xvEPA EPA Document# EPA-740-R-25-012 January 2025 United States Office of Chemical Safety and Environmental Protection Agency Pollution Prevention Physical Chemistry Assessment for Diisononyl Phthalate (DINP) Technical Support Document for the Risk Evaluation CASRNs: 28553-12-0 and 68515-48-0 (Representative Structure) January 2025 ------- TABLE OF CONTENTS SUMMARY 4 1 INTRODUCTION 5 2 EVIDENCE INTEGRATION FOR PHYSICAL AND CHEMICAL PROPERTIES 5 2.1 Final Selected Physical and Chemical Property Values for DINP 5 2.2 Endpoint Assessments 5 2.2.1 Melting Point 5 2.2.2 Boiling Point 6 2.2.3 Density 6 2.2.4 Vapor Pressure 6 2.2.5 Vapor Density 6 2.2.6 Water Solubility 6 2.2.7 Log Octanol:Water Partitioning Coefficient 7 2.2.8 Henry's Law Constant 7 2.2.9 Flashpoint 7 2.2.10 Autoflammability 7 2.2.11 Viscosity 7 2.3 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the Physical and Chemical Property Assessment 8 REFERENCES 9 LIST OF TABLES Table 2-1. Summary of Physical and Chemical Property Information for DINP 5 Page 2 of 10 ------- KEY ABBREVIATIONS AND ACRONYMS Atm Atmospheres atmm3/mol Atmospheres - cubic meters per mole C Celsius (°C) CASRN Chemical Abstracts Service Registry Number CP Centipoise DIDP Diisodecyl phthalate DINP Diisononyl phthalate EPA Environmental Protection Agency EPI Suite™ Estimation Program Interface Suite™ F Fahrenheit (°F) g/cm3 Grams per cubic centimeter K Kelvin Koa Octanol:air partition coefficient Kow Octanol:water partition coefficient mg/L Milligrams per liter mol Mole mmHg Millimeters of mercury N/A Not applicable NR Not reported Pa (hPa) Pascals (hectopascals; 1 hPa =100 Pa) RSC Royal Society of Chemistry SVOC Semi-volatile organic compound Page 3 of 10 ------- SUMMARY EPA gathered and evaluated physical and chemical property data and information according to the process described in the Systematic Review Protocol for DiisononylPhthalate (DINP) (U.S. EPA. 2025b). During the evaluation of DINP, EPA considered both measured and estimated physical and chemical property data/information summarized in Table 2-1, as applicable. Information on the full, extracted data set is available in the Data Quality Evaluation and Data Extraction Information for Physical and Chemical Properties for Diisononyl Phthalate (DINP) (U.S. EPA. 2025a). DINP is a clear, oily, viscous liquid with a mild odor (HSDB. 2015). As a branched phthalate ester, DINP is used as plasticizer that melts around -48 °C (NCBI. 2020; RSC. 2019; NLM. 2015; O'Neil. 2013; NTP-CERHR. 2003). DINP is considered insoluble in water with water solubility of 0.00061 mg/L at 20 °C (Letinski et al.. 2002) and an octanol:water partition coefficient (log Kow) of 8.8 (ECHA. 2016). With a vapor pressure of 5.40x 10~7 mmHg at 25 °C (NLM. 2015) and a boiling point exceeding than 400 °C (ECHA. 2016). DINP has low volatility and is categorized as a semi-volatile organic compound (SVOC) (ECCC/HC. 2020). The selected Henry's Law constant for DINP was 9.14x 10~5 atmm3/mol at 25 °C (Cousins and Mackav. 2000). Page 4 of 10 ------- 1 INTRODUCTION DINP is produced by the esterification of phthalic anhydride with isononanol. Commercially, DINP is not a single compound but rather a complex mixture of phthalate esters having branched alkyl chains with an average chain length of nine. The following sections present the general physical and chemical properties of DINP. 2 EVIDENCE INTEGRATION FOR PHYSICAL AND CHEMICAL PROPERTIES Due to the large quantity of available data, only studies with an overall data quality ranking of "High" were selected for use in determining the representative physical and chemical properties of DINP for the purposes of the risk evaluation (Table 2-1). 