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

Microbial Pathogens in the Environment: Assessment of Public Health Risks

Room: Key Ballroom 4   10:30 AM- 12:00 PM

Chair(s): David Oryang

Sponsored by MRASG


Abstract: The main objectives of this research were to establish risks related to (i) direct or indirect incidental ingestion of water in Arenales river in three scenarios: primary contact, children and secondary contact; (ii) consumption of uncooked vegetables irrigated with A. lumbricoides contaminated water; and (iii) incidental ingestion of irrigated water by farmers working in the fields. The study area focused on the Arias-Arenales river, which is in the northwestern region of Salta province in Argentina. Eleven locations on the Arenales river were selected for a thirteen-month monitoring study. A quantitative microbial risk assessment (QMRA), based on observed nematode density, was performed to calculate the annual probability of helminth infection in various scenarios associated with direct or indirect exposure to Ascaris lumbricoides in surface waters. The highest estimated mean risk from direct or indirect ingestion of surface water per person per year (pppy) from a single exposure scenario was found in children (21.23%), followed by adults (12.49%) and secondary exposure (1.54%). We estimated the mean annual risks from consumption of raw (uncooked and unpeeled) vegetables irrigated with polluted water as a worst case scenario. The mean risk was highest in lettuce (0.659%) and lowest in cucumber (0.011%) for the total population. A similar pattern was found for the consumer-only population as well. Here, the risks from consumption of vegetables were 0.27% for cucumbers and 1.54% for lettuce. The annual risk of infection in farmers due to accidental ingestion of irrigated water was 1.06%. The risk varied from as low as 0.005% to a high value of 41% in farmers working in the field without using any protective clothing like gloves, rain boots and so forth. We also estimated risks associated with four scenarios for treating left-censored observations: (i) one-half the detection limit (DL) was assumed for the censored data; (ii) DL was assumed for censored data; (iii) bounding for the censored observations; and (iv) observations with zeroes.

T2-D.2  10:50  Risk of Cryptosporidium Infection to Recreational Swimmers in Swimming Pools. Suppes L*, Canales R, Gerba C, Reynolds K; The University of Wisconsin - Eau Claire and The University of Arizona

Abstract: Infection risk estimates from swimming in treated recreational water venues are lacking and needed to identify vulnerable populations and water quality improvement needs. Currently, state and local health departments lack standardized pool safety regulations since there is no U.S. federal pool code. Infection risk differs among populations because ingestion, visit frequency, and swim duration depend on activity and age. Objectives of this study were to estimate per-swim and annual Cryptosporidium infection risks in adults (greater than 18), children (18 or less), lap, and leisure swimmers (splashing, playing, diving, wading, standing, and sitting). Risks were estimated using oocyst concentration data from the literature, and new experimental data collected in this study on swimmer ingestion, activity, and pool-use frequency. The average estimated per-swim risk of Cryptosporidium infection was 3.7 x 10-4 infections/swim event. We estimated 3.3 x 10-2 infections occur each year from swimming in treated recreational water venues, which exceeds fresh and marine water swimming risk limits set by the United States Environmental Protection Agency (8 and 19 x 10-3 infection/year, respectively). Leisure swimmers had the highest annual risk estimate of 2.6 x 10-1 infections/year. Results suggest standardized pool water quality monitoring for Cryptosporidium, development of interventions that reduce intentional ingestion, and improvement of oocyst removal from pool water are needed. Leisure swimmers were the most vulnerable sub-population, and should be targeted in healthy swimming education campaigns.

T2-D.3  11:10  Assessment of relative potential for Legionella species inhalation exposure from common water uses. Taft SC*, Hines SA, Chappie DJ, Janke RJ, Lindquist HA, Ernst HS; U.S. Environmental Protection Agency; Battelle Memorial Institute

Abstract: The intentional or accidental introduction of microbial contaminants such as Legionella into a drinking water system could pose a health hazard to water customers. The Legionella species have been identified as important waterborne pathogens in terms of disease morbidity and mortality. A preliminary exposure assessment of Legionella spp. drinking water contamination was conducted to better understand potential inhalation exposure pathways, develop a means of prioritizing exposure pathways for further assessment, estimate potential inhalation exposure doses, and identify critical knowledge gaps for further study. Potentially complete exposure pathways were compiled, and a screening level exposure assessment was conducted for pathways where inhalation doses could be quantitatively estimated. Considerable variability in the calculated exposure doses was identified between the exposure pathways, with the doses differing by over five orders of magnitude in each of the evaluated exposure scenarios. The exposure pathways that have been epidemiologically associated with legionellosis transmission (ultrasonic and cool mist humidifiers) were assessed to have higher estimated inhalation doses than pathways where epidemiological evidence of transmission has been less strong (faucet and shower) or absent (toilets and therapy pool). This presentation will describe the complex assessment design and methodology to demonstrate applicability of these assessments to a wide range of microbial contaminants. While ingestion exposures of contaminated drinking water historically have been examined, there are still major gaps in the understanding of inhalation and dermal exposures of aerosolized pathogens during common uses of water.

T2-D.4  11:30  Monitoring and Mapping Conditions Associated with Enteric Pathogens using Rainfall and Satellite Vegetation Index Data. Anyamba A*, Small J, Oryang D, Fanaselle W; NASA Goddard Space Flight Center

Abstract: Food borne outbreaks associated with fresh produce are increasing in the United States and around the world. The increase in the proportion of food borne outbreaks linked to fresh produce from the 1970s (<1%) to the 1990s (6%) provides a vivid description of the increase. The increase is largely due to a combination of an increase in the consumption of fresh produce, along with improved outbreak surveillance techniques. However such outbreak surveillance while important is behind the curve in detecting areas or regions of risk. In an attempt to shift the detection time of potential pathogen contamination (Salmonella, E. coli 0157 and human norovirus), FDA’s Center for Food Safety and Applied Nutrition in collaborations with NASA’s Goddard Space Flight Center are using time series rainfall and satellite derived vegetation index data to test and operationalize these climate and environmental variables as leading indicators and drivers of potential contamination. This is based on the assumption that periods of elevated rainfall result in heavy overland runoff leading to accumulation of fecal matter and other waste in zones of potential contamination of agricultural land. Additionally excess irrigation (that can be detected by satellite vegetation) can create conditions for contamination. An index of cumulative precipitation and vegetation index is derived and shown to provide an early warning of potential environmental contamination over the major produce areas of Salinas Valley, Central Valley and Imperial Valley of California. This method is currently being adapted into a real-time Geospatial Risk Assessment model to monitor and provide an advanced alert to FDA and industry about locations and times of likely contamination of leafy greens by enteric pathogens.

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