BackgroundReleases to the environment of toxic substances stemming from industrial metal production and processing installations can pose a health problem to populations in their vicinity.ObjectivesTo investigate whether there might be excess leukemia-related mortality in populations residing in towns in the vicinity of Spanish metal industries included in the European Pollutant Emission Register.MethodsEcologic study designed to examine mortality due to leukemia at a municipal level, during the period 1994–2003. Population exposure to pollution was estimated on the basis of distance from town of residence to pollution source. Using Poisson regression models, we analyzed: risk of dying from leukemia in a 5-kilometer zone around installations which had become operational prior to 1990; effect of pollution discharge route and type of industrial activity; and risk gradient within a 50-kilometer radius of such installations.ResultsExcess mortality (relative risk, 95% confidence interval) was detected in the vicinity of pre-1990 installations (1.07, 1.02–1.13 in men; 1.05, 1.00–1.11 in women), with this being more elevated in the case of installations that released pollution to air versus water. On stratifying by type of industrial activity, statistically significant associations were also observed among women residing in the vicinity of galvanizing installations (1.58, 1.09–2.29) and surface-treatment installations using an electrolytic or chemical process (1.34, 1.10–1.62), which released pollution to air. There was an effect whereby risk increased with proximity to certain installations.ConclusionsThe results suggest an association between risk of dying due to leukemia and proximity to Spanish metal industries.