2.1 Final Selected Physical and Chemical Property Values for DINP Table 2-1. Summary of 'hysical and Chemical Property Information for DINP Property Selected Value Reference Overall Quality Determination Molecular formula C26H42O4 Molecular weight 418.62 g/mol Physical form Clear Liquid (NLM. 2015) High Melting point 1 00 O O (O'Neil. 2013) High Boiling point >400 °C (ECHA. 2016) High Density 0.97578 g/cm3 (De Lorenzi et al.. 1998) High Vapor pressure 5.40E-07 mmHg (NLM. 2015) High Water solubility 0.00061 mg/L (Letinski et al.. 2002) High Octanol: water partition coefficient (log Kow) 8.8 (ECHA. 2016) High Octanol:air partition coefficient (log Koa) 11.9 (EPI Suite™) (U.S. EPA. 2017) High Henry's Law constant 9.14E-05 atm m3/mol at 25 °C (Cousins and Mackav. 2000) High Flash point 213 °C (O'Neil. 2013) High Autoflammability 400 °C (ECHA. 2016) High Viscosity 77.6 cP (ECHA. 2016) High 2.2 Endpoint Assessments 2.2.1 Melting Point EPA extracted and evaluated eleven sources containing DINP melting point information. Five of the sources were identified and evaluated as overall high-quality data sources, four as overall medium- quality data sources, and the remaining two as overall low-quality data sources. The overall high-quality sources reported DINP melting points ranging from -48 to -43 °C (NCBI. 2020; RSC. 2019; NLM. Page 5 of 10 ------- 2015; O'Neil. 2013; NTP-CERHR. 2003). EPA selected a melting point value of-48 ± 1 °C (O'Neil. 2013) as a representative value of the identified information from the overall high-quality data sources. In addition, the identified value is consistent with the value selected in the final scope document for DINP (U.S. EPA. 2021). 2.2.2 Boiling Point The EPA extracted and evaluated 10 data sources containing DINP boiling point information. Four of the sources were identified and evaluated as overall high-quality data sources, three as overall medium- quality data sources, and the remaining three as overall low-quality data sources. The overall high- quality sources reported DINP boiling points ranging from 244 °C to greater than 400 °C (NCBI. 2020; ECHA 2016; O'Neil. 2013; NTP-CERHR. 2003). EPA selected a boiling point value of greater than 400 °C (ECHA. 2016) as a representative value under normal environmental conditions within the identified information in the overall high-quality data sources. 2.2.3 Density EPA extracted and evaluated 12 data sources containing DINP density information. Seven of the sources were identified and evaluated as overall high-quality data sources, three as overall medium-quality data sources, and the remaining two as overall low-quality data sources. The overall high-quality sources reported DINP density values ranging from 0.97 to 0.98 g/cm3 (NCBI. 2020; ECHA. 2016; NLM. 2015; O'Neil. 2013; NTP-CERHR. 2003; ExxonMobil. 2001; De Lorenzi et al.. 1998). EPA selected a density of 0.97578 g/cm3 (De Lorenzi et al.. 1998) as DINP's representative density value within the identified information obtained from the overall high-quality data sources. In addition, the identified value is consistent with the value selected in the final scope document for DINP (U.S. EPA. 2021). 2.2.4 Vapor Pressure The EPA extracted and evaluated 11 data sources containing DINP vapor pressure information. Five of the sources were identified and evaluated as overall high-quality data sources and the remaining six as overall medium-quality data sources. The overall high-quality sources reported DINP vapor pressure ranging from 9.6x 10~8 to 5.4x 10~7 mmHg at 20 to 25 °C (ECHA 2016; NLM. 2015; Lu. 2009; Howard et al.. 1985). EPA selected a vapor pressure value of 5.40x 10~7 mmHg (NLM. 2015) as a representative value of the identified information obtained from the overall high-quality data sources under normal environmental conditions. In addition, the identified value is consistent with the value selected in the final scope document for DINP (U.S. EPA. 2021). 