Safety factors

Safety factors are used to set an ADI that provides an adequate safety margin for the consumer by assuming that man is 10 times more sensitive than the test animal. A further factor of 10 is included which assumes that the variation in sensitivity within the human population is within a 10-fold range. The no-effect level, determined in an appropriate animal study, is traditionally divided by a safety factor of 100 (i.e., 10 x 10) to set the ADI. A food additive is considered safe for its intended use if the human intake figure is less than or equivalent to ADI. ADI is usually derived from the results of lifetime studies in animals and therefore relates to lifetime use in man. This provides a sufficient safety margin so that no particular concern is felt if man is exposed to levels higher than the ADI in the short term, provided that the average intake over longer periods does not exceed it. Higher safety factors may be used if the nature of the chemical's toxicity is of particular concern (e.g., if the substance is a carcinogen through a secondary mechanism, as is the case for bladder tumors following the formation of bladder stones caused by mineral imbalance), or if the chemical's toxicological profile is incomplete. Occasionally, lower safety factors may be used if there are human data to indicate that human sensitivity varies by less than 10-fold.

If a similar approach were applied to some essential nutrients (e.g., vitamin A, vitamin D, certain essential amino acids, and iron) it would become apparent that they may cause toxic effects at levels less than 10 times higher than those needed to satisfy the nutritional requirements for good health. This can be summarized as shown in the diagram below (Figure 17.3).

tolerable risk safety margin benefit from use contaminan, or natural toxin nutrient additive tolerable risk safety margin benefit from use nutrient additive

Figure 17.3 Use of safety factors. Small safety margins (2-10) are acceptable for essential nutrients e.g., selenium and vitamin A. Conversely, large safety margins (>100) should be set for contaminants. Additives will fall in-between (usually ~100). Source: ILSI Europe.

Figure 17.3 Use of safety factors. Small safety margins (2-10) are acceptable for essential nutrients e.g., selenium and vitamin A. Conversely, large safety margins (>100) should be set for contaminants. Additives will fall in-between (usually ~100). Source: ILSI Europe.

Using an ADI derived from a no-effect level found in an appropriate animal study and a suitable safety factor, implies an in-built conservatism reflecting the uncertainty of the extrapolation of experimental animal data to the diverse human population. In the case of contaminants, extrapolation is difficult from high-dose animal experiments to the human situation in which lower doses are consumed (see Section 17.4.2). The ADI also makes some allowance for the possible synergistic effects humans experience when additives are consumed together in foodstuffs. The effect of the interacting additives may be different from the responses to the individual additives.

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100 Health Tips

100 Health Tips

Breakfast is the most vital meal. It should not be missed in order to refuel your body from functional metabolic changes during long hours of sleep. It is best to include carbohydrates, fats and proteins for an ideal nutrition such as combinations of fresh fruits, bread toast and breakfast cereals with milk. Learn even more tips like these within this health tips guide.

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