Substances that are highly flammable, corrosive, toxic and easily react or cause explosion when mixed with other substances. They may exist in a liquid, solid or semi solid form (sludge). There are 77 categories of scheduled waste as established by the Department of Environment Malaysia (Jabatan Alam Sekitar). There are strict laws by the government, requiring companies to manage their waste properly or face hefty fines. Handling of scheduled wastes requires permits issued by Department of Environment (DOE).