The Toxicologist - Society of Toxicology

monize sample preparation and analytical techniques, and a more robust documentation
of QA/QC protocols is necessary to ensure accuracy, precision, representativeness,
and comparability. Also, a consistent method of collection and analysis is
needed. Accurate measurement of As in air is critical to providing a more robust understanding
of As exposures and associated human health risks, particularly in the
context of regulatory decision making.
1938 THE ROLE OF IRON IN THE REDUCED
BIOAVAILABILITY OF ARSENIC IN SOIL.
V. L. Mitchell 1 , C. N. Alpers 2 , N. T. Basta 3 , T. Burlak 4 , S. W. Casteel 5 , R. L.
Fears 1 , A. L. Foster 6 , C. S. Kim 7 , P. A. Myers 1 and E. Petersen 8 . 1 Toxic Substances
Control, Cal EPA, Sacramento, CA, 2 U.S. Geological Survey, Sacramento, CA,
3 Ohio State University, Columbus, OH, 4 California State University, Sacramento,
CA, 5 University of Missouri, Columbia, MO, 6 U.S. Geological Survey, Menlo Park,
CA, 7 Chapman University, Orange, CA and 8 University of Utah, Salt Lake City, UT.
Arsenic (As) is a naturally occurring element in soil and often the key chemical of
concern at former mines in the California Mother Lode Region. Risk based screening
levels are often below the naturally occurring background concentrations of As
in soil. These screening levels assume 100% bioavailability, which can be greatly affected
by the association of As with other elements. Iron(Fe)-bearing minerals are
known to bind As and reduce its bioavailability; however the mechanism is not
completely understood. The soils in the Mother Lode Region are relatively high in
Fe, ranging from 2-10%. Total As in soils collected from the Empire Mine State
Historic Park ranged from 16 to 9,700 mg/kg. Bulk soil samples were sieved to