Revisions to the California Safe Drinking Water and Toxic Enforcement Act, commonly known as Proposition 65, go into effect on April 1, 2020. The amendments are intended to clarify methods of compliance by upstream parties, including manufacturers, producers, packagers, importers, suppliers, or distributors of products with chemicals subject to warning requirements under the Act. They also include a modified definition of the key phrase “actual knowledge,” one of the triggers that can result in retailer responsibility for warnings.