Toluene is a potentially hazardous liquid that occurs naturally in crude oil, and can be obtained from the tolu tree. Toluene is used in manufacturing paints, adhesives, and rubber,as well as in the leather-making and printing industries. People can be exposed to toluene by breathing automobile exhaust, fumes from paints, kerosene, and heating oils, or by drinking well-water that is contaminated with toluene. At high doses, toluene may causes dizziness, unconsciousness, and possibly death. High doses may cause kidney damage, while low doses may cause nausea, hearing and vision problems, disorientation, and fatigue. Toluene in air is very reactive so it increases photochemical smog and leads to the production of peroxybenzoylnitrate, a potent eye irritant. The Environmental Protection Agency (EPA) does not classify toluene as a carcinogen, although the EPA has set a limit of 1 milligram per liter for safe drinking water.