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Teeguarden JG, Tan YM, Edwards SW, Leonard JA, Anderson KA, Corley RA, Harding AK, Kile ML, Simonich SM, Stone D, Tanguay RL, Waters KM, Harper SL, Williams DE. Completing the Link between Exposure Science and Toxicology for Improved Environmental Health Decision Making: The Aggregate Exposure Pathway Framework. Environ Sci Technol 2016; 50:4579-86. [PMID: 26759916 PMCID: PMC4854780 DOI: 10.1021/acs.est.5b05311] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Driven by major scientific advances in analytical methods, biomonitoring, computation, and a newly articulated vision for a greater impact in public health, the field of exposure science is undergoing a rapid transition from a field of observation to a field of prediction. Deployment of an organizational and predictive framework for exposure science analogous to the "systems approaches" used in the biological sciences is a necessary step in this evolution. Here we propose the aggregate exposure pathway (AEP) concept as the natural and complementary companion in the exposure sciences to the adverse outcome pathway (AOP) concept in the toxicological sciences. Aggregate exposure pathways offer an intuitive framework to organize exposure data within individual units of prediction common to the field, setting the stage for exposure forecasting. Looking farther ahead, we envision direct linkages between aggregate exposure pathways and adverse outcome pathways, completing the source to outcome continuum for more meaningful integration of exposure assessment and hazard identification. Together, the two frameworks form and inform a decision-making framework with the flexibility for risk-based, hazard-based, or exposure-based decision making.
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Affiliation(s)
- Justin. G. Teeguarden
- Health Effects and Exposure Science, Pacific Northwest
National Laboratory, Richland, WA 99352
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
- Corresponding Author: 902 Battelle Blvd. Richland, WA
99352, (P) 509-376-4262,
| | - Yu-Mei Tan
- National Exposure Research Laboratory, U.S. Environmental
Protection Agency, Durham, NC 27709
| | - Stephen W. Edwards
- National Health and Environmental Effects Research Laboratory,
U.S. Environmental Protection Agency, Durham, NC 27709
| | - Jeremy A. Leonard
- Oak Ridge Institute for Science and Education, Oak Ridge,
Tennessee 37831
| | - Kim A. Anderson
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
| | - Richard A. Corley
- Health Effects and Exposure Science, Pacific Northwest
National Laboratory, Richland, WA 99352
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
| | - Anna K Harding
- School of Biological and Population Health Sciences, Oregon
State University, Corvallis, OR 93771
| | - Molly L. Kile
- School of Biological and Population Health Sciences, Oregon
State University, Corvallis, OR 93771
| | - Staci M Simonich
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
| | - David Stone
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
| | - Robert L. Tanguay
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
| | - Katrina M. Waters
- Health Effects and Exposure Science, Pacific Northwest
National Laboratory, Richland, WA 99352
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
| | - Stacey L. Harper
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
- School of Chemical, Biological and Environmental
Engineering, Oregon State University, Corvallis, OR 97331
| | - David E. Williams
- Department of Environmental and Molecular Toxicology, Oregon
State University, Corvallis, OR 93771
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Bradford DF, Knapp RA, Sparling DW, Nash MS, Stanley KA, Tallent-Halsell NG, McConnell LL, Simonich SM. Pesticide distributions and population declines of California, USA, alpine frogs, Rana muscosa and Rana sierrae. Environ Toxicol Chem 2011; 30:682-691. [PMID: 21298712 DOI: 10.1002/etc.425] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 08/16/2010] [Accepted: 09/28/2010] [Indexed: 05/30/2023]
Abstract
Atmospherically deposited pesticides from the intensively cultivated Central Valley of California, USA, have been implicated as a cause for population declines of several amphibian species, with the strongest evidence for the frogs Rana muscosa and Rana sierrae at high elevation in the Sierra Nevada mountains. Previous studies on these species have relied on correlations between frog population status and either a metric for amount of upwind pesticide use or limited measurements of pesticide concentrations in the field. The present study tested the hypothesis that pesticide concentrations are negatively correlated with frog population status (i.e., fraction of suitable water bodies occupied within 2 km of a site) by measuring pesticide concentrations in multiple media twice at 28 sites at high elevation in the southern Sierra Nevada. Media represented were air, sediment, and Pseudacris sierra tadpoles. Total cholinesterase (ChE), which has been used as an indicator for organophosphorus and carbamate pesticide exposure, was also measured in P. sierra tadpoles. Results do not support the pesticide-site occupancy hypothesis. Among 46 pesticide compounds analyzed, nine were detected with ≥ 30% frequency, representing both historically and currently used pesticides. In stepwise regressions with a chemical metric and linear distance from the Central Valley as predictor variables, no negative association was found between frog population status and the concentration of any pesticide or tadpole ChE activity level. By contrast, frog population status showed a strong positive relationship with linear distance from the Valley, a pattern that is consistent with a general west-to-east spread across central California of the amphibian disease chytridiomycosis observed by other researchers.
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Affiliation(s)
- David F Bradford
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, Las Vegas, Nevada, USA.
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Bradford DF, Stanley K, McConnell LL, Tallent-Halsell NG, Nash MS, Simonich SM. Spatial patterns of atmospherically deposited organic contaminants at high elevation in the southern Sierra Nevada mountains, California, USA. Environ Toxicol Chem 2010; 29:1056-1066. [PMID: 20821540 PMCID: PMC3104601 DOI: 10.1002/etc.139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Atmospherically deposited contaminants in the Sierra Nevada mountains of California, USA have been implicated as adversely affecting amphibians and fish, yet little is known about the distributions of contaminants within the mountains, particularly at high elevation. The hypothesis that contaminant concentrations in a high-elevation portion of the Sierra Nevada decrease with distance from the adjacent San Joaquin Valley was tested. Air, sediment, and tadpoles were sampled twice at 28 water bodies in 14 dispersed areas in Sequoia and Kings Canyon National Parks (2,785-3,375 m elevation; 43-82 km from Valley edge). Up to 15 chemicals were detected frequently in sediment and tadpoles, including current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons. Only beta-endosulfan was found frequently in air. Concentrations of all chemicals detected were very low, averaging in the parts-per-billion range or less in sediment and tadpoles, and on the order of 10 pg/m3 for beta-endosulfan in air. Principal components analysis indicated that chemical compositions were generally similar among sites, suggesting that chemical transport patterns were likewise similar among sites. In contrast, transport processes did not appear to strongly influence concentration differences among sites, because variation in concentrations among nearby sites was high relative to sites far from each other. Moreover, a general relationship for concentrations as a function of distance from the valley was not evident across chemical, medium, and time. Nevertheless, concentrations for some chemical/medium/time combinations showed significant negative relationships with metrics for distance from the Valley. However, the magnitude of these distance effects among high-elevation sites was small relative to differences found in other studies between the valley edge and the nearest high-elevation sites.
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Affiliation(s)
- David F Bradford
- U.S. Environmental Protection Agency, National Exposure Research Laboratory, 944 East Harmon Avenue, Las Vegas, Nevada 89119, USA.
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