… processes. Source: jzehnder / fotolia.com Nickel belongs to the heavy metals and usually occurs bound to other substances. In ambient air arsenic is measured … important source is the metal industry Health risks Nickel is mainly obtained from food although it can hardly be resorbed by the gastrointestinal tract. Occupational … Another important source is the metal industry … Nickel is mainly obtained from food although it can hardly be resorbed by the gastrointestinal tract. Occupational …