Assessing the health risk of reuse of bottom ash in road paving.

Although the reuse of bottom ash has been favored gradually, reflected on regulations and researches, the associated risk is still an issue of great concern. This study quantified the health risks from multimedia transport and multi-pathway exposure to the concerned chemicals as a result of reusing bottom ash in road paving with consideration of various application scenarios. In particular, the using duration of the pavement was taken into consideration because movement of chemicals in the soils and groundwater would affect the subsequent exposure and risk. By using soil and groundwater transport modeling linked to food chain exposure assessment and incorporating the Monte Carlo method, the study identified Cr as the crucial toxicant and ingestion of drinking water and vegetables as the key exposure pathways. Furthermore, control of the using duration of road pavement is an essential factor of management and regulations to minimize the leaching of the hazardous constituents into the groundwater and subsequent contamination of food chain.