1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 SEPA PUBLIC RELEASE DRAFT December 2024 EPA Document# EPA-740-D-24-023 December 2024 United States Office of Chemical Safety and Environmental Protection Agency Pollution Prevention Draft Environmental Hazard Assessment for Dibutyl Phthalate (DBP) Technical Support Document for the Draft Risk Evaluation CASRN 84-74-2 December 2024 ------- 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 PUBLIC RELEASE DRAFT December 2024 TABLE OF CONTENTS ACKNOWLEGEMENTS 5 SUMMARY 6 1 INTRODUCTION 7 1.1 Approach and Methodology 7 2 ENVIRONMENTAL HAZARD 8 2.1 Aquatic Species 8 2.1.1 Acute Toxicity of DBP in Aquatic Vertebrates 8 2.1.2 Chronic Toxicity of DBP in Aquatic Vertebrates 10 2.1.3 Acute Toxicity of DBP in Aquatic Invertebrates 13 2.1.4 Chronic Toxicity of DBP in Aquatic Invertebrates 14 2.1.5 Acute Toxicity of DBP in Benthic Invertebrates 16 2.1.6 Chronic Toxicity of DBP in Benthic Invertebrates 16 2.1.7 Toxicity of DBP in Aquatic Plants and Algae 19 2.2 Terrestrial Species 20 2.2.1 Toxicity of DBP in Terrestrial Vertebrates 20 2.2.2 Toxicity of DBP in Soil Invertebrates 21 2.2.3 Toxicity of DBP in Terrestrial Plants 22 2.3 Hazard Thresholds 24 2.3.1 Acute Aquati c C oncentrati on of C oncern 25 2.3.2 Chronic Aquatic Vertebrate Concentration of Concern 26 2.3.3 Chronic Aquatic Invertebrate Concentration of Concern 26 2.3.4 Acute Benthic Concentration of Concern 26 2.3.5 Chronic Benthic Concentration of Concern 27 2.3.6 Aquatic Plant and Algae Concentration of Concern 27 2.3.7 Terrestrial Vertebrate Hazard Value 27 2.3.8 Soil Invertebrate Hazard Value 28 2.3.9 Terrestrial Plant Hazard Value 28 2.4 Weight of Scientific Evidence and Conclusions 29 2.4.1 Quality of the Database; Consistency; Strength (Effect Magnitude) and Precision; and Biological Gradient (Dose-Response) 30 2.4.2 Relevance (Biological; Physical/Chemical; Environmental) 34 3 CONCLUSIONS 36 REFERENCES 38 APPENDICES 46 Appendix A RUBRIC FOR WEIGHT OF THE SCIENTIFIC EVIDENCE 46 A. 1 Confidence Levels 46 A.2 Types of Uncertainties 46 Appendix B SPECIES SENSITIVITY DISTRIBUTION FOR ACUTE AQUATIC HAZARD 50 Appendix C ENVIRONMENTAL HAZARD STUDIES 57 Appendix D SUPPLEMENTAL SUBMITTED DATA TO BE CONSIDERED FOR FINAL RISK EVALUATION 64 ------- 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 PUBLIC RELEASE DRAFT December 2024 LIST OF TABLES Table ES-1. Environmental Hazard Thresholds for DBP 6 Table 2-1. Acute Toxicity of DBP in Aquatic Vertebrates 9 Table 2-2. Chronic Toxicity of DBP in Aquatic Vertebrates 12 Table 2-3. Acute Toxicity of DBP in Aquatic Invertebrates 14 Table 2-4. Chronic Toxicity of DBP in Aquatic Invertebrates 15 Table 2-5. Acute Toxicity of DBP in Aquatic Benthic Invertebrates 16 Table 2-6. Chronic Toxicity of DBP in Benthic Invertebrates 17 Table 2-7. Toxicity of DBP in Aquatic Plants and Algae 20 Table 2-8. Toxicity of DBP to Terrestrial Vertebrates 21 Table 2-9. Toxicity of DBP in Soil Invertebrates 21 Table 2-10. Toxicity of DBP in Terrestrial Plants 23 Table 2-11. Acute Aquatic COC and Multiomics PODs 26 Table 2-12. DBP Evidence Table Summarizing the Overall Confidence Derived from Hazard Thresholds 29 LIST OF APPENDIX TABLES TableApx A-l. Considerations that Inform Evaluations of the Strength of the Evidence within an Evidence Stream (i.e., Apical Endpoints, Mechanistic, or Field Studies) 48 Table Apx B-l. Species Sensitivity Distribution (SSD) Model Input for Acute Exposure Toxicity in Aquatic Vertebrates and Invertebrates - Empirical Data 50 Table Apx B-2. SSD Model Predictions0 for Acute Exposure Toxicity to Aquatic Vertebrates (Fish).. 51 Table Apx B-3. Species Sensitivity Distribution (SSD) Model Input for Acute Exposure Toxicity in Aquatic Vertebrates and Invertebrates - Web-ICE Data 51 Table_Apx C-l. Acute Aquatic Vertebrate Toxicity of DBP 57 Table_Apx C-2. Chronic Aquatic Vertebrate Toxicity of DBP 58 Table_Apx C-3. Acute Aquatic Invertebrate Toxicity of DBP 59 Table Apx C-4. Chronic Aquatic Invertebrate Toxicity of DBP 59 TableApx C-5. Chronic Benthic Invertebrate Toxicity of DBP 59 Table Apx C-6. Aquatic Plants and Algae Toxicity of DBP 60 Table_Apx C-l. Terrestrial Vertebrate Toxicity of DBP 61 Table_Apx C-8. Acute Soil Invertebrate Toxicity of DBP 62 Table Apx C-9. Chronic Soil Invertebrate Toxicity of DBP 62 Table_Apx C-10. Terrestrial Plant Toxicity of DBP 63 LIST OF APPENDIX FIGURES FigureApx B-l. AICc for the Six Distribution Options in the SSD Toolbox for Acute DBP Toxicity to Aquatic Vertebrates and Invertebrates (Etterson, 2020) 54 Figure Apx B-2. Q-Q Plots of Acute DBP Toxicity to Aquatic Vertebrates and Invertebrates with the A) Gumbel, B) Weibull, C) Burr, and D) Logistic Distributions (Etterson, 2020) 55 Figure Apx B-3. Species Sensitivity Distribution (SSD) for Acute DBP Toxicity to Aquatic Vertebrates and Invertebrates (Etterson, 2020) 56 Page 3 of 64 ------- 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 PUBLIC RELEASE DRAFT December 2024 ABBREVIATIONS AND ACRONYMS AF Assessment factor ChV Chronic value CI Confidence interval coc Concentration(s) of concern EC50 Effect concentration at which 50% of test organisms exhibit an effect EPA Environmental Protection Agency HC05 Hazard concentration that is protective of 95% of the species in the SSD HV Hazard value LC50 Lethal concentration at which 50 percent of test organisms die LD50 Lethal dose at which 50 percent of test organisms die LOAEC Lowest-observed-adverse-effect-concentration LOAEL Lowest-observed-adverse-effect-level LOEC Lowest-observed-effect-concentration LOEL Lowest-observed-effect-level MATC Maximum acceptable toxicant concentration NOAEC No-observed-adverse-effect-concentration NOAEL No-observed-adverse-effect-level NOEC No-observed-effect-concentration NOEL No-observed-effect-level OCSPP Office of Chemical Safety and Pollution Prevention OPPT Office of Pollution Prevention and Toxics POD Point of departure QSAR Quantitative structure-activity relationship SSD Species sensitivity distribution TOC Total organic carbon TRV Toxicity reference value TSCA Toxic Substances Control Act U.S. United States Web-ICE Web-based Interspecies Correlation Estimation Page 4 of 64 ------- 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 PUBLIC RELEASE DRAFT December 2024 ACKNOWLEGEMENTS This report was developed by the United States Environmental Protection Agency (U.S. EPA or the Agency), Office of Chemical Safety and Pollution Prevention (OCSPP), Office of Pollution Prevention and Toxics (OPPT). Acknowledgements The Assessment Team gratefully acknowledges the participation, review, and input from EPA OPPT and OSCPP senior managers and science advisors. The Agency is also grateful for assistance from the following EPA contractors for the preparation of this draft technical support document: General Dynamics Information Technology, Inc. (Contract No. HHSN316201200013W); ICF, Inc. (Contract No. 68HERC23D0007); SpecPro Professional Services, LLC (Contract No. 68HERC20D0021); and SRC, Inc. (Contract No. 68HERH19D0022 and 68HERC23D0007). As part of an intra-agency review, this technical support document was provided to multiple EPA Program Offices for review. Comments were submitted by EPA's Office of Research and Development (ORD). Docket Supporting information can be found in the public docket, Docket ID EPA-HQ-QPPT-2018-0503. Disclaimer Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government. Authors: Collin Beachum (Management Lead), Mark Myer (Assessment Lead, Environmental Hazard Assessment Lead), Jennifer Brennan (Assessment Lead, Environmental Hazard Discipline Lead), Christopher Green (Environmental Hazard Discipline Lead), Emily Griffin (Environmental Hazard Assessor) Contributors: Azah Abdallah Mohamed, Rony Arauz Melendez, Sarah Au, Maggie Clark, Jone Corrales, Daniel DePasquale, Lauren Gates, Ryan Klein, Sydney Nguyen, Brianne Raccor, Maxwell Sail, Andrew Sayer, Joe Valdez, Leora Vegosen. Technical Support: Mark Gibson, Hillary Hollinger, S. Xiah Kragie This draft technical support document was reviewed and cleared for release by OPPT and OCSPP leadership. Page 5 of 64 ------- 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 PUBLIC RELEASE DRAFT December 2024 SUMMARY This technical document is in support of the Draft Risk Evaluation for Dibutyl Phthalate (DBP) (U.S. EPA, 2024). DBP is a common name for the chemical substance 1,2-benzenedicarboxylic acid, 1,2- dibutyl ester (CASRN 84-74-2). See the draft risk evaluation for a complete list of all the technical support documents for DBP. EPA considered all reasonably available information identified through the systematic review process under the Toxic Substances Control Act (TSCA) to characterize environmental hazard endpoints for DBP. After evaluating the reasonably available information, environmental hazard thresholds were derived for aquatic vertebrates, aquatic invertebrates, benthic invertebrates, aquatic plants and algae, terrestrial vertebrates, soil invertebrates, and terrestrial plants. These hazard thresholds are summarized in Table ES-1. EPA's rationale for selecting these hazard thresholds, as well as the level of confidence in each is based on the weight of scientific evidence, is described in Section 2.42.3 and 0. Table ES-1. Environmental Hazard Thresholds for DBP Receptor Group Exposure Duration Hazard Threshold (COC or HV) Citation Aquatic Vertebrates (Including Amphibians) Acute (96 hours) 347.6 jig/L SSD (see Section 2.3.1) Chronic (112 days) 1.56 jig/L (EAG Laboratories. 2018) Aquatic Invertebrates Acute (96 hours) 347.6 jig/L SSD (see Section 2.3.1) Chronic (14 days) 12.23 jig/L (Taeatz et al.. 1983) Benthic Invertebrates Acute (96 hours) 347.6 jig/L SSD (see Section 2.3.1) Chronic (10 days) 114.3 mg DBP/kg dry sediment (Call et al.. 2001a) Aquatic Plants and Algae 96 hours 31.6 jig/L (Adachi et al.. 2006) Terrestrial Vertebrates 17 weeks 80 mg/kg-bw/day (NTP. 1995) Soil Invertebrates 21 days 14 mg DBP/kg dry soil (Jensen et al.. 2001) Terrestrial Plants 40 days 10 mg DBP/kg dry soil (Gao et al.. 2019) COC = concentration of concern; HV = hazard value Page 6 of 64 ------- 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 PUBLIC RELEASE DRAFT December 2024 1 INTRODUCTION Dibutyl phthalate is an organic substance primarily used as a plasticizer in a wide variety of consumer, commercial and industrial products. DBP may be released during industrial activities and through consumer use, with most releases occurring to air and water. EPA reviewed studies of the toxicity of DBP to aquatic and terrestrial organisms and its potential environmental hazards. 1.1 Approach and Methodology EPA utilized studies with overall quality determinations of high and medium to characterize the environmental hazards of DBP to surrogate species representing various receptor groups, including aquatic vertebrates, aquatic invertebrates, benthic invertebrates, aquatic plants and algae, terrestrial mammals, soil invertebrates, and terrestrial plants. Mechanistic (transcriptomic and metabolomic) and behavioral points of departure (PODs) from an acute exposure of DBP to fathead minnows were compared to the acute aquatic vertebrate hazard threshold. Hazard studies with mammalian wildlife exposed to DBP were not available; therefore, EPA used ecologically relevant endpoints from the laboratory rat and mouse—model organisms that are commonly used to evaluate human health hazards—to establish a hazard threshold for terrestrial mammals. Although two studies with overall quality determinations of high and medium containing avian hazard data were available for exposures to DBP, no apical hazards were observed in those studies. Because no apical hazards were observed in any avian studies, EPA was not able to establish a definitive hazard threshold for avian species. TSCA requires that EPA use data and/or information in a manner consistent with the best available science and that the Agency base decisions on the weight of scientific evidence. To meet the TSCA science standards, EPA applies a systematic review process to identify data and information across taxonomic groups for both aquatic and terrestrial organisms with a focus on apical endpoints (e.g., those affecting survival, growth, or reproduction). The data collection, data evaluation, and data integration stages of the systematic review process are used to develop the hazard assessment to support the integrative risk characterization. EPA completed the review of environmental hazard data/information sources during risk evaluation using the data quality review evaluation metrics and the rating criteria described in the 2021 Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substances (U.S. EPA. 2021) and the Draft Systematic Review Protocol for Dibutyl Phthalate (DBP) (U.S. EPA. 2024c). Studies identified and evaluated by the Agency were assigned an overall quality determination of high, medium, low, or uninformative. Study quality was evaluated based on a rubric that included consideration of the following seven overarching domains: test substance, test design, exposure characterization, test organism, outcome assessment, confounding/variable control, and data presentation/analysis. Several metrics within each of these domains were evaluated for each study, and an overall study quality determination was assigned based on the overall evaluation. Because data on toxicity of DBP are numerous, EPA systematically evaluated all data for this hazard characterization, but relied only on high-quality and medium-quality studies for purposes of risk characterization. Page 7 of 64 ------- 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 PUBLIC RELEASE DRAFT December 2024 2 ENVIRONMENTAL HAZARD 2.1 Aquatic Species EPA reviewed 68 studies for DBP toxicity to aquatic organisms. Some studies may have included multiple endpoints, species, and test durations. Of these 68 studies, those that received an overall quality determination of low or uninformative were not considered for quantitative risk evaluation. For the 55 studies that received an overall quality determination of high and medium, those that demonstrated no acute or chronic adverse effects at the highest concentration tested (unbounded no-observed-effect- concentration [NOECs]), or where hazard values exceeded the limit of solubility for DBP in water as determined by EPA at 11.2 mg/L (U.S. EPA. 2024a). are listed in Appendix C. Those studies were excluded from consideration for development of hazard thresholds (see Section 2.3). Of the 68 studies, 55 were considered for the development of hazard thresholds as outlined below. 2.1.1 Acute Toxicity of DBP in Aquatic Vertebrates EPA reviewed 17 studies that received overall quality determination of high or medium for acute toxicity in aquatic vertebrates (Table 2-1). Two studies received overall quality determinations of low or unacceptable and were not considered. Of the 17 high and medium quality studies, 13 contained acceptable acute endpoints that identified definitive hazard values below the DBP limit of water solubility. Additionally, predicted hazard data for 53 species were generated using EPA's Web-Based Interspecies Correlation Estimation (Web-ICE) tool, including predictions for 31 aquatic vertebrates, 5 aquatic invertebrates, 16 benthic invertebrates, and 1 amphibian species. For the fathead minnow {Pimephales promelas), bluegill {Lepomis macrochirus), and rainbow trout (Oncorhynchus mykiss), the 96-hour mortality LC50s ranged from 0.48 to 2.02 mg/L DBP (Smithers Viscient. 2018; Adams et al.. 1995; EnviroSvstem. 1991; Defoe et al.. 1990; McCarthy and Whitmore. 1985; EG&G Bionomics. 1983a. b; Buccafusco et al.. 1981). Additional endpoints were established in two fish species, including a 144-hour mortality LC50 of 0.92 mg/L and 96-hour mortality NOEC/LOEC of 0.53/8.3 mg/Lin the fathead minnow (Smithers Viscient. 2018; EG&G Bionomics. 1984a) and a 72-hour mortality LC50 of 0.63 mg/L in the zebrafish {Danio rerio) (Chen et al.. 2014). Hazard values for development and growth were also identified in the African clawed frog (Xenopus laevis). For these endpoints, the 96-hour EC50s ranged from 0.9 to 8.40 mg/L. DBP was found to have significant effects on developmental malformations in tadpoles at 0.5 mg/L (0.1 mg/L NOEC) with a 96- hour EC50 of 0.9 mg/L (Lee et al.. 2005) at 6.3 mg/L (lowest concentration tested) with a 96-hour EC50 of 7.5 mg/L (Xu and Gve. 2018). and in tadpole embryos at 8.3 mg/L (5.8 mg/L NOEC) with a 96-hour EC5 of 8.4 mg/L (Gardner et al.. 2016). The bolded values in Table 2-1 describe data which were used as inputs for generating Web-ICE predictions and within a species-sensitivity distribution analysis (SSD) (Appendix B). TSCA section 4(h)(1)(B) requires EPA to encourage and facilitate the use of scientifically valid test methods and strategies that reduce or replace the use of vertebrate animals while providing information of equivalent or better scientific quality and relevance that will support regulatory decisions. One avenue of research for reducing the time needed for toxicity testing in vivo is the use of transcriptomic and metabolomic points of departure, which allow for studies with much shorter durations that still provide the necessary robust experimental data to characterize hazard and provide important evidence for mechanisms of action and affected cellular and metabolic pathways. A multiomics study was conducted by EPA in which fathead minnows {Pimephales promelas) were exposed for 24 hours to several phthalates, including DBP (Bencic et al.. 2024). PODs were derived for transcriptomic change (tPOD), metabolomic change (mPOD), and behavioral change (bPOD). Additionally, a 24-hour mortality Page 8 of 64 ------- 282 283 284 285 286 287 288 289 290 291 292 293 PUBLIC RELEASE DRAFT December 2024 NOEC/LOEC of 0.8/2.1 mg/L was identified. At 2.1 mg/L DBP, 100 percent mortality was observed. The tPOD identifies the DBP concentration at which gene expression is significantly affected. RNA was isolated from exposed minnows at each treatment level and analyzed for significant deviation from the control fish, and the tPOD was defined as the median benchmark dose limit (BMDL) for the lowest affected gene ontology. For DBP, the tPOD was 0.12 mg/L. The mPOD identifies the DBP concentration at which the metabolome is significantly affected. The mPOD was defined as the 10th percentile benchmark dose (BMD) for change in metabolomics vs. the control. For DBP, the mPOD was 0.11 mg/L. The bPOD identifies the DBP concentration at which startle behavior is significantly affected. The bPOD was defined as the SD50, or the concentration which causes a 50% reduction in startle response in the fish larvae. For DBP, the bPOD was 0.24 mg/L. Table 2-1. Acute Toxicity of DBP in Aquatic Vertebrates Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) 0.1/0.5 mg/L 96-hour NOEC/LOEC Development/ Growth (Lee et al.. 2005) (High) 0.9 mg/L 96-hour EC50 African clawed frog (Xenopus laevis) 7.5 mg/L 96-hour EC50 Growth (Xu and Gve. 2018) 6.3 mg/L 96-hour LOEC (High) 8.40 mg/L 96-hour EC50 Growth (Gardner et al.. 2016) (Medium) 5.8/8.3 mg/L 96-hour NOEC/LOEC 1.54 mg/L 96-hour LC50 Mortality (Adams et al.. 1995) (High) 0.8/2.1 mg/L 24-hour NOEC/ LOEC Mortality (Bencic et al.. 2024) Fathead minnow 0.92 mg/L 144-hour LC50 Mortality (EG&G Bionomics. 