Modeling pesticides in global surface soils: Evaluating spatiotemporal patterns for USEtox-based steady-state concentrations

Improved Pesticide Product Labeling Information for Household Lawn Management: Recommended Safe Durations in Support of Minimizing Children’s Exposure to Pesticides

“…The half-lives of pesticides in the lawn environment were obtained from modeling studies in the literature (first-order kinetic screening models). ,, Because the household application method of pesticides typically differs from that of croplands (i.e., intensive aerial sprays), in this study, we assumed that, after pesticide application on lawns, pesticide residues would first deposit on the grass surface and in surface soil compartments and then be transported to the air. Thus, dissipation half-lives of pesticides on the grass surface and in surface soil compartments were used, and the residue level in the air was estimated based on a simple partitioning rule. , …”

“…The overall dissipation process of the pesticide in the surface soil compartment comprises degradation, volatilization, and water-induced elimination (surface runoff and infiltration) processes. ,, The overall dissipation half-life of the pesticide in the surface soil can then be expressed as follows: where (d) is the overall dissipation half-life of the pesticide in the surface soil. k d,Soil , k Plant , k Air , k Rain ,Soil , and k Irri,Soil are first-order rate constants (d –1 ) of the pesticide for degradation, plant uptake, volatilization, rainfall-induced elimination, and irrigation-induced elimination processes, respectively.…”

“…k d,Soil , k Plant , k Air , k Rain ,Soil , and k Irri,Soil are first-order rate constants (d –1 ) of the pesticide for degradation, plant uptake, volatilization, rainfall-induced elimination, and irrigation-induced elimination processes, respectively. These rate constants of pesticides were obtained from a modeling study on the fate and transport of pesticides in soil. , The plant uptake and water-induced elimination processes of the pesticide could be described using the first-order kinetic rate constants because it was demonstrated that these elimination processes of the pesticide in the surface soil can be approximated as a continuous advection process (time-weighted rainfall- or irrigation-induced advection transport) . Similar to the surface soil compartment, the overall dissipation half-life of the pesticide in the grass surface compartment ( ) can be expressed as follows: where k GS , k Rain ,GS , and k Irri ,GS are the dissipation (no precipitation), rainfall-induced elimination, and irrigation-induced elimination rate constants, respectively.…”

“…Studies have shown that weather conditions (temperature, humidity, and precipitation) substantially affect the overall dissipation process of pesticides in soil, presenting spatial patterns of residue half-lives in soil. , Thus, the recommended safe duration should be specific to the region. The regional-specific T RSD values can be derived using regional-specific and values of pesticides, for which the simulation method used was from modeling studies , (Supporting Information).…”

“…Studies have shown that weather conditions (temperature, humidity, and precipitation) substantially affect the overall dissipation process of pesticides in soil, presenting spatial patterns of residue half-lives in soil. , Thus, the recommended safe duration should be specific to the region. The regional-specific T RSD values can be derived using regional-specific and values of pesticides, for which the simulation method used was from modeling studies , (Supporting Information). For the regional-specific estimate of the reduced children’s exposure to residues in the lawn environment, we simplified the weather-adjusted modeling of and values by considering air temperature and annual average rainfall intensity and using a default value of the air relative humidity (50%).…”