Society For Risk Analysis Annual Meeting 2017

Session Schedule & Abstracts

* Disclaimer: All presentations represent the views of the authors, and not the organizations that support their research. Please apply the standard disclaimer that any opinions, findings, and conclusions or recommendations in abstracts, posters, and presentations at the meeting are those of the authors and do not necessarily reflect the views of any other organization or agency. Meeting attendees and authors should be aware that this disclaimer is intended to apply to all abstracts contained in this document. Authors who wish to emphasize this disclaimer should do so in their presentation or poster. In an effort to make the abstracts as concise as possible and easy for meeting participants to read, the abstracts have been formatted such that they exclude references to papers, affiliations, and/or funding sources. Authors who wish to provide attendees with this information should do so in their presentation or poster.

Common abbreviations

Ambient and Occupational Airborne Hazards

Room: Salon K   3:30 pm–5:00 pm

Chair(s): Katherine Walker

Sponsored by Dose Response, Exposure Assessment, Occupational Health & Safety, Economics & Benefits Analysis Specialty Groups

W4-I.1  3:30 pm  Case Study in Data Access and Reanalysis: Diesel Engine Exhaust and Lung Cancer Mortality in the Diesel Exhaust in Miners Study (DEMS) Cohort Using Alternative Exposure Estimates and Radon Adjustment. McClellan RO*, Chang ET, Lau EC, Van Landingham C, Crump KS, Moolgavkar SH; Toxicology and Human Health Risk Analysis

Abstract: The Diesel Exhaust in Miners Study (DEMS), conducted by NIOSH and NCI, included 12,315 workers with 200 observed lung cancers from 8 U.S. non-metal mines (3 trona, 3 potash, 1 salt and 1 limestone). Retrospective cohort and case-control analyses yielded a positive association between diesel exhaust exposure (DEE), represented by a respirable elemental carbon (REC) metric estimated retrospectively from carbon monoxide measurements, and lung cancer mortality. This finding was a major factor in the IARCresearch on classification of DEE as a human carcinogen. Our team was given access to the DEMS data and conducted analyses to first replicate the original analyses and then conduct extended re-analyses. Our re-analyses focused on (a) use of an alternative exposure metric developed using historical data on diesel equipment, engine horse power and ventilation rates without dependence on use of carbon monoxide as a surrogate for REC, (b) inclusion of radon as a covariate in statistical models, and (c) subgroup heterogeneity. Associations with cumulative REC and average REC intensity using the alternative REC estimates were generally attenuated compared with those found using the original DEMS REC estimate. Most findings were statistically nonsignificant, especially after control for radon exposure, which substantially weakened associations with the original and alternative REC estimates. No significant findings were detected among all miners who worked exclusively underground. However, associations were anomalously strong among limestone miners; no association with REC or radon was found among workers at the other seven mines. The large differences in results based on alternative exposure estimates, control for radon, and stratification by worker location or mine type highlight areas of uncertainty and the limited robustness of the DEMS data. These limitations must be considered in any extrapolation of the DEMS findings to other populations, and especially in using them for quantitative risk assessment.

W4-I.2  3:50 pm  What does the current unit risk estimate used for diesel particulate matter cancer risk calculations indicate for worker and environmental health? Pagone F*, Persky J; RHP Risk Management Inc.

Abstract: In 2012, the IARC classified diesel engine exhaust as carcinogenic to humans (Group 1). Since this classification, there has been limited research on Diesel Particulate Matter (DPM) excess lifetime inhalation cancer risks (ELCR). DPM potentially effects workers (e.g. truck drivers, construction) as well as non-workers (e.g. general population); therefore, the need for classification, characterization, and communication of actual and perceived DPM risk is timely. This study calculated the DPM ECR using the Unit Risk Estimate (URE) developed by the California ARB/OEHHA (CARB) and compared DPM risks with other pollutants. The individual ELCR associated with exposure to DPM were calculated by multiplying the 1998 CARB DPM URE of 3E-4 (µg/m3)-1 by the estimated dose modeled by the USEPA as part of the 2011 National Air Toxics Assessment (NATA). NATA DPM emissions were based on the EPA 2011 National Emissions Inventory (NEI) measurements of mobile source PM10. The maximum ELCR due to modeled and estimated DPM dose in Cook County was 1.1E-3 (i.e., 1 in 1,000) with a census tract mean of 3.4E-4. All census tract level DPM risks were above the upper bound USEPA’s ELCR of 1 in 10,000. The maximum NATA ELCR from all other NATA carcinogens combined, excluding DPM, was 1 in 10,000. During the period of 2009-2013 in Cook County, IL, there were reported 16,799 cases of Lung and Bronchus Cancer, with cigarette smoke and radon being the leading causes. Whether a meaningful reduction in actual lung and bronchus cancer rates would have been realized because of DPM dose reduction is difficult to express with the current approach utilizing theoretical DPM modeled concentrations and the 1998 DPM URE. Perhaps these results indicate that a more specific way to express DPM cancer risk needs to be developed for purposes of decision-making alternatives as well as for communicating the extent and practical significance of DMP dose reduction.

