Cadmium is a metal that has not been shown to be essential to human health. Its main sources of uptake are cigarettes, industrial pollution, and some foodstuffs.
Cadmium intake is generally quite low (though low iron increases its uptake), however it does not leave the body quickly and therefore can cause damage later in life. Cadmium is particularly toxic to kidney function, can cause reduced bone density, and is associated with increased cancer risk.
Seafood and organ meats have relatively high levels of cadmium, though grains and cereals as well as fruits and vegetables are a source, particularly as they are more common in the diet.
Seafood, organ meats, grains, vegetables, fruit
Dartmouth Toxic Metals
Food Standards Agency