Analysis - The Institute for Southern Studies
Analysis - The Institute for Southern Studies
Analysis - The Institute for Southern Studies
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Exhibit 5A-6<br />
Potential Future Human Cancer Cases from the Disposal of CCR Based on Arsenic Cancer-Slope Factor from EPA/IRIS<br />
Disposal of CCR<br />
Disposal of Conventional CCR<br />
Co-Managed with Coal Refuse<br />
WMU Adult Child Totals Adult Child Totals<br />
Unlined Landfills 0.1 0.1 0.2 0.1 0.1 0.2<br />
Clay-Lined Landfills 0.1 0.1 0.2 0.0 0.0 0.0<br />
Unlined Surface Impoundments 20.1 16.3 36.4 98.1 67.6 166.7<br />
Clay-Lined Surface Impoundments 4.8 3.5 8.3 17.6 12.6 309.2<br />
Totals 25.1 20.0 45 115.8 80.3 196<br />
Step 5. Estimate Arsenic Cancer Risks Using Recent NRC Science <strong>for</strong> Arsenic<br />
Based on the NRC data source, lifetime exposure to 10 ug/L arsenic in drinking water would lead to 23 excess male bladder cancers and 14<br />
excess male lung cancers per 10,000 people. Under the exposure factor assumptions used by the NRC the equivalent cancer slope factor (CSF)<br />
is 26 mg/kg/d -1 . For details of how this cancer slope factor was calculated, see Appendix K4 – Cancer Calculations. 121 Exhibit 5A-7 below<br />
displays the population risk estimates <strong>for</strong> CCR disposal base on the NRC source. 122 Using the NRC (2001) cancer slope factor one would<br />
expect between approximately 778 and 3,392 cancer cases over 75 years as a result of arsenic consumed through contaminated groundwater.<br />
Using the ratios of conventional CCR co-managed with coal refuse produces a best estimate within this range of 2,509 cancers.<br />
Exhibit 5A-7<br />
Potential Future Human Cancer Cases from CCR Disposal Based on Arsenic Cancer-Slope Factor from NRC<br />
Disposal of CCR<br />
Disposal of Conventional CCR<br />
Co-Managed with Coal Refuse<br />
WMU Adult Child Totals Adult Child Totals<br />
Unlined Landfills 2 2 4 1 1 2<br />
Clay-Lined Landfills 1 1 2 1 1 2<br />
Unlined Surface Impoundments 348 281 629 1,696 1,169 2,865<br />
Clay-Lined Surface Impoundments 82 61 144 305 218 523<br />
Totals 433 345 778 2,003 1,389 3,392<br />
121 EPA is currently in the process of revising the arsenic cancer slope factor in EPA’s Integrated Risk In<strong>for</strong>mation System (IRIS).<br />
122 EPA also conducted a sensitivity analysis assuming the female cancer slope factor in Appendix K5 of this RIA.<br />
120