W4-I.3  4:10 pm  Commuter Exposure to Air Pollutants During Transportation in Hong Kong. Lau AKH*, Che WW, Li ZY, Frey HC; The Hong Kong University of Science and Technology; North Carolina State University

Abstract: Daily commutes contribute disproportionately to overall daily exposure to urban air pollutants such as fine particulate matter (PM2.5) and carbon monoxide (CO). The on-road and near-road microenvironments are of concern because of proximity to traffic emissions. Over the past three years, we have carried out a range of exposure measurements in several transportation microenvironments in Hong Kong, including the Mass Transit Railway (MTR) subway system, transit buses, trams, minibuses, pedestrians, bus terminal and stops. PM2.5 and CO concentrations were measured and compared across and within these microenvironments. Variability in the transportation mode concentration ratios of PM2.5 and CO is quantified. Factors affecting variability in PM2.5 and CO concentrations are identified. Preliminary results indicate that the on-road or near-road microenvironmental concentrations are sensitive to transportation mode, operation of ventilation, and proximity to nearby emission sources. Significantly higher PM2.5 concentrations were identified for tram, pedestrian, bus terminal and stops than other microenvironments, by a factor of 2 to 3 of that on MTR trains. The highest CO concentrations were observed on single- or double-decker buses, with average concentrations of 2.0 ppm and 2.5 ppm, respectively, indicating the influence of exhaust emission. Heterogeneity in exposure concentration was observed for bus and MTR based on simultaneous sampling at multiple locations inside the cabin. Spikes in PM2.5 concentrations were found on MTR during door opening period, indicating the influence of the pollution inside the track tunnel. Commuter’s exposure to PM2.5 was elevated by 15% during a 35-minute journey on MTR if standing near door compared to the middle of the cabin. Inter-run variability in concentration was observed for each of the selected transportation modes, indicating that multiple runs are needed for a reasonable understanding of the transport exposure concentration.

W4-I.4  4:30 pm  Approaches to estimating the burden of outdoor air pollution in Ontario. Greco SL*, Kim JH, Copes R; Public Health Ontario

Abstract: As part of a multi-year effort to estimate the environmental burden of disease (EBD) for the province, Public Health Ontario (PHO; a Crown corporation dedicated to protecting and promoting the health of the approximately 14 million Ontario residents) is estimating the burden of outdoor air pollution for the province. The burden of outdoor air pollution has figured prominently in previous EBD analyses (e.g., the Global Burden of Disease study). For our burden estimation, a number of analytical decisions had to be made: which pollutants to include (fine particulate matter, PM2.5; ozone; nitrogen dioxide), how to assess exposure (data from ambient monitoring stations versus satellites), how to model the dose-response relationship (slope factors, hazard ratios), which studies to obtain data from (a single site-specific epidemiological study versus a meta-analysis including regions around the world), which health outcomes to consider (ischemic heart disease, lung cancer, all-cause mortality), and which approaches to use (attributable fraction, single- or multi-pollutant models). To examine the influence of our assumptions, we performed sensitivity testing whenever possible. For example, for lung cancer from diesel PM2.5 exposure, we found a three-fold difference in estimated cases when using an attributable fraction approach compared to a slope factor approach. This presentation will outline how PHO made analytical decisions to estimate the air pollution burden and what impacts differing assumptions may have on the estimates of burden.

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