We dumped lead all over the environment. You can basically assume anything grown has lead, the only question being how much. Likewise, mercury. In some areas there's a lot of arsenic.
Most everything high on the periodic table is nasty. The few that we willingly associate with are because they are non-reactive enough to not actually pose a threat even if in theory they're harmful. (Consider the use of barium to image the digestive system. They use a form of it that's sufficiently insoluble that you don't get poisoned.)
What proportion of these labels are false positives?