A Database of Produced Water Constituents with Ranking of Human Health Risk By Sydney M. Joffre B.S. Chemical Engineering, University of Colorado, 2018 B.S. Environmental Engineering, University of Colorado, 2019 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirement for the degree Master of Science Department of Civil, Environmental, and Architectural Engineering 2020 Committee Members: Cloelle Danforth Karl Linden James Rosenblum Joseph Ryan i Abstract: Sydney M. Joffre (Master of Science, Civil, Environmental, and Architectural Engineering) A Database of Produced Water Constituents with Ranking of Human Health Risk Thesis Directed by Professor Joseph N. Ryan Produced water is the largest waste stream of upstream oil and gas production in terms of volume. This study aims to address the implications of produced water reuse applications and inadvertent releases. We created a database of compounds identified in produced water from onshore oil and gas operations in North America and developed a prioritization scheme for those chemicals based on potential risk to human health. Through a comprehensive literature review, we found 179 studies that met our inclusion criteria. In total, there were 1,337 chemicals with a Chemical Abstract Service (CAS) number and 41 general water quality parameters (e.g., total dissolved solids, alkalinity) in produced water reported by the studies. We used the database to create a list of unique chemicals that had data available through the U.S. Environmental Protection Agency’s CompTox Dashboard and were in two or more individual samples at concentrations above the method detection limit. This resulted in a working list of 581 chemicals, comprised of 458 organic chemicals, 98 inorganic chemicals, and 25 radionuclides. Our prioritization scheme focused on the 390 organic chemicals in the working list that had at least one hazard metric available. Our prioritization scheme equally integrated aspects of exposure and hazard using the Toxicological Prioritization Index (ToxPi) to generate a ranking of compounds based on risk. The seven chemicals with the highest relative risk were organochlorine insecticides that are not expected to be associated with the oil and gas industry. The eighth-ranked compound, dodecahydro-1H-phenalene, was a hydrocarbon, which are expected to be identified in produced water. As research efforts into characterizing produced water expands, this database can provide a platform for potential uses such as generating a list of chemicals from a specific location that can then be prioritized using the scheme laid out in this study. ii Table of Contents LIST OF TABLES V LIST OF FIGURES VI 1 INTRODUCTION ……………………………………………………………………………………………………………………………………….. 1 1.1 PRODUCED WATER COMPOSITION AND SOURCES ………………………………………………………………………………………………….. 3 1.1.1 Produced water composition …………………………………………………………………………………………………………... 4 1.1.2 Produced water sources ………………………………………………………………………………………………………………….. 6 1.1.3 Produced water analytical challenges …………………………………………………………………………………………….. 9 1.2 POTENTIAL HEALTH AND ENVIRONMENTAL IMPACTS FROM PRODUCED WATER REUSE AND SPILLS……………………………………. 10 1.3 THE ROLE OF RISK ASSESSMENT……………………………………………………………………………………………………………………….. 14 1.4 OBJECTIVES………………………………………………………………………………………………………………………………………………… 15 2 METHODS……………………………………………………………………………………………………………………………………………….. 16 2.1 PART I: DATABASE CREATION …………………………………………………………………………………………………………………………. 16 2.1.1 Literature review …………………………………………………………………………………………………………………………… 16 2.1.2 Database development …………………………………………………………………………………………………………………. 17 2.2 PART II: RISK PRIORITIZATION STRATEGY OF CHEMICALS IN PRODUCED WATER …………………………………………………………… 20 2.2.1 Produced water chemicals working list …………………………………………………………………………………………. 20 2.2.2 Associated data sources ……………………………………………………………………………………………………………….. 23 2.2.3 Exposure pathway ………………………………………………………………………………………………………………………… 25 2.2.4 Exposure domain ………………………………………………………………………………………………………………………….. 27 2.2.5 Hazard domain ……………………………………………………………………………………………………………………………… 34 2.2.6 Data integration and prioritization using the Toxicological Prioritization Index …………………………….. 35 2.2.7 Data availability ……………………………………………………………………………………………………………………………. 39 2.2.8 Sensitivity analysis ………………………………………………………………………………………………………………………… 43 2.2.9 Reference compounds ………………………………………………………………………………………………………………….. 44 3 RESULTS AND DISCUSSION……………………………………………………………………………………………………………………… 46 3.1 PART I: DATABASE……………………………………………………………………………………………………………………………………….. 46 3.1.1 Identification of publications, samples, and chemicals in produced water through comprehensive literature review …………………………………………………………………………………………………………………………………………. 