The document describes the EPA's CompTox Chemistry Dashboard, which provides access to data on over 760,000 chemicals. It focuses on how the Dashboard can be used to access information on chemicals used in hydraulic fracturing. Key features include searching for chemicals by name or formula, viewing associated property and hazard data, and links to other resources. The process of curating chemical lists from sources like EPA's hydraulic fracturing study involves mapping names to CAS numbers and structures through iterative checking. This allows accessing additional screening data, exposure information, and integrating identifiers to support searches.

1. Accessing information for chemicals in
hydraulic fracturing fluids using the US
EPA CompTox Chemistry Dashboard
Antony Williams1, Andrew McEachran2, Jon Sobus3,
Chris Grulke1 and Ann Richard1
1) National Center for Computational Toxicology, U.S. Environmental Protection Agency, RTP, NC
2) Oak Ridge Institute of Science and Education (ORISE) Research Participant, Research Triangle Park, NC
3) National Exposure Research Laboratory, U.S. Environmental Protection Agency, RTP, NC
March 2018
ACS Spring Meeting, New Orleans
http://www.orcid.org/0000-0002-2668-4821
The views expressed in this presentation are those of the author and do not necessarily reflect the views or policies of the U.S. EPA

2. The CompTox Chemistry Dashboard
• A publicly accessible website delivering access:
– ~760,000 chemicals with related property data
– Experimental and predicted physicochemical property data
– Experimental Human and Ecological hazard data
– Integration to “biological assay data” for 1000s of chemicals
– Information regarding consumer products containing chemicals
– Links to other agency websites and public data resources
– “Literature” searches for chemicals using public resources
– “Batch searching” for thousands of chemicals
– Real time prediction of physchem and toxicity endpoints
– DOWNLOADABLE Open Data for reuse and repurposing
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3. CompTox Chemistry Dashboard
https://comptox.epa.gov/dashboard
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4. 1 of ~761,000 Chemical Pages
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5. Advanced Searches
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6. Batch Searches
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7. Real-Time Predictions
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8. Real-Time Predictions
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9. Real-Time Predictions
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10. What’s under the Data Tabs?
Focus on Hydraulic Fracturing Chemicals
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11. Surfacing Lists of Chemicals
• Specific subsets of chemicals, “lists”, can
be displayed on the dashboard
• If there are chemicals that map together
then these link to existing:
– Property data
– Hazard data
– Exposure data
– In vitro bioassay data
– Documents and Literature
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12. EPA’s Hydraulic Fracturing Site
https://www.epa.gov/hfstudy
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13. Draft Database
• Early draft database is available
associated with the June 2015 draft report
• Contained list of CAS Numbers/Names
aggregated from various sources
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14. What were the original sources?
• Federal- and state-collected data sets
• Databases maintained by federal and state
government agencies
• Publicly available data (e.g )
• Industry data provided to the EPA - two
information requests to oil and gas service
companies and production well operators
(some data claimed as CBI under TSCA)
• http://ofmpub.epa.gov/eims/eimscomm.getfile?p_download_id=530159
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15. Delivering a Better Database
• An improved database would provide:
– Curated CAS Number-Name mappings
– Chemical structures
– Access to related data of interest
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16. Registration and Curation
• Consolidation and registration of the original
chemical lists into the underlying database
(DSSTox)
• Careful (and time-consuming) curation
– Confirming mappings of chemical names and CASRNs
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17. Names to CASRN Mappings
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18. Subtleties
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E/Z-stereochemistry E-stereochemistry
“4-Decene”

