Some state and local governments require food makers, restaurants and grocery stores to post warnings about products containing ingredients regulators deem harmful. Those laws are often tougher than federal Food and Drug
Administration rules or cover substances not regulated by federal law. California, for example, requires businesses to disclose the presence of chemicals that the state believes cause cancer, birth defects or other reproductive
harm. Michigan and Connecticut mandate allergen warnings about preservatives such as sulfur dioxide at salad bars and other settings.