1984a) (High) (Pimephales promelas) 2.02 mg/L 96-hour LC50 Mortality (McCarthy and Whitmore. 1985) (Medium) 0.85 mg/L 96-hour LC50 Mortality (Defoe et al.. 1990) (Hish) 1.1 mg/L 1.0 mg/L 96-hour LC50 Mortality (Smithers Viscient. 2018) (Medium) 0.53/1.4 mg/L 96-hour NOEC/LOEC Page 9 of 64 ------- 294 295 296 297 298 299 300 301 302 303 304 305 306 PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) 0.8/2.1 mg/L 24-hour NOEC/LOEC Mortality (Bencic et al.. 2024) 0.12 mg/L 24-hour tPOD Transcriptomic change 0.11 mg/L 24-hour mPOD Metabolomic change 0.24 mg/L 24-hour bPOD Behavior Bluegill (Lepomis mctcrochirus) 1.2 mg/L 96-hour LC50 Mortality (Buccafusco et al.. 1981) (Medium) 0.85 mg/L 96-hour LC50 Mortality (EG&G Bionomics. 1983b) (High) 0.48 mg/L 96-hour LC50 Mortality (Adams et al.. 1995) (High) Rainbow trout (iOncorhynchus mykiss) 1.60 mg/L 96-hour LC50 Mortality (Adams et al.. 1995) (High) 1.60 mg/L 96-hour LC50 Mortality (EG&G Bionomics. 1983a) (High) 1.4 mg/L 96-hour LC50 Mortality (EnviroSvstem. 1991) (High) Zebrafish (Danio rerio) 0.63 mg/L 72-hour LC50 Mortality (Chen et al.. 2014) (Medium) Bolded values indicate data used to derive acute aquatic COC using SSD 2.1.2 Chronic Toxicity of DBP in Aquatic Vertebrates EPA reviewed 16 studies with overall quality determinations of high or medium for chronic toxicity in aquatic vertebrates (Table 2-2). One study received an overall quality determination of unacceptable and was not considered. Of the 16 high and medium quality studies, 11 contained acceptable chronic endpoints that identified definitive hazard values below the DBP limit of water solubility for five fish species and two amphibians. In zebrafish, there was a significant effect on offspring mortality resulting from females exposed to 0.1 and 0.5 mg/L DBP for 15 days. In the same study, zebrafish embryos exposed to 0.025 and 0.1 mg/L DBP experienced developmental malformations. Further, exposure to DBP incited liver peroxisome proliferation and up-regulation of aromatases in zebrafish embryos and adult females (Ortiz-Zarragoitia et al.. 2006). In rainbow trout, the 99-day growth NOEC/LOEC was 0.10/0.19 mg/L (0.14 mg/L maximum acceptable toxicant concentration [MATC]), representing significant effects on fish length Page 10 of 64 ------- 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 PUBLIC RELEASE DRAFT December 2024 and weight (Rhodes et al.. 1995; EnviroSvstem. 1991). Additionally, a 13-day NOEC/LOEC of 0.52/1.0 mg/L (1.3 mg/L LC50) and a 99-day NOEC/LOEC of 0.19/0.40 mg/L (0.28 mg/L MATC) for mortality was identified in the rainbow trout (EnviroSvstem. 1991). In a Bagrid catfish (Pseudobagrusfitlvidraco) feeding study, which used DBP concentrations of 100, 500, and 1000 mg DBP/kg diet, there was an observed significant reduction in body weight in fish that were fed 1000 mg/kg over 8-weeks resulting in an 8-week NOEC/LOEC of 500/1000 mg DBP/kg diet. Additionally, significant effects of acetylcholinesterase activity were observed in the brain at concentrations of 100 mg DBP/kg diet, in the liver, muscle, and kidney at 500 mg DBP/kg diet, in the heart at 1000 mg DBP/kg diet, and in gill tissue at 1000 mg DBP/kg diet. The authors stated that feeding was conducted at a rate of 3% body weight per day based on group biomass at Week 0 and Week 4. Based on this rate, the three given doses in dietary concentration (100/500/1000 mg DBP/kg diet) can be converted to a dose in terms of fish body weight as 3/15/30 mg DBP/kg-bw/day. No significant effects were observed in fish mortality during the 8-week period (Jee et al.. 2009). In the fathead minnow, a 20- day NOEC/LOEC of 0.53/0.97 mg/L and 0.97/1.74 mg/L were identified for hatching rate and larval survival, respectively (McCarthy and Whitmore. 1985). In a multi-generational Japanese medaka (Oryzias latipes) study, an LC50 of 0.82 mg/L was identified in embryos exposed (in an aqueous solution) to 0, 0.67, 0.74, 0.80, 1.0, and 1.3 mg/L DBP. In the F0 generation exposed to DBP concentrations of 0, 12, 65, and 776 mg/kg-bw/day via diet, egg production per female fish was significantly reduced at all test concentrations, however there were no significant effects on survival, growth, or sexual development. In the F1 and F2 generations, there were no effects on survival and growth, but there was an observed increase in hepatic vitellogenin levels in the F2 65 mg/kg-bw/day DBP group (12/65 mg/kg-bw/day NOEL/LOEL). Further, in the F1 and F2 generations, there was no egg production at the highest DBP dose (776 mg/kg-bw/day). (Patyna. 1999). In another multigenerational Japanese medaka study in which parental fish were aqueously exposed to DBP at concentrations of 0.015, 0.038, 0.066, 0.103, and 0.305 mg/L for 218 days, significant effects were observed in growth of both male and female F1 and F2 generations. In the male and female F1 generation (subadults), weight was significantly less when compared to controls at 70-days, resulting in NOEC/LOECs of 0.103/0.305 and 0.0387/0.066 mg/L in males and females, respectively. Additionally, in the female F2 generation (subadults), length was significantly less compared to controls at day 70, resulting in a NOEC/LOEC of 0.0156/0.0387 mg/L. Similarly, in the male and female F2 generation (adults), weight was significantly less compared to controls at 98-days, resulting in NOEC/LOECs of 0.103/0.305 and 0.0156/0.0387 mg/L in males and females, respectively. In this study, unbounded effects (unbounded LOEC) were also observed for growth at the lowest concentration tested. Specifically, male F1 adult weight at 112-days, male F2 adult weight and length at 70-days, and male F2 adult length at 98-days were significantly inhibited at 0.015 mg/L DBP (EAG Laboratories. 2018). Page 11 of 64 ------- PUBLIC RELEASE DRAFT December 2024 345 Table 2-2. Chronic Toxicity of DBP in Aquatic Vertebrates Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) African clawed frog (Xenopus laevis) 0.1 mg/L 30-week LOEC Growth (Lee and Veeramachaneni. 2005) (High) 2/10 mg/L 22-day NOEC/LOEC Growth (Shen et al.. 2011) (High) 0.00476/0.0134 mg/L 21-day NOEC/LOEC Growth (Battelle. 2018) (Hiah) Japanese wrinkled frog (Glandirana rugosa) 0.28/2.8 mg/L 21-day NOEC/LOEC Growth (Ohtani et al.. 2000) Medium) Zebrafish (Danio rerio) 0.1 mg/L 5-week LOEC Mortality (Ortiz-Zarraaoitia et al.. 2006) (Medium) Rainbow trout (iOncorhynchus mvkiss) 0.1/0.19 mg/L 99-day NOEC/LOEC Growth (Rhodes et al.. 1995) (High) 1.3 mg/L 13-day LC50 Mortality (EnviroSvstem. 1991) 0.52/1.0 mg/L 13-day NOEC/LOEC 0.28 mg/L 99-day MATC 0.19/0.40 mg/L 99-day NOEC/LOEC (High) 0.14 mg/L 99-day MATC Growth 0.10/0.19 mg/L 99-day NOEC/LOEC Bagrid catfish (Pseudobagrus fitlvidraco) 15/30 mg/kg- bw/day (feeding study) 8-week NOEC/ LOEC Growth (Jee et al.. 2009) (Hiah) Fathead minnow {Pimephales promelas) 0.53/0.97 mg/L 20-day NOEC/ LOEC Mortality - hatch rate (McCarthy and Whitmore. 1985) (Medium) 0.97/1.74 mg/L Mortality - larval survival Japanese medaka 0Oryzias latipes) <12/12 mg/kg- bw/day (Feeding study) 180-day LOEC Reproduction - F0 egg production per female (Patvna. 1999) (Hiah) 65/776 mg/kg- bw/day (Feeding study) 180-day NOEC/ LOEC Reproduction - F1 egg production per female 65/776 mg/kg- bw/day (Feeding study) 180-day NOEC/ LOEC Growth - weight, female F1 0.82 mg/L 17-day LC50 Mortality 0.103/0.305 mg/L 70-day NOEC/ LOEC Growth - weight, male F1 subadults (EAG Laboratories. 2018)(High) 0.0156/0.0387 Growth - length, Page 12 of 64 ------- 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) Japanese medaka 0Oryzias latipes) mg/L male F1 subadults 0.0387/0.066 mg/L Growth - weight, female F1 subadults 0.0156/0.0387 mg/L Growth - length, female F1 subadults <0.0156 mg/L/ 0.0156 mg/L 112-day LOEC Growth - weight, male F1 adults 0.0156/0.0387 mg/L 112-day NOEC/LOEC Growth - length, male F1 adults 0.066/0.103 mg/L Growth - weight and length, female F1 adults <0.0156 mg/L/ 0.0156 mg/L 70-day LOEC Growth - weight and length, male F2 subadults 0.0156/0.0387 mg/L 70-day NOEC /LOEC Growth - length and weight, female F2 subadults <0.0156 mg/L/ 0.0156 mg/L 98-day LOEC Growth - length, male F2 adults 0.103/0.305 mg/L 98-day NOEC /LOEC Growth - weight, male F2 adults 0.0156/0.0387 mg/L Growth - length and weight, female F2 adults Bolded values indicate hazard value used in determining concentration of concern (COC). 2.1.3 Acute Toxicity of DBP in Aquatic Invertebrates EPA reviewed 11 studies that received overall quality determinations of high or medium for acute toxicity in aquatic invertebrates (Table 2-3). Three studies received overall quality determinations of low or unacceptable and were not considered. All 11 of the high and medium quality studies contained acceptable chronic endpoints that identified definitive hazard values below the DBP limit of water solubility for 9 aquatic invertebrate species. Additionally, predicted hazard data for 53 species were generated using EPA's Web-ICE tool, including predictions for 31 aquatic vertebrates, 5 aquatic invertebrates, 16 benthic invertebrates, and 1 amphibian species. In the opposum shrimp, the mortality 96-hour LC50s ranged from 0.50 to 0.75 mg/L. Mortality was assessed at 48- and 72-hours, resulting in a 0.87 and 0.77 mg/L LC50, respectively (EG&G Bionomics. 1984b). In the water flea {Daphnia magna), the 48-hour mortality LC50s ranged from 2.55 to 5.2 mg/L (Wei et al.. 2018; McCarthy and Whitmore. 1985). In the water flea, additional endpoints of immobilization were also identified, resulting in 24-hour LC 50 of 8.0 mg/L and 48-hour EC50 of 2.99 mg/L. In Taiwan abalone (Haliotis diversicolor), at DBP concentrations of 0, 0.5, 0.2, 2.0, 10, and 15 mg/L, one study identified abnormal growth of embryos exposed to 10 mg/L DBP, resulting in a 96- hour NOEC/LOEC of 2.0/10 mg/L (Yang et al.. 2009). Another Taiwan abalone embryo study that Page 13 of 64 ------- 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 PUBLIC RELEASE DRAFT December 2024 utilized DBP concentrations of 0, 0.0017, 0.0207, 0.196, 1.984, 20.09, 9.22, and 39.47 mg/L demonstrated significant effects on embryonic development resulting in a 9-hour EC50 of 8.37 mg/L. Additionally, metamorphosis was found to be disrupted at 10 mg/L DBP resulting in a 96-hour NOEC/LOEC of 2.0/10 mg/L. Lastly, there was a significant increase in population growth and a negative effect on sexual reproduction in the rotifer {Brcichionus calyciflorus) with a resulting 0.5/1.0 mg/L 48-hour no-observed-adverse-effect-concentration (NOAEC)/lowest-observed-adverse-effect- concentration (LOAEC) and 1.0/2.0 mg/L 96-hour NOAEC/LOAEC, respectively (Cruciani et al.. 2015). The bolded values in Table 2-3 describe data which were used as inputs for generating Web-ICE predictions and within an SSD (Appendix B). Table 2-3. Acute Toxicity of DBP in Aquatic Invertebrates Test Organism (Species Hazard Values Endpoint Effect Citation (Study Quality) Opossum shrimp (Americamysis bcthia) 0.75 mg/L 96-hour LC50 Mortality (EG&G Bionomics. 1984b) 0.77 mg/L 72-hour LC50 Mortality 0.87 mg/L 48-hour LC50 Mortality 0.50 mg/L 96-hour LC50 Mortality (Adams et al.. 1995) (High) Water flea (Daphnict magna) 2.99 mg/L 48-hour EC50 Immobilization Taiwan abalone (Haliotis diversicolor) 2/10 mg/L 96-hour NOEC/ LOEC Development/Growth (Yane et al.. 2009) (Medium) Taiwan abalone (Haliotis diversicolor) 8.37 mg/L 9-hour EC50 Development/Growth (Liu et al.. 2009) (Medium) 0.0207/0.196 mg/L 96-hour NOEC/ LOEC Development/Growth - metamorphosis Water flea (Daphnia magna) 5.2 mg/L 48-hour LC50 Mortality (McCarthy and Whitmore. 1985) (Medium) 2.55 mg/L 48-hour LC50 Mortality (Wei et al.. 2018) (High) 4.31 mg/L Mortality 2.83 mg/L Mortality 8.0 mg/L 24-hour LC50 Immobilization (Huana et al.. 2016) (High) Rotifer (Brachionus calyciflorus) 1.0/2.0 mg/L 96-hour NOAEC/ LOAEC Reproduction (Cruciani et al.. 2015) 0.5/1.0 mg/L 48-hour NOAEC/ LOAEC Population (Medium) Bolded values indicate data used to derive acute aquatic COC using SSD. 2.1.4 Chronic Toxicity of DBP in Aquatic Invertebrates EPA reviewed 13 studies which received an overall quality determination of high or medium for chronic toxicity in aquatic invertebrates (Table 2-4). One study received an overall quality determination of low and was not considered. Of the 13 high and medium quality studies, 8 contained chronic endpoints that Page 14 of 64 ------- 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 PUBLIC RELEASE DRAFT December 2024 identified definitive hazard values below the DBP limit of water solubility for 10 aquatic invertebrate species. A 21-day mortality NOEC/LOEC of 0.96/2.5 mg/L and a 21-day mortality LC50 of 1.92 mg/L were identified in the water flea (Daphnia magna). Reproduction, population, development, and growth endpoints were also identified. For reproduction, there was an observed decrease of fecundity in three studies resulting in a range of NOEC/LOECs of 0.07/0.23 (number of days between eggs laid) to 1.05/1.92 mg/L (1.64 mg/L, 21-day EC50). In the water flea, there was also an observed reduction in population growth rate (total neonates) with a NOEC/LOEC of 0.42/0.48 mg/L and a reduction in development/growth (length) with a NOAEC/LOAEC of 0.278/2.78 mg/L (Wei et al.. 2018; Defoe et al.. 1990; Springborn Bionomics. 1984b). In the rotifer {Brachionus calyciflorus) at aqueous concentrations of 0, 0.000005, 0.00005, 0.0005, 0.005, 0.05, 0.5, and 5.0 mg/L, significant effects on mortality and reproductive rates were observed after 6 days, resulting in a NOEC/LOEC of 0.05/0.5 mg/L for both endpoints (Zhao et al.. 2009). Table 2-4. Chronic Toxicity of DBP in Aquatic Inverl ebrates Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) Water flea (Daphnia magna) 0.07/0.23 mg/L 21-day NOAEC/ LOAEC Reproduction - # days between egg laid (Wei et al.. 2018) (Hieh) <0.07/0.07 mg/L Reproduction - Fecundity 0.42/0.48 mg/L 21-day NOAEC/ LOAEC Population 0.278/2.78 mg/L 14-day NOAEC/ LOAEC Development/ Growth (Sevoum and Pradhan. 2019) (Medium) 0.96/2.5 mg/L 21-day NOAEC/ LOAEC Mortality (Sprineborn Bionomics. 1984b) (Medium) 0.96/2.5 mg/L 21-day NOAEC/ LOAEC Reproduction 1.92 mg/L 21-day LC50 Mortality (Defoe et al.. 1990) (Hiah) 1.64 mg/L 21-day EC50 Reproduction 1.05/1.91 mg/L 21-day NOAEC/ LOAEC Scud (Gammarus piilex) 0.1/0.5 mg/L 20-day NOAEC/ LOAEC Behavior (Thuren and Woin. 1991) (Medium) Amphipod crustacean (Corophium acherusicum) 0.044/0.34 mg/L 14-day NOAEC/ LOAEC Population - Abundance (Taaatz et al.. 1983) (Medium) Rotifer (Brachionus calyciflorus) 0.05/0.5 mg/L 6-day NOAEC/LOAEC Mortality (Zhao et al.. 2009) (Medium) Rotifer (Brachionus calyciflorus) 0.05/0.5 mg/L 6-day NOAEC/LOAEC Reproduction Bolded values indicate hazard value used in determining COC. Page 15 of 64 ------- 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 PUBLIC RELEASE DRAFT December 2024 2.1.5 Acute Toxicity of DBP in Benthic Invertebrates EPA reviewed four studies that received an overall quality determination of high or medium for acute toxicity in aquatic benthic invertebrates (Table 2-5). All four studies contained acute endpoints that identified definitive hazard values below the DBP limit of water solubility for three aquatic invertebrate species. In the harpacticoid copepod (Nitocra spinipes) and the midge (Paratcmytarsus parthenogeneticus), the 96-hour mortality LC50s ranged from 1.7 to 6.29 mg/L (Adams et al.. 1995; Linden et al.. 1979). In the midges (Paratcmytarsus parthenogeneticus and Chironomus plumosus), the 48-hour mortality LC50s ranged from 4.0 to 5.8 mg/L (EG&G Bionomics. 1984c; Streufort 1978). Table 2-5. Acute Toxicity of DBP in Aquatic Benthic Invertebrates Test Organism Hazard Values Endpoint Effect Citation (Study Quality) Harpacticoid copepod (Nitocra spinipes) 1.7 mg/L 96-hour LC50 Mortality (Linden et al.. 1979) (Medium) Midge (Paratanytarsus parthenogeneticus) 5.8 mg/L 48-hour LC50 Mortality (EG&G Bionomics. 1984c) (High) Midge (Paratanytarsus parthenogeneticus) 6.29 mg/L 96-hour LC50 Mortality (Adams et al.. 1995) (Hish) Midge (Chironomus plumosus) 4.0 mg/L 48-hour LC50 Mortality (Streufort. 