A medication is considered “hazardous” if it has one of four key characteristics: Ignitable. This type of waste is flammable. Examples include alcohol-based cough syrups and aerosol cans with flammable propellants. Corrosive. Pharmaceuticals that are preserved in corrosive materials such as nitric acid are considered corrosive. This category includes acids as well as bases and is determined by pH. Reactive. This waste negatively interacts with other chemicals, causing explosions or generating toxic gases or fumes. Pharmaceuticals generally do not fall into this category. Toxic. Although many products could be considered toxic, from a waste perspective, the EPA only designates certain chemicals as toxic if they are present in specific concentrations. To determine these concentrations, organizations can have a test performed known as the toxicity characteristic leaching procedure (TCLP). Some examples of chemicals that can be considered toxic are selenium, silver, and mercury.