If present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. For infants and children, exposure to high levels of lead in drinking water can result in delays in physical or mental development. Infants who consume mostly mixed formula can receive a greater percentage because of the large volume of water they consume relative to their body size. For adults, exposure to high levels of lead can result in kidney problems or high blood pressure. Although the main sources of exposure to lead are ingesting paint chips and inhaling dust, the EPA estimates that 10 to 20 percent of human exposure to lead may come from drinking water.