EPA's new testing methods for arsen c and lead in
contaminated soil could save millions in cleanup costs

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www.epa.gov/research

science in ACTION

INNOVATIVE RESEARCH FOR A SUSTAINABLE FUTURE

Issue

Cleaning up arsenic and lead
at contaminated sites can be an
expensive proposition. Currently,
if contaminant levels are high,
the top layer of soil is removed
and transported to a hazardous
materials landfill for treatment to
isolate and remove toxic metals.
The price tag for such remediation
activities can reach into the
millions of dollars per acre.

However, not all toxic metals
present in soil are in a form that
can harm humans or animals.
Certain forms of arsenic and lead
are not fully available, or absorbed
by the human body. The amount
that is absorbed is referred to as
"bioavailable," meaning it is in a
form that can enter the bloodstream
and affect human health. Improved
methods are needed to determine
bioavailability of metals to protect
human health.

Action

EPA scientists are developing rapid,
reliable, inexpensive methods for
assessing the bioavailability of
arsenic and lead in contaminated
soils. This research is part of EPA's
Community Public Health Project.

One of these new methods
involves the use of mice to mimic
how the human digestive system
absorbs arsenic. Mice are given
food and soil containing arsenic,
replicating measurements taken at
a contaminated site. After a certain
amount of time, scientists measure
the amount of toxic metals found
in the animals' urine and compare
it to the amount that was given in
food The difference between the
two is the amount of lead or arsenic

the mice have absorbed — in other
words, the amount that is
bioavailable.

EPA scientists are also working on
a chemical extraction laboratory
method that mimics the human
gastrointestinal system. As part of
this effort, they are using advanced
instruments to determine the
chemical form of arsenic and lead
in soil samples and assess whether
they are potentially bioavailable.

Scientists plan to use the mouse
method to validate the new lab
method. If successful, researchers
will be able to determine
the bioavailability of these
contaminants without having to
rely on animals at all.

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Results and Impact

The use of bioavailability methods
is a much more cost-effective
way to obtain accurate data for
contaminated sites and could have
a big impact on the way Superfund
and other contaminated sites are
managed.

Results from this bioavailability
research have already provided
information and protocols
for assessing Superfund and
community sites. When researchers
evaluated arsenic-contaminated soil
samples from a site using the newly
developed bioavailability methods,
they found that only about half the
arsenic was bioavailable.

In this example, only
approximately 90 acres of soil
needed to be removed, which
reduced the price of the cleanup
from $24 million to $15 million.

Additionally, once the development
of the chemical laboratory
method is complete, researchers
will be able to determine the
bioavailability of contaminants
without the use of animal
studies. The use of site-specific
bioavailability information has the
potential to allow for customized
cleanup levels that could result in
millions of dollars in savings, while
being protective of human health.

References:

• Bradham, K.D., K.G. Scheckel,
C.M. Nelson, P. E. Seales, G.

E. Lee, M. F. HUGHES, B. W.
Miller, A. YEOW, T. Gilmore, S.L.
Harper, AND D.J. Thomas. Relative
Bioavailability and Bioaccessability
and Speciation of Arsenic in
Contaminated Soils. Environmental
Health Perspectives. 119( 11): 1629-
1634, (2011).

•	Bradham, K.D., Diamond, G.,
Scheckel, K.G., Hughes, M.F.,
Castell, S., Miller, B.W., D.J.
Thomas. 2013. Mouse Assay
for Determination of Arsenic
Bioavailability in Contaminated
Soils. Journal of Toxicology and
Environmental Health. 76:13, 815-
826.

•	Nelson, C., T. Gilmore, J.
Harrington, K. Scheckel, B. Miller,
AND K. Bradham. "Evaluation

of a Low-Cost Commercially
Available Extraction Device for
Assessing Lead Bioaccessibility in
Contaminated Soils." Environmental
Science: Processes & Impacts.
RSC Publishing, Cambridge, Uk,
15(3):573-578, (2013).

Technical Contact:

Karen Bradham, Ph.D.
Bradham.karen@epa.gov

Learn More:

www.epa.gov/lieasd/research/
bioavailabilitv.html

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