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ATSDR Presentation to the Washington, DC, Scientific Advisory Board

Regarding Exposure Investigations

Presented by Susan Metcalf, MD, MSPH on April 25, 2001

Slide 1
Agency for Toxic Substances
and Disease Registry
  • Susan W. Metcalf, MD, MSPH

Slide 2
Exposure Investigation
Spring Valley Chemical Munitions
Washington, DC
  • Ketna Mistry, M.D., F.A.A.P
  • Ken Orloff, Ph.D., DABT
Slide 3
ATSDR

The primary public health agency for addressing human health issues that might arise from exposure to hazardous substances
Slide 4

Continuum for Relating Environmental Contamination
with Clinical Disease

diagram of a continuum, going from environmental
contamination, to people being exposed, to some biological effect, to clinical disease> 
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Slide 5<br>
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<center>Purpose of an Exposure Investigation
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To better characterize past, current, and possible future human exposures to hazardous 
substances in the environment.


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Slide 6<br>
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<center>Exposure Investigation: Data Gathering<br>

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<ul>
<li>Environmental samples</li>
<li>Biomarkers</li>
<li>Exposure-dose reconstruction</li>
</ul>
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Slide 7<br>
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<center>Arsenic Biomarkers:  Blood<br>
</center>
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<ul>
<li>Quantifies the absorbed Arsenic</li>
<li>Clears within a few hours</li>
<li>Not useful for low-level exposure</li>
</ul>
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slide 8<br>
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<center>Arsenic Biomarkers:  Urine <br> </center>
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<ul>
<li>Good marker of recent exposure
<ul><li>(3-4 days)</li></ul></li>
<li>Includes both inorganic and organic forms</li>
<li>Reference range available</li>
</ul>
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slide 9<br>
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<center>Total Arsenic in Urine<br> </center>
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<ul>
<li>Inorganic As (As+3, As+5)</li>
<li>MMA (monomethylarsonic acid)</li>
<li>DMA  (dimethylarsenic acid)</li>
<li>Trimethylated forms 
<ul>
<li>Arsenobetaine</li>
<li>Arsenocholine</li>
</ul></ul>
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slide 10<br>
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<center>Arsenic Biomarkers:  Hair
<br> </center>
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<ul>
<li>Measures several months of exposure</li>
<li>Collection is non-invasive</li>
</ul>
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slide 11<br>
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<center>Limitations of Hair as Biomarker
<br> </center>
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<ul>
<li>Possibility of external contamination</li>
<li>Paucity of reference range data for unexposed populations</li>
</ul>
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slide 12<br>
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<center>Playground Arsenic Levels
<br> </center>
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<ul>
<li>Soil arsenic levels 
<ul><li>Average 57 ppm</li>
<li>Highest level 498 ppm</li></ul>
<li>Children immediately relocated to another area of the campus</li>
</ul>
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slide 13<br>
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<center>Playground Characteristics	
<br> </center>
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<ul>
<li>Covered with 2 inches of mulch or grass in some areas</li>
<li>Playground is periodically remulched</li>
</ul>
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slide 14<br>
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<center>Target Population	
<br> </center>
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<ul>
<li>Daycare roster:
<ul><li>28 children</li>
<li>4 adult staff</li></ul>
<li>Length of time at daycare: 
<ul><li>~50% present: < 7 months</li>
<li>~50% present: > 1 year</li></ul>
</li>
</ul>
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slide 15<br>
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<center>Other Sources of Arsenic 	
<br> </center>
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<ul>
<li>Wood preservatives</li>
<li>Pesticides</li>
<li>Arsenic containing herbal medicines</li>
<li>Parental occupational exposure</li>
<li>Hobbies</li>
<li>Consumption of seafood</li>
<li>Pica (soil eating) behavior</li>
</ul>
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slide 16<br>
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<center>Results	
<br> </center>
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<ul>
<li>Hair samples for arsenic:</li>
<li>24/ 32 hair samples :  not detected</li>
<li>8 / 32 hair samples: detected </li>
<li>8 Arsenic detected hair samples ranged 
from 0.10 ppm to 0.14 ppm</li>
</ul>
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slide 17<br>
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<center>Background Hair Arsenic Levels
<br> </center>
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<ul>
<li>Textbooks: < 1 ppm</li>
<li>National Research Council:  0.2 ppm</li>
<li>NCEH:  95th percentile: 0.28 ppm</li>
</ul>
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slide 18<br>
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<center>Conclusion
<br> </center>
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<ul>
<li>Hair arsenic levels were not elevated in the 32 participants of this exposure 
investigation</li>
<li>Therefore, no unusual exposure to arsenic was found in the participants at the 
Child Daycare Center
</li>
</ul>
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slide 19<br>
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<center>Speciated Urine Arsenic (µg/L)(Kalman, 1990)
<br><br>
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<table border=1 cellpadding=5>
<tr align=middle><td>
Age Group<br>
(boys)
</td>
<td>Rushton</td>
<td>Control</td>
</tr>
<tr align=middle>
<td>0-6 years</td>
<td>65</td>
<td>11</td>
</tr>
<tr align=middle>
<td>7-13 years</td>
<td>30</td>
<td>13</td>
</tr>
<tr align=middle>
<td>14-20 years</td>
<td>10</td>
<td>9</td>
</tr>
<tr align=middle>
<td>Mean As soil conc</td>
<td>353 ppm</td>
<td>7-57 ppm</td>
</tr>

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slide 20<br>
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<center><a href="http://www.idealibrary.com/servlet/doi/10.1006/enrs.1996.3691">Hwang 1997</a>
<img src="/img/exit.gif" width="30" height="11">
<br> </center>
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<ul>
<li>Measured speciated urinary As in 300 children near smelter site</li>
<li>Average soil levels 121-236 ppm</li>
<li>Average urinary arsenic levels 8.6 µg/L</li>
</ul>
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slide 21<br>
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<center><a href="http://www.atsdr.cdc.gov/HAC/pha/bird2/bla_basic.html">Panther Creek, 1998</a>
<br> </center>
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<ul>
<li>Mining site</li>
<li>Soil levels up to 3500 ppm</li>
<li>Urine samples tested for As
<ul><li>20/23 below detection levels</li>
<li>6-8 µg/g Cr As in samples where As detected</li>
</li>
</ul>
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slide 22<br>
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<center><a href="http://www.atsdr.cdc.gov/HAC/pha/bird2/bla_basic.html">Panther Creek, ID</a>
<br> </center>
<font face="Helvetica, Arial,sans-serif" size=3>
<ul>
<li>
Hair analysis
<ul>
<li>26/36 below level of detection</li>
<li>7 had elevated hair levels
<ul>
<li>Urine levels not elevated</li>
<li>All were remediation workers</li>
<li>Likely due to external contamination</li>
</ul></li>
</li>
</ul>
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slide 23<br>
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<center>Past studies of exposure to Arsenic in soil
<br> </center>
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<ul>
<li>At soil levels < 100 ppm, average urine arsenic is similar to background levels</li>
<li>At soil levels > 100 ppm, urinary levels may show exposure but are below levels 
associated with health effects</li>
</ul>
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This page last updated on January 15, 2002
<BR> <BR>
Dana Abouelnasr / <A HREF="mailto:DAbouelnasr@cdc.gov">DAbouelnasr@cdc.gov</A>
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