Reference intakes definition

Such population studies also permit the definition of a range of acceptable intakes. Quite apart from determining average requirements, and then reference intakes (Section 1.2.4), it is useful to know the range of intakes that is compatible with normal health. 

Institute of Medicine. Proposed definition of dietary fiber. A report of the panel on the definition of dietary fiber and the standing committee on the scientific evaluation of dietary reference intakes, food and nutrition board National Academies Press Washington, DC, 2001. 

The term acceptable is used widely to describe safe levels of intake and is apphed for chemicals to be used in food production such as, e.g., food additives, pesticides, and veterinary dmgs. The term tolerable is applied for chemicals unavoidably present in a media such as contaminants in, e.g., drinking water and food. The term PTWI (Provisional Tolerable Weekly Intake) is generally used for contaminants that may accumulate in the body, and the weekly designation is used to stress the importance of limiting intake over a period of time for such substances. The tolerable intake is similar in definition and intent to terms such as Reference Dose and Reference Concentration (RfD/RfC), which are widely used by, e.g., the US-EPA. For some substances, notably pesticides, the ARID (Acute Reference Dose), is also established, often from shorter-term studies than those that would support the ADI. The ARfD is defined as the amount of a substance in food that can be consumed in the course of a day or at a single meal with no adverse effects. 

The Margin of Exposure (MOE) in the context of the assessment of compounds that are both genotoxic and carcinogenic, as defined in EFSA (2005), is different from the OECD/IPCS definition given above The Margin of Exposure (MOE) is the ratio between a defined point on the dose-response curve (reference point) for the adverse effect of the compound in the animal carcinogenicity study and the estimated human intake of the compound. ... 

For the classification of ascorbic acid status as deficient, sufficient, or optimal, a relatively clear range of reference values exists. Table V shows the reference range for the definition of ascorbic acid status. Data derived from dietary records on the intake of ascorbic acid have to be handled carefully, since the concentrations in food show a wide range depending on several sources of variation (genotype, seasonal, food processing, etc.). Empirically estimated intake data are not always satisfactory... 

Chapters in this part of the book present and discuss lead exposure in human populations. Exposure here refers to actual, not potential, contact with lead in one or more environmental media by human populations. Furthermore, the term here also refers to both intake of media lead into various receiving body compartments and subsequent uptake into the human body. Other definitions of the term exist in the lead literature. For example, exposure is confined to lead intake into receiving body compartments and lead contact by an absorbing surface. 

The reference dose (RfD) assumes there is a threshold of exposure below which a chemical does not produce a toxic effect because the body is able to detoxify and/or eliminate it. The reference dose is derived either from a no observed adverse effect level (NOAEL) or from a benchmark dose (BMD) determined in an animal toxicity study. The NOAEL or BMD is divided by at least two uncertainty factors or safety factors a factor of 10 to account for the uncertainty involved in extrapolating from animals to humans, and a second factor of 10 to account for variation in human sensitivity. If the animal toxicity data supporting the NOAEL or BMD are not definitive, a third safety factor of 10 is included. Thus, the RfD is set equal to the NOAEL or BMD divided by 100 alternatively, it is set equal to a number approximating the NOAEL or BMD divided by 1,000. The acceptable daily intake (ADI) is the same as the reference dose. The reference concentration (RfG) refers to the concentration of a pollutant in the air. It differs from the... 

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