46 3.2 PART II: PRIORITIZATION OF CHEMICALS IN PRODUCED WATER ………………………………………………………………………………. 47 3.2.1 Working list for prioritization scheme ……………………………………………………………………………………………. 47 3.2.2 Collection and analysis of toxicity data for chemicals in prioritization scheme ………………………………. 50 3.2.3 Data integration and prioritization using ToxPi …………………………………………………………………………….. 53 3.2.4 Sensitivity analysis ………………………………………………………………………………………………………………………... 71 3.2.5 Inorganic compounds without toxicity data ………………………………………………………………………………….. 87 3.2.6 Radionuclides ……………………………………………………………………………………………………………………………….. 87 3.3 PART III: INTEGRATED FINDINGS …………………………………………………………………………………………………………………….. 89 3.3.1 Future use of database …………………………………………………………………………………………………………………. 89 3.3.2 Compound rank summary …………………………………………………………………………………………………………….. 90 3.3.3 Organic compounds with toxicity data ………………………………………………………………………………………….. 92 3.3.4 Prioritization scheme sensitivity ……………………………………………………………………………………………………. 93 3.3.5 Comparison to Danforth et al. (2020) …………………………………………………………………………………………… 94 4 CONCLUSION …………………………………………………………………………………………………………………………………………. 98 5 WORKS CITED ………………………………………………………………………………………………………………………………………… 99 6 APPENDIX ……………………………………………………………………………………………………………………………………………. 115 6.1 DATABASE CREATION …………………………………………………………………………………………………………………………………. 115 iii 6.1.1 Literature review search logic ……………………………………………………………………………………………………… 115 6.1.2 Abbreviations used in database ………………………………………………………………………………………………….. 116 6.2 EXPOSURE DOMAIN: IONIZED COMPOUNDS …………………………………………………………………………………………………….. 117 6.3 DATABASE RESULTS ……………………………………………………………………………………………………………………………………. 120 6.4 TOXPI RESULTS …………………………………………………………………………………………………………………………………………. 123 6.4.1 Analysis ……………………………………………………………………………………………………………………………………….. 123 6.4.2 Organic compounds without toxicity data …………………………………………………………………………………… 163 6.4.3 Inorganic compounds with toxicity data ……………………………………………………………………………………… 167 6.5 SENSITIVITY ANALYSES ………………………………………………………………………………………………………………………………… 169 6.5.1 Missing data ……………………………………………………………………………………………………………………………….. 169 6.5.2 Domain weights ………………………………………………………………………………………………………………………….. 180 6.6 INORGANIC COMPOUNDS WITHOUT TOXICITY DATA …………………………………………………………………………………………… 192 6.7 RADIONUCLIDES ……………………………………………………………………………………………………………………………………….. 194 6.8 FUTURE USE OF DATABASE …………………………………………………………………………………………………………………………… 195 6.9 COMPARISON TO DANFORTH ET AL. (2020) ……………………………………………………………………………………………………. 196 iv List of Tables Table 1. Isomer mixtures on the working list ............................................................................................................. 22 Table 2. Mobility calculation parameters .................................................................................................................. 32 Table 3. Search logic for identifying acids and bases ................................................................................................. 33 Table 4. Scaling equations for the exposure domain metrics.................................................................................... 37 Table 5. Cases used in the missing data treatment sensitivity analysis .................................................................... 43 Table 6. Cases used to evaluate the sensitivity of the hazard and exposure domains............................................. 44 Table 7. Experimental values of exposure metrics for the exposure domain reference compounds ...................... 45 Table 8. Experimental toxicity values for the five hazard domain reference compounds ....................................... 45 Table 9. Organic compounds not included on the working list ................................................................................. 48 Table 10. Availability of experimental and predicted toxicity values for the 556 organic and inorganic compounds on the working list ............................................................................................................................................. 51 Table 11. Availability of experimental and predicted toxicity values for the 458 organic compounds on the working list ........................................................................................................................................................ 52 Table 12. Availability of experimental toxicity values for the 98 inorganic compounds on the working list .......... 52 Table 13. Rank and ToxPi scores for the 40 organic compounds with toxicity data that had the highest relative risk. ...................................................................................................................................................................