1978) (Medium) Bolded values indicate data used to derive acute aquatic COC using SSD. 2.1.6 Chronic Toxicity of DBP in Benthic Invertebrates EPA reviewed five studies which received an overall quality determination of high or medium for chronic toxicity in benthic invertebrates (Table 2-6). All five studies contained acceptable chronic endpoints that identified definitive hazard values below the DBP limit of water solubility for six benthic invertebrate species. A study (Call et al.. 2001a) examining the effects of DBP in sediment pore water and sediment for high, medium, and low TOC (total organic carbon) in Hyalella azteca resulted in 10- day development/growth (decrease in weight compared to controls) NOEC/LOECs of 4.76/10.7 mg/L and 3,410/26,200 mg/kg, 4.20/12.9 mg/L and 748/3,340 mg/kg, and 0.70/4.59 mg/L and 41.6/360 mg/kg, respectively. In that study, there were no significant effects on H. azteca mortality. In the midge (Chironomus tentans), effects on mortality and growth were observed in the high, medium, and low TOC sediment groups. For high TOC, a 10-day NOEC/LOEC of 0.448/5.85 mg/L in sediment pore water and 508/3550 mg/kg in sediment was observed for an increase in weight. For medium TOC, a 10- day NOEC/LOEC of 3.85/16 mg/L in sediment pore water and 423/3090 mg/kg in sediment was observed for an increase in weight relative to controls. For mortality, the 10-day NOEC/LOEC for sediment pore water and sediment in high, medium, and low TOC was 0.448/5.85 mg/L and 508/3550 mg/kg, 3.85/16 mg/L and 423/3090 mg/kg, and 0.672/4.59 mg/L and 50.1/315 mg/kg, respectively (Call et al.. 2001a). Another benthic invertebrate study examined the effects of DBP aqueous exposures and observed significant effects in the midge and H. azteca. Specifically, in the midge, a 10-day growth and development (weight) NOEC/LOEC of 1.78/4.52 mg/L (2.81 mg/LEC50) and a 10-day mortality LC50 of 2.64 mg/L was observed. In H. azteca, a 10-day mortality LC50 of 0.63 mg/L was identified (Call et al.. 2001b). Page 16 of 64 ------- 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 PUBLIC RELEASE DRAFT December 2024 Lake Superior Research Institute (1997) also examined the effects of aqueous and sediment (high, medium, and low TOC) DBP exposures in the midge and the scud. Ten-day LC50s were calculated via multiple methods including Trimmed Spearman-Karber, probit analysis, and/or linear interpolation. In the midge, the high, medium, and low TOC pore water 10-day mortality LC50s ranged from 4.22 to 6.21 mg/L, 10.3 mg/L (one value), and 6.86 to 6.95 mg/L, respectively. The high, medium, and low TOC sediment 10-day mortality LC50s ranged from 4,730 to 5,213 mg/kg, 2,261 to 4,730 mg/kg, and 706 to 827 mg/kg, respectively. Most LC50s were unable to be calculated for the scud due to low mortality, however there was a calculated 10-day mortality LC50 of 52,363 mg/kg in the medium sediment TOC group. That study also conducted water only tests in which 10-day mortality LC50s for the midge ranged from 2.64 to 3.08 mg/L and 0.59 to 0.63 mg/L for the scud (Lake Superior Research Institute. 1997). In the mollusk (several species), segmented worm (several species), Actiniaria (unidentified species), and sea squirt (Molgula manhcittensis), the 14-day population (abundance and diversity) NOEC/LOECs were 0.34/3.7 mg/L. In the amphipod crustacean (Corophium acherusicum), the abundance NOEC/LOEC was slightly more sensitive at 0.044/0.34 mg/L (Tagatz et al.. 1983). Two additional endpoints were available in two studies for the worm (Lumbricuius variegatus) and the scud (Gammarus pulex). In the worm, a 2.48 mg/L (in water) 10-day LC50 was identified for mortality (Call et al.. 2001b). In the scud (Gammarus pulex), there was a significant effect on distance moved and changes in direction resulting in a 20-day NOAEC/ LOAEC of 0.1/0.5 mg/L (in water) (Thuren and Woin. 1991). Table 2-6. Chronic r "oxicity of DBP in Bent thic Invertebrates Test Organism (Species) and TOC Hazard Values Endpoint Effect Citation (Study Quality) Hvalella azteca high TOC 4.76/10.7 mg/L 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001a) (High) 3,410/26,200 mg/kg dry sediment Hyalella azteca Medium TOC 4.20/12.9 17 mg/L 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001a) (High) 748/ 3340 mg/kg dry sediment 52,363 mg/kg bulk sediment (Probit) 10-day LC50 Mortality (Lake Superior Research Institute. 1997)(Hiah) Hvalella azteca low TOC 0.70/4.59 mg/L 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001a) (High) 41.6/360 mg/kg dry sediment Midge (Chironomns ten tans) high TOC 6.12 mg/L (Probit) 10-day LC50 Mortality (Lake Superior Research Institute. 1997)(High) 6.21 mg/L (Linear Interpolation) 5,213 mg/kg (Linear Interpolation) 4.22 mg/L (Trimmed Spearman-Karber) 4,730 mg/kg (Trimmed Spearman-Karber) 0.448/5.85 mg/L 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001a) Page 17 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) and TOC Hazard Values Endpoint Effect Citation (Study Quality) Midge (Chironomus ten tans) high TOC 508/3,550 mg/kg dry sediment 10-day NOAEC/ LOAEC (High) 0.448/5.85 mg/L 10-day NOAEC/ LOAEC Mortality 4.22 mg/L 10-day LC50 508/3,550 mg/kg dry sediment 10-day NOAEC/ LOAEC 4,730 mg/kg diy sediment 10-day LC50 Midge (Chironomus tentcms) medium TOC 2,261 mg/kg dry sediment (Linear Interpolation) 10-day LC50 Mortality (Lake Superior 10.3 mg/L (Trimmed Speannan-Karber) Research Institute. 1997)(High) 4,730 mg/kg (Trimmed Speannan-Karber) 423/3,090 mg/kg diy sediment 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001a) (High) 3.85/16 mg/L 10-day NOAEC/ LOAEC 423/3,090 mg/kg diy sediment 10-day NOAEC/ LOAEC Mortality 1,664 mg/kg dw 10-day LC50 3.85/16 mg/L 10-day NOAEC/ LOAEC 10.3 mg/L 10-day LC50 Midge (Chironomus tentcms) low TOC 6.95 mg/L (Trimmed Speannan-Karber) 10-day LC50 Mortality (Lake Superior Research Institute. 1997)(Hiah) 827 mg/kg (Trimmed Speannan-Karber) 6.88 mg/L (Probit) 820 mg/kg (Probit) 6.86 mg/L (Linear Interpolation) 706 mg/kg dry sediment (Linear Interpolation) 0.672/4.59 mg/L 10-day NOAEC/ LOAEC (Call et al.. 2001a) (High) 50.1/315 mg/kg diy sediment 10-day NOAEC/ LOAEC Midge (Chironomus tentcms) 1.78/4.52 mg/L 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001b) (High) 2.81 mg/L 10-day EC50 2.64 mg/L 10-day LC50 Mortality Page 18 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) and TOC Hazard Values Endpoint Effect Citation (Study Quality) Hyalella azteca 0.63 mg/L 10-day LC50 Mortality (Call etal.. 2001b) (High) Midge (Chironomus tentcms) water only test 2.64 mg/L (Trimmed Speannan-Karber) 10-day LC50 Mortality (Lake Superior Research Institute. 1997)(High) 3.08 mg/L (Linear Interpolation) Hyalella Azteca water only test 0.63 mg/L (Trimmed Speannan-Karber) 10-day LC50 Mortality (Lake Superior 0.62 mg/L (Probit) Research Institute. 1997)(High) 0.59 mg/L (Linear Interpolation) Mollusk (several species) 0.34/3.7 mg/L 14-day NOAEC/ LOAEC Population - Abundance and Diversity (Taeatz et al.. 1983) (Medium) Segmented worm (several species) 0.34/3.7 mg/L 14-day NOAEC/ LOAEC Population - Abundance and Diversity Amphipod crustacean (Corophium acheriisicum) 0.044/0.34 mg/L 14-day NOAEC/ LOAEC Population - Abundance Actiniaria (unidentified species) 0.34/3.7 mg/L 14-day NOAEC/ LOAEC Population - Diversity Sea squirt (Molgula manhattensis) 0.34/3.7 mg/L 14-day NOAEC/ LOAEC Population - Abundance and Diversity Worm (Lumbricuius variegatus) 2.48 mg/L 10-day LC50 Mortality (Call etal.. 2001b) (High) Scud (Gammarus pulex) 0.1/0.5 mg/L 20-day NOAEC/ LOAEC Behavior (Thuren and Woin. 1991) (Medium) TOC = total organic carbon " Value slightly greater than DBP water solubility. Species included for mollusk are Diastema varium. Laevicardium mortoni, Tellina sp.,Anomalocardia auberiana, Marginella apicina, Morula didyma, Anadara transversa, Mitrella lunata, Crassostrea virginica, Eupleura sulcidentata, Mangelia quadrata, Thais haemastoma, Bursatella leachii pleii, Atrina rigida. and Polinices duplicatus. Species included for the segmented worm include Haploscoloplos robustus, Tharvx marioni, Loimia viridis, Scoloplos rubra, Mediomastus californiensis, Malacoceros vanderhorsti, Aricidea fragilis, Arm an di a agilis,Axiothella mucosa, Nephtvs picta, Prionospio heterobranchia, Unidentified Sabcllidac.. Imphictene sp., Galathowenia sp., Glycera americana, Lumbrineris sp..Magelona rosea, Minuspio sp., Neanthes succinea, and Pectinaria gouldii. Bolded values indicate hazard value used in determining COC. 450 2.1.7 Toxicity of DBP in Aquatic Plants and Algae 451 EPA reviewed seven studies which received overall quality determinations of high or medium for 452 toxicity in aquatic plants and algae (Table 2-7). Three studies received overall quality determinations of 453 low or unacceptable and were not considered. Of the 7 high and medium quality studies, 3 contained 454 acceptable endpoints that identified definitive hazard values below the DBP limit of water solubility for 455 one species of green algae (Selenastrum capricormitum). A 10-day static toxicity test examined the 456 percent increase or decrease of chlorophyll a at DBP concentrations of 0.05, 0.08, 0.13, 0.39, 0.77, and 457 1.45 mg/L. Chlorophyll a was found to increase slightly at lower concentrations, then decreased at 458 higher concentrations with an observed 100 percent decrease in chlorophyll a at 1.45 mg/L DBP Page 19 of 64 ------- 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 PUBLIC RELEASE DRAFT December 2024 resulting in a 10-day EC50 of 0.75 mg/L. The study authors noted that there was considerable loss of phthalate esters from the test solutions and thus the EC50 values were calculated based on concentrations measured at the beginning of the study (Springborn Bionomics. 1984c). Two other studies examined the effects of DBP on S. capricornutum abundance. Adams et al. (1995) identified a 96-hour EC50 of 0.40 in S. capricornutum with DBP concentrations ranging from 0.21 to 377 mg/L and Adachi et al. (2006) identified a 96-hour NOEC/LOEC of 0.1/1.0 mg/L in S. capricornutum at concentrations ranging from 0.1 to 10 mg/L. Table 2-7. Toxicit y of DBP in Aquatic Plants and Algae Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) Green algae (Selenastrum capricornutum) 0.75 mg/L 10-day EC50 Population (Chlorophyll a concentration) (SDrinsborn Bionomics. 1984c) (High) 0.40 mg/L 96-hour EC50 Population (Abundance) (Adams et al.. 1995) (High) 0.1/1 mg/L 96-hour NOEC/ LOEC Population (Abundance) (Adachi et al.. 2006) (Medium) Bolded values indicate hazard value used in determining COC. 2.2 Terrestrial Species EPA reviewed 35 studies for DBP toxicity to terrestrial organisms. Some studies may have included multiple endpoints, species, and test durations. Of these 35 studies, those that received an overall quality determination of low or uninformative were not considered for quantitative risk evaluation. For the 30 studies that received an overall quality determination of high and medium, those that demonstrated no acute or chronic adverse effects at the highest dose tested (unbounded NOAELs) are listed in Appendix C and were excluded from consideration for development of hazard thresholds. In addition to the 30 high or medium quality terrestrial wildlife studies, EPA considered 13 terrestrial vertebrate studies for toxicity to DBP in human health animal model rodent species that contained ecologically relevant reproductive endpoints (TableApx C-7). 2.2.1 Toxicity of DBP in Terrestrial Vertebrates No reasonably available information was identified for exposures of DBP to mammalian wildlife. EPA reviewed 13 studies for toxicity to DBP in human health animal model rodent studies that contained ecologically relevant reproductive endpoints (Table Apx C-7). EPA's decision to focus on ecologically relevant (population level) reproductive endpoints in the rat and mouse data set for DBP for consideration of a hazard threshold in terrestrial mammals is due to the known sensitivity of these taxa to DBP in eliciting phthalate syndrome (U.S. EPA. 2024b). Of the 13 rat and mouse studies containing ecologically relevant reproductive endpoints, EPA selected the study with the most sensitive LOAEL for deriving the hazard threshold for terrestrial mammals (Table 2-8). The most sensitive endpoint resulted from a Sprague-Dawley rat (Rattus norvegicus) study in which a 17-week LOAEL for significant reduction in number of live pups per litter was observed at 80 mg/kg-bw/day DBP intake in dams (NTP. 1995). Page 20 of 64 ------- 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 PUBLIC RELEASE DRAFT December 2024 Table 2-8. Toxicit y of DBP to Terrestrial Vertebrates Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) Rat (Rattus norvegicus) 80 mg/kg-bw/day 17-week LOAEL Reproduction (NTP. 1995) (Hieh) 2.2.2 Toxicity of DBP in Soil Invertebrates EPA reviewed 14 studies that received an overall quality determination of high or medium for acute toxicity in soil invertebrates (Table 2-9). One study received an overall quality determination of low and was not considered. Of the 14 high and medium quality studies, 12 contained acute endpoints that identified definitive hazard values below the DBP limit of water solubility for five soil invertebrate species. In the European house dust mite {Dermatophagoides pteronyssinus), American house dust mite (Dermatophagoides farina), and copra mite (Tyrophagusputrescentiae), the 24-hour mortality LC50s with fabric contact to DBP were found to range from 0.017 to 0.03 mg/cm2 and 0.077 to 0.079 mg/cm2 (LD50s) via direct application of DBP (Wang et al.. 2011; Kim et al.. 2008. 2007; Kang et al.. 2006; Tak et al.. 2006; Kim et al.. 2004). In the earthworm (Eiseniafetida), the 48-hour mortality LC50 via DBP on filter paper ranged from 1.3 to 6.8 mg/cm2 (Du et al.. 2015; Neuhauser et al.. 1985). Because filter paper contact is not considered a relevant exposure pathway for soil invertebrates due to the absorbed amount of chemical via dermal contact being uncertain, EPA did not establish a hazard threshold from the filter paper data set. In the nematode (Caenorhabditis e/egans), the 24-hour reproduction NOEC/LOEC were 2.783/27.83 mg/L and 27.83/139.17 mg/L for hatching rate and brood size, respectively. Specifically, nematodes exposed to DBP at concentrations of 0.0278, 2.78, 27.8, and 139 mg/L experienced an increase in embryonic lethality (reduced hatch rate) at 27.8 mg/L and a decrease in mean number of eggs laid at 139 mg/L (Shin et al.. 2019). In the springtail (Folsomiaflmetarid), the 21-day mortality LC10 and LC50 for juveniles was 11.3 and 19.4 mg/kg, respectively, and 33 and 305 mg/kg, respectively, for adults. Adult springtail reproduction was also significantly affected with an observed 21-day EC10 and EC50 of 14 and 68 mg/kg (Jensen et al.. 2001). A 14-day earthworm {Eisenia fetida) study identified a mortality LC50 of 2,364.8 mg/kg. In this study, mechanistic endpoints were also observed; superoxide dismutase and catalase were found to be significantly reduced at 100 mg/kg DBP on day 28; glutathione-S-transferase was increased after day 21 in the 10 to 50 mg/kg DBP group; glutathione was found to increase on days 7 to 28 in the 50 mg/kg DBP group; and malondialdehyde was greater in all dosage groups and time frames compared to controls (Du et al.. 2015). Table 2-9. Toxicity of DBP in Soil Invertebrates Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) European house dust mite (Dermatophagoides pteronyssinus) 0.07779 mg/cm2 (Direct application) 24-hour LD50 Mortality (Kans et al.. 2006) (Medium) 0.02323 mg/cm2 (Fabric contact) 24-hour LC50 (Wans et al.. 2011) (Medium) 0.02851 mg/cm2 (Fabric contact) 24-hour LC50 (Kim et al.. 2008) (Medium) Page 21 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) 0.03159 mg/cm3 (Fabric contact) 24-hour LC50 (Kim et al.. 2004) (Medium) 0.01881 mg/cm2 (Fabric contact) 24-hour LC50 (Kim et al.. 2007) (Medium) American house dust mite (Dermatophagoides farina) 0.07954 mg/cm2 (Direct application) 24-hour LD50 Mortality (Kana et al.. 2006) (Medium) 0.02189 mg/cm2 (Fabric contact) 24-hour LC50 (Wans et al.. 2011) (Medium) 0.0281 mg/cm2 (Fabric contact) 24-hour LC50 (Kim et al.. 2008) (Medium) 0.03392 mg/cm3 (Fabric contact) 24-hour LC50 (Kim et al.. 2004) (Medium) 0.01739 mg/cm2 (Fabric contact) 24-hour LC50 (Kim et al.. 2007) (Medium) Copra mite (Tyrophagns putrescentiae) 0.02523 mg/cm2 (Fabric contact) 24-hour LC50 Mortality (Tak et al.. 2006) (Medium) Earthworm (Eisenia fetida) 6.8 mg/cm2 (Filter paper) 48-hour LC50 Mortality (Du et al.. 2015) (Medium) 1.360 mg/cm2 (Filter paper) 48-hour LC50 Mortality (Neuhauser et al.. 1985) (Medium) Nematode (Caenorhabditis elegans) 2.783/27.83 mg/L in solution 24-hour NOEC/LOEC Reproduction (Hatch rate) (Shin et al.. 2019) (Hieh) 27.83/139.17 mg/L in solution 24-hour NOEC/LOEC Reproduction (Brood size) Springtail (Folsomia fimetaria) - Juvenile 11.3 mg/kg dry soil 21-day LC10 Mortality (Jensen et al.. 2001) (Hieh) 19.4 mg/kg dry soil 21-day LC50 Springtail (Folsomia fimetaria) - Adult 33 mg/kg dry soil 21-day LC10 305 mg/kg dry soil 21-day LC50 14 mg/kg dry soil 21-day EC10 Reproduction 68 mg/kg dry soil 21-day EC50 Earthworm {Eisenia fetida) 2364.8 mg/kg dry soil 14-day LC50 Mortality (Du et al.. 2015) (Medium) Bolded values indicate hazard value used in determining a hazard value. 