Tolerable daily intake

Tolerable daily intake (TDI) refers to the daily amount of a chemical contaminant that has been assessed safe for human 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 (e.g. 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.

Examples of Tolerable Daily Intake

World Health Organization

The World Health Organization (WHO) has introduced a TDI for melamine as 0.2 milligrams (mg)/kg body weight (b.w.) as of 2008.^[5] Similarly the established TDI range for dioxins according to WHO is 1-4 picograms toxic equivalency/kg body weight as of 1998.^[6] WHO's provisional maximum tolerable daily intake for all sources of iodine combined is 0.017 mg/kg b.w.^[7]

North America

Canada

The Canadian Government Health Protection Branch also uses tolerable daily intake.^[8] They have established TDI's for a wide variety of chemicals, listed below.

Substance	TDI (oral)	TDI (inhalation)	Category
aniline	7 micrograms/kg b.w./day[8]	-	non-carcinogenic effects
bis (2-ethylhexyl phthalate)	0.044 mg/kg b.w./day[8]	-	non-carcinogenic effects
chlorobenzene	0.43 mg/kg b.w./day[8]	0.01 mg/m3 (provisional)[8]	non-carcinogenic effects
dibutyl phthalate	0.063 mg/kg b.w./day[8]	-	non-carcinogenic effects
dichlorobenzene	0.11 mg/kg b.w./day[8]		non-carcinogenic effects
dichloromethane	0.05 mg/kg b.w./day[8]	-	non-carcinogenic effects
hexachlorobenzene	500 ng/kg b.w./day[8]	-	non-carcinogenic effects
inorganic fluoride	200 micrograms/kg b.w./day (provisional)[8]	-	non-carcinogenic effects
arsenic and its inorganic compounds		7.8 micrograms/m3 (air) 840 micrograms/litre (drinking water)[8]	carcinogenic effects
benzene		15 mg/m3[8]	carcinogenic effects
cadmium		5.1 micrograms/m3[8]	carcinogenic effects

United States

The United States Food and Drug Administration has used TDI for substances such as melamine, which is currently set at 0.063 mg/kg b.w./day.^[9]

Europe

European Food Safety Authority

The European Food Safety Authority has set a TDI for Bisphenol A at 0.2 nanograms per kilogram of b.w./day as of 2023.

Asia

Taiwan

As of 2011, the Taiwan Food and Drug Administration follows the TDI values set by the European Food Safety Administrations.^[10] This change was prompted by a 2011 food scandal where citizens where exposed to DEHP (di-2-ethylhexyl phthalate) after its intentional addition to food products.^[10]

Korea

The Official Journal of Korean Society of Toxicology as requested by the Korean National Institute for Food and Drug Safety Evaluation has recommend a TDI for BPA to be set at 0.05 mg/kg b.w./day.^[11]

See also

Recommended daily allowance

Tolerable weekly intake

Acceptable daily intake