2.2.5 Vapor Density A value for vapor density was not identified during systematic review or the initial data review for the final scope document for DINP (U.S. EPA. 2021). 2.2.6 Water Solubility Water solubility informs many endpoints not only within the realm of fate and transport of DINP in the environment, but also informs modelling decisions in industrial processes, engineering, human and ecological hazards, and exposure. A systematic review of reasonably available data on the water solubility of DINP was conducted. The EPA extracted and evaluated 15 data sources containing DINP water solubility information. Six of the sources were identified and evaluated as overall high-quality data sources, seven as overall medium-quality data sources, and the remaining two as overall low- quality data sources. During examination, many methods used a shake flask or continuous stirring method which has been shown in high molecular weight phthalates to cause colloidal suspensions of small amounts of free product in solution. These suspensions are stable and attempts to determine analytically may lead to erroneously high measurements of true solubility for DINP. As a result, water Page 6 of 10 ------- solubility measurements obtained in these tests may exceed the true water solubility of DINP. However, Letinski (2002) reported DINP water solubility of 0.00061 mg/L in a slow stir method designed to minimize the presence of colloidal suspensions. Water solubility values collected in the systematic review process for DINP exhibited a range of values from 0.0006 to 0.2 mg/L (ECCC/HC. 2020; EC HA. 2016; NLM. 2015; NTP-CERHR. 2003; Letinski et al.. 2002; Howard et al.. 1985). A representative value of 0.00061 mg/L was selected for use in the risk evaluation (Letinski et al.. 2002). 2.2.7 Log OctanolrWater Partitioning Coefficient EPA extracted and evaluated 13 data sources containing DINP octanol:water partition coefficient information. Five of the sources were identified and evaluated as overall high-quality data sources, seven as overall medium-quality data sources, and one as overall low-quality data sources. The overall high-quality sources reported DINP log Kow ranging from 8.8 to 9.7 (ECCC/HC. 2020; ECHA 2016; NLM. 2015; O'Neil. 2013; NTP-CERHR. 2003). EPA selected a measured read across log Kow value of 8.8 (ECHA. 2016) for this risk evaluation. 2.2.8 Henry's Law Constant The Henry's Law constant selected in the final scope document for DINP (U.S. EPA. 2021) was a value calculated in Estimation Program Interface (EPI) Suite™ from the vapor pressure and water solubility of DINP and was 2.08xl0~5 atm-m3 /mole at 25 °C EPI Suite™ (U.S. EPA. 2012). One overall high- quality and two overall medium studies were identified in the systematic revie process for DINP, ranging from 9.14><10"5 to 4.09xl0~4 atm-m3 /mole (ECHA. 2013; Cousins et al.. 2007; Cousins and Mackav. 2000). The EPA identified Henry's Law constant value of 9.14><10~5 atmm3/mol at 25 °C (Cousins and Mackav. 2000) for this risk evaluation. Based on the identified Henry's Law constant value, DINP is considered an SVOC. 2.2.9 Flashpoint EPA extracted and evaluated four data sources containing DINP flash point information. Three of the sources were identified and evaluated as overall high-quality data sources and one as overall medium- quality data sources. The overall high-quality sources reported DINP flash points ranging from 213 to 236 °C (NCBI. 2020; ECHA 2016; O'Neil. 2013). EPA selected a flash point value of 213 °C (O'Neil. 2013) as a representative value of the available information identified from the overall high-quality data sources under normal environmental conditions. In addition, the identified value is consistent with the value selected in the final scope document for DINP (U.S. EPA. 2021). 