Some good, natural sources of saltpeter are caves and sheltered areas, deserts and lake beds. Saltpeter, also known as potassium nitrate, is also found in soil and occasionally in high-nitrite vegetables. As of November 2015, potassium nitrate is usually manufactured in laboratories and rarely found from natural sources.
Uses for potassium nitrate include the creation of gunpowder and small explosives, the curing of meats and the treatment of medical wounds. A dose of 35 milligrams or higher is considered fatal. Potassium nitrate is also used by some toothpaste manufacturers as an additive to reduce tooth sensitivity, although there is no medical research that proves its effectiveness. Drinking water may also contain potassium nitrate in rare occasions due to runoff from surrounding soil.