High incidence of acute leukemia in the proximity of some industrial facilities in El Bierzo, northwestern Spain.

OBJECTIVES To estimate the incidence of acute leukemia (AL) in El Bierzo (BZ) and to carry out a cross-association analysis in order to suggest some etiological clues. MATERIALS AND METHODS We registered all new AL cases diagnosed 2000-2005. Annual standardized incidence rate (SIR) was calculated by the direct method. A cross-association analysis was performed by non-parametric methods and we checked the potential interaction between putative etiological factors by calculating Chi-square-for-trend. RESULTS SIR was 5.1 cases per 100 000, surpassing the Spanish, European and world average figures and heterogeneous throughout the region. We detected a negative correlation between acute myeloblastic leukemia (AML) SIR in every municipality and both the air distance to the nearest thermoelectric power plant (TPP) (Rho = -0.409; p = 0.01) and to the point of maximum density of the high-power lines (HPL) network (Rho = -0.329; p = 0.04). Accordingly, SIR was higher in the municipalities situated < 7.5 km away from TPP (9.58 vs. 1.72; p = 0.004) or < 10 km away from HPL (3.90 vs. 3.19; p = 0.045). A positive relation between both factors was observed (Chi-square-for-trend = 9.209; p = 0.006). CONCLUSIONS SIR of AL in BZ is higher than the Spanish average and that of most countries in the world. Residing near TPP or HPL confers a higher risk of AML, with synergistic effect between both factors.