It occurs naturally in petroleum crude oil. Petroleum crude oil is by far the largest source of toluene. US demand for toluene is expected to grow moderately over the next several years. Companies also add toluene to aerosol spray paints, wall paints, lacquers, paint strippers, adhesives, printing ink, spot removers, cosmetics, perfumes, and antifreeze. Exposure to toluene can occur in the workplace or in the environment following releases to air, water, land, or groundwater.
Exposure can also occur when people use gasoline and other products that contain toluene.
Toluene enters the body when breathed in with contaminated air or when consumed with contaminated food or water. It can also be absorbed through skin contact. Toluene does not remain in the body due to its breakdown and removal. Toluene evaporates when exposed to air. It dissolves only slightly when mixed with water.