Risk analysis of a farm area near a lead-and cadmium-contaminated industrial site

The Asua Valley is an area on the outskirts of Bilbao where industry and small farms still coexist despite decades of serious environmental pollution. The present study was carried out to estimate the risk to which the residents of the area are exposed as a result of soil/dust ingestion and consumption of locally grown fresh produce, and, on the basis of this data, to delimit the areas that might require environmental clean-up. The relation between lead and cadmium content in soil and plant samples was assessed by multiple linear regression. The level of soil lead content for proposing intervention was determined by assessing the exposure of young children due to soil ingestion, assuming a "central-estimate" ingestion rate of 110 mg/day. Vegetable sampling was stratified according to the level of cadmium in the soil. The intervention content of cadmium was established as the midpoint of the soil sampling stratum previous to the one registering a vegetable consumption hazard quotient of 1; in this interval the intake reached 57% of the TDI.