To: Harry Harbold
EPA, Region III
Federal Facilities Section 3HS13
1650 Arch St
Philadelphia, PA 19103
I am writing in response to your request that the Agency for Toxic Substances and Disease
Registry (ATSDR) evaluate the public health significance of arsenic in creek sediments.
You asked about four sediment samples taken from four residences on Glenbrook Road, near
American University. The levels of arsenic in these samples were 4.0, 9.5, 9.6, and 9.7
ppm. We considered that children have ready access to the creek, and that a child might
play in this creek every day. For this exposure scenario, ATSDR has derived a “comparison
value” for arsenic of 20 ppm. A comparison value is a concentration in soils and sediments
at which no adverse health effects are expected to occur. For arsenic, this level is based
upon epidemiological studies of humans, including children, who were inadvertently exposed
to arsenic. No adverse health effects were observed in these people at a dose which is
higher than would occur from the creek sediments at this site. For this reason, no adverse
health effects are expected to result from this exposure.
Signed
Dana Abouelnasr, Ph.D.
Senior Scientist
This page last updated on December 31, 2001
Dana Abouelnasr / DAbouelnasr@cdc.gov
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