Abstract: Protective coatings, such as paints and liquid formulations therefor, containing a masked chromogen which signals contact with a body fluid when the protective coating is masticated or ingested are disclosed. The chromogen is capable of producing a contrasting color when masticated and/or ingested, thereby signaling that the individual who masticated and/or ingested the chromogen may have ingested an undesirable or hazardous substance, e.g., a lead-based paint, that has been covered by the protective coating. The chromogen is substantially indiscernible in the paint and converts by reaction with an activator substance, e.g., by reaction with saliva, gastric juices, or the like, to a colored form which then stains the body fluids and/or the body tissues, and which may also stain the original source of the undesirable substance.