Tolerable daily intake (TDI) refers to the daily amount of a chemical contaminant that has been assessed safe for human being exposure on long-term basis (usually whole lifetime).[1] TDI specifically occurs to chemicals that humans are exposed to unintentionally or as a contaminant,[1] where acceptable daily intake refers to chemicals that are intentional added.[2] TDI is generally written as a value of exposure (eg in milligrams) per kilogram (kg) body weight.[3] Both ADI and TDI are usually assessed based on animal experiments, and it is most often hundreds of times lower than the dose causing no observable adverse effect (NOAEL) in the most sensitive tested animal species.[2][4] Because the confounding factors (safety factors) may vary depending on the quality of data and the type of adverse effect, TDI values are not good estimates of the harmfulness of chemicals, and must be considered administrative tools to set allowable limits for chemicals, rather than scientific measures. The threshold limit value (TLV) of a chemical substance is a level to which it is believed a worker can be exposed day after day for a working lifetime without adverse effects.