Nickel
Occurrence in nature: Nickel is present in all types of soils.. The main sources of contamination are waste disposal and discharge from industrial processes. Agricultural soil may contain high levels of nickel as a result of fertilization with sewage sludge.
Occurrence in tobacco: Nickel is taken up from the agricultural soil by the roots of the tobacco plant as a pollution and is transported to the leaves. Nickel has no function in the plant.
Occurrence in foodstuffs: Nickel is present in trace amounts in virtually all foodstuffs, such as carrots, lettuce and cereals. Relatively high levels can be found as a result of contamination from process equipment, for example in wheat products. There exists no threshold value for nickel in foodstuffs in Sweden.