As to the Mercury, most is from
China and all the coal they burn. That air pollution has to go
somewhere.

It's actually from ALL the countries that burn coal. Here in the U.S.
according to numerous researchers, you will find mercury levels in just
about all fish from all lakes, even the previously pristine Adirondack's
lakes. Luckily, small amounts of mercury can be chelated out of the body
with certain supplements over time.