Other nickel compounds that don't dissolve reach the ground through gravity and air turbulence. Nickel does not seem to build up in the flesh of fish. Ash pond wastewater discharged into public waterways may contain small amounts of nickel, but these amounts are regulated by local permits. People are commonly exposed to nickel in the foods they eat. For example, chocolate, soy beans, nuts, and oatmeal all contain nickel.
Foods can also pick up small amounts of nickel from cooking utensils.
People may drink water or breathe particles in the air that carry trace amounts of nickel, and those who smoke may inhale nickel found in tobacco. People are also exposed when they handle coins and wear jewelry made from nickel alloys. Finally, industrial workers may breathe nickel dust or fumes, or touch substances that contain nickel. Very small amounts of nickel in people's diets may promote good health. However, some people exposed to small amounts of nickel for a long time develop an allergic reaction to it.