524 2.2.3 Toxicity of DBP in Terrestrial Plants 525 EPA reviewed 12 studies that received an overall quality determination of high or medium for hazard in 526 terrestrial plants (Table 2-10). Three studies received overall quality determinations of low or Page 22 of 64 ------- 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 PUBLIC RELEASE DRAFT December 2024 unacceptable and were not considered. Of the 12 high and medium quality studies, 6 contained acceptable endpoints that identified definitive hazard values for 10 terrestrial plant species. The main endpoint observed to be affected by exposure to DBP was growth. In the dutch clover (Trifolium repens), turnip (Brassica rapa ssp. rapa), rippleseed plantain (Plantago major), and velvetgrass {Holcus lanatus), there was an observed reduction in total biomass after DBP administration via fumigation, resulting in a 62-day growth EClOs of 0.00033, 0.00077, 0.00239, 0.00879 mg/m3, respectively. Similarly, in the common bean {Phaseolus vulgaris) that was harvested after 42 days, there was an observed reduction in total biomass resulting in an EC 10 of 0.00232 mg/m3 (Dueck et al.. 2003). Because fumigation is not considered a relevant exposure pathway for soil invertebrates due to the exposure of the amount of chemical being uncertain, EPA did not establish a hazard threshold from the fumigation data set. For plants exposed to DBP via soil, there was an observed reduction in biomass resulting in a 72-hour EC50, 72-hour NOEC/LOEC, and 45-day NOEC/LOEC of 1,559 mg/kg, 5/20 mg/kg, and 10/100 mg/kg in mung bean (Vigna radiata), bread wheat (Triticum aestivum), and false bok choy {Brassicaparachinensis), respectively (Zhao et al.. 2016; Ma et al.. 2015; Ma et al.. 2014). Unbound LOAECs were also observed in which significant effects on growth were observed at the lowest concentration tested. Specifically, in the common onion {Allium cepa), alfalfa {Medicago sativa), radish (Raphamts sativus), cucumber (Cucumis sativus), and common oat (Avena sativa), growth was significantly less compared to controls at 5 mg/kg soil (Ma et al.. 2015). In false bok choy there were also observed mechanistic effects including a reduction in chlorophyll content, intercellular CO2 concentration, and catalase, as well as an increase in malondialdehyde—all of which resulted in a NOEC/LOEC of 10/100 mg/kg (Zhao et al.. 2016). In bread wheat exposed to DBP at concentrations of 0, 5, 10, 20, 30, and 50 mg/L, significant decreases in the growth of roots and shoots up until germination were identified resulting in growth EClOs and EC50s of 5.08 and 37.70 mg/L and 8.02 and 42.73 mg/L, respectively. Additionally, seed germination was inhibited by DBP and was found to be 76.51 percent at 40 mg/L (Gao et al.. 2017). Similarly, a 40- day LOEL of 10 mg/kg DBP (lowest concentration used in the study) for reduced weight in bread wheat was observed (Gao et al.. 2019). In rapeseed {Brassica napus), a reduction in weight was also observed at the lowest concentration used in the study resulting in an unbound LOEC of 50 mg/kg (Kong et al.. 2018). Lastly, in the Chinese sprangletop {Leptochloa chinensis) and rice {Oryza sativa) exposed to DBP concentrations of 1.2, 2.4, and 4.8 kg/ha via soil surface, there was an observed reduced seedling growth (emergence) and weight in sprangletop resulting in a 14-day NOEC/LOEC of 1.2/2.4 kg/ha and reduced root length, shoot height, and weight in rice resulting in a 14-day NOEC/LOEC 2.4/4.8 kg/ha (Chuahet al.. 2014). Table 2-10. Toxicity of DBP in Terrestrial Plants Test Organism Hazard Values Endpoint Effect Citation (Species) (Study Quality) Dutch clover 0.00033 mg/m3 62-day EC 10 Growth {Trifolium repens) (Fumigation) Turnip {Brassica rapa ssp. rapa) 0.00077 mg/m3 (Fumigation) 62-day EC 10 Growth Rippleseed plantain {Plantago major) 0.00239 mg/m3 (Fumigation) 62-day EC 10 Growth (Dueck et al.. 2003) (High) Velvetgrass {Holcus lanatus) 0.00879 mg/m3 (Fumigation) 62-day EC 10 Growth Common bean 0.00232 mg/m3 42-day EC 10 Growth Page 23 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) Hazard Values Endpoint Effect Citation (Study Quality) (Phctseolus vulgaris) (Fumigation) Mung bean (Vigna radiata) 1559 mg/kg dry soil 72-hour EC50 Growth (Maetal.. 2014) (Medium) Common onion (Allium cepct) <5 mg/kg soil/5 mg/kg soil 168-hour LOEC Growth (Maetal.. 2015) Alfalfa (Medicctgo sativa) <5 mg/kg soil/5 mg/kg soil 72-hour LOEC Radish (Raphanus sativus) <5 mg/kg soil/5 mg/kg soil Cucumber (Cucumis sativus) <5 mg/kg soil/5 mg/kg soil (High) Common oat (Avert a sativa) <5 mg/kg soil/5 mg/kg soil Bread wheat (Triticum aestivum) 5/20 mg/kg soil 72-hour NOEC/ LOEC 5.08 mg/L Until germination EC10 Growth (Roots) (Gao et al.. 2017) (High) 37.70 mg/L Until germination, EC50 8.02 mg/L Until germination EC10 Growth (Shoots) 42.73 mg/L Until germination EC50 30/40 mg/L Until germination NOEC/LOEC Reproduction (Germination) <10 mg/kg dry soil/10 mg/kg dry soil 40-day LOEL Growth (Gao et al.. 2019) (High) False bok choy (Brassica parachinensis) 10/100 mg/kg dry soil 45-day NOAEC/ LOAEC Growth (Zhao et al.. 2016) (Medium) Chinese sprangletop (Leptochloa chinensis) 1.2/2.4 kg/ha 14-day NOEC/ LOEC Growth (Chuah et al.. 2014) (Medium) <500 mg/L 7-day LOEC Reproduction (Germination) Rice (Oryza sativa) 2.4/4.8 kg/ha 14-day NOEC/ LOEC Growth Rapeseed (Brassica napus) <50 mg/kg dry soil/50 mg/kg dry soil 30-day LOEC Growth (Kona et al.. 2018) (Medium) Bolded values indicate hazard value used in determining a hazard value. 564 2.3 Hazard Thresholds 565 EPA calculates hazard thresholds to identify potential concerns to aquatic and terrestrial species. After 566 weighing the scientific evidence, EPA selects the appropriate toxicity value from the integrated data to 567 use for hazard thresholds. See 0 for more details about how EPA weighed the scientific evidence and Page 24 of 64 ------- 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 PUBLIC RELEASE DRAFT December 2024 Section 2.4 for the weight of scientific evidence conclusions. 2.3.1 Acute Aquatic Concentration of Concern For aquatic species EPA uses probabilistic approaches (e.g., an SSD) when enough data are available, and deterministic approaches (e.g., deriving a geometric mean of several comparable values) when more limited data are available. An SSD is a type of probability distribution of toxicity values from multiple species. It can be used to visualize which species are most sensitive to a toxic chemical exposure, and to predict a concentration of a toxic chemical that is hazardous to a percentage of test species. This hazardous concentration is represented as an HCP, where p is the percent of species below the threshold. EPA used an HCos (a Hazardous Concentration threshold for 5% of species) to estimate a concentration that would protect 95 percent of species. This HCos can then be used to derive a COC, which is the estimated hazardous concentration of DBP in water for aquatic organisms. For the deterministic approaches, COCs are calculated by dividing a hazard value by an assessment factor (AF) according to EPA methods (U.S. EPA. 2016. 2014. 2012). However, for the probabilistic approach used for acute aquatic hazard in this TSD, the lower bound of the 95 percent confidence interval (CI) of the HCos can be used to account for uncertainty instead of dividing by an AF. EPA has more confidence in the probabilistic approach when enough data are available because an HCos is representative of a larger portion of species in the environment. Generally, EPA considers the probabilistic approach for aquatic hazard (i.e., an SSD) appropriate when hazard values for at least eight species are represented in the data set. The aquatic acute COC for DBP was derived from an SSD that contained 96-hour LC50s for 9 species identified in systematic review, bolstered by an additional 53 predicted LC50 values from the Web-ICE v4.0 toxicity value estimation tool. Web-ICE (Web-based Interspecies Correlation Estimation) is a tool developed by U.S. EPA's Office of Research and Development that estimates the acute toxicity of a chemical to a species, genus, or family from the known toxicity of the chemical to a surrogate species. It was used to obtain estimated acute toxicity values for DBP in species that were not represented in the empirical data set. All empirical studies included in the SSD were rated high or medium quality. After reviewing the possible statistical distributions for the SSD, the maximum likelihood method was chosen with a Gumbel distribution. This choice was based on an examination of p-values for goodness of fit, visual examination of Q-Q plots, and evaluation of the line of best fit near the low-end of the SSD. The HC05 for this distribution is 414.9 |ig/L DBP. After taking the lower 5th percentile of this HC05 as an alternative to the use of assessment factors, the acute aquatic COC for vertebrates and invertebrates is 347.6 |ig/L DBP. See Appendix B for details of the SSD that was used to derive the acute aquatic COC for DBP. The multiomics-based PODs derived by EPA in Bencic et al. (2024) suggest that Pimephalespromelas (fathead minnow) larvae exhibited changes in gene expression, metabolite levels, and swimming behavior at concentrations of DBP near the SSD-derived COC. EPA did not use the multiomics-based PODs for hazard thresholds because it is uncertain if these sub-organismal and individual-level effects (e.g., behavior) at short exposure durations scale up to ecologically relevant outcomes, such as survival and reproduction, in wild fish populations. Notably, the PODs derived from the multiomics study are similar to the SSD-derived acute aquatic COC (Table 2-11). This provides additional confidence in the acute aquatic COC for DBP, as the multiomics approach resulted in a similar hazard value to that derived from empirical and modeled data in the SSD. Page 25 of 64 ------- 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 PUBLIC RELEASE DRAFT December 2024 Table 2-11. Acute Aquatic COC and Multiomics PODs Acute Aquatic COC (SSD-Derived) Transcriptomic POD Metabolomic POD Behavioral POD 347.6 jig/L 120 jig/L 110 (ig/L 240 jig/L 2_.3.2 Chronic Aquatic Vertebrate Concentration of Concern EPA reviewed 17 studies on chronic toxicity in aquatic vertebrates. The most sensitive organism for which a clear population-level fitness endpoint could be obtained was for Japanese medaka (O. latipes) (EAG Laboratories. 2018). This study was rated high quality. In this multi-generational study, the growth of the F1 and F2 generations of fish was significantly affected by exposure to DBP. In male F1 generation Japanese medaka, there was a significant inhibition of body weight at the lowest concentration studied, with an unbounded LOEC value of 15.6 |ig/L DBP. The ChV (Chronic value, the geometric mean of the NOEC and LOEC) for bodyweight inhibition in female F1 generation Japanese medaka was 82.4 |ig/L DBP. In the F2 generation, the ChV for bodyweight inhibition in male fish was 177.2 |ig/L DBP, while the ChV for bodyweight inhibition in F2 female fish was 24.6 |ig/L DBP. The most sensitive of these endpoints is the unbounded LOEC for inhibition of bodyweight in F1 males at 15.6 |ig/L DBP. At the lowest dose (15.6 |ig/L), bodyweight was inhibited by 13.4 percent relative to the vehicle control, and there was a statistically significant trend toward greater bodyweight inhibition with increasing dose, culminating at 34.0 percent inhibition at the highest dose (305 |ig/L). Based on the presence of a statistically significant dose-response relationship and a population-level fitness endpoint, the 112-day ChV for bodyweight inhibition in F1 male Japanese medaka was selected to derive the chronic COC for aquatic vertebrates. Because the most sensitive endpoint in this study was an unbounded LOEC, an AF of 10 was applied. This is to account for the uncertainty in the actual threshold dose, which may have been lower than the lowest dose studied. After applying an AF of 10, the chronic COC for aquatic vertebrates is 1.56 |ig/L DBP. ^.3.3 Chronic Aquatic Invertebrate Concentration of Concern EPA reviewed 13 studies on chronic toxicity from DBP in aquatic invertebrates. The most sensitive organism for which a clear population-level fitness endpoint could be obtained was for the marine amphipod crustacean Monocorophium acherusicum (Tagatz et al.. 1983). with a 14-day ChV of 122.3 |ig/L DBP for reduction in population abundance. Populations were reduced by 91 percent at the LOEC, which was 340 |ig/L DBP. Higher doses resulted in a complete loss of amphipods in the aquaria. This study was rated medium quality. Based on the presence of a clear dose-response relationship and a population-level fitness endpoint, the 14-day ChV for reduction in population abundance in the marine amphipod crustacean was selected to derive the chronic COC for aquatic invertebrates. After applying an AF of 10, the chronic COC for aquatic invertebrates is 12.23 |ig/L DBP. 2.3.4 Acute Benthic Concentration of Concern Acute toxicity data from three empirical studies, representing LC50 estimates for three species of benthic invertebrates, were included in the SSD for acute aquatic organisms. The acute aquatic COC (see Section 2.3.1), because it was derived from an SSD that contained empirical LC50 data for benthic invertebrates as well as WeblCE-derived predicted LC50s for additional benthic species including worms (Lumbriculus variegatus), snails (Physella gyrina, Lymnaea stagricilis), and copepods (Tigriopus jciponicus), is expected to encompass the level of concern for benthic invertebrates as well. The acute benthic invertebrate COC is therefore 347.6 |ig/L DBP in water. There were no studies available to Page 26 of 64 ------- 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 PUBLIC RELEASE DRAFT December 2024 characterize the acute toxicity of DBP in sediment to benthic invertebrates; therefore, no COC was derived for the sediment exposure pathway. 2.3.5 Chronic Benthic Concentration of Concern EPA reviewed five studies on chronic toxicity from DBP in benthic invertebrates. Of these, the most sensitive was the midge (Chironomus tentans) (Lake Superior Research Institute. 1997). with a 10-day ChV for population loss of 1,143.3 mg DBP/kg dry sediment in medium-TOC sediments (4.80% TOC). This study was rated high quality. This ChV was the middle of three for the midge; the experiment was repeated with low, medium, and high TOC sediments and toxicity decreased with the increase in TOC, as expected for a relatively hydrophobic compound like DBP based on equilibrium partitioning theory. The chosen endpoint for deriving the COC, medium-TOC, was selected because it is the closest to the assumed TOC level (4%) used in Point Source Calculator to estimate DBP exposure in benthic organisms. Population was reduced by 76.7 percent at the LOEC, which was 3,090 mg DBP/kg dry sediment. Higher doses resulted in a similar degree of population loss in the medium-TOC treatment; however, all population losses were significantly different from controls. This endpoint was considered acceptable to derive a COC because of population-level relevance and a demonstrated dose-response relationship. After applying an AF of 10 to the ChV at 1,143.3 mg/kg, the chronic COC for benthic invertebrates is 114.3 mg DBP/kg dry sediment. 2.3.6 Aquatic Plant and Algae Concentration of Concern EPA reviewed six studies on toxicity from DBP in aquatic plants and algae. Of these, the most sensitive was green algae (Selenastrum capricornntam) (Adachi et al.. 2006) with a 96-hour ChV of 316 |ig/L DBP for reduced population abundance. This study was rated medium quality. There was significant reduction in the algal population at the LOEC, which was 1,000 |ig/L DBP, relative to an increase in the algal population at the NOEC of 100 |ig/L DBP and in controls. The population reduction was increased with a higher dose of DBP. Therefore, this endpoint was considered acceptable to derive a COC because of population-level relevance and a demonstrated dose-response relationship. After applying an AF of 10, the COC for aquatic plants and algae is 31.6 |ig/L DBP. 2.3.7 Terrestrial Vertebrate Hazard Value EPA reviewed 15 studies on toxicity from DBP in terrestrial vertebrates. Of these, the most sensitive among acceptable-quality studies was the Sprague-Dawley rat (Rattus norvegicus) (NTP. 1995). with a 17-week LOAEL for significant reduction in number of live pups per litter at 80 mg/kg-bw/day DBP intake in dams. This study was assigned an overall quality determination of high. The above referenced study also found a LOAEL for reduced bodyweight in F2 pups at the same dose (80 mg/kg-bw/day). The lowest bounded NOAEL/LOAEL pair for which a ChV could be calculated was significantly reduced bodyweight in F1 pups at a ChV of 115.4 mg/kg-bw/day, but this effect was not as sensitive as reduced number of live pups per litter. Other effects of DBP exposure included significantly decreased female body weight in dams, significantly reduced male sex ratio (percentage of male pups), significantly decreased mating index and pregnancy index in the F1 generation, and significantly reduced male pup weight gain. Because the most sensitive endpoint in this study was an unbounded LOAEL, the actual threshold dose may have been lower than the lowest dose studied. However, no information was available in the study to adjust the value to account for this uncertainty. Other reproductive endpoints for which bounded NOAEL/LOAEL pairs were observed in rats and mice (see Table Apx C-7) indicated ChV that were higher than this unbounded LOAEL; therefore, it is not clear whether an adjustment for uncertainty is necessary to adequately characterize the toxicity of DBP to terrestrial mammals. Based on reduction in Page 27 of 64 ------- 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 PUBLIC RELEASE DRAFT December 2024 live pups per litter, the results found in NTP (1995) indicated that toxicity in terrestrial vertebrates occurs at 80 mg/kg-bw/day. 2.3.8 Soil Invertebrate Hazard Value EPA reviewed 10 studies on acute toxicity from DBP in terrestrial invertebrates; however, the majority (8 of the 10 studies identified) focused on the use of DBP as a pesticide fumigant and the DBP dose that was experienced by the invertebrates studied could not be determined from the available data. There were two studies identified for which doses could be determined—for the fruit fly (Drosophila melcmogaster) (Misra et al.. 2014) and the nematode (Caenorhabditis elegans) (Shin et al.. 2019). Both studies were rated medium quality. For the fruit fly, the 72-hour LC50 value in feed (an agar-grape juice solution) was 505,100 mg/L. This exposure was not considered ecologically relevant, as the dose would need to be present in fruit at a concentration that is not possible based on the physicochemical properties of DBP. Such a fruit would be nearly 33 percent DBP by mass. For the nematode, after 24-hours there was no significant mortality observed at any dose examined up to the NOEL of 139.17 mg/L DBP in a buffered water solution. However, this study did not observe any effect of DBP at any dose examined; therefore, this exposure is not appropriate for use in calculating a hazard value. The same study also examined hatch rate in the nematode (Caenorhabditis elegans) on agar plates and had a 24-hour ChV of 8.8 mg/L DBP in agar. However, the magnitude of this effect was small even at the highest DBP dose (an increase in embryonic mortality from approximately 3 to 8%), and it was unclear whether a change of this magnitude has a population-level relevance. Therefore, this study was not considered acceptable to derive a hazard threshold. EPA reviewed two studies on chronic toxicity from DBP in soil invertebrates. Of these, the most sensitive was the springtail (Folsomiafimetaria) (Jensen et al.. 2001) with a 21-day EC 10 of 14 mg DBP/kg dry soil for reduced reproduction. This study was rated high quality. Reproduction was reduced by approximately 60 percent at the lowest concentration tested, which was 100 mg DBP/kg dry soil, with reproduction completely eliminated at higher doses. Therefore, this endpoint was considered acceptable to derive a hazard value because of population-level relevance and a clear dose-response relationship. The hazard value for soil invertebrates is calculated as the geometric mean of ChV, EC20, and EC 10 values for mortality, reproduction, or growth endpoints from acceptable studies. Because the data set contained one EC10 for reproduction of 14 mg DBP/kg dry soil, this value will be used as the hazard value for soil invertebrates. 