http://www.fda.gov/fdac/reprints/mercury.html

Mercury Is Everywhere


Mercury occurs naturally in the environment. According to FDA toxicologist
Mike Bolger, Ph.D., approximately 2,700 to 6,000 tons of mercury are
released annually into the atmosphere naturally by degassing from the
Earth's crust and oceans. Another 2,000 to 3,000 tons are released annually
into the atmosphere by human activities, primarily from burning household
and industrial wastes, and especially from fossil fuels such as coal.




The Hawke