Exposure Science in the 21st Century A Vision and a Strategy (2012) / Chapter Skim
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5 Scientific and Technologic Advances
5 Scientific and Technologic Advances
Pages 106-153
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From page 106... ...
Obtaining more accurate estimates of internal exposure reduces exposure-measurement error and provides a more realistic understanding of potential health effects of environmental and occupational exposures (Carroll et al.
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From page 107... ...
Biologic monitoring and sensing increasingly offer the potential to assess internal exposures. The convergence of these scientific methods and technologies raises the possibility that in the near future embedded, ubiquitous, and participatory sensing systems will facilitate individual-level exposure assessments on large populations of humans or other species.
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From page 108... ...
TRACKING SOURCES, CONCENTRATIONS, AND RECEPTORS WITH GEOGRAPHIC INFORMATION TECHNOLOGIES Three major technologic advances in geographic information technologies -- remote sensing, global positioning and related locational technologies, and GIS -- have dramatically affected exposure science. As outlined by Goodchild (2007)
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From page 109... ...
Box 5-2 and Figure 5-2 demonstrate how the results of a 1-km retrieval of the MODIS AOD substantially improve the resolution and thus the utility of remote sensing for health and ecologic studies; the current grid size has a 10-km retrieval. FIGURE 5-1 Selected scientific and technologic advances considered in relation to the conceptual framework.
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For example, the 10 km aerosol product offered by MODIS is sufficient for climate applications but insufficient for detailed exposure assessment from sources that are variable over small areas, such as traffic emissions. In that regard, Hoff and Christo pher (2009)
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From page 111... ...
. Green cover is also associated with higher levels of physical activity, and RS has been used with geolocation technologies to show associations between physical activity of children and their exposure to green cover (Almanza et al.
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More recently HI techniques were utilized to assess the extent of the Deepwater Horizon Oil Spill and possible exposures to oil in pelagic and nearshore ecosystems (Bradley et al. 2011; Lavrova and Kostianoy 2011; Bulgarelli and Djavidnia 2012; Mishra et al.
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From page 113... ...
Retrieval of high-resolution AOD to discern spatial patterns of pollution in urban environments through frequent daily temporal coverage based on orbital sensors. Global Positioning System and Geolocation Technologies Launched in the 1980s for defense applications, the GPS offers exposure scientists a simple means of tracking the geographic position of a person or other species.
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. Another important role of GIS in exposure assessment is the quantification of topologic relationships.
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From page 115... ...
. Web-Based Geographic Information Systems for Exposure Assessment Web-based GIS is becoming more common (Maclachlan et al.
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For example, Google Earth and Google Fusion Tables with Airborne/Visible Infared Imaging Spectrometer data (AVIRIS 2012) were used to provide public, real mapping of the Deepwater Horizon Oil Spill (Bradley et al.
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From page 117... ...
to improve access to data on and understanding of potential exposures. UBIQUITOUS SENSING FOR INDIVIDUAL AND ECOLOGIC EXPOSURE ASSESSMENT Limitations of Current Environmental and Personal Monitors and the Potential of Ubiquitous Sensing Lack of personal and individual exposure data is one of the greatest limitations in exposure science.
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. The last 20 years have seen substantial technologic advances in personal environmental monitoring.
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From page 119... ...
LocHNESs illustrates how ubiquitous mobile phones can supply anony mous information on location that can be combined with embedded tracking networks on public infrastructure to deliver real-time data on environmental exposures. BOX 5-4 Ubiquitous Sensing of Physical Activity and Location Increasing availability of ubiquitous mobile devices -- particularly smart telephones with motion sensing, GPS, and wireless capabilities -- has created opportunities to develop new tools and methods to study and intervene to address sedentary lifestyles, obesity, and ambient risk factors, such as air pollution, noise, or ultraviolet radiation.
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From page 120... ...
The system can communicate information, telling a person to respond to a survey when particular events are observed, such as a period of physical activity, exposure to air pollution, use of steroid inhalants, or consumption of particular food. Responding to these surveys provides opportunities to obtain important information about an exposure or outcome, such as mood, stress, behaviors, and other information (Intille 2007; Duntun et al.
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From page 121... ...
For example, users have access to a weekly impact report and a locational trace of where they have been. Personal Samplers for Particles, Volatile Organic Chemicals, and TimeActivity Information: Current and Future Technologies This section discusses personal exposure measurement devices that can be used to obtain information on exposures to particles and volatile organic chemicals (VOCs)
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Pretoddler Inhalable Particulate Environmental Robotic Bioaerosol Sampler A Pretoddler Inhalable Particulate Environmental Robotic (PIPER) personal sampler to measure indoor particulate matter (PM)
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The timeactivity information is used to estimate overall personal exposures on the basis of exposure measurements made with fixed monitors in each microenvironment. Black-Carbon Monitor (microAeth)
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Future Developments with Nanosensors Developing ubiquitous monitoring networks for personal exposure assessment will depend on rapid advances in pollution-sensor technologies. Although advances have been made with the technologies described, most of them are still not capable of measuring multiple pollutants continuously.
