Chromium is a metallic mineral that affects many different areas of the body, but is nonessential for human life. It occurs in trace amounts in a wide range of foods, making it very difficult to suffer from a chromium deficiency. Most people consume this mineral in processed meats, whole grains and related products, coffee, spices, green beans, broccoli, beer, wine and dairy products. Cooking and storing food in stainless steel containers also contributes significant quantities of chromium to the diet.

While chromium deficiencies are vanishingly rare, chromium overdoses are a very real risk, especially for industrial or chemical workers who may be exposed to the mineral on the job. Contaminated drinking water can also produce chromium poisoning. Some people who have had metallic prosthetic implants must have periodic chromium tests to make sure they do not suffer from chromium toxicity. 

Most chromium compounds are not a health hazard, but the chromium(VI) is considered a carcinogen. Hexavalent chromium is considered a hazardous substance and can damage the blood cells, kidneys and liver, produce an increased risk of several types of cancer and irritate the skin. 

Chromium blood tests require no special preparations, as it is difficult to inaccurately influence their results through diet or environmental factors. Most healthy people have blood chromium levels of less than 0.3 nanograms per milliliter, but levels up to 0.5 micrograms per milliliter are considered normal. Higher levels may indicate a potential health problem that will not correct itself.