Quantitative-spatial assessment of the risks associated with high Pb loads in soils around Lavrio, Greece

The advantages of quantitative environmental risk assessment techniques over the more commonly used qualitative approach is widely accepted. Yet, correct implementation of quantitative risk assessment is a difficult task, given the present state of understanding of the environmental processes. One important parameter related to the level of risk is the extent and geographic spread of pollutants. Geographic information systems (GIS) provide a very powerful and highly flexible tool that increases the sophistication of the risk assessment methodology. Through spatial representation, the estimated risk becomes more comprehensive, thus facilitating the decision making process. In addition, valuable qualitative information can be incorporated into the risk assessment procedure with the help of GIS. This paper illustrates a methodology which incorporates a probabilistic risk assessment model within a GIS. The case study utilised to illustrate the methodology is a large industrial area around a number of decommissioned minerals production and processing sites with known high heavy metal loads at Lavrio, Greece. The spatial distribution of Pb concentration in soils was derived from 425 soil samples collected over a total area of 120 km2. A risk assessment model was constructed to simulate and assess the risk associated with high Pb loads in soils in the study area. The methodology consists of a typical exposure assessment model, constructed for adult and child populations. The Pb exposure for both populations is compared with relevant reference dose levels providing hazard quotients. The results of the quantitative risk assessment study are analysed and presented in the form of GIS maps covering the study area.