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Chemical Selectivity Although nanosensors have demonstrated extremely high sensitivity, their selectivity poses a challenge. Most of the chemical sensing of small molecules in the vapor phase is carried out indirectly with physical sensors modified with chemical interfaces or biologic receptors.
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From page 126... ...
and highperformance GC can enhance chemical selectivity. The committee envisions that future nanosensors, where each sensor provides an orthogonal signal, will be able to detect multiple analytes with an arraybased concept.
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Sensors for Ecosystem Exposure Assessment Scientific and technologic advances in exposure assessment in nonhuman species have been driven largely by environmental laws and policies administered by various state and federal agencies, but these advances have typically been enabled by advances in exposure and health assessments for humans. Three recommendations from the Environmental Protection Agency (EPA)
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Although promising, issues of validation for ubiquitous and participatory sensing networks will remain a key issue. If exposure assessments are to be conducted using sensing networks and nanosensors, greater assurance about measurement accuracy and precision will be needed.
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Nevertheless, the committee considers it important to advance measurement of internal exposures as an element of the vision for exposure science. Analytic methods enable detection of both much lower concentrations of stressors internally and measurement of multiple stressors in single samples.
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. However, inferring the sources and routes of these internal exposures remains a research challenge (Tan et al.
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. While the Bayesian, Monte Carlo, and other computational approaches for applying PBPK models to population-level exposure assessments are well developed, the limited availability of population-level data on variability in external exposures and on individual genetic variation, hinders consistent application to populations.
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, however, monitoring techniques do not provide the quantitative information needed for use in ecologic risk assessments. There is a need to develop rapid-response, quantitative exposureassessment tools that can provide information useful for exposure assessment in ecologic risk assessments.
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of a measurement, and the ability to link a measurement to scientific or regulatory goals of ecologic risk assessment.
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Here we consider the role that exposure models need to play in supporting exposure science in the 21st century. Types of Models in Exposure Science The types of models used in exposure science vary widely.
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: "This growth is in response to greater demands for quantitative assessment of regulatory activities, including analysis of how well environmental regulatory activities fulfill their objectives and at what cost. Models are essential for estimating a variety of relevant characteristics -- including pollutant emissions, ambient conditions, and dose -- when direct observa tion would be inaccessible, infeasible, or unethical." Predictive exposure models have become particularly important in risk, life-cycle, and sustainability assessments, where there is a need for rapid exposure assessment (NRC 2007, 2009)
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. Model Performance Evaluation Key to the future of exposure models is how they incorporate the everincreasing amounts of observations of natural and human processes and envi
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From page 137... ...
In some cases, cost and feasibility may limit direct measurements to a modest number of locations for specified periods; in other cases, remote-sensing technologies may yield an enormous quantity of data that need to be summarized. An important element of any exposure assessment is quantifying the degree of uncertainty about the exposure estimates.
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From page 138... ...
For example, in radiation epidemiology, use of the Monte Carlo uncertainty estimates in analyzing health effects has become somewhat standard, as in the analysis of the Hanford Thyroid Disease Study (Stram and Kopecky 2003)
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From page 139... ...
ExpoCastDB, developed as a component of ExpoCastTM (Gangwal 2011) , has begun the effort to consolidate observational human exposure data, improve access, and provide links to health-related data.
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From page 140... ...
Without comparable investments in the development of new statistical analytic techniques to address correlated data on many more variables than subjects and without advances in computation, such as parallel-processing techniques, the analysis of the mountains of data threatens to become the new limiting factor in further progress. Exposure models will continue to support diverse efforts, such as risk analysis, impact assessments, life-cycle and sustainability assessments, epidemiology, and energy analysis.
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in air pollution exposure assessment.
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1987. Dose, species and route extrapolation using physiologically based pharmacokinetic models.
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2011. Social and physical con textual influences on children's leisure-time physical activity: An ecological mo mentary assessment study.
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2012a. SHEDS-Multimedia: Stochastic Human Exposure and Dose Model for Multimedia, Multipathway Chemicals.
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2008. Uncertainty and Data Quality in Exposure Assessment, Part 1.
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2009. Environmental sup portiveness for physical activity in English school children: A study using Global Positioning Systems.
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2006. Towards a Global Lake Ecological Observatory Network.
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2010. Use of land surface remotely sensed satellite and airborne data for environmental exposure assessment in cancer research.
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2003. Chemicapactive microsensors for volatile organic compound detection.
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2003. Effects of exposure measurement error when an exposure variable is constrained by a lower limit.
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2007. Reverse dosimetry: Interpreting triha lomethanes biomonitoring data using physiologically based pharmacokinetic mod eling.
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2010. Global estimates of ambient fine particulate matter concentra tions from satellite-based aerosol optical depth: Development and application.
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2011. Ge nomic and physiological footprint of the Deepwater Horizon oil spill on resident marsh fishes.
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