Nickel is a naturally occurring element found in soil, water, and some foods . It is actually an essential nutrient that the body needs in very small amounts. Nickel helps with some chemical processes in the body, but exactly what these functions are is not fully understood WebMD:
Small amounts of nickel can be found in many vitamin supplements.
There is no recommended daily amount of nickel, and most people get enough nickel through their diet. Foods that contain nickel include nuts, dried beans, chocolate, and whole grains.
High doses of nickel can be toxic and can cause health problems. Nickel exposure can occur through inhalation, ingestion, or skin contact. Inhalation exposure is most common in workplaces where nickel is used.
Skin contact with nickel is a common cause of allergic dermatitis, which is a red, itchy rash. People who are sensitive to nickel may also experience a rash from contact with jewelry or other objects that contain nickel.
Inhaling high levels of nickel dust can irritate the lungs and cause respiratory problems. Long-term exposure to nickel dust can also increase the risk of lung cancer.