The risk associated with waste exposure depends on the level of emissions arising from waste disposal and from the effects of these emissions on human health (dose-response). In 2007 an epidemiological study was conducted in two Italian provinces of the Campania Region, namely Naples and Caserta, with the aim of assessing the health effects deriving from exposure to waste. In these studies, the important aspect is the population exposure assessment, in relation to the different types of waste disposal. The Regional Agency for Environmental Protection (ARPA Campania) has identified and characterized the various authorized/unauthorized dumping sites in the provinces of Naples and Caserta. Most of the waste disposal used are illegal and invisible (sunken or buried); thus, the toxic substances therein contained are unknown and difficult to identify. In order to locate the possible areas exposed to a higher waste-related health risk, a synthetical "hazard index" (at the municipality level) was designed. By means of GIS, the number of waste impact areas was identified for each of the 196 municipalities in the two provinces; then, Census data (ISTAT 2001) was used to estimate the proportion of the population living in the impact areas. The synthetical hazard index at municipality level accounts for three elements: a) the intrinsic characterization of the waste disposal, determining the way in which the pollutant is released; b) the impact area of the dumping site (within 1 km radius), same areas are influenced by more than one site; c) the density of the population living in the "impact area" surrounding the waste disposal site.