2.3.9 Terrestrial Plant Hazard Value EPA reviewed 12 studies on toxicity from DBP in vascular plants. An unbounded LOEL for growth at 10 mg DBP/kg dry soil was obtained in a study rated high quality for a 40-day exposure in bread wheat (Triticum aestivam) (Gao et al.. 2019). and at 50 mg DBP/kg dry soil for rapeseed (Brassica napus) in a medium quality study (Kong et al.. 2018). The most sensitive endpoint was the LOEL for reduction in leaf and root biomass in bread wheat seedlings observed in Gao et al. (2019). which was 10 mg/kg dry soil. There was a clear dose-response observed, with biomass reduction increasing as the dose of DBP increased. At the highest dose (40 mg/kg), root and leaf biomass were reduced by 29.93 and 32.10 percent, respectively. Because the most sensitive endpoint in this study was an unbounded LOAEL, the actual threshold dose may have been lower than the lowest dose studied. However, no information was available in the study to adjust the value to account for this uncertainty. The HV for terrestrial plants for DBP derived from this study is 10 mg/kg dry soil. The most sensitive ChV expressed in water concentration (mg/L) was calculated for growth inhibition Page 28 of 64 ------- 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 PUBLIC RELEASE DRAFT December 2024 for a 42-day exposure in bok choy (Brassica rapa ssp. Chinensis) (Liao et al.. 2009) at 3.16 mg/L DBP in hydroponic solution. This study was rated medium quality. Biomass was reduced by 27 percent at the LOAEL (10 mg/L), with a clear dose-response at increasing doses up to 76 percent reduced biomass at the highest dose (100 mg/L). However, this study was conducted in hydroponic solution rather than in soil; therefore, it was not considered ecologically relevant for the purpose of deriving a hazard value. Other ChVs included a 72-hour exposure in bread wheat (Triticum aestivum) (Ma et al.. 2015) at 100 mg DBP/kg wet soil. This study was rated high quality. Unbounded LOELs for growth inhibition were also obtained from (Ma et al.. 2015) for a 72-hour exposure in the common oat (Avena sativa), a 168-hour exposure in the common onion (Allium cepa), a 72-hour exposure in alfalfa (Medicago sativa), and a 72- hour exposure in the radish (Raphanus sativus). All of the aforementioned unbounded LOELs were at 5 mg/kg wet soil. However, because the study did not provide information on the water content of the soil, this study was not considered acceptable to derive a hazard value. Furthermore, in this study a comparator non-food crop plant (perennial ryegrass, Lolium perenne) had no observable effects on growth even at the highest dose of 500 mg/kg wet soil. Other studies investigated soil fumigation, application to fields (in kg/hectare), or direct application to leaves (in |ig/cm2), and the dose to each plant could not be calculated from the information given. Another study, rated medium quality, examined a 45-day exposure in false bok choy (Brassica parachinensis) with a ChV of 31.62 mg DBP/kg dry soil (Zhao et al.. 2016); however, the lowest dose (10 mg DBP/kg dry soil) resulted in statistically increased growth relative to controls. 2.4 Weight of Scientific Evidence and Conclusions After calculating the hazard thresholds that were carried forward to characterize risk, a table describing the weight of the scientific evidence and uncertainties was completed to support EPA's decisions (Table 2-12). See 0 for more detail on how EPA weighed the scientific evidence. Table 2-12. DBP Evidence Table Summarizing the Overall Confidence Derived from Hazard Thresholds Types of Evidence Quality of the Database Consistency Strength and Precision Biological Gradient/Dose- Response Relevance Hazard Confidence Aquatic Acute Aquatic (SSD) +++ +++ +++ +++ +++ Robust Chronic Aquatic Vertebrates +++ ++ +++ +++ +++ Robust Chronic Aquatic Invertebrates +++ +++ +++ +++ +++ Robust Chronic Benthic Invertebrates ++ +++ +++ ++ +++ Robust Aquatic Plants & Algae ++ +++ ++ ++ ++ Moderate Terrestrial Terrestrial Vertebrates +++ ++ ++ +++ ++ Moderate Soil Invertebrates ++ ++ +++ +++ +++ Robust Terrestrial Plants ++ ++ ++ ++ ++ Moderate Page 29 of 64 ------- 775 776 111 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 PUBLIC RELEASE DRAFT December 2024 Types of Evidence Quality of the Database Consistency Strength and Precision Biological Gradient/Dose- Response Relevance Hazard Confidence 11 Relevance includes biological, physical/chemical, and environmental relevance. +++ Robust confidence suggests thorough understanding of the scientific evidence and uncertainties. The supporting weight of the scientific evidence outweighs the uncertainties to the point where it is unlikely that the uncertainties could have a significant effect on the hazard estimate. ++ Moderate confidence suggests some understanding of the scientific evidence and uncertainties. The supporting scientific evidence weighed against the uncertainties is reasonably adequate to characterize hazard estimates. + Slight confidence is assigned when the weight of the scientific evidence may not be adequate to characterize the scenario, and when the assessor is making the best scientific assessment possible in the absence of complete information. There are additional uncertainties that may need to be considered. 2.4.1 Quality of the Database; Consistency; Strength (Effect Magnitude) and Precision; and Biological Gradient (Dose-Response) For the acute aquatic assessment, the database consisted of 28 studies with overall quality determinations of high/medium with both aquatic invertebrates and vertebrates represented. Data from nine of these studies were supplemented by using Web-ICE version 4.0 to obtain additional estimated acute toxicity values and generate a subsequent SSD output; therefore, a robust confidence was assigned to quality of the database. DBP had similar effects on the same species across multiple studies, well within one order of magnitude. For example, 96-hour LC50 values in the fathead minnow {Pimephales promelas) ranged from 0.85 mg/L to 2.02 mg/L across three independent studies, from 0.48 mg/L to 1.2 mg/L in the bluegill {Lepomis macrochirus) across three independent studies, and from 1.4 to 1.60 mg/L in the rainbow trout (Oncorhynchus mykiss) across two independent studies. For the water flea {Daphnia magna), 48-hour LC50s ranged from 2.55 mg/L to 5.2 mg/L across two independent studies. Because LC50 values were comparable among independent studies conducted in well-characterized test organisms, a robust confidence was assigned to consistency of the acute aquatic assessment. The effects observed in the DBP empirical data set for acute aquatic assessment were mortality, with 48-, 72-, or 96- hour LC50s represented empirically (depending on species) with additional predicted LC50 values reported from Web-ICE. Because more than 50 species were represented in the acute data set with LC50 values, robust confidence was assigned to the strength and precision consideration. Dose-response is a prerequisite of obtaining reliable LC50 values and was observed in the empirical studies that were used in the SSD. Because dose-response was observed in the empirical studies, a robust confidence was assigned to the dose-response consideration. For the chronic aquatic vertebrate assessment, the database consisted of 16 studies with overall quality determinations of high/medium. Of these studies, 11 contained acceptable chronic endpoints that identified definitive hazard values below the DPB limit of water solubility for 5 fish species and 2 amphibians, resulting in robust confidence for quality of the database. DBP had chronic effects on growth which spanned several orders of magnitude among aquatic vertebrate taxa, with effects on growth in the African clawed frog (Xenopus laevis) ranging from NOEC/LOEC pairs of 0.00476/0.0134 mg/L to 2/10 mg/L in 21- and 22-day independent studies, respectively. Among fish, effects on growth ranged from an unbounded LOEC at 0.0156 mg/L in Japanese medaka (Oryzias latipes) to 0.19/0.40 mg/L in rainbow trout (Oncorhynchus mykiss) in 112-day and 99-day studies, respectively. Among the same species, in a three-generation reproductive study that received a high quality study evaluation, (EAG Laboratories. 2018). effects on growth in Japanese medaka (Oryzias latipes) ranged from an unbounded LOEC at 0.0156 mg/L in F1 male fish to a NOEC/LOEC pair at 0.103/0.305 mg/L in F2 male fish. Because chronic effects were seen at concentrations that spanned several orders of magnitude among aquatic vertebrates, a moderate confidence was assigned to the consistency consideration. In the study chosen to derive the COC, EAG Laboratories (2018). body weight was inhibited by 13.4 percent Page 30 of 64 ------- 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 PUBLIC RELEASE DRAFT December 2024 relative to the vehicle control, and there was a statistically significant trend toward greater bodyweight inhibition with increasing dose, culminating at 34.0 percent inhibition at the highest dose (305 |ig/L). Similarly strong dose-response effects were observed in other studies in the database. Because there was a strong biologically relevant effect and dose-response effects were observed in the study chosen to derive the COC and among other studies in the database, a robust confidence was assigned to the strength and precision consideration and the dose-response consideration for the chronic aquatic invertebrate assessment. For the chronic aquatic invertebrate assessment, the database consisted of 13 studies with overall quality determinations of high/medium. Of these studies, 8 contained acceptable chronic endpoints that identified definitive hazard values below the DPB limit of water solubility for 10 aquatic invertebrate species, resulting in robust confidence for quality of the database. DBP had similar effects on the same species across multiple studies, within one order of magnitude. For example, in the water flea (Daphnia magna), 21-day mortality studies resulted in paired NOEC/LOECs of 0.96/2.5 mg/L, and an LC50 of 1.92 mg/L, in independent studies. Paired 21-day NOEC/LOECs for reproductive effects on the number of juveniles produced ranged from 0.42/0.48 mg/L to 0.96/2.5 mg/L across three independent studies. In other species, effects on population, reproduction, and mortality were observed. Because effects were similar across multiple studies and were seen at concentrations that were within an order of magnitude within the same species, a robust confidence was assigned to the consistency consideration. In the study chosen to derive the COC, (Tagatz et al.. 1983). populations of the marine amphipod Monocorophhm acherusicum were reduced by 91 percent at the LOEC. Higher doses resulted in a complete loss of amphipods in the aquaria. Similarly strong dose-response effects were observed in other studies in the database. Because there was a strong biologically relevant effect and dose-response effects were observed in the study chosen to derive the COC and among other studies in the database, a robust confidence was assigned to the strength and precision consideration and dose-response consideration for the chronic aquatic invertebrate assessment. For the chronic benthic invertebrate assessment, the database consisted of three studies with overall quality determinations of high. Reporting of these studies was extremely detailed and included multiple species, endpoints, durations, and organic carbon contents, but only two species were represented. Additionally, some of the results were repeated among the three studies and the author lists overlapped, and it was unclear in some cases whether certain experiments were conducted independently among the three studies. This lack of clarity about whether the studies were conducted independently resulted in a moderate confidence assigned for the quality of the database consideration. In the studies examined, the experiment was repeated with low, medium, and high TOC sediments and toxicity decreased with the increase in TOC, as expected for a relatively hydrophobic compound like DBP based on equilibrium partitioning theory. Among the same species, effects were generally within one order of magnitude for repeated experiments in the same TOC. Because effects were seen at comparable concentrations within species, a robust confidence was assigned to the consistency consideration. In the study chosen to derive the COC, Lake Superior Research Institute (1997). population in the midge (Chironomus tentans) was reduced by 76.7 percent at the LOEC, which was 3,090 mg DBP/kg dry sediment. Population reduction in other treatments and TOC levels was generally as expected given equilibrium partitioning theory. Because the effect size of DBP exposure was large, and other treatments resulted in effects that were as expected based on equilibrium partitioning theory, a robust confidence was assigned to the strength and precision consideration for the chronic benthic invertebrate assessment. Higher doses resulted in a similar degree of population loss in the medium-TOC treatment; however, all population losses were significantly different from controls. There was a clear dose-response effect observed in other studies in the database, and among sub-studies using different TOC levels. Because dose-response was non- monotonic in the medium-TOC treatment—but was as expected, with higher doses increasing the Page 31 of 64 ------- 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 PUBLIC RELEASE DRAFT December 2024 observed population loss, in other sub-studies involving different TOC levels within the same study—a moderate confidence was assigned to the dose-response consideration for the chronic benthic invertebrate assessment. For the aquatic plants and algae assessment, the database consisted of seven high/medium quality studies for toxicity in aquatic plants and algae. Of these studies, three contained acceptable endpoints that identified definitive hazard values below the DBP limit of water solubility for one species of green algae (Selencistrum capricornutum). Because only one species was identified, and several of the studies in the database were not acceptable because exposure concentrations were above the limit of solubility for DBP, confidence was decreased in the quality of the database. However, because three independent studies were available in the species examined, a moderate confidence level was assigned for the quality of the database. DBP had similar effects on population, measured as either chlorophyll a concentration or cell abundance, in three independent studies. Effects were within an order of magnitude, ranging from a 96-hour NOEC/LOEC pair at 0.1/1 mg/L to a 10-day EC50 at 0.75 mg/L. Because effects on the same species were observed at DBP concentrations within one order of magnitude, a robust confidence was assigned to the consistency consideration. In the study chosen to derive the COC, (Adachi et al.. 2006). a significant reduction in the algal population at the LOEC, which was 1,000 |ig/L DBP, relative to an increase in the algal population at the NOEC of 100 |ig/L DBP and in controls. The population reduction was increased with a higher dose of DBP. Due to the increase in algal population at the NOEC relative to controls, a moderate confidence was assigned to the strength and precision and dose-response considerations for the aquatic plants and algae assessment. For the terrestrial vertebrate assessment, the database consisted of 2 high/medium quality studies for toxicity in environmentally relevant terrestrial vertebrates (chicken, Gallus gallus, and Japanese quail, Coturmx japonica), supplemented by 13 high/medium quality studies for toxicity in human-relevant terrestrial vertebrates (rat, Rattus norvegicus, and mouse, Mus musculus). Because 15 studies representing four species were identified, a robust confidence was assigned to the quality of the database. Among the two avian species, no effects were observed on growth at any DBP dose. Among studies in rats, effects on reproduction were observed at NOEC/LOEC pairs ranging from 100/200 mg/kg-bw/day from gestational day 1 to 14 (Giribabu et al.. 2014). to 10,000/20,000 mg/kg-bw/day from gestational day 0 to 20 (NTP. 1995). In mice, effects on reproduction were observed at NOEC/LOEC pairs ranging from 50/300 mg/kg-bw/day from gestational day 7 to 9 (Xia et al.. 2011) to 10,000/20,000 mg/kg-bw/day from gestational day 0 to postnatal day 28 (NTP. 1995). Because effective doses spanned two orders of magnitude among independent studies in the same species, but effective doses for similar reproductive endpoints were much closer within each study, a moderate confidence was assigned to the consistency consideration for terrestrial vertebrates. In the study chosen to derive the HV, (NTP. 1995). 