Exposure Science in the 21st Century A Vision and a Strategy (2012) / Chapter Skim
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1 Introduction
1 Introduction
Pages 19-41
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From page 19... ...
Although methods of assessment will depend on the situation, exposure science has two primary goals: to understand how stressors affect human and ecosystem health and to prevent or reduce contact with harmful stressors or to promote contact with beneficial stressors to improve public and ecosystem health. The impact of environmental stressors on human and ecologic health is enormous.
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From page 20... ...
Exposure science strives to create a narrative that captures the spatial and temporal dimensions of exposure events with respect to acute and long-term effects on human populations and ecosystems. For the purposes of this report, the committee focuses on environmental risk factors and excludes behavioral or lifestyle factors -- such as diet, alcohol, and smoking -- although it includes contaminants in food, water, and environ mental tobacco smoke.
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From page 21... ...
For example, extensive exposure assessments of polycyclic aromatic hydrocarbons (PAHs) have been linked to liver damage in bottom-dwelling fish in Puget Sound, and field studies have demonstrated that containment of PAH sources has led to declines in PAH concentrations and a resulting decline in liver damage in fish (Myers et al.
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From page 22... ...
Collection of better exposure data can also provide more precise information regarding alternative control or regulatory measures and lead to more efficient and cost-effective protection of public and ecologic health. In addition to its applications to other fields, exposure science data can be used independently to define trends, assess spatial or population variability, provide information on prevention and intervention, identify populations or ecosystems that have disproportionate exposures, and evaluate regulatory effectiveness.2 Exposure science is also poised to play a critical role in improving the ability to understand and address increasingly important human health and ecologic challenges and to support the development of sustainable industrial, agricultural, and energy technologies.
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From page 23... ...
The evolution of the field over the past 15 years has included a greater emphasis on the use of internal markers of exposure to assist in defining exposure-response relationships. As such, the conceptual basis of the field includes both external and internal exposures, using external measurement and modeling methods and internal markers as tools for characterizing past or current exposures.
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, it is important to understand its historical context. Exposure science arose from such disciplines as industrial hygiene, radiation protection, and environmental toxicology, in which the importance of assessing exposure has been demonstrated.
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Rhythms and cycles Blood/Tissues/Organs Cells Target FIGURE 1-3 An illustration of how exposures can be measured or modeled at different levels of integration in space and time, from source to dose, and among different human, biologic, and geographic systems. That is exposure science can be applied at any level of biologic organization -- ecologic, community, or individual -- and, within the individual, at the level of external exposure, internal exposure, or dose.
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From page 26... ...
By the middle 1980s, exposure evaluations had evolved into an established scientific discipline that moved beyond single routes, single chemicals, and single pathways toward an understanding of "total" exposure. The 1991 National Research Council report Human Exposure Assessment for Airborne Pollutants (NRC 1991a)
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That was followed in 1993 by the initiation of the National Human Exposure Assessment Survey (NHEXAS) , which evaluated human exposure to multiple chemicals on a community and regional scale (EPA 2009b)
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The Centers for Disease Control and Prevention's National Health and Nutrition Examination Survey (NHANES) published the first National Human Exposure Report in 2001, which used a subset of its subjects to assess the US population's exposure to environmental chemicals on the basis of biomonitoring data.
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From page 29... ...
This information will be essential for evaluating the efficacy of exposure reduction policies, and for prioritizing and assessing chemical risks. A prime example of the benefits of improved methods of exposure assessment is their use in environmental epidemiology, in which more accurate estimates of the health effects of important stressors have been achieved by reducing exposure misclassification, for example, in air pollution (Jerrett et al.
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From page 30... ...
Toxicity Testing in the 21st Century laid the foundation for a paradigm shift toward the use of new scientific tools to expand in vitro pathway-based toxicity testing. A key component of that report is the generation and use of population-based and individual human exposure data for interpreting test results and using toxicity biomarker data with exposure data for biomonitoring, surveillance, and epidemiologic studies.
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Elucidating relationships between exposure and key abiotic and biotic ecologic factors is necessary if we are to understand risk. ROADMAP The present report builds on the concepts presented in the National Research Council reports Toxicity Testing in the 21st Century and Science and Decisions: Advancing Risk Assessment to develop a framework for bringing exposure science to a point where it fully complements toxicology and risk assessment and can be used to protect human health and the environment better.
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provide rapid assessment protocols and technologies to respond to natural and human-caused disasters and the needs for community participation and environmental justice. The report describes new technologies and opportunities to make exposure science even more effective in its traditional roles of evaluating environmental control measures, improving understanding of the link between environmental stressors and disease, and designing more cost-effective ways to reduce and prevent health risks.
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From page 33... ...
that promote plant growth. Algal growth can become excessive and sometimes lead to harmful algal blooms (Paerl 1997; Cloern 2001; Anderson et al.
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. The presence of particular species can provide buffers to expo sure in some cases; for example, some algal blooms are known to reduce uptake of methylmercury into freshwater food webs (Pickhardt et al.
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2002. Harmful algal blooms and eutrophication: Nutrient sources, composition, and consequences.
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2009. Biologically relevant exposure science for 21st century toxicity testing.
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2009b. Human Exposure Measurements: National Human Exposure Assessment Survey (NHEXAS)
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1990. Assessing total human exposure to contaminants: A multidisciplinary approach.
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1991a. Human Exposure Assessment for Airborne Pollutants: Advances and Opportunities.
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Human Exposure Assessment Series WHO/EHG/95.09. Geneva: World Health Organization.
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1987. The Total Exposure Assessment Methodology (TEAM)
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