2.2.10 Autoflammability A value for the automatability of DINP was not identified in the initial data review for the final scope document for DINP (U.S. EPA. 2021). The systematic review process identified one overall high-quality and two overall medium-quality references reporting autoflammability values ranging from 380 to 400 °C (NCBI. 2020; ECHA. 2016. 2013). EPA selected an autoflammability temperature of 400 °C for DINP (ECHA. 2016) for this risk evaluation. 2.2.11 Viscosity In the final scope document for DINP (U.S. EPA. 2021). a value of 55.334 cP at 25 °C was identified as the viscosity for DINP (De Lorenzi et al.. 1998). Four overall high-quality data sources were identified during the systematic review process reporting viscosity values from 55.334 to 102 cP (NCBI. 2020; ECHA. 2016; NLM. 2015; De Lorenzi et al.. 1998). EPA selected a value of 77.6 cP at 20 °C as a representative value of the mode viscosity for DINP (ECHA. 2016). replacing the original scoping value. Page 7 of 10 ------- 2.3 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the Physical and Chemical Property Assessment Due to the water solubility of DINP, certain physical and chemical properties may be difficult to measure experimentally (water solubility, octanol:water partitioning coefficient, organic carbon partitioning coefficients) with traditional guideline tests. The representative physical and chemical property values were selected based on professional judgement and the overall data quality ranking of the associated references. In some instances where no data were available, or there was a wide range of data that generally, but did not consistently agree with one another, models such as EPI Suite™ were used to estimate the value for the endpoint (octanol water partitioning coefficient and organic carbon partitioning coefficient) and cross-checked with reported data from systematic review. Page 8 of 10 ------- REFERENCES Cousins. AP; Remberger. M; Kai. L; Ekheden. Y; Dusan. B; Brorstroem-Lunden. E. (2007). Results from the Swedish National Screening Programme 2006. Subreport 1: Phthalates (pp. 39). (B1750). Stockholm, SE: Swedish Environmental Research Institute. http://www3.ivl.se/rapporter/pdf/B1750.pdf Cousins. I; Mackav. D. (2000). Correlating the physical-chemical properties of phthalate esters using the 'three solubility' approach. Chemosphere 41: 1389-1399. http://dx.doi.org/10.1016/S0Q45- 6535(00)00005-9 De Lorenzi. L; Fermeglia. M; Torriano. G. (1998). Density, kinematic viscosity, and refractive index for bis(2-ethylhexyl) adipate, tris(2-ethylhexyl) trimellitate, and diisononyl phthalate. Journal of Chemical and Engineering Data 43: 183-186. http://dx.doi.org/10.1021/ie970200z ECCC/HC. (2020). Screening assessment - Phthalate substance grouping. (Enl4-393/2019E-PDF). Environment and Climate Change Canada, Health Canada. https://www.canada.ca/en/environment-climate-change/services/evaluating-existing- substances/screening-assessment-phthalate-substance-grouping.html ECHA. (2013). Evaluation of new scientific evidence concerning DINP and DIDP in relation to entry 52 of Annex XVII to REACH Regulation (EC) No 1907/2006. Helsinki, Finland. http://echa.europa.eu/documents/10162/31b4067e-de40-4044-93e8-9c9ffl960715 ECHA. (2016). Committee for Risk Assessment RAC - Annex 1 - Background