with greater risk to vulnerable populations such as children and socioeconomically less favored individuals.
Habermann
Mateus
M
Universidade de São Paulo, São Paulo, SP, Brasil. mathab@usp.br
Marcílio
Izabel
I
Lopes
Marina
M
Prado
Rogério
R
Souza
Miriam
M
Gouveia
Nelson
N
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001938:Brazil; D002648:Child; D003430:Cross-Sectional Studies; D004559:Electric Wiring / Q000706:statistics & numerical data*; D004574:Electromagnetic Fields; D004781:Environmental Exposure / Q000191:economics / Q000706:statistics & numerical data*; D006801:Humans; D008875:Middle Aged; D011834:Radiation Monitoring / Q000379:methods / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D055815:Young Adult