*2.8. Calculation of BCFs and Management Concentration in Soil*

The concept of BCF was used to calculate the uptake rate of residual fluopyram from the soil into crops [17–19]. The BCF refers to the ratio of the concentration in the organism to the concentration in the environment, in the process of accumulating a specific pollutant in the organism. The BCF was calculated using Equation (3):

$$\text{BCF} = \mathsf{C}\_{\text{plant}} / \mathsf{C}\_{\text{soil}} \tag{3}$$

where Cplant is the residual concentration in scallion at DAP 48, which indicated a fullgrown (100% mature) scallion, and Csoil is the residual concentration in soil on the day of planting (DAP 0).

The management concentration in soil (MCsoil), which represents the concentration of fluopyram in the soil where the residual pesticide in the crop at harvest does not exceed the MRL, was calculated using Equation (4):

$$\text{MC}\_{\text{soil}} = \text{MRL}\_{\text{plant}} / \text{BCF}\_{\prime} \tag{4}$$

where the MRLplant for fluopyram in leaf-and-stem vegetable by unintentional contamination is 0.2 mg/kg [20].