17-week LOAEL for significant reduction in number of live pups per litter was identified at 80 mg/kg-bw/day DBP intake in dams. That study also found a LOAEL for reduced bodyweight in F2 pups at the same dose (80 mg/kg-bw/day). The lowest bounded NOAEL/LOAEL pair for which a ChV could be calculated was significantly reduced bodyweight in F1 pups at a ChV of 115.4 mg/kg-bw/day, but this effect was not as sensitive as reduced number of live pups per litter. Other effects of DBP exposure included significantly decreased female body weight in dams, significantly reduced male sex ratio (percentage of male pups), significantly decreased mating index and pregnancy index in the F1 generation, and significantly reduced male pup weight gain. Because clear dose-response relationships were found for many endpoints, robust confidence was assigned for the dose-response consideration. However, the effect size for reduction in live pups per litter was relatively small (a 7.8% reduction in litter size at the LOAEL, with a 17% reduction at the highest dose Page 32 of 64 ------- 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 PUBLIC RELEASE DRAFT December 2024 administered), leading to a moderate confidence for the strength and precision consideration for the terrestrial vertebrate assessment. For the soil invertebrate assessment, the database consisted of three high/medium quality studies, of which two contained acceptable chronic endpoints that identified definitive hazard values below the DPB limit of water solubility for two soil invertebrate species. Because only two high/medium quality studies were identified that contained usable hazard values, and two species were represented, a moderate confidence was assigned to the quality of the database. Among multiple endpoints and lifestages, 21-day LC50 values in the springtail (Folsomiafimetaria) ranged from 19.4 mg/kg dry soil in juveniles to 305 mg/kg dry soil in adults. No comparison to other studies was available for the EC10 and EC50 values for reproduction in springtails, or for the 14-day LC50 value from a second study in the earthworm (Eisenia fetida). Because comparisons among organisms within the same study or for the same organisms among independent studies were not possible given the available data, but no inconsistencies were observed among the studies examined (i.e., widely different toxicities among the same organism), a moderate confidence evaluation was assigned to the consistency criterion. In the study chosen to derive the HV, (Jensen et al.. 2001). reproduction was reduced by approximately 60 percent at the lowest concentration tested, which was 100 mg DBP/kg dry soil, with reproduction completely eliminated at higher doses. Clear dose-response relationships were observed in other studies in the data set for soil invertebrates. Because there was a strong biologically relevant effect and dose- response effects were observed in the study chosen to derive the HV and among other studies in the database, robust confidence was assigned to the strength and precision and dose-response criteria for the soil invertebrate assessment. For the terrestrial plant assessment, the database comprised 12 high/medium quality studies, of which 6 contained acceptable endpoints that identified definitive hazard values below the DBP limit of water solubility for 10 terrestrial plant species. However, the majority of acceptable studies characterized doses in a way that was unsuitable for a hazard determination (in mg/m3 soil fumigation, kg DBP/ha agricultural application, or mg/kg wet soil). These dosing regimes made it impossible to characterize dose in the unit EPA uses for exposure estimates to terrestrial plants, mg/kg dry soil. After filtering the database to only those endpoints that characterized dose in mg/kg dry soil, four studies remained. Because most of the studies characterized doses in a way that was not useful for developing a hazard value, moderate confidence was assigned to the quality of the database. Effects on growth were observed at a wide range of concentrations among terrestrial plants, ranging from unbounded 72- or 168- hour LOECs at 5 mg/kg soil in agricultural crops including common oat (Avena sativa), alfalfa (Medicago sativa), radish (Raphanus sativus), cucumber (Cucumis sativus), and common onion (Allium cepa\ to an unbounded 72-hour NOEC at 500 mg/kg soil in perennial ryegrass (Loliumperetme) and a 72-hour EC50 at 1559 mg/kg dry soil in the mung bean (Vigna radiata). Since consistent growth effects were seen in a variety of species, but the observed effects were distributed over a wide range of concentrations, a moderate confidence was assigned to the consistency consideration. In the study selected to derive the HV, (Gao et al.. 2019). the most sensitive endpoint was the LOEL for reduction in leaf and root biomass in bread wheat seedlings at 10 mg/kg dry soil. There was a clear dose-response observed, with biomass reduction increasing as the dose of DBP increased. At the highest dose (40 mg/kg), root and leaf biomass were reduced by 29.93 and 32.10 percent, respectively. However, for other studies in the data set, strong and precise effects of DBP on plant growth were not observed, and dose-response was not observed in all studies. For example, in Zhao et al. (2016). a 45-day exposure in false bok choy (Brassicaparachinensis) had a ChV of 31.62 mg DBP/kg dry soil; however, the lowest dose (10 mg DBP/kg dry soil) resulted in statistically increased Page 33 of 64 ------- 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 PUBLIC RELEASE DRAFT December 2024 growth relative to controls. A strong biologically relevant effect was not observed among all studies in the database, and dose-response effects were not observed among some studies in the database. Because of the added uncertainty from some studies in similar plants showing a lack of strong biologically relevant effects or clear dose-response, moderate confidence was assigned to the strength and precision and dose-response considerations for the terrestrial plants assessment. 2.4.2 Relevance (Biological; Physical/Chemical; Environmental) For the acute aquatic assessment, mortality was observed in the empirical data for 9 invertebrates and fish, several of which are considered representative test species for aquatic assessments; mortality was predicted in 53 additional species using Web-ICE. Although modeled approaches such as Web-ICE can have more uncertainty than empirical data when determining the hazard or risk, the use of the probabilistic approach within this risk evaluation increases confidence compared to a deterministic approach. The use of the lower 95 percent CI of the HC05 in the SSD instead of a fixed AF also increases confidence, as it is a more data-driven way of accounting for uncertainty. Because empirical data was available for mortality for nine species, and predicted mortality data was available for 53 more through Web-ICE, robust confidence was assigned to the relevance consideration for the acute aquatic assessment. For the chronic aquatic vertebrate assessment, ecologically relevant population level effects (growth and mortality) were observed in seven different species, five of which are considered representative test species for aquatic toxicity tests (African clawed frog, Xenopus laevis\ zebrafish, Danio rerio\ rainbow trout, Oncorhynchus mykiss\ fathead minnow, Pimephales promelas; and Japanese medaka, Oryzicis latipes). Because relevant population level effects were observed in several species, including representative test species, robust confidence was assigned to the relevance consideration for the chronic aquatic vertebrate assessment. For the chronic aquatic invertebrate assessment, ecologically relevant population level effects (mortality and reproduction) were observed in 10 species, 2 of which (water flea, Daphnia magna, and the worm Lumbricuius variegatus) are considered representative test species for aquatic toxicity tests. Although the COC was derived from a less-common species (the amphipod crustacean Monocorophium acherusicum), effects on reproduction were seen at similar DBP doses in Daphnia magna, which increases confidence in the biological relevance of effects that are expected to occur at the COC. Because ecologically relevant effects were observed in 10 species, including 2 representative test species, robust confidence was assigned to the relevance consideration for the chronic aquatic invertebrate assessment. For the chronic benthic invertebrate assessment, ecologically relevant population level effects (growth and mortality) were observed in two different species (scud, Hyalella azteca, and midge, Chironomus plumosus), both of which are considered representative test species for benthic toxicity tests. Because ecologically relevant effects were observed in two representative test species, robust confidence was assigned to the relevance consideration for the chronic benthic invertebrate assessment. For the aquatic plant and algae assessment, an ecologically relevant population level effect (population abundance, measured as either chlorophyll a concentration or cell count) was observed in one species of green algae (Selenastrum capricornutum). This species is ubiquitous in the environment and is considered a representative test species for algal toxicity tests. However, because only one species was represented in the database, moderate confidence was assigned to the relevance consideration for the aquatic plant and algae assessment. Page 34 of 64 ------- 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 PUBLIC RELEASE DRAFT December 2024 For the terrestrial vertebrate assessment, ecologically relevant population level effects were not observed in ecologically relevant species. Data from human-relevant terrestrial vertebrates (rat, Rattus norvegicus, and mouse, Mus musculus) were used to supplement the data set. A relevant population-level effect (reproduction) was observed in both species. Because the study used to develop the COC was conducted in rats, which are less ecologically relevant than other potential vertebrate species, moderate confidence was assigned to the relevance consideration for the terrestrial vertebrate assessment. For the soil invertebrate assessment, ecologically relevant endpoints (mortality and reproduction) were observed for two ecologically relevant species (springtail, Folsomici fimetaria, and earthworm, Eisenici fetida). Both species are considered representative test species for soil invertebrate toxicity testing. Because ecologically relevant effects were observed in two representative test species, robust confidence was assigned to the relevance consideration for the chronic benthic invertebrate assessment. Robust confidence was also assigned to the relevance consideration for the soil invertebrate assessment. For the terrestrial plant assessment, an ecologically relevant endpoint (growth) was observed for 10 plant species. However, of those species for which doses were measured in a way that was usable for determining an HV (in mg/kg dry soil), only agricultural crops were represented. Additionally, for non- food crop plants represented in the data set (Norway spruce, Picea abies, and perennial ryegrass, Lolium perenne), no effects were observed at any tested DBP dose. This raises doubts whether ecologically relevant effects of DBP exposure can be expected to occur in a non-agricultural context, so moderate confidence was assigned to the relevance consideration for the terrestrial plant assessment. Page 35 of 64 ------- 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 PUBLIC RELEASE DRAFT December 2024 3 CONCLUSIONS EPA considered all reasonably available information identified through the systematic review process under TSCA to characterize environmental hazard endpoints for DBP. The following bullets summarize the hazard values and overall hazard confidence: • Aquatic species: o LC50 values from nine exposures to DBP in fish and aquatic invertebrates were used alongside quantitative structure-activity relationship (QSAR)-derived hazard estimates to develop an SSD. The lower confidence interval of the HCos was used as the COC and indicated that acute toxicity occurs at 347.6 |ig/L. EPA has robust confidence that this hazard value represents the level of acute DBP exposure at which ecologically relevant effects will occur in fish and aquatic invertebrates. o A three-generation reproductive study in Japanese medaka (Oryzias latipes) found significantly reduced bodyweight in F1 male fish after a 112-day exposure to DBP. The COC based on this study indicated that chronic toxicity in aquatic vertebrates occurs at 1.56 |ig/L. EPA has robust confidence that this hazard value represents the level of chronic DBP exposure at which ecologically relevant effects will occur in aquatic vertebrates. o A 14-day exposure to DBP in the marine amphipod crustacean Monocorophium acherusicum found a significant reduction in population abundance. The COC based on this study indicated that chronic toxicity in aquatic invertebrates occurs at 12.23 |ig/L. EPA has robust confidence that this hazard value represents the level of chronic DBP exposure at which ecologically relevant effects will occur in aquatic invertebrates. o A 96-hour exposure to DBP in the green algae Selenastrum capricornutum found a significant reduction in population growth. The COC based on this study indicated that toxicity in aquatic plants and algae occurs at 31.6 |ig/L. EPA has moderate confidence that this hazard value represents the level of DBP exposure at which ecologically relevant effects will occur in algae, because hazard information for only one species was identified in the database, and several of the studies in the database were not acceptable since exposure concentrations were above the limit of solubility for DBP. • Benthic species: o A 10-day exposure to DBP in the midge (Chironomus tentcms) in sediment found a significant reduction in population abundance. The COC based on this study indicated that chronic toxicity in benthic invertebrates occurs at 114.3 mg/kg dry sediment. EPA has robust confidence that this hazard value represents the level of chronic DBP exposure at which ecologically relevant effects will occur in benthic invertebrates. • Terrestrial species: o A 17-week perinatal exposure to DBP in Sprague-Dawley rats (Rattus norvegicus) found a significant reduction in number of live pups born per litter. The HV derived from this study indicated that chronic toxicity in terrestrial vertebrates occurs at 80 mg/kg-bw/day. EPA has moderate confidence that this hazard value represents the level of DBP exposure at which ecologically relevant effects will occur in terrestrial vertebrates, because effective doses for reproductive effects spanned two orders of magnitude among independent studies in the same species, effect sizes were relatively small, and human- toxicology model organisms were used instead of ecologically relevant species. o A 21-day exposure to DBP in the springtail (Folsomia fimetarici) found a significant reduction in reproduction. The HV derived from this study indicated that chronic toxicity in soil invertebrates occurs at 14 mg/kg dry soil. EPA has robust confidence that this hazard value represents the level of DBP exposure at which ecologically relevant effects Page 36 of 64 ------- 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 PUBLIC RELEASE DRAFT December 2024 will occur in soil invertebrates, o A 40-day exposure to DBP in bread wheat (Triticum aestivum) found a significant reduction in leaf and root biomass in seedlings. The HV derived from this study indicated that toxicity in terrestrial plants occurs at 10 mg/kg dry soil. EPA has moderate confidence that this hazard value represents the level of DBP exposure at which ecologically relevant effects will occur in terrestrial plants, because most of the studies characterized doses in a way that was not useful for developing a hazard value, and because only agricultural crops were represented in the studies for which an adverse effect of DBP exposure was observed. Page 37 of 64 ------- 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 PUBLIC RELEASE DRAFT December 2024 REFERENCES Abdul-Ghani. S; Yanai. J; Abdul-Ghani. R; Pinkas. A; Abdeen. Z. (2012). The teratogenicity and behavioral teratogenicity of di(2-ethylhexyl) phthalate (DEHP) and di-butyl Phthalate (DBP) in a chick model. Neurotoxicol Teratol 34: 56-62. http://dx.doi.Org/10.1016/i.ntt.2011.10.001 Adachi. A: Asa. K; Okano. T. (2006). Efficiency of rice bran for removal of di-n-butyl phthalate and its effect on the growth inhibition of Selenastrum capricornutum by di-n-butyl phthalate. Bull Environ Contam Toxicol 76: 877-882. http://dx.doi.org/10.1007/s00128-006-100Q-4 Adams. WJ: Biddinger. GR; Robillard. KA; Gorsuch. JW. (1995). A summary of the acute toxicity of 14 phthalate esters to representative aquatic organisms. Environ Toxicol Chem 14: 1569-1574. http://dx.doi.org/10.1002/etc.562014Q916 Aoki. KA: Harris. CA; Katsiadaki. I; Sumpter. JP. (2011). Evidence suggesting that di-n-butyl phthalate has antiandrogenic effects in fish. Environ Toxicol Chem 30: 1338-1345. http: //dx. doi. or g/10.1002/etc. 5 02 BASF Aktiengesellschaft. (1989). Report on the study of the acute toxicity of dibutylphthalat on the Golden Orfe (Leuciscus idus L., golden variety). (10F0449/895178). Ludwigshafen, Germany. Battelle. (2018). 