Oil shale is found in many parts of the world, and the world’s total recoverable resources are estimated at 2.6 trillion barrels. They have been used in the production of fuel oil for gas turbines, automobile gasoline, and additives for petroleum fuel oil with a high sulfur content. In the People’s Republic of China, shale oil has been used as raw material for refineries and for electricity generation. They can also be used to produce gasoline, kerosene, diesel fuel, and coke. Oil shale industries operate in Europe (Estonia), South America (Brazil), and Asia (China). The largest use is in Estonia—in northeastern Estonia, about 85% of this material is burned as fuel in electric power plants, and the rest is returned for shale oil and used for the production of fuel and petrochemical products. Exposure to shale oil causally linked to skin cancer, especially scrotal cancer. 1-Hydroxypyrene is the most representative urinary metabolite from shale oils.