Wood dust was added to the Proposition 65 list as a chemical known to the State of California to cause cancer on December 18, 2009.
Health and Safety Code, §25249.5 et seq. of the California Safe Drinking Water and Toxic Enforcement Act of 1989 (Proposition 65) requires anyone who, during the course of doing business in California, knowingly and intentionally exposes an individual to a chemical known to the State to cause cancer or reproductive toxicity to first give a clear and reasonable warning regarding the presence of such chemicals.
Drilling, sawing, sanding or machining wood products generates wood dust, a substance known to the State of California to cause cancer.
Material Safety Data Sheet is available here.
Download the warning sign (two signs per page for easy printing)