21-d amphibian metamorphosis assay (AMA) of dibutyl phthalate with African clawed frog, xenopus laevis. (BATT01-00397). Washington, DC: U.S. Environmental Protection Agency. Bello. UM; Madekurozwa. M. -C: Groenewald. HB; Aire. TA; Arukwe. A. (2014). 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Benchmark dose technical guidance [EPA Report], (EPA100R12001). Washington, DC: U.S. Environmental Protection Agency, Risk Assessment Forum. https://www.epa.gov/risk/benchmark-dose-technical-guidance U.S. EPA. (2014). Framework for human health risk assessment to inform decision making. Final [EPA Report], (EPA/100/R-14/001). Washington, DC: U.S. Environmental Protection, Risk Assessment Forum, https://www.epa.gov/risk/framework-human-health-risk-assessment-inform- decision-making U.S. EPA. (2016). Weight of evidence in ecological assessment [EPA Report], (EPA/100/R-16/001). Washington, DC: Office of the Science Advisor. https://nepis.epa. gov/Exe/ZvPURL.cgi?Dockev=P100SFXR.txt U.S. EPA. (2021). Draft systematic review protocol supporting TSCA risk evaluations for chemical substances, Version 1.0: A generic TSCA systematic review protocol with chemical-specific methodologies. (EPA Document #EPA-D-20-031). Washington, DC: Office of Chemical Safety and Pollution Prevention. https://www.regulations.gov/document/EPA-HQ-OPPT-2021-0414- 0005 U.S. EPA. (2024a). Draft Environmental Exposure Assessment for Diisodecyl Phthalate (DIDP). Washington, DC: Office of Pollution Prevention and Toxics. https://www.regulations.gov/document/EPA-HQ-OPPT-2024-0073-0024 U.S. EPA. (2024b). Draft Non-cancer Human Health Hazard Assessment for Dibutyl Phthalate (DBP). Washington, DC: Office of Pollution Prevention and Toxics. U.S. EPA. (2024c). Draft Systematic Review Protocol for Dibutyl Phthalate (DBP). Washington, DC: Office of Pollution Prevention and Toxics. Wang. Z; Kim. HK; Tao. W: Wang. M; Ahn. YJ. (2011). Contact and fumigant toxicity of cinnamaldehyde and cinnamic acid and related compounds to Dermatophagoides farinae and Dermatophagoides pteronyssinus (Acari: Pyroglyphidae). J Med Entomol 48: 366-371. http://dx.doi.org/10.1603/ME10127 Wei. J: Shen. O: Ban. Y; Wang. Y; Shen. C: Wang. T; Zhao. W: Xie. X. (2018). Characterization of Acute and Chronic Toxicity of DBP to Daphnia magna. Bull Environ Contam Toxicol 101: 214- 221. http://dx.doi.org/10.1007/sQ0128-018-2391-8 Williams. MJ; Wiemerslage. L; Gohel. P; Kheder. S: Kothegala. LV; Schioth. HB. (2016). Dibutyl Phthalate Exposure Disrupts Evolutionarily Conserved Insulin and Glucagon-Like Signaling in Drosophila Males. Endocrinology 157: 2309-2321. http://dx.doi.org/10.1210/en.2015-20Q6 Wine. RN: Li. LH; Barnes. LH; Gulati. DK; Chapin. RE. (1997). Reproductive toxicity of di-n- butylphthalate in a continuous breeding protocol in Sprague-Dawley rats. Environ Health Perspect 105: 102-107. http://dx.doi.org/10.1289/ehp.97105102 Wolf. C: Lambright. C: Mann. P; Price. M; Cooper. RL; Ostbv. J: Gray. LE. Jr. (1999). Administration of potentially antiandrogenic pesticides (procymidone, linuron, iprodione, chlozolinate, p,p'- DDE, and ketoconazole) and toxic substances (dibutyl- and diethylhexyl phthalate, PCB 169, and ethane dimethane sulphonate) during sexual differentiation produces diverse profiles of reproductive malformations in the male rat. Toxicol Ind Health 15: 94-118. http://dx.doi.org/10.1177/0748233799015001Q9 Xia. H: Chi. Y. i: Oi. X: Su. M: Cao. Y: Song. P: Li. X: Chen. T: Zhao. A: Zhang. Y: Cao. Y: Ma. X: Jia. W. (2011). Metabolomic evaluation of di-n-butyl phthalate-induced teratogenesis in mice. Metabolomics 7: 559-571. http://dx.doi.org/10.1007/sll306-011-0276-5 Xu. Y; Gve. MC. (2018). Developmental toxicity of dibutyl phthalate and citrate ester plasticizers in Xenopus laevis embryos. Chemosphere 204: 523-534. Page 44 of 64 ------- 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 PUBLIC RELEASE DRAFT December 2024 http: //dx. doi. or g/ 10.1016/i. chemosphere .2018.04.077 Yang. ZH; Zhang. XJ; Cat ZH. (2009). Toxic effects of several phthalate esters on the embryos and larvae of abalone Haliotis diversicolor supertexta. Chin J Oceanol Limnol 27: 395-399. http://dx.doi.org/10.1007/s00343-009-91Q3-5 Zhao. HM: Du. H: Xiang. L: Li. YW: Li. H: Cai. OY: Mo. CH: Cao. G: Wong. MH. (2016). Physiological differences in response to di-n-butyl phthalate (DBP) exposure between low- and high-DBP accumulating cultivars of Chinese flowering cabbage (Brassica parachinensis L.). Environ Pollut 208: 840-849. http://dx.doi.org/10.1016/i.envpol.2015.11.009 Zhao. LL; Xi. YL; Huang. L; Zha. CW. (2009). Effects of three phthalate esters on the life-table demography of freshwater rotifer Brachionus calyciflorus Pallas. Aquatic Ecology 43: 395-402. http://dx.doi.org/10.1007/slQ452-008-9179-6 Page 45 of 64 ------- 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 PUBLIC RELEASE DRAFT December 2024 APPENDICES Appendix A RUBRIC FOR WEIGHT OF THE SCIENTIFIC EVIDENCE The weight of the scientific evidence fundamentally means that the evidence is weighed (i.e., ranked) and weighted (i.e., a piece or set of evidence or uncertainty may have more importance or influence in the result than another). Based on the weight of the scientific evidence and uncertainties, a confidence statement was developed that qualitatively ranks (i.e., robust, moderate, slight, or indeterminate) the confidence in the hazard threshold. The qualitative confidence levels are described below. The evidence considerations and criteria detailed within U.S. EPA (2021) guides the application of strength-of-evidence judgments for environmental hazard effect within a given evidence stream and were adapted from Table 7-10 of the 2021 Draft Systematic Review Protocol (U.S. EPA. 2021). EPA used the strength-of-evidence and uncertainties from U.S. EPA (2021) for the hazard assessment to qualitatively rank the overall confidence rating for environmental hazard (Table Apx A-l). Confidence levels of robust (+ + +), moderate (+ +), slight (+), or indeterminant are assigned for each evidence property that corresponds to the evidence considerations (U.S. EPA. 2021). The rank of the Quality of the Database consideration is based on the systematic review overall quality determination (High, Medium, or Low) for studies used to calculate the hazard threshold, and whether there are data gaps in the toxicity data set. Another consideration in the Quality of the Database is the risk of bias (i.e., how representative is the study to ecologically relevant endpoints). Additionally, because of the importance of the studies used for deriving hazard thresholds, the Quality of the Database consideration may have greater weight than the other individual considerations. The high, medium, and low systematic review overall quality determination ranks correspond to the evidence table ranks of robust (+ + +), moderate (+ +), or slight (+), respectively. The evidence considerations are weighted based on professional judgment to obtain the overall confidence for each hazard threshold. In other words, the weights of each evidence property relative to the other properties are dependent on the specifics of the weight of the scientific evidence and uncertainties that are described in the narrative and may or may not be equal. Therefore, the overall score is not necessarily a mean or defaulted to the lowest score. The confidence levels and uncertainty type examples are described below. A.l Confidence Levels • Robust (+ + +) confidence suggests thorough understanding of the scientific evidence and uncertainties. The supporting weight of the scientific evidence outweighs the uncertainties to the point where it is unlikely that the uncertainties could have a significant effect on the exposure or hazard estimate. • Moderate (+ +) confidence suggests some understanding of the scientific evidence and uncertainties. The supporting scientific evidence weighed against the uncertainties is reasonably adequate to characterize exposure or hazard estimates. • Slight (+) confidence is assigned when the weight of the scientific evidence may not be adequate to characterize the scenario, and when the assessor is making the best scientific assessment possible in the absence of complete information. There are additional uncertainties that may need to be considered. A.2 Types of Uncertainties The following uncertainties may be relevant to one or more of the weight of scientific evidence Page 46 of 64 ------- 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 PUBLIC RELEASE DRAFT December 2024 considerations listed above and will be integrated into that property's rank in the evidence table: • Scenario Uncertainty: Uncertainty regarding missing or incomplete information needed to fully define the exposure and dose. o The sources of scenario uncertainty include descriptive errors, aggregation errors, errors in professional judgment, and incomplete analysis. • Parameter Uncertainty: Uncertainty regarding some parameter. o Sources of parameter uncertainty include measurement errors, sampling errors, variability, and use of generic or surrogate data. • Model Uncertainty: Uncertainty regarding gaps in scientific theory required to make predictions on the basis of causal inferences. o Modeling assumptions may be simplified representations of reality. Table 2-12 summarizes the weight of the scientific evidence and uncertainties, while increasing transparency on how EPA arrived at the overall confidence level for each exposure hazard threshold. Symbols are used to provide a visual overview of the confidence in the body of evidence, while de- emphasizing an individual ranking that may give the impression that ranks are cumulative (e.g., ranks of different categories may have different weights). Page 47 of 64 ------- PUBLIC RELEASE DRAFT December 2024 1506 TableApx A-l. Considerations that Inform Evaluations of the Strength of the Evidence within an Evidence Stream {i.e., Apical 1507 Endpoints, Mechanistic, or Field Studies) Consideration Increased Evidence Strength (of the Apical Endpoints, Mechanistic, or Field Studies Evidence) Decreased Evidence Strength (of the Apical Endpoints, Mechanistic, or Field Studies Evidence) The evidence considerations and criteria laid out here guide the application of strength-of-evidence judgments for an outcome or environmental hazard effect within a given evidence stream. Evidence integration or synthesis results that do not warrant an increase or decrease in evidence strength for a given consideration are considered "neutral" and are not described in this table (and, in general, are captured in the assessment-specific evidence profile tables). Quality of the database'1 (risk of bias) • A large evidence base of high- or medium-quality studies increases strength. • Strength increases if relevant species are represented in a database. • An evidence base of mostly /ow-quality studies decreases strength. • Strength also decreases if the database has data gaps for relevant species, i.e., a trophic level that is not represented. • Decisions to increase strength for other considerations in this table should generally not be made if there are serious concerns for risk of bias; in other words, all the other considerations in this table are dependent upon the quality of the database. Consistency Similarity of findings for a given outcome (e.g., of a similar magnitude, direction) across independent studies or experiments increases strength, particularly when consistency is observed across species, life stage, sex, wildlife populations, and across or within aquatic and terrestrial exposure pathways. • Unexplained inconsistency (i.e., conflicting evidence; see U.S. EPA (2005) decreases strength.) • Strength should not be decreased if discrepant findings can be reasonably explained by study confidence conclusions; variation in population or species, sex, or life stage; frequency of exposure (e.g., intermittent or continuous); exposure levels (low or high); or exposure duration. Strength (effect magnitude) and precision • Evidence of a large magnitude effect (considered either within or across studies) can increase strength. • Effects of a concerning rarity or severity can also increase strength, even if they are of a small magnitude. • Precise results from individual studies or across the set of studies increases strength, noting that biological significance is prioritized over statistical significance. • Use of probabilistic model (e.g., Web-ICE, SSD) may increase strength. Strength may be decreased if effect sizes that are small in magnitude are concluded not to be biologically significant, or if there are only a few studies with imprecise results. Biological gradient/dose- response • Evidence of dose-response increases strength. • Dose-response may be demonstrated across studies or within studies and it can be dose- or duration- dependent. • A lack of dose-response when expected based on biological understanding and having a wide range of doses/exposures evaluated in the evidence base can decrease strength. Page 48 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Consideration Increased Evidence Strength (of the Apical Endpoints, Mechanistic, or Field Studies Evidence) Decreased Evidence Strength (of the Apical Endpoints, Mechanistic, or Field Studies Evidence) • Dose response may not be a monotonic dose- response (monotonicity should not necessarily be expected, e.g., different outcomes may be expected at low vs. high doses due to activation of different mechanistic pathways or induction of systemic toxicity at very high doses). • Decreases in a response after cessation of exposure (e.g., return to baseline fecundity) also may increase strength by increasing certainty in a relationship between exposure and outcome (this particularly applicable to field studies). • In experimental studies, strength may be decreased when effects resolve under certain experimental conditions (e.g., rapid reversibility after removal of exposure). • However, many reversible effects are of high concern. Deciding between these situations is informed by factors such as the toxicokinetics of the chemical and the conditions of exposure, see (U.S. EPA. 1998). cndooint severity, judgments regarding the potential for delayed or secondary effects, as well as the exposure context focus of the assessment (e.g., addressing intermittent or short-term exposures). • In rare cases, and typically only in toxicology studies, the magnitude of effects at a given exposure level might decrease with longer exposures (e.g., due to tolerance or acclimation). • Like the discussion of reversibility above, a decision about whether this decreases evidence strength depends on the exposure context focus of the assessment and other factors. • If the data are not adequate to evaluate a dose-response pattern, then strength is neither increased nor decreased. Biological relevance Effects observed in different populations or representative species suggesting that the effect is likely relevant to the population or representative species of interest (e.g., correspondence among the taxa, life stages, and processes measured or observed and the assessment endpoint). An effect observed only in a specific population or species without a clear analogy to the population or representative species of interest decreases strength. Physical/chemical relevance Correspondence between the substance tested and the substance constituting the stressor of concern. The substance tested is an analog of the chemical of interest or a mixture of chemicals which include other chemicals besides the chemical of interest. Environmental relevance Correspondence between test conditions and conditions in the region of concern. The test is conducted using conditions that would not occur in the environment. " Database refers to the entire data set of studies integrated in the environmental hazard assessment and used to inform the strength of the evidence. In this context, database does not refer to a computer database that stores aggregations of data records such as the ECOTOX Knowledgebase. 