In 1997 the U.S. Institute of Medicine established a reference value called the Tolerable Upper Intake Level (UL) for selected nutrients, which is also being used as a model for other countries.
tolerable upper intake levels.
The dietary reference intake lists the tolerable upper intake level for adults as 45 mg/day.
For children under 14 years old the upper intake level is 40 mg/day (Pospiech and Walkowiak 2010).
In addition, the daily intake estimated through rice consumption, for all detected metals, was much lower than the Tolerable Upper Intake Level.
Similar approaches may be used to calculate the likelihood that intake exceeds the Adequate Intake or the Tolerable Upper Intake Level.
The tolerable upper intake level (UL) (1000 μg/day)of folic acid was established as one-fifth of the lowest observed adverse effect level (5000 μg/day) associated with a potential adverse outcome [32].
Recommended dietary allowances (RDA) and tolerable upper intake levels (UL), that is likely to pose no risk of adverse health effects, of the metals along with relevant references are presented in Table 6.
These metals are classified by USP stimuli article "General Chapter on Inorganic Impurities: heavy metals, Pharmacopeia form 34/5" as class IV that is recognized as micronutrient with a high upper intake limit [33].
Copper, Cr, Mo, and Se metals are classified by USP stimuli article "General Chapter on Inorganic Impurities: Heavy metals, Pharmacopeia form 34/5" as class III and are recognized as micronutrient with a low established upper intake limit [33].
As such, the highest daily intake of Zn in sample MV8 exceeds the RDA value, but is still below Tolerable Upper Intake levels (40 mg/day), and hence there is no health risk of Zn intake in all these samples.