document to the Opinion proposing harmonised classification and labelling at EU level of 1,2-Benzenedicarboxylic acid, di-C8-10-branched alkylesters, C9- rich; [1] di-"isononyl" phthalate; [2] [DINP] EC Number: 271-090-9 [1] 249-079-5 [2] CAS Number: 68515-48-0 [1] 28553-12-0 [2], Helsinki, Finland. https://echa.europa.eu/documents/10162/23665416/clh bd dinp 7397 en.pdf/28ab9b6c-d3f4- 31f0-8be3-clald4cf61d3 ExxonMobil. (2001). JAYFLEX® Plasticizers: Jayflex DINP Plasticizer: Diisononyl Phthalate [Website], http ://www. exxonmobilchemical. com/Chem- English/Files/Resources/OXO Jayflex DINP NA en-FPS.pdf Howard. PH; Baneriee. S; Robillard. KH. (1985). Measurement of water solubilities octanol-water partition coefficients and vapor pressures of commercial phthalate esters. Environ Toxicol Chem 4: 653-662. http://dx.doi.org/10.1002/etc.56200405Q9 HSDB. (2015). Di-isodecyl phthalate (CASRN: 26761-40-0). Bethesda, MD: National Library of Medicine, https://pubchem.ncbi.nlm.nih.gov/compound/33599#source=HSDB Letinski. DJ; Connelly Jr. MJ; Peterson. PR; Parkerton. TF. (2002). Slow-stir water solubility measurements of selected alcohols and diesters. Chemosphere 43: 257-265. http://dx.doi.org/10.1016/50045-6535(02)00086-3 Lu. C. (2009). Prediction of environmental properties in water-soil-air systems for phthalates. Bull Environ Contam Toxicol 83: 168-173. http://dx.doi.org/10.1007/sQ0128-009-9728-2 NCBI. (2020). PubChem database: compound summary: diisononyl phthalate. https://pubchem.ncbi.nlm.nih.gov/compound/Diisononyl-phthalate NLM. (2015). PubChem: Hazardous Substance Data Bank: Di-isononyl phthalate, 28553-12-0 [Website], https://pubchem.ncbi.nlm.nih.gov/compound/590836#source=HSDB NTP-CERHR. (2003). NTP-CERHR monograph on the potential human reproductive and developmental effects of di-isononyl phthalate (DINP) (pp. i-III90). (NIH Publication No. 03- 4484). Research Triangle Park, NC: National Toxicology Program Center for the Evaluation of Risks to Human Reproduction. http://ntp.niehs.nih.gov/ntp/ohat/phthalates/dinp/dinp monograph final.pdf O'Neil. MJ. (2013). Diisononyl phthalate. In MJ O'Neil; PE Heckelman; PH Dobbelaar; KJ Roman; CM Kenney; LS Karaffa (Eds.), (15th ed., pp. 517). Cambridge, UK: Royal Society of Chemistry. RSC. (2019). ChemSpider: Diisononyl phthalate (DINP) [Website], Page 9 of 10 ------- http://www.chemspider.com/Chemical-Stmcture.513622.html U.S. EPA. (2012). Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11 [Computer Program], Washington, DC. Retrieved from https://www.epa.gov/tsca-screening-tools/epi- suitetm-estimation-program-interface U.S. EPA. (2017). Estimation Programs Interface Suite™ v.4.11. Washington, DC: U.S. Environmental Protection Agency, Office of Pollution Prevention Toxics. Retrieved from https://www.epa.gov/tsca-screening-tools/download-epi-suitetm-estimation-program-interface- v411 U.S. EPA. (2021). Final scope of the risk evaluation for di-isononyl phthalate (DINP) (1,2-benzene- dicarboxylic acid, 1,2-diisononyl ester, and 1,2-benzenedicarboxylic acid, di-C8-10-branched alkyl esters, C9-rich); CASRNs 28553-12-0 and 68515-48-0 [EPA Report], (EPA-740-R-21- 002). Washington, DC: Office of Chemical Safety and Pollution Prevention. https://www.epa.gov/svstem/files/documents/2021-08/casrn-28553-12-0-di-isononyl-phthalate- final-scope.pdf U.S. EPA. (2025a). Data Quality Evaluation and Data Extraction Information for Physical and Chemical Properties for Diisononyl Phthalate (DINP). Washington, DC: Office of Pollution Prevention and Toxics. U.S. EPA. (2025b). Systematic Review Protocol for Diisononyl Phthalate (DINP) Washington, DC: Office of Pollution Prevention and Toxics. Page 10 of 10 ------- |