Society For Risk Analysis Annual Meeting 2013

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

Ground & Drinking Waters: New Methods, New Analysis

Room: Key Ballroom 5   10:30 AM- 12:00 PM

Chair(s): Donna Vorhees

Sponsored by EASG

W2-E.1  10:30  Computer-based exposure modeling to support drinking water guidance. Greene CW*, Wilkes C, Koontz M, Shubat PJ; Minnesota Department of Health; Versar, Inc.

Abstract: The Minnesota Department of Health (MDH) develops health-based guidance values for contaminants of emerging concern (CECs) in drinking water. To account for non-drinking water exposures, MDH uses a chemical-specific Relative Source Contribution (RSC) factor to allocate only a fraction of the toxicological reference dose to drinking water exposure. Pharmaceuticals, personal care products, pesticides, and other CECs found in drinking water sources have complicated exposure profiles that may include ubiquitous exposure at low levels, deliberate self-exposure, high exposures to infants and children, and exposures approaching the reference dose. CEC-specific data to quantify these exposures and accurately understand cumulative and relative risks are not readily available and, until now, MDH has relied on default assumptions based on U.S. EPA guidance. Working with a contractor, MDH explored the potential for using computer models to improve upon the default approach by estimating multipathway, multiroute exposures. We have identified the key media and exposure routes of concern, evaluated numerous models that cover these key media and routes, and developed a set of preferred models based on the model’s fitness to meet our exposure evaluation needs, its strength in representing actual physical/chemical processes, its input demands, and its user friendliness. The preferred models include EPA’s Exposure and Fate Assessment Screening Tool (E-FAST) and Multimedia, Multipathway, and Multireceptor Risk Assessment (3MRA) model, the California Population Indoor Exposure Model (CPIEM), and the Total Exposure Model (TEM). We developed a set of procedures to apply these models to the problem of estimating RSC values for CECs. The procedures were evaluated using a test group of six CECs that cover a range of exposure pathways and routes. Beyond estimation of the RSC, the modeling process may also be of use to risk managers seeking to target resources towards reducing total exposures.

W2-E.2  10:50  Pesticides in groundwater of the United States: Occurrence and decadal-scale changes. Toccalino PL*, Gilliom RJ, Lindsey BD, Rupert MG; U.S. Geological Survey

Abstract: This study by the U.S. Geological Survey’s National Water-Quality Assessment Program evaluated (1) the occurrence of pesticides in groundwater and (2) decadal-scale changes in pesticide concentrations over a 20-year period. Untreated groundwater samples were collected from 1,309 wells located in 60 nationally distributed well networks and analyzed for as many as 83 pesticide compounds. Each well network was sampled once during 1993–2001 (Cycle 1) and once during 2002–2011 (Cycle 2). Shallow (mostly monitoring) wells were sampled in agricultural and urban areas. Deeper (mostly domestic and public) wells, which tap major aquifers used for water supply, were sampled in mixed land-use areas. Pesticides were frequently detected—about two-thirds of the samples from agricultural areas and about half of the samples from urban areas contained one or more pesticides. More than one-third of samples from major aquifers contained one or more pesticides, but concentrations seldom (about 1% of samples) exceeded human-health benchmarks. The five most frequently detected pesticide compounds—atrazine, deethylatrazine, simazine, metolachlor, and prometon—each were detected in 9% to 36% of all samples, and each had statistically significant changes in concentrations between Cycle 1 and Cycle 2 in one or more land uses. For all agricultural land-use networks combined, concentrations of atrazine, metolachlor, and prometon decreased from Cycle 1 to Cycle 2; prometon concentrations also decreased in urban areas. Conversely, for all major aquifers combined, concentrations of atrazine, deethylatrazine, and simazine increased; deethylatrazine concentrations also increased in urban areas. The magnitude of these concentration changes from decade to decade was small, and ranged from 0.001 to 0.09 µg/L (35- to 230,000-fold less than benchmarks). More than half of the individual well networks showed statistically significant changes in one or more pesticide concentrations between Cycles 1 and 2.

W2-E.3  11:10  Evaluating public health benefits from reductions in drinking water lead levels at US Schools. Triantafyllidou S, Le TH, Gallagher DL*, Edwards MA; Virginia Tech

Abstract: After high drinking water lead concentrations were found in elementary schools in Seattle and Los Angeles, both school districts undertook steps to reduce children’s exposure. This research used reported water lead concentration distributions before and after remediation steps as inputs to the US EPA Integrated Exposure Uptake Biokinetic (IEUBK) model to estimate the resulting distribution of blood lead levels in exposed children. Sixty-three elementary schools in Seattle and 601 elementary schools in Los Angeles were evaluated. Seattle undertook active remediation measures by installing filters and replacing lead plumbing. The mean first-draw water lead levels across all Seattle schools decreased from 24.4 to 2.1 ppb, and mean 30-second flushed water lead levels decreased from 3.4 to 0.7 ppb. This reduced the estimated percentage of students exceeding a blood lead level of 5 ug/dL from 11.2% to 4.8%, with the post-remediation value primarily attributable to lead exposure from sources other than drinking water. While pre-remediation water lead levels and percent blood level exceedances varied widely from school to school, post remediation risks indicated a much lower variability. The Los Angeles school district used a flushing program to reduce exposure, with limited post-remediation testing. First draw and 30-second samples were 11.0 and 4.0 ppb respectively. Assuming flushing eliminated first-draw exposures, the percent blood level exceedances dropped from 8.6% to 6.0% across the 601 schools. School water lead remediation efforts can therefore be significant in reducing health risks to US elementary students.

W2-E.4  11:30  Exposure to highly contaminated drinking water in a rural Nigerian Village. Kponee K*, Vorhees D, Heiger-Benays W; Boston University School of Public Health

Abstract: In 2011, the United Nations Environment Programme (UNEP) reported findings from its study of petroleum hydrocarbon contamination in the Ogoniland region of Nigeria where frequent and massive oil spills have destroyed vast areas, including farmland, fisheries, and water supplies. UNEP recommended research and remedial action to protect human health, with some recommendations focused on the Ogale community where residents rely on a drinking water supply contaminated with benzene and other petroleum hydrocarbons. Benzene alone has been detected at concentrations almost 2,000 times higher than the USEPA drinking water standard. UNEP staff observed people using the contaminated drinking water and noted that its strong odor. Because such elevated exposures are likely to be associated with a range of acute and chronic effects, UNEP recommended emergency provision of clean drinking water, medical surveillance, and implementation of a prospective cohort study to investigate the effects of exposure to the contaminated drinking water in Ogale. There are no reports indicating that these recommendations have been implemented except for provision of clean water in late 2011. This study implements some of UNEP’s recommendations for Ogale. Based on an investigator-administered questionnaire to one hundred households, this study provides a (1) detailed assessment of exposure to the contaminated water supply; and (2) a preliminary comparison of self-reported symptoms and health outcomes in the community served by the contaminated drinking water supply and a nearby comparable community served by a relatively clean drinking water supply. This study represents the logical next step to determine whether the extremely high levels of exposure in Ogale might be associated with acute and chronic adverse health effects. It also might improve understanding of how oil spills affect human health, a question that has eluded those investigating oil spills involving lower levels of exposure.

[back to schedule]