In Chemicals and Cancer: Establishing Causation through Medical Toxicology, chemical toxicology expert witness Nachman Brautbar, M.D. writes:
Chemical exposure and cancer date back several thousand years. The famous occupational physician, Ramazzini, was one of the first to describe examples of occupationally-induced cancers.
In the last 20 years, benzene has been shown to be a carcinogenic agent causing leukemias, lymphomas, and other hematological cancers. Other chemicals, such as chlorinated hydrocarbons, asbestos, and hexavalent chromium, have been shown to be carcinogenic.