Tolerable daily intake

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Tolerable daily intake (TDI) refers to the daily amount of a chemical that has been assessed safe for human being on long-term basis (usually whole lifetime). Originally acceptable daily intake (ADI) was introduced in 1961 to define the daily intake of a food additive which, during the entire lifetime, appears to be without appreciable risk. [1] For contaminants and other foreign chemicals not used intentionally, the term TDI is often preferred. [2] 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. [1] [3] 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.

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Toxicity Degree of harmfulness of substances

Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell (cytotoxicity) or an organ such as the liver (hepatotoxicity). By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large. Sometimes the word is more or less synonymous with poisoning in everyday usage.

Broadly speaking, a risk assessment is the combined effort of:

  1. identifying and analyzing potential (future) events that may negatively impact individuals, assets, and/or the environment ; and
  2. making judgments "on the tolerability of the risk on the basis of a risk analysis" while considering influencing factors.

A reference dose is the United States Environmental Protection Agency's maximum acceptable oral dose of a toxic substance.Reference doses are most commonly determined for pesticides. The EPA defines an oral reference dose as:

[A]n estimate, with uncertainty spanning perhaps an order of magnitude, of a daily oral exposure to the human population that is likely to be without an appreciable risk of deleterious effects during a lifetime.

Acceptable daily intake or ADI is a measure of the amount of a specific substance in food or drinking water that can be ingested (orally) daily over a lifetime without an appreciable health risk. ADIs are expressed usually in milligrams per kilograms of body weight per day.

The threshold limit value (TLV) is believed to be a level to which a worker can be exposed per shift in the worktime without adverse effects. Strictly speaking, TLV is a reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH). TLVs issued by the ACGIH are the most widely accepted occupational exposure limits both in the United States and most other countries. However, it is sometimes loosely used to refer to other similar concepts used in occupational health and toxicology, such as acceptable daily intake (ADI) and tolerable daily intake (TDI). Concepts such as TLV, ADI, and TDI can be compared to the no-observed-adverse-effect level (NOAEL) in animal testing, but whereas a NOAEL can be established experimentally during a short period, TLV, ADI, and TDI apply to human beings over a lifetime and thus are harder to test empirically and are usually set at lower levels. TLVs, along with biological exposure indices (BEIs), are published annually by the ACGIH.

Pesticide residue refers to the pesticides that may remain on or in food after they are applied to food crops. The maximum allowable levels of these residues in foods are often stipulated by regulatory bodies in many countries. Regulations such as pre-harvest intervals also often prevent harvest of crop or livestock products if recently treated in order to allow residue concentrations to decrease over time to safe levels before harvest. Exposure of the general population to these residues most commonly occurs through consumption of treated food sources, or being in close contact to areas treated with pesticides such as farms or lawns.

Ochratoxin A Chemical compound

Ochratoxin A—a toxin produced by different Aspergillus and Penicillium species — is one of the most-abundant food-contaminating mycotoxins. It is also a frequent contaminant of water-damaged houses and of heating ducts. Human exposure can occur through consumption of contaminated food products, particularly contaminated grain and pork products, as well as coffee, wine grapes, and dried grapes. The toxin has been found in the tissues and organs of animals, including human blood and breast milk. Ochratoxin A, like most toxic substances, has large species- and sex-specific toxicological differences.

Exposure assessment is a branch of environmental science and occupational hygiene that focuses on the processes that take place at the interface between the environment containing the contaminant of interest and the organism being considered. These are the final steps in the path to release an environmental contaminant, through transport to its effect in a biological system. It tries to measure how much of a contaminant can be absorbed by an exposed target organism, in what form, at what rate and how much of the absorbed amount is actually available to produce a biological effect. Although the same general concepts apply to other organisms, the overwhelming majority of applications of exposure assessment are concerned with human health, making it an important tool in public health.

The no-observed-adverse-effect level (NOAEL) denotes the level of exposure of an organism, found by experiment or observation, at which there is no biologically or statistically significant increase in the frequency or severity of any adverse effects of the tested protocol. In drug development, the NOAEL of a new drug is assessed in laboratory animals, such as mice, prior to initiation of human trials in order to establish a safe clinical starting dose in humans. The OECD publishes guidelines for Preclinical Safety Assessments, in order to help scientists discover the NOAEL.

Patulin is an organic compound classified as a polyketide. It is a white powder soluble in acidic water and in organic solvents. It is a lactone that is heat-stable, so it is not destroyed by pasteurization or thermal denaturation. However, stability following fermentation is lessened. It is a mycotoxin produced by a variety of molds, in particular, Aspergillus and Penicillium and Byssochlamys. Most commonly found in rotting apples, the amount of patulin in apple products is generally viewed as a measure of the quality of the apples used in production. In addition, patulin has been found in other foods such as grains, fruits, and vegetables. Its presence is highly regulated.

