Well, I asked the doctor, "How in hell did I get lead poisoning?" He said, hard to tell there are a lot of toxins out there.
I have cast a lot of lead balls for muzzleloaders so I got some lead there. But the main culprit, I went to Mexico in 1975 and brought back some black and red glazed pottery. And I used it to eat from, and to drink margueritas from, for several years.
And I bought a test kit, and tested that Mexican drinking cup, and it was loaded up with lead.

On the mercury I just don't know, but my mom used to spray my bedroom at night with Raid, just before I went to bed, and back in the fifties there was mercury in Raid.

There are a lot of toxins out there and it is a crap shoot as to whether they make you sick or not.