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Abstracts (PDF file, 1.8MB) - Society for Risk Analysis

Abstracts (PDF file, 1.8MB) - Society for Risk Analysis

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SRA 2013 Annual Meeting <strong>Abstracts</strong><br />

P.72 Chang, CH; Chuang, YC; Chen, CC; Wu, KY*; National<br />

Taiwan University; achchg@gmail.com<br />

Probabilistic Assessment of Cancer <strong>Risk</strong> <strong>for</strong><br />

N-Nitrosodimethylamine in Drinking Water by Using<br />

Bayesian Statistics with MarKov Chain Monte Carlo<br />

Simulation<br />

N-Nitrosodimethylamine (NDMA) is an emerging nitrogenated<br />

Disinfection By-Product (N-DBP) in drinking water <strong>for</strong>med<br />

during chloramination and chlorination. NDMA is genotoxic and<br />

carcinogenic to rodents after cytochrome P-450 metabolism by<br />

the liver as its target organ. The potential health risk posed by<br />

NDMA exposures through water consumption has been of great<br />

concern. With the majority of NDMA data in drinking water<br />

below detection limit, the research community has yet to<br />

per<strong>for</strong>m its cancer risk assessment. In order to deal with a<br />

majority of Non-detectable (ND) data of NDMA in drinking<br />

water, a Bayesian statistics with Markov chain Monte Carlo<br />

simulation was first used to assess probabilistic cancer risk <strong>for</strong><br />

NDMA in drinking water in WinBUGS1.4 (Bayesian analysis<br />

software Using Gibbs Sampling <strong>for</strong> Windows Version 1.4). The<br />

dataset of NDMA concentration was cited from a published<br />

study in Taiwan; from which 50 drinking water samples were<br />

collected and only one sample was detected at 4.5ng/L.<br />

Posterior distributions revealed a mean concentration of NDMA<br />

in drinking water at 0.54ng/L. The estimated 95th percentile of<br />

lifetime cancer risk was 2.897E-6. These results suggest that<br />

the NDMA levels in drinking water in Taiwan do not pose<br />

significant cancer risk; regulation of NDMA may be needed in<br />

order to fully protect the general public.<br />

T1-H.2 Chatterjee, S*; Salazar, D; Hora, S; CREATE, University<br />

of Southern Cali<strong>for</strong>nia; samrat.chatterjee@usc.edu<br />

Frequency-severity relationships <strong>for</strong> human-caused<br />

extreme events<br />

Rare but extremely severe events can occur due to intentional<br />

and accidental hazards. This study explores the relationship<br />

between the frequency and severity of such human-caused<br />

events. Tools of extreme value statistics and statistical learning<br />

are employed to analyze data from The Global Terrorism<br />

Database (GTD)-developed by the START Center at the<br />

University of Maryland and The Hazardous Materials Incident<br />

Database-developed by the U.S. Department of Transportation<br />

Pipeline and Hazardous Materials Safety Administration. Event<br />

severity is expressed in terms of fatalities, injuries, and direct<br />

property damage. We also investigate the scale invariance<br />

property in such human-caused events.<br />

M3-E.3 Che, WW*; Frey, HC; Lau, AKH; The Hong Kong<br />

University of Science & Technology North Carolina State<br />

University; wenweicherren@gmail.com<br />

Sensitivity of estimated children PM2.5 exposure to<br />

activity patterns, and geographic and seasonal variations<br />

Children’s exposure to ambient Particulate Matter (PM)<br />

depends on activity patterns and ventilation in<br />

micro-environments, which in turn can depend on climate zone<br />

and season. Distribution of inter-individual variability in daily<br />

PM2.5 exposure <strong>for</strong> school age children (5-18) were estimated<br />

using the U.S. Environmental Protection Agency’s Air<br />

Pollutants Exposure model (APEX). The key inputs to APEX<br />

include ambient concentration, air exchange rate, penetration<br />

factor, deposition rate, census data and activity diary data.<br />

Inter-individual variability in exposure of elementary school<br />

(6-11), middle school (12-14) and high school (15-18) children<br />

were estimated and compared <strong>for</strong> selected regions in North<br />

Carolina (NC), New York City (NYC) and Texas (TX) <strong>for</strong> four<br />

seasons (spring, summer, fall and winter). Home and school are<br />

the most important microenvironments <strong>for</strong> children’s exposure<br />

on school days; while home and outdoors are predominant on<br />

non-school days. The ratio of ambient exposure to ambient<br />

PM2.5 concentration (E/C) is significantly different (P

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