The penetration of pesticides into the groundwater is influenced by a series of factors. 1 , 2 , 7 , 8 In this process, the physicochemical properties of the compounds used as well as their mobility and persistence play a decisive role. 3 , 4 , 6 In addition, the practice of application used in agriculture, i.e., frequency and date of application, the quantity used, and the technique of application are of importance. 9 As regional factors, the vulnerability of the groundwater has to be taken into account where geologic formation has an influence on the possible contamination of groundwater by pesticides as well as soil texture, clay content, and content of organic carbon in the soil.