I've heard that.. one of the first symptoms of mercury toxicity is brain fog and chronic fatigue.
And that..
Women of childbearing age are are at risk as mercury is transported through the placenta to the developing fetus
and occupational exposure to mercury has been documented
to cause infertility and miscarriage.

A documentary has been produced in Norway about the neurological and autoimmune diseases suffered by dental hygientists.

See:

Neurotoxic Effects of Mecury in Amalgam Dental Fillings

http://www.mercurypolicy.org/new/documents/FDADentalMPPNorwayFinal090706.pdf

2004 EPA Report

Government analysis nearly doubled the estimate of the number of newborn children at risk for health problems because of unsafe mercury levels in their blood. Environmental Protection Agency scientists said yesterday that new research had shown that 630,000 U.S. newborns had unsafe levels of mercury in their blood in 1999-2000.