Letter to the Editor pubs.acs.org/est
Expanding on Successful Concepts, Models, and Organization “aggregate exposure”, which refers to the combined exposures to a single chemical across multiple routes and pathways.4 The AEP framework embraces existing methods for collection, prediction, organization, and interpretation of human and ecological exposure data cited by Dr. von Göetz. We remain hopeful that wider recognition and use of an organizing concept for exposure information across the exposure science, toxicology, and epidemiology communities advances the development of the kind of infrastructure and models Dr. von Göetz discusses. This outcome would be a step forward, rather than a step backward.
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n her letter to the editor1 regarding our recent Feature Article “Completing the Link between Exposure Science and Toxicology for Improved Environmental Health Decision Making: The Aggregate Exposure Pathway Framework”,2 Dr. von Göetz expressed several concerns about terminology, and the perception that we propose the replacement of successful approaches and models for exposure assessment with a concept. We are glad to have the opportunity to address these issues here. If the goal of the AEP framework was to replace existing exposure models or databases for organizing exposure data with a concept, we would share Dr. von Göetz concerns. Instead, the outcome we promote is broader use of an organizational framework for exposure science. The framework would support improved generation, organization, and interpretation of data as well as modeling and prediction, not replacement of models. The field of toxicology has seen the benefits of wide use of one or more organizational frameworks (e.g., mode and mechanism of action, adverse outcome pathway). These frameworks influence how experiments are designed, data are collected, curated, stored and interpreted and ultimately how data are used in risk assessment. Exposure science is poised to similarly benefit from broader use of a parallel organizational framework, which Dr. von Göetz correctly points out, is currently used in the exposure modeling community. In our view, the concepts used so effectively in the exposure modeling community, expanded upon in the AEP framework, could see wider adoption by the field as a whole. The value of such a framework was recognized by the National Academy of Sciences.3 Replacement of models, databases, or any application with the AEP framework was not proposed in our article. The positive role broader more consistent use of such a framework might have in enabling and advancing “general activities such as data acquisition, organization···,” and exposure modeling was discussed in some detail. Like Dr. von Göetz, we recognized the challenges associated with acceptance of the terminology, definitions, and structure proposed in the paper. To address these challenges, an expert workshop was held in May, 2016 to consider and revise the “basic elements” outlined in the paper. The attendees produced revisions to the terminology (e.g., key events) that align with terminology currently in use in the field. We were also careful in our paper to acknowledge a point raised by Dr. von Göetz, that the term AEP implies aggregation, providing these clarifications: “The simplest form of an AEP represents a single source and a single pathway and may more commonly be referred to as an exposure pathway,”; and “An aggregate exposure pathway may represent multiple sources and transfer through single pathways to the TSE, single sources and transfer through multiple pathways to the target site exposure (TSE), or any combination of these.” These clarifications address the concern that the AEP term is not accurate or logical, and further expands upon the word “aggregate” in a broader context. Our use of AEP is consistent with the definition for © 2016 American Chemical Society
Justin G. Teeguarden*,†,‡ Yu-Mei Tan∥ Stephen W. Edwards⊥ Jeremy A. Leonard# Kim A. Anderson‡ Richard A. Corley‡,† Molly L. Kile§ Staci L. Massey Simonich‡ David Stone‡ Robert L. Tanguay‡ Katrina M. Waters‡,† Stacey L. Harper‡,∇ David E. Williams‡ †
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Health Effects and Exposure Science, Pacific Northwest National Laboratory, Richland, Washington 99352, United States ‡ Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 93771, United States § School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon 93771, United States ∥ National Exposure Research Laboratory, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States ⊥ National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Durham, North Carolina 27709, United States # Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831, United States ∇ School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, Oregon 97331, United States
AUTHOR INFORMATION
Corresponding Author
*Phone: 509-371-6982; fax:
[email protected]. Received: June 16, 2016 Accepted: July 12, 2016 Published: August 10, 2016 8921
DOI: 10.1021/acs.est.6b03027 Environ. Sci. Technol. 2016, 50, 8921−8922
Environmental Science & Technology
Letter to the Editor
Notes
The U.S. Environmental Protection Agency has provided administrative review and has approved for publication. The views expressed in this paper are those of the authors and do not necessarily reflect the views of the U.S. Environmental Protection Agency. The authors declare no competing financial interest.
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REFERENCES
(1) von Götz, N. Organizing exposure data is beyond conceptualization. Environ. Sci. Technol. 2016, DOI: 10.1021/acs.est.6b02402. (2) Teeguarden, J. G.; Tan, Y. M.; Edwards, S. W.; Leonard, J. A.; Anderson, K. A.; Corley, R. A.; Kile, M. L.; Simonich, S. M.; Stone, D.; Tanguay, R. L.; Waters, K. M.; Harper, S. L.; Williams, D. E. Completing the Link between Exposure Science and Toxicology for Improved Environmental Health Decision Making: The Aggregate Exposure Pathway Framework. Environ. Sci. Technol. 2016, 50 (9), 4579−86 PMC4854780. (3) NRC, Exposure Science in the 21st Century: a Vision and a Strategy; National Academies Press: Washington, DC, 2012. (4) U.S. Environmental Protection Agency, General Principles for Performing Aggregate Exposure and Risk Assessment; Environmental Protection Agency, 2001.
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DOI: 10.1021/acs.est.6b03027 Environ. Sci. Technol. 2016, 50, 8921−8922
