Either way, the list of heavy metals generally includes arsenic, lead, cadmium, mercury, chromium, copper, zinc, nickel, selenium, silver, antimony, manganese, and several others. The Food & Drug Administration only has specific safety levels for a few of these—cadmium, lead, arsenic, and mercury—because those are the elements within this category that most commonly make their way into the food supply. The Environmental Protection Agency also monitors heavy metals, since they’re environmental contaminants. But all this being said, there’s no one definition of “heavy metal” and they’re not all equally dangerous. Generally, health experts agree that the most worrying members of this category, are arsenic, cadmium, chromium, lead, and mercury.