Print this pageFrias, Abraham1, Dibyendu Sarkar1
(1) University of Texas at San Antonio, San Antonio, TX
ABSTRACT: Bioavailability of Arsenic in Pesticide-Applied Cotton Soils of Texas
Years of widespread application of arsenic-based pesticides have increased the
background concentrations of As in certain agricultural soils, such as in the cotton
fields of Texas, where arsenical compounds were applied for defoliation during harvest.
Due to rapid encroachment of suburban development on former agricultural lands in fast
expanding cities, 
soil
ingestion by children from incidental hand-to-mouth activity is now
an important issue in assessing human health risks associated with exposure to this
Group-A carcinogen. Human health risk from ingested arsenic is generally associated with
those geochemical forms of arsenic that are soluble in gastric and intestinal juices and
are potentially absorbed by the intestinal membrane. We have developed an appropriate
“in-vitro” technique that has the capability of simulating human bioavailability
of arsenic. An incubation study is currently in progress to dissect the relationship
between soil-speciation of arsenic and arsenic bioavailability in the Houston Black soil
series (the state soil of Texas, most commonly used for growing cotton) amended with one
inorganic and one organic arsenical pesticide using our in-vitro model. A sandy soil from
the Immokalee series with minimal arsenic retention capacity is used as the control to
identify the effect of soil properties on arsenic speciation, hence, bioavailability. The
soils have been amended with the arsenical compounds at 3 rates, representing normal,
high, and excessive pesticide application. Concentrations of arsenic are to be measured
using a graphite furnace atomic absorption spectrometer at 3 times, immediately after
pesticide application, after 6 months, and after one year of soil
-pesticide equilibration.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.