There is no question the incidents in Japan were human supplied mercury. On the other hand, that was a very local situation and the levels were absurdly high.

Otherwise, mercury levels in deep ocean fish like tuna and shark are uniform around the world, indicating they are likely mostly natural.

The one item most mysterious to me was the position of tilefish at the top of the FDA mercury chart. This did not make sense because these are not big predators like tuna and shark, they are bottom feeders that eat molusks and crustaceans, generally at considerable depth.

I recently found the complete FDA chart and it shows Atalantic tilefish (the biggest ones) at a very safe level. More investigation turned up that the high mercury was found not by the FDA but by the National Marine Fisheries Service using a limited sample of 60 fish all from the Gulf of Mexico.

I would just about bet the samples were either all picked from within a single industrial polution fan-out - or the numbers are simply in error. Data that is suspect should be flagged as suspect rather than being used for a broad brush condemnation.

The FDA admits their 1 ppm limit was very conservative and based on inadequate data and they issued the warning to women because they hadn't the slightest idea what level might be dangerous to fetal development - the figures from Japan were so extreme you just couldn't make a reasoned judgement from them. Now that WAG (Wild Ass Guess) figure has been cast as gospel fact by the usual array of "do gooders".

Since then the University of Rochester study in the Republic of the Seychelles has issued it's report. They tracked a large number of children from fetus to late teens. Women in the Seychelles eat 10 times the amount of fish American women eat thus have 10 times the mercury exposure. The reseachers said they were "shocked" to find no adverse effects whatever.

Two other high profile studies were published about a month ago declaring eating fish safe and highly beneficial. "Environmentalist" groups denounced the studies for not "emphasizing the danger of eating fish".

We have severe environmental problems that need to be resolved, but I'm sick and tired of self declared "environmentalists" who all seem to be brain damaged with "one issue" minds as impervious to evidence as any wingnut evangelical from West Virgina ever was. Cut from the same cloth, they are.

More info and links to the FDA charts, Rochester study and other sites can be found at the bottom of my [link|http://www.clovegarden.com/ingred/seafish.html#med|Fish Page]