Food heavy metals largely unabsorbed by the human body

Heavy metals such as lead, cadmium, mercury and arsenic naturally occur in soil, water and the food chain. The human gastrointestinal tract acts as a selective filter, blocking, binding and eliminating most of these nonessential metals.

Only a small fraction of the metals in food is absorbed into the bloodstream. Reported average absorption rates for adults are roughly 3‑10% for lead, 3‑8% for cadmium, 12‑79% for mercury and 60‑70% for arsenic. Even these percentages apply to already low concentrations, and most food servings contain metal levels well below federal and international safety limits.

Thus, while trace amounts of heavy metals appear in many foods, the body's limited bioavailability means the majority passes through without causing harm.