Epidemiologic studies indicate that an increased incidence of lung cancer may be associated with specific work areas in ferrous foundries. With the exception of crane operators, who were found to have an elevated lung cancer rate in one foundry, the excess lung cancer incidence is generally confined to molders, casters, and cleaning room operators whose lung cancer risk is two- to threefold higher than that of standard populations. These studies reflect conditions that existed in the foundries several decades ago. The lung cancer risk today may differ as a result of the introduction of new foundry practices and the use of new molding materials. Benzo(a)pyrene and certain other polycyclic aromatic hydrocarbons have been found in many locations in the foundries. It is not known if tumor promoters, co-carcinogens, or other classes of chemical carcinogens are present. The contribution of tobacco smoke to the lung cancer risk of ferrous foundry workers is also unknown. Current studies are examining the composition and long-term health effects of emissions from molds composed of modern synthetic chemical molding materials as well as those from the more traditional green sand molds.