TCLP is a Federal EPA test method that is used to characterize waste as either hazardous or non-hazardous for the purpose of disposal. TCLP is an acronym for Toxicity Characteristic Leaching Procedure. The TCLP test measures the potential for mercury (or another chemical) to seep or "leach" into groundwater from waste potentially disposed in a landfill. In the TCLP test, lamps are crushed into small pieces and mixed with an acidic solution. The acidic solution is then filtered from the lamp pieces. If less than 0.2 mg of mercury are found per liter of acidic test solution, the waste is characterized as non-hazardous waste under federal law.
Low mercury, "green end" or "environmentally preferable" fluorescent lamps are developed by lamp manufacturers to pass the TCLP test; however, some manufacturers use additives to influence the TCLP test and mask the true mercury content of the lamp. Furthermore, the TCLP test is irrelevant for lamps that are burned in an incinerator; all of the mercury content of these lamps will be released into the atmosphere. For these reasons it is best to handle all mercury lamps, including those that pass TCLP, as hazardous or universal waste.