Actually I did think about all that.

I grew up when lead was still in fuel.
Half my career as a plumber was with 50/50 lead based solder. Not really any exposure to old piping, lead, and asbestos because it was all new construction. I know I have had high levels of copper in my system from running copper pipe for days on end. I think that leaves your system though whereas lead and mercury don't.

Not sure about California pollution as they don't have any coal fired power plants. The main source was smog from the bay area from autos, and lots of dust, pollens, and allergens where I lived. In the summer the central valley would have a high pressure dome sitting over it all summer so there was no air exchange. Bay area smog would filter over. I don't think heavy metals are high though.

Growing up in Northern Michigan is anyones guess. Less likely because it is rural northern but I did spend tons of time in the woods. It all depends on if Dow Chemical and the like bothered to drive this far to illegally dump their toxic waste in the woods. There is plenty of woods in Southern Michigan for them to dump. Hard to know but I think the area I grew up in had pretty clean air and water even back then. Mercury and acid rain were problems then.

I don't know how to get it checked out. It would certainly be worth the test. I will look into it. My pdoc will probably poo poo it.

The depression definitely started before the plumbing. The most likely sources then would have been mercury and lead in the air. Oh and I forgot......In 7th grade science class after school we played with mercury like it was a toy. It is a very cool and bizarre element. The fact it has such a high density and is a liquid.

I am sure I have fillings with mercury in them if they haven't fallen out. A lot of the old ones fell out. I could have swallowed them.

Maybe I will print this post and give it to my docs.

Thanks for your concern.