1508 Page 49 of 64 ------- 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 PUBLIC RELEASE DRAFT December 2024 Appendix B SPECIES SENSITIVITY DISTRIBUTION FOR ACUTE AQUATIC HAZARD The SSD Toolbox is a resource that can fit SSDs to environmental hazard data (Etterson. 2020). It runs on Matlab 2018b (9.5) for Windows 64 bit. For this draft DBP risk evaluation, EPA created one SSD with the SSD Toolbox Version 1.1 to evaluate acute aquatic vertebrate and invertebrate toxicity. The use of this probabilistic approach increases confidence in the hazard threshold identification as it is a more data-driven way of accounting for uncertainty. For the acute SSD, acute exposure hazard data for aquatic vertebrates and invertebrates were curated to prioritize study quality and to assure comparability between toxicity values. For example, the empirical data set included only LCsos for high and medium quality acute duration assays that measured mortality for aquatic vertebrates and invertebrates. TableApx B-l shows the empirical data that were used in the SSD. To further improve the fit and representativeness of the SSD, Web-ICE acute toxicity predictions for 53 additional species were added (TableApx B-2). With this data set, the SSD Toolbox was used to apply a variety of algorithms to fit and visualize SSDs with different distributions. An HCos is calculated for each (Table Apx B-2) The SSD Toolbox's output contained several methods for choosing an appropriate distribution and fitting method, including goodness-of-fit, standard error, and sample-size corrected Akaike Information Criterion (AICc, (Burnham and Anderson. 2002)). Most P values for goodness-of-fit were above 0.05, showing no evidence for lack of fit. The distribution and model with the lowest AICc value, and therefore the best fit for the data was the Gumbel Model (Figure Apx B-l). Because numerical methods may lack statistical power for small sample sizes, a visual inspection of the data were also used to assess goodness-of-fit. For the Q-Q plot, the horizontal axis gives the empirical quantiles while the vertical axis gives the predicted quantiles (from the fitted distribution). The Q-Q plot demonstrates a good model fit with the data points in close proximity to the line across the data distribution. Q-Q plots were visually used to assess the goodness-of-fit for the distributions (Figure Apx B-2) with the Gumbel distribution demonstrating the best fit near the low end of the distribution, which is the region from which the HC05 is derived. The results for this model (Figure Apx B-3) predicted 5 percent of the species (HC05) to have their LC50s exceeded at 415 |ig/L (348 to 517 |ig/L 95% CI). The HCso was estimated at 1,159 |ig/L (951 to 1,444 |ig/L 95% CI) and the HC95 was estimated at 7,213 |ig/L (4,376 to 11,443 |ig/L 95% CI). Table Apx B-l. Species Sensitivity Distribution (SSD) Model Input for Acute Exposure Toxicity in Aquatic Vertebrates and Invertebrates - Empirical Data Species Description Acute Toxicity Value LC50 (Hg/L) Citation(s) Americctmysis bahia Aquatic invertebrate 612 (Adams et al.. 1995; EG&G Bionomics. 1984b) Danio rerio Aquatic invertebrate 630 (Chen et al.. 2014) Lepomis macrochirns Aquatic vertebrate 788 (Adams et al.. 1995; EG&G Bionomics. 1983b; Buccafusco et al.. 1981) Pimephcdes promelas Aquatic vertebrate 1,178 (Smithers Viscient. 2018; Adams et al.. 1995; Defoe et al.. 1990; McCarthy and Whitmore. 1985; EG&G Bionomics. 1984a) Page 50 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Species Description Acute Toxicity Value LC50 (M.g/L) Citation(s) Oncorhvnchus mykiss Aquatic vertebrate 1,497 (Adams et al.. 1995; EnviroSvstem. 1991; EG&G Bionomics. 1983a) Nitocra spinipes Benthic invertebrate 1,700 (Linden et al.. 1979) Daphnia magna Aquatic invertebrate 3,443 (Wei et al.. 2018; Adams et al.. 1995; McCarthy and Whitmore. 1985) Chironomus plumosus Benthic invertebrate 4,648 (Streufort. 1978) Paratany tarsus parthenogeneticus Benthic invertebrate 5,800 (EG&G Bionomics. 1984c) 1544 1545 1546 TableApx B-2. SSD Model Predictions" for Acute Exposure Toxicity to Aquatic Vertebrates (Fish) Distribution6 HC05 (jig/L) P value Normal 381 0.0839 Logistic 348 0.0100 Triangular 364 0.4386 Gumbel 415 0.0559 Weibull 239 0.0280 Burr 400 0.0150 11 The SSD was generated using SSD Toolbox vl.l. h The model with the lowest AICc value, and therefore the best model fit, is bolded in this table. 1548 1549 1550 Table Apx B-3. Species Sensitivity Distribution (SSD) Model Input for Acute Exposure Toxicity 1551 in Aquatic Vertebrates and Invertebrates - Web-ICE Data Species Description Acute Toxicity Value LC50 (jig/L) Gammarus pseudolimnaeus Benthic invertebrate 228 Menidia peninsulae Aquatic vertebrate 327 Lctgodon rhomboides Aquatic vertebrate 451 Catostomus commersonii Aquatic vertebrate 501 Menidia menidia Aquatic vertebrate 502 Caecidotea brevicauda Benthic invertebrate 532 Percaflavescens Aquatic vertebrate 535 Allorchestes compressa Benthic invertebrate 545 Cyprinodon bovinus Aquatic vertebrate 546 Page 51 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Species Description Acute Toxicity Value LC50 (^g/L) Jordanellct floridae Aquatic vertebrate 547 Sander vitreus Aquatic vertebrate 549 Crcissostreci virginica Benthic invertebrate 595 Ptychocheilus lucius Aquatic vertebrate 647 Oncorhvnchiis kisutch Aquatic vertebrate 673 Oncorhvnchiis clarkii Aquatic vertebrate 674 Salvelinus namciycush Aquatic vertebrate 782 Salmo scdar Aquatic vertebrate 796 Lumbriculus variegatus Benthic invertebrate 818 Salvelinus fontinalis Aquatic vertebrate 853 Oreochromis mossambicus Aquatic vertebrate 872 Micropterus salmoides Aquatic vertebrate 908 Oncorhvnchiis tshawytscha Aquatic vertebrate 920 Simocephalus vetulus Aquatic invertebrate 930 Amblema plicata Benthic invertebrate 1,039 Cyprinus carpio Aquatic vertebrate 1,342 Acipenser brevirostrum Aquatic vertebrate 1,342 Cyprinodon variegatus Aquatic vertebrate 1,463 Xyrauchen texanus Aquatic vertebrate 1,505 Oncorhvnchiis gilae Aquatic vertebrate 1,506 Lasmigona complanata Benthic invertebrate 1,521 Salmo trutta Aquatic vertebrate 1,528 Poecilia reticulata Aquatic vertebrate 1,541 Menidia beryllina Aquatic vertebrate 1,573 Ictalurus punctatus Aquatic vertebrate 1,581 Megalonaias nervosa Benthic invertebrate 1,751 Lepomis cyanellus Aquatic vertebrate 1,823 Lithobates catesbeianus Amphibian 1,938 Oryzias latipes Aquatic vertebrate 2,097 Oncorhvnchiis nerka Aquatic vertebrate 2,141 Page 52 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Species Description Acute Toxicity Value LC50 (^g/L) Utterbackict imbecillis Benthic invertebrate 2,244 Cctrctssius auratus Aquatic vertebrate 2,275 Ceriodctphnict dubia Aquatic invertebrate 2,372 Thamnocephcdus platyurus Aquatic invertebrate 2,855 Margctritifera fcdcata Benthic invertebrate 2,858 Daphnia pulex Aquatic invertebrate 2,892 Physa gyrina Benthic invertebrate 3,052 Brcmchinecta lynchi Aquatic invertebrate 3,142 Lampsilis siliquoidea Benthic invertebrate 3,155 Notropis mekistocholas Aquatic vertebrate 3,447 Gammctrus fasciatus Benthic invertebrate 3,539 Tigriopus japonicus Benthic invertebrate 3,642 Lvmnaea stagnalis Benthic invertebrate 3,738 Paratanytarsus dissimilis Benthic invertebrate 5,419 1552 Page 53 of 64 ------- PUBLIC RELEASE DRAFT December 2024 -Aj ModelSelection Percentile of interest: Model-averaqed HCp; Model-averaqed SE of HCd: CV of HCp: AICc Table 5 367.6771 46.3176 0.12597 X Distribution AICc delta AICc Wt HCp SE HCp 1 triangular 1.0313e+03 0 0.6230 364.0017 30.3446 2 normal 1.0328e+03 1.4955 0.2950 380.7975 55.3481 3 logistic 1.0372e+03 5.8312 0.0338 348.2229 58.4528 4 burr 1.0385e+03 7.1684 0.0173 400.4899 64.1671 5 weibull 1.0386e+03 7.2289 0.0168 238.9533 58.6521 6 gumbel 1.0389e+03 7.5662 0.0142 414.8611 40.8076 1553 1554 FigureApx B-l. AICc for the Six Distribution Options in the SSD Toolbox for Acute DBP 1555 Toxicity to Aquatic Vertebrates and Invertebrates (Etterson. 2020) 1556 Page 54 of 64 ------- PUBLIC RELEASE DRAFT December 2024 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Predicted Quantiles 0.2 0.3 0.4 0.5 0.6 0.7 Predicted Quantiles 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Predicted Quantiles 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Predicted Quantiles 1557 FigureApx B-2. Q-Q Plots of Acute DBP Toxicity to Aquatic Vertebrates and Invertebrates with 1558 the A) Gumbel, B) Weibull, C) Burr, and D) Logistic Distributions (Etterson. 2020) 1559 Page 55 of 64 ------- PUBLIC RELEASE DRAFT December 2024 1560 1561 1562 0.9 0.8 0.7 2? I06 1 e 0. ro D I 0.4 0.3 0.2 0.1 gumbel-ML ~ HC05 •••• 95% CL HC05 Notmpis mekisteyholas • Bmochiipa.i X S ' si s ' 2.5 3.5 Log 10 LC50 (pg/L) Benthic Invertebrate Aquatic Vertebrate Aquatic Invertebrate Amphibian 4.5 Figure Apx B-3. Species Sensitivity Distribution (SSD) for Acute DBP Toxicity to Aquatic Vertebrates and Invertebrates (Etterson. 2020) Page 56 of 64 ------- PUBLIC RELEASE DRAFT December 2024 1563 Appendix C ENVIRONMENTAL HAZARD STUDIES 1564 This appendix summarizes the aquatic and terrestrial endpoints and studies not included in the DBP 1565 quantitative risk evaluation, due to hazard values above the limit of solubility, lack of observed toxic 1566 effects, or inconsistency in the reported dose-response relationship. 1567 1568 Table Apx C-l. Acute Aquatic Vertebrate Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) African clawed frog (Xenopus laevis) 14.1/21.0 mg/L 96-hour NOEC/LOEC Mortality (Xu and Gve. 2018) (High) 12.88 mg/L 96-hour LC50 Mortality (Gardner et al.. 2016) (Medium) 11.7/14.7 mg/L 96-hour NOEC/LOEC Sheepshead Minnow 0Cyprinodon variegatus) >0.6 mg/L 96-hour NOEC Mortality (Sprinsborn Bionomics. 1984a) (High) Nile tilapia (iOreochromis niloticus) 11.8 mg/L 96-hour LC50 Mortality (Khalil et al.. 2016) (Medium) >10 mg/L 96-hour NOEC Mortality Growth (Erkmen et al.. 2017) (Hieh) Ide (Leuciscus idus) >10 mg/L 96-hour NOEC Mortality (BASF Aktieneesellschaft. 1989) (Medium) 1569 1570 Page 57 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Table Apx C-2. C ironic Aquatic Vertebrate Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) Zebrafish (Danio rerio) >0.1 mg/L 5-week NOEC Mortality (Ortiz-Zarraaoitia et al.. 2006) (Medium) >0.5 mg/L 95-day NOEC Mortality Growth Reproduction (Chen et al.. 2015) (High) Three-spined stickleback (Gasterosteus aculeatus) >0.0352 mg/L 22-day NOEC Growth (Aoki et al.. 2011) (Medium) Fathead minnow (Pimephales promelas) >0.062 mg/L 21-day NOEC Growth Mortality Reproduction (Smithers Viscient. 2018) (Medium) Crimson-spotted rainbowfish (Melanotaenia fliiviatilis) >0.457 mg/L 7-day NOEC Growth Mortality (Bhatia et al.. 2013) (Hiah) >113 mg/L 7-day NOEC Growth Mortality (Bhatia et al.. 2014) (Hiah) >0.05 mg/L (Nominal) 90-day NOEC Mortality (Bhatia et al.. 2015) (Hiah) >0.005 mg/L (Nominal) Growth Japanese medaka 0Oryzias latipes) >12 mg/kg bw/d 540-day NOEC Growth Reproduction (Patvna. 1999) (Hiah) 1572 1573 Page 58 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Table Apx C-3. Acute Aquatic Inveri tebrate Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) Opossum shrimp (Americamysis bcthia) >1.3 mg/L 24-hour LC50 Mortality (EG&G Bionomics. 1984c)(Hiah) 1575 1576 1577 Table Apx C-4. Chronic Aquatic Invertebrate Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) Water flea (Daphnict magna) >2.08 mg/L 16-day NOAEC Reproduction (McCarthy and Whitmore. 1985)(Medium) Midge (Chironomiis plamoms) >0.695 mg/L 40-day NOAEC Growth (Streufort. 1978)(Medium) Daggerblade grass shrimp (Palaemonetes pugio) >21.5 mg/L 38-day NOAEC Development/ Growth (Lauahlin Rb et al.. 1978)(Medium) 1578 1579 Table Apx C-5. C ironic Benthic Invertebrate Toxicity of DBP Test Organism Hazard Values Duration Endpoint Citation (Study Quality) Scud (Hyalella azteca) high TOC >71,900 mg/kg dw 10-day LC50 Mortality (Call et al.. 2001a)(High) >13.2 mg/L 10-day NOAEC Scud (Hyalella azteca) medium TOC >29,500 mg/kg dw 10-day LC50 Mortality (Call et al.. 2001a)(Hiah) 82.4 mg/L (Probit) 10-day LC50 Mortality (Lake Superior Research Institute. 1997)(Hiah) Scud (Hvalella azteca) low TOC >62.9 mg/L 10-day NOAEC Mortality (Call et al.. 2001a)(High) >17,400 mg/kg dw 10-day LC50 Midge {Chironomiis tentans) medium TOC 12.2 mg/L (Linear Interpolation) 10-day LC50 Mortality (Lake Superior Research Institute. 1997)(Hiah) 3.85/16 mg/L 10-day NOAEC/ LOAEC (Call et al.. 2001a)(Hiah) Midge {Chironomiis tentans) low TOC >74.2 mg/L 10-day NOAEC/ LOAEC Development/ Growth (Call et al.. 2001a)(High) >17,000 mg/kg dry sediment 10-day NOAEC 1581 1582 Page 59 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Table Apx C-6. Aquatic Plants and Algae Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) Green algae (Selenastrum cctpri cornu turn) 2.78/27.8 mg/L 7-day NOEC/LOEC Population (Biomass) (Melin and Eaneus. 1983) (Medium) Green algae 0Scenedesmus acutus var. acutus) 15.3 mg/L 96-hour EC50 Population (Abundance) (Guetal.. 2017) (High) Green algae 0Scenedesmus acutus vctr. acutus) 30.2 mg/L 96-hour EC50 Population (Abundance) (Kuans et al.. 2003) (Medium) 39.8 mg/L Population (Population growth rate) 44.7 mg/L Population (Chlorophyll a concentration) Diatom (Skeletonema costatum) 200/500 mg/L 4-day NOEC/LOEC Population (Population growth rate) (Medlin. 1980) (Medium) 1584 1585 Page 60 of 64 ------- PUBLIC RELEASE DRAFT December 2024 1586 Table Apx C-7. Terrestrial Vertebrate Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation 1250/2,500 ppm GD-0 PND 28 (NTP. 1995) 100/200 mg/kg- bw/day GD 1-14 (Giribabu et al.. 2014) 120/600 mg/kg- bw/day GD 0-20 (Nikonorow et al.. 1973) 250/500 mg/kg- bw/day PND 21-25 (Wolf et al.. 1999) 250/500 mg/kg- bw/day PND 21-25 (Grav et al.. 1988) 500/1,000 mg/kg- bw/day PND 21-25 256/509 mg/kg- bw/day 17 weeks (NTP. 1995) (Wine et al.. 1997) 385/794 mg/kg- bw/day 17 weeks 5,000/10,000 ppm 63 days Rat (Rattus 500/630 mg/kg- bw/day GD 7-15 (Ema et al.. 1993) norvegicus) 630/750 mg/kg- bw/day GD 7-15 500/1,000 mg/kg- bw/day GD 15-17 Reproduction 1,000/1,500 mg/kg- bw/day GD 12-14 500/750 mg/kg- bw/day GD 3-PND 20 (Mvlchreest et al.. 1998) 579/879 mg/kg- bw/day 4 weeks post- weaning (NTP. 1995) 7,500/10,000 mg/kg- bw/day GD 0-PND 28 10,000/20,000 mg/kg-bw/day GD 0-20 10,000/20,000 mg/kg-bw/day GD 0-PND 28 10,000/30,000 mg/kg-bw/day PND 1-22 50/300 mg/kg- bw/day GD 7-9 (Xia et al.. 2011) Mice 370/660 mg/kg- bw/day GD 0-18 (Shiota and Nishimura. 1982) (Shiota et al.. 1980) 660/2,100 mg/kg- bw/day Gd 0-18 Page 61 of 64 ------- PUBLIC RELEASE DRAFT December 2024 Test Organism (Species) Hazard Values Duration Endpoint Citation 3,000/10,000 mg/kg- bw/day 15 weeks (NTP. 1995) 5,000/7,500 mg/kg- bw/day GD 0-PND 28 7,500/10,000 ppm GD 0-PND 28 10,000/20,000 ppm GD 0-PND 28 525/1,750 mg/kg- bw/day 18 weeks (Ntp. 1984) (Lamb et al.. 1987) 525/1,750 mg/kg- bw/day 18 weeks (Nto. 1984) Chicken (Gctllus gallus) >100 mg/kg egg NR (until hatching) NOEL Mortality Growth (Abdul-Ghani et al.. 2012) (High) Japanese quail (Coturnix jctponicct) >400 mg/kg bw/d 30-day NOEL Growth (Bello et al.. 2014) (Medium) 1587 1588 Table Apx C-8. Acute Soil Invertebrate Toxicity of DI tP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) European house dust mite (Dermatophagoides pteronvs sinus) >0.152 mg/cm3 (Fumigation) 24-hour NOEC Mortality (Kane et al.. 2006) (Medium) American house dust mite (Dermatophagoides farina) >0.152 mg/cm3 (Fumigation) 24-hour NOEC Mortality (Kane et al.. 2006) (Medium) Fruit fly {Drosophila melanogaster) 505,100 mg/L feed 72-hour LC50 Mortality (Misra et al.. 2014) (Medium) 278.3/2783 mg/L feed 72-hour NOEC/LOEC (Adult exposure) Reproduction 27.83/139.17 mg/L in solution 24-hour NOEC/LOEC Nematode (Caenorhabditis elegans) >139.17 mg/L 24-hour NOEC Mortality (Shin et al.. 2019) (High) 27.83/139.17 mg/L in solution 24-hour NOEC/LOEC Reproduction (Brood size) Table Apx C-9. C ironic Soil Inverte irate Toxicity of DBP Test Organism (Species) Hazard Values Duration Endpoint Citation (Study Quality) Fruit fly (Drosophila melanogaster) >0.418 mg/L feed NR (egg until 5 to 6 days post hatch) Mortality (Williams et al.. 2016) (Medium) Page 62 of 64 ------- PUBLIC RELEASE DRAFT December 2024 1592 Table Apx C-10.r "errestrial Plant Toxicity of DBP Test Organism Hazard Values Duration Endpoint Citation (Study Quality) Tobacco (Nicotiana tabacum) >2783 mg/L 7-day NOEC Growth (Dene et al.. 2017) (High) 139.17/278.34 mg/L 3-day NOEC/LOEC Reproduction (Germination) Norway spruce (Piceci abies) >0.010 mg/m3 (Fumigation) 76-day NOEC Growth (Dueck et al.. 2003) (High) Perennial ryegrass (Lolium perenne) >500 mg/kg soil 72-hour NOEC Growth (Ma et al.. 2015) (High) Rapeseed (Brassica napus) <2.4 jig/cnr leaf 15-day LOEL Physiology (Injury - Chlorosis) (Lokke and Rasmussen. 1983) (Medium) Common yarrow (Achillea millefolium) >2.9 jig/cnr leaf 15-day NOEL Physiology (Injury - Chlorosis) White mustard (Sinapis alba) <3.5 (ig/cm2 leaf 15-day LOEL Physiology (Injury - Chlorosis) Rice (Oryza sativa) >100 mg/L 5-day NOEC Growth (Isoaai et al.. 1972) (Medium) 1594 Page 63 of 64 ------- PUBLIC RELEASE DRAFT December 2024 1595 Appendix D SUPPLEMENTAL SUBMITTED DATA TO BE 1596 CONSIDERED FOR FINAL RISK EVALUATION 1597 On July 10, 2024, EPA received supplemental information from DBP Consortium member companies 1598 related to ecotoxicity data supporting the risk evaluation for DBP. The Agency was unable to 1599 incorporate this data into the draft DBP ecological hazard assessment due to its late submission in the 1600 draft risk evaluation development process. However, EPA has included these data in the DBP risk 1601 evaluation docket (Docket ID: EPA-HO-OPPT-2Q18-0503) and will be considering the submission in 1602 the development of the final risk evaluation for DBP. Page 64 of 64 ------- |