http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~pyuUbK:1

 The list of 22 chemicals of specific interest to the Superfund cleanup
efforts provided to NIEHS by the EPA Office of Solid Waste and Emergency,
contains eight metals: lead, chromium, arsenic, cadmium, zinc, copper,
mercury, and nickel. Many human health problems, including cancer and
heart/circulatory diseases, are linked to external exposure to toxic metals
or disruption of normal cellular processes involving endogenous metals. The
overall objectives of the Program Project Toxic Metals in the Northeast:
From Biological to Environmental Implications are to understand, assess and
attenuate the adverse effects on human health resulting from environmental
exposure to the toxic metals lead, chromium, arsenic, cadmium, zinc, copper,
mercury, nickel and iron. These toxic metals emanate from highly
contaminated Superfund sites and lead to high levels of exposure to living
organisms. Most of these same metals also are often found ubitquitously in
low to moderate levels in the environment and lead to chronic low levels of
exposure to living organisms. The combination of acute high level exposure
to toxic metals coupled with chronic lower level exposure to toxic metals
may result in unique biological and environmental consequences.