19. Registration and Curation
• Registration of the chemical list into the
underlying database (DSSTox)
• Careful (and time-consuming) curation
– Confirming mappings of chemical names and CASRNs
– CASRN checking – Active, Alternate and Deleted
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20. CAS Registry Numbers
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21. Registration and Curation
• Registration of the chemical list into the
underlying database (DSSTox)
• Careful (and time-consuming) curation
– Confirming mappings of chemical names and CASRNs
– CASRN checking – Active, Alternate and Deleted
– Misspellings, alternative synonyms, misassociations
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22. Alternative Synonyms
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23. Registration and Curation
• Registration of the chemical list into the
underlying database (DSSTox)
• Careful (and time-consuming) curation
– Confirming mappings of chemical names and CASRNs
– CASRN checking – Active, Alternate and Deleted
– Misspellings, alternative synonyms, misassociations
– Iterative checking on how the list was assembled
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24. A List of Lists of Chemicals
https://comptox.epa.gov/dashboard/chemical_lists
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25. The EPA List of
Hydraulic Fracturing Chemicals
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26. The List as “Structures”
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27. Browsing the List of Chemicals
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28. Detailed Chemical Pages
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29. Access to Chemical Hazard Data
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30. In Vitro Bioassay Screening
ToxCast and Tox21
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31. Sources of Exposure to Chemicals
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32. Identifiers to Support Searches
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33. Literature Searches and Links
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34. External Links to Data and Services
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35. Integrated Linkouts
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36. Integrated Linkouts
Comparative Toxicogenomics DB
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37. Batch Access to Dashboard Data
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38. Batch Search Through Dashboard
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39. Batch Search Through Dashboard
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40. Batch Access to Dashboard Data
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41. Many Hydraulic Fracturing
Chemicals are “Complex”
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42. UVCB Chemicals
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43. Di-sec-butylphenol
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CAS Representation
Dashboard Representation

44. “Markush Structures”
https://en.wikipedia.org/wiki/Markush_structure
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45. AFTER CURATION
1640 Chemicals
• 528/1640 chemicals without explicit structures
• 483/1640 chemicals examined in ToxCast – 94
not active in any assay
• 1036/1640 chemicals with Hazard Data
• 141/1640 chemicals with IRIS Assessment
Reports (Integrated Risk Information System)
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46. Curated Database for Download
https://www.epa.gov/hfstudy
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47. Download Files from EPA Site
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48. Suspect Screening and Non-Targeted
Analysis Workflow
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DSSTox Chemical Database
“Molecular Features”
Extracted Samples
Raw Samples
Raw Features
Matched Formulas
Mapped Structures
Prioritized Structures
(using ToxPi)
Confirmed Structures
(using ToxCast standards)
Processed Features
Prioritized Features
Predicted Formulas
Candidate Structures
Sorted Structures
Predicted Retention Times
Predicted/Observed Functional Use
Top Candidate Structure(s)
Suspect Screening Non-Targeted Analysis
Predicted Concentrations
Predicted/Observed Media Occurrence
Predicted Mass Spectra
Methodological Concordance
Red = Analytical Chemistry
Blue = Data Processing & Analysis
Green = Informatics & Web Services
Purple = Mathematical & QSPR Modeling
Color Key
Content from J. Sobus, US-EPA-NERL

49. The Dashboard to Support
MS-Analysis
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MS-Ready
Structures
Underpin
Analysis

50. Specific Data-Mappings
“MS-Ready Structures”
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51. MS-Ready Mappings
• Input Formula: C10H16N2O8
• EXACT Formula Search: 3 Chemicals
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52. MS-Ready Mappings
• Same Input Formula: C10H16N2O8
• MS Ready Formula Search: 88 Chemicals
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53. Complexity to Simplicity
88 Chemicals – 7 in EPAHFR
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54. Complexity to Simplicity
88 Chemicals – 7 in the list
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55. Searching batches
Formula (or mass) searching
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56. Conclusions
• The CompTox Chemistry Dashboard is
useful for delivering access to lists
– The EPA Hydraulic Fracturing Chemical List
– The ToxCast Bioassay Screening List
– NIOSH International Chemical Safety Cards
– Algal Toxins
• Lists can be updated with new chemicals
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57. Conclusions
• Registering chemical lists gives access to:
– Human and Ecological Hazard data
– ToxCast/Tox21 in vitro screening data
– Exposure data – consumer products & functional use
– Physicochemical and environmental fate and
transport experimental and predicted data
– Integrated mappings into multiple public sites
• Curation is time-consuming, iterative and
high-value
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58. Acknowledgments
• Hydraulic Fracturing Drinking Water Study Team
• The CompTox Chemistry Dashboard team
• Todd Martin (TEST Predictions), US-EPA-NRMRL
• NERL colleagues:
– Jon Sobus, Elin Ulrich, Mark Strynar, Seth Newton (NTA Analysis)
– Katherine Phillips, Kathie Dionisio, Kristin Isaacs (Consumer Products
Database)
• Emma Schymanski – Luxembourg Center for
Systems Biomedicine (MS-ready/NTA)
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59. Contact
Antony Williams
US EPA Office of Research and Development
National Center for Computational Toxicology (NCCT)
Williams.Antony@epa.gov
ORCID: https://orcid.org/0000-0002-2668-4821
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