Letter to the Editor pubs.acs.org/est
Organizing Exposure Data Is Beyond Conceptualization
T
he title of the feature article by Teeguarden et al.1 promises a new framework for organizing exposure data to better link exposure and effect and the associated article promotes the term “aggregate exposure pathway” (AEP) to match alliteratively with the concept of adverse outcome pathways (AOP) in toxicology. However, the authors do not sufficiently take into account the state of knowledge and established terminology in exposure science, making their conceptualization appear like a step back. • The suggested term “aggregate exposure pathway AEP”: The terminology is not appropriate because an exposure pathway by itself cannot be “aggregate”; the aggregation is done across exposure pathways. What the authors describe has already been defined earlier2 as “exposure pathway”. • The conceptual framework of joining an AEP to the AOP: This concept does not take into account the existence of sophisticated models for calculating exposure (e.g., multimedia models,3,4 migration models,5 and aggregate exposure models4,6), which already provide a quantitative framework, but takes the step back to a “conceptual framework” while even for assessing internal exposure at the target site integrative model platforms already exist4 or are under development.7,8 • The suggestion of organizing exposure data: This is not a new idea and concrete efforts have been made on organizing exposure factors in databases and data repositories, such as the exposure factors handbook by USEPA,9 the ConsExpo Fact Sheets developed by RIVM,10 the ExpoFacts database hosted by the Joint Research Centre JRC of the EU,11 and many more national repositories. Probabilistic exposure models like MCRA for food12 and PACEM for consumer products6 have built-in databases for relevant exposure factors and can be linked to databases for substance concentrations. This is a more suitable way of organizing exposure data than the proposed “AEP” concept. What is currently missing in exposure science is not concepts for data organization, but acquiring or estimating substancespecific data on concentrations in products and media, which are costly to generate and rapidly outdated.13 • The definition of “key events” in the conceptual framework: The described key events, like change of a chemical state,1 can well be captured in multimedia models,14 which calculate external exposure. Transforming that into internal exposure with a pharmacokinetic (PK) model yields the “target site exposure”. Thus, by using a suite of models, exposure and effects can easily be linked directly at the target site and “key events”, which are appropriate in a toxicological context, are not necessary for organizing data in exposure science. Consequently, the suggested term “AEP” should not be used, sinceas discussed aboveit is not correct for logical and methodological reasons. Admittedly, the organization and publication of exposure data is a very important and challenging © 2016 American Chemical Society
topic. The authors rightly point out that there is a great need to better integrate exposure databases with exposure models, PK models, and effect data, but for this model platforms provide the best structure. Key is to collect substance-specific data in databases and that industry takes the proactive role of sharing such data.
Natalie von Goetz*
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Swiss Federal Institute of Technology Zurich, Institute of Chemical and Bioengineering, Zurich, Switzerland
AUTHOR INFORMATION
Corresponding Author
*Phone: 0041-446320975; fax: 0041-446321189; e-mail:
[email protected]. Notes
The author declares no competing financial interest.
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REFERENCES
(1) Teeguarden, J. 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. (2) Zartarian, V.; Bahadori, T.; MacKone, T. Adoption of an official ISEA glossary. J. Exposure Anal. Environ. Epidemiol. 2005, 15, 1−5. (3) Fenner, K.; et al. Comparing Estimates of Persistence and LongRange Transport Potential among Multimedia Models. Environ. Sci. Technol. 2005, 44, 8360−8364. (4) EPA, 2015, https://www.epa.gov/chemical-research/stochastichuman-exposure-and-dose-simulation-sheds-estimate-humanexposure. (5) Oldring, P. K. T.; O’Mahony, C.; Dixon, J.; Vints, M.; Mehegan, J.; Dequatre, C.; Castle, L. Development of a new modelling tool (FACET) to assess exposure to chemical migrants from food packaging. Food Addit. Contam., Part A 2014, 31, 444−465. (6) Dudzina, T.; Delmaar; Biesterbos, J. W. H.; Bakker, M. I.; Bokkers, B. G. H.; Scheepers, P. T. J.; van Engelen, J. G. M.; Hungerbuehler, K.; von Goetz, N. The probabilistic aggregate consumer exposure model (PACEM): Validation and comparison to a lower-tier assessment for the cyclic siloxane D5. Environ. Int. 2015, 79, 8−16. (7) Merlin Expo, 2016, http://merlin-expo.eu/. (8) Integra, 2016, http://www.integra-lri.eu/. (9) EPA, 2011, https://cfpub.epa.gov/ncea/risk/recordisplay. cfm?deid=236252. (10) RIVM, 2016, http://www.rivm.nl/en/Topics/C/ConsExpo/ Fact_sheets. (11) JRC, 2016, http://expofacts.jrc.ec.europa.eu/. (12) Van der Voet, H.; de Boer, W. J.; Kruisselbrink, J. W.; Goedhart, P. W.; van der Heijden, G. W. A. M.; Kennedy, M. C.; Boon, P. E.; van Klaveren, J. D. The MCRA model for probabilistic single-compound and cumulative risk assessment of pesticides. Food Chem. Toxicol. 2015, 79, 5−12.
Received: May 13, 2016 Accepted: July 12, 2016 Published: August 9, 2016 8919
DOI: 10.1021/acs.est.6b02402 Environ. Sci. Technol. 2016, 50, 8919−8920
Environmental Science & Technology
Letter to the Editor
(13) Manová, E.; von Goetz, N.; Hungerbuehler, K. Aggregate consumer exposure to UV filter ethylhexyl methoxycinnamate via personal care products. Environ. Int. 2015, 74, 249−257. (14) Fenner, K.; Scheringer, M.; Hungerbühler, K. Persistence of Parent Compounds and Transformation Products in a Level IV Multimedia Model. Environ. Sci. Technol. 2000, 34, 3809−3817.
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DOI: 10.1021/acs.est.6b02402 Environ. Sci. Technol. 2016, 50, 8919−8920
