Got to this posting thread late. All new pesticides are tested for environmental persistence including their soil binding properties, water solubility, and leaching potential. We can find any number of things in urine due to improvements in detection methods that can now detect parts per trillion (or lower) in some cases. We can find arsenic in most human urine samples too since it is found in many foods and comes from its natural occurrence in many soils. Risk = hazard x exposure. In other words, the dose makes the poison. Many required dietary nutrients are also toxic at high levels. Finally, follow pesticide labels. They are the result of many years of testing for effectiveness, human safety, and environmental safety.