Disodium ribonucleotides Flavor enhancer

Disodium 5'-ribonucleotides, E number E635, is a flavor enhancer which is synergistic with glutamates in creating the taste of umami. It is a mixture of disodium inosinate (IMP) and disodium guanylate (GMP) and is often used where a food already contains natural glutamates or added monosodium glutamate (MSG). It is primarily used in flavored noodles, snack foods, chips, crackers, sauces and fast foods. It is produced by combining the sodium salts of the natural compounds guanylic acid (E626) and inosinic acid (E630).

Food contaminant

Food contamination refers to the presence of harmful chemicals and microorganisms in food, which can cause consumer illness. This article addresses the chemical contamination of foods, as opposed to microbiological contamination, which can be found under foodborne illness.

An occupational exposure limit is an upper limit on the acceptable concentration of a hazardous substance in workplace air for a particular material or class of materials. It is typically set by competent national authorities and enforced by legislation to protect occupational safety and health. It is an important tool in risk assessment and in the management of activities involving handling of dangerous substances. There are many dangerous substances for which there are no formal occupational exposure limits. In these cases, hazard banding or control banding strategies can be used to ensure safe handling.

Dioxins and dioxin-like compounds Class of chemical compounds

Dioxins and dioxin-like compounds (DLCs) are a group of chemical compounds that are persistent organic pollutants (POPs) in the environment. They are mostly by-products of burning or various industrial processes - or, in case of dioxin-like PCBs and PBBs, unwanted minor components of intentionally produced mixtures.

A co-carcinogen is a chemical that promotes the effects of a carcinogen in the production of cancer. Usually, the term is used to refer to chemicals that are not carcinogenic on their own, such that an equivalent amount of the chemical is insufficient to initiate carcinogenesis. A chemical can be co-carcinogenic with other chemicals or with nonchemical carcinogens, such as UV radiation.

Toxic equivalency factor (TEF) expresses the toxicity of dioxins, furans and PCBs in terms of the most toxic form of dioxin, 2,3,7,8-TCDD. The toxicity of the individual congeners may vary by orders of magnitude.

Epoxidized soybean oil (ESBO) is a collection of organic compounds obtained from the epoxidation of soybean oil. It is used as a plasticizer and stabilizer in polyvinyl chloride (PVC) plastics. ESBO is a yellowish viscous liquid.

Dietary exposure assessments involve the evaluation of dietary consumption and chemical residue data while taking into consideration additional factors that may affect a specified population of interest or sensitive population. The process of conducting a dietary exposure assessment involves the determination of the chemical residues on a particular food or foods and the calculation of the dietary exposure to these chemicals based on consumption data for the specified food or foods. In the most simplified form, a dietary exposure assessment can be summarized with the following calculation:

Tolerable weekly intake (TWI) estimates the amount per unit body weight of a potentially harmful substance or contaminant in food or water that can be ingested over a lifetime without risk of adverse health effects. TWI is generally preceded by "provisional" to indicate insufficient data exists, increasing uncertainty. The term TWI should be reserved for when there is a well-established and internationally accepted tolerance, backed by sound and uncontested data. Although similar in concept to tolerable daily intake (TDI), which is of the same derivation of acceptable daily intakes (ADIs), TWI accounts for contaminants that do not clear the body quickly and may accumulate within the body over a period of time. An example is heavy metals such as arsenic, cadmium, lead, and mercury. The concept of TWI takes into account daily variations in human consumption patterns.

Threshold dose is the minimum dose of drug that triggers minimal detectable biological effect in an animal. At extremely low doses, biological responses are absent for some of the drugs. The increase in dose above threshold dose induces an increase in the percentage of biological responses. Several benchmarks have been established to describe the effects of a particular dose of drug in a particular species, such as NOEL(no-observed-effect-level), NOAEL(no-observed-adverse-effect-level) and LOAEL(lowest-observed-adverse-effect-level). They are established by reviewing the available studies and animal studies. The application of threshold dose in risk assessment safeguards the participants in human clinical trials and evaluates the risks of chronic exposure to certain substances. However, the nature of animal studies also limits the applicability of experimental results in the human population and its significance in evaluating potential risk of certain substances. In toxicology, there are some other safety factors including LD50, LC50 and EC50.


  1. 1 2 Faustman, Elaine M.; Omenn, Gilbert S. (2001). "Risk assessment". In Klaassen, Curtis D. (ed.). Casarett & Doull's Toxicology: The Basic Science of Poisons (6th ed.). New York: McGraw-Hill. pp.  92–4. ISBN   978-0-07-134721-1.
  2. "Consultation on assessment of the health risk of dioxins; re-evaluation of the tolerable daily intake (TDI): Executive Summary". Food Additives and Contaminants. 17 (4): 223–40. 2000. doi:10.1080/713810655. PMID   10912238. S2CID   216644694.
  3. Renwick, A. G. (1999). "Toxicokinetics". In Ballantyne, Bryan; Mars, Tore; Syversen, Timothy (eds.). General and Applied Toxicology (2nd ed.). London: MacMillan Reference. pp. 91–2. ISBN   978-1-56159-242-5.