Abstract Chromium exists in several different valence states but most important is chromium(III), which is considered to be of low toxicity and essential for health in trace amounts. For the general population, foods, such as broccoli, apple, meat, yeast, and whole grains, are major sources of chromium(III). Nickel is a silvery-white and very hard metal that is widely used in alloys with other metals. It naturally occurs in the Earth's crust and the Earth's core is composed of 6% nickel. Nickel and its compounds have no characteristic odor or taste. Copper is a reddish metal that is extensively used as the metal or alloy in the manufacture of wire, sheet metal, coins, pipe, and other metal products. The European Food Safety Authority has established an acceptable daily intake of 0.15mg per kg bw per day. Aluminum is one of the most abundant elements on earth and is widely used as a metal and in various compound forms. For adults, the estimates of mean dietary exposure to aluminum-containing food additives from consumption of cereals and cereal-based products are up to the provisional tolerable weekly intake (PTWI) of 2mg per kg bw per week, which was established by the Joint FAO/WHO Expert Committee on Food Additives in 2011.