Improving screening model of pesticide risk assessment in surface soils: Addressing regional specific human exposure risks and regulatory management

In this study, a simple screening approach was proposed to evaluate region-specific population health risks of soil pesticides, which was achieved by introducing region-specific factors of pesticides, including fate factors (FFs), environmental distribution factors (DFs), and intake factors (IFs). These region-specific factors were characterized using simple weather variables and calculated the characterization factors (CFs) to link pesticide emissions to population exposure risks. The CF at the reference state indicates the potential of a pesticide entering the human body. Simulations for over 700 pesticides showed that pesticides that are thermodynamically stable in soil organics have large CFs. In addition, we conducted a case study on the region-specific risk assessment of malathion in the United States. The results indicated that colder regions have larger CFs of malathion than those of the warmer regions due to the large FF values for the same emission rates. However, from a regulatory perspective, colder regions should have less strict malathion soil standards than those of warmer regions as children in colder regions spend limited time outdoors. Although other region-specific factors such as soil type and population density need to be considered to improve the model, the approach proposed in this study can be used as a simple screening tool to evaluate region-specific population health risks and manage soil residues for different regions