What factors increase leaching or groundwater contamination?
“Whether pesticides that leach into the groundwater pose a hazard to humans or animals depends on the toxicity and concentration of the compounds and how they ‘degrade’ or break down as they move through the soil.” 67 The factors that increase groundwater contamination include: • pesticide properties such as high water solubility, low adsorption (the ability of a pesticide to remain in the soil), and high persistence (how long it takes for the chemical to degrade) • soil characteristics such as high permeability, high porosity, no soil compaction, low amounts of organic material, and high amounts of sand and gravel content • site conditions such as shallow depth to groundwater, high amount of precipitation, and excessive irrigation • management practices such as poor timing of pesticide application, not incorporating the pesticide into the soil, poor handling of the chemical, and solely relying on chemicals for pest control Once the pesticides reach the groundwater, breakdown continues
