Draft Physical Chemistry Assessment for Diisononyl Phthalate (DINP) Technical Support Document for the Draft Risk Evaluation CASRNs: 28553-12-0 and 68515-48-0


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EPA Document #EPA-740-D-24-013

May 2024

United States	Office of Chemical Safety and

Environmental Protection Agency	Pollution Prevention

Draft Physical Chemistry Assessment for Diisononyl Phthalate

(DINP)

Technical Support Document for the Draft Risk Evaluation

CASRNs: 28553-12-0 and 68515-48-0

(Representative Structure)

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27	TABLE OF CONTENTS	

28	SUMMARY	5

29	1 INTRODUCTION	6

30	2 EVIDENCE INTEGRATION FOR PHYSICAL AND CHEMICAL PROPERTIES	7

31	2.1 Final Selected Physical and Chemical Property Values for DINP	7

32	2.2 Endpoint Assessments	7

33	2.2.1 Melting Point	7

34	2.2,2 Boiling Point	7

35	2.2,3 Density	8

36	2.2.4 Vapor Pressure	8

37	2.2.5 Vapor Density	8

38	2.2.6 Water Solubility	8

39	2.2.7 Log Octanol/Water Partitioning Coefficient	9

40	2.2.8 Henry's Law Constant	9

41	2.2.9 Flashpoint	9

42	2.2,10 Autoflammability	9

43	2.2,11 Viscosity	9

44	2.3 Strengths, Limitations, Assumptions, and Key Sources of Uncertainty for the Physical and

45	Chemical Property Assessment	9

46	REFERENCES	11

47

48	LIST OF TABLES	

49	Table 2-1. Summary of DINP's Physical and Chemical Property Information	7

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ABBREVIATIONS AND ACRONYMS

Atm	Atmospheres

atmm3/mol Atmospheres - cubic meters per mole

C	Celsius

CASRN	Chemical Abstract Service registry number

cP	Centipoise

DIDP	Diisodecyl phthalate

DINP	Diisononyl phthalate

EPA	Environmental Protection Agency

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

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ACKNOWLEDGMENTS

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, input, and review comments from
OPPT and OCSPP senior managers and science advisors and assistance from EPA contractors SRC, Inc.
(Contract No. 68HERH19D0022).

As part of an intra-agency review, this draft report was provided to multiple EPA Program Offices for
review. Comments were submitted by EPA's Office of Air and Radiation (OAR), Office of Children's
Health Protection (OCHP), Office of General Counsel (OGC), Office of Research and Development
(ORD), and Office of Water (OW).

Docket

Supporting information can be found in the public docket, Docket ID (EPA-HQ-OPPT-2024-0Q73).
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: Juan Bezares-Cruz, Ryan Sullivan

Contributors: Andrew Middleton, Marcella Card

Technical Support: Mark Gibson, Hillary Hollinger

This report was reviewed and cleared by OPPT and OCSPP leadership.

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SUMMARY	

EPA gathered and evaluated physical and chemical property data and information according to the
process described in the Draft Risk Evaluation for Diisononyl Phthalate (DINP) - Systematic Review
Protocol (U.S. EPA. 2024a). 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 dataset is available in the file Draft Risk Evaluation for Di-isononyl
Phthalate (DINP) - Systematic Review Supplemental File: Data Quality Evaluation and Data
Extraction Information for Physical and Chemical Properties (U.S. EPA. 2024b).

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 a 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 greater 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).

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120	1 INTRODUCTION	

121	DINP is produced by the esterification of phthalic anhydride with isononanol. Commercially, DINP is

122	not a single compound but rather a complex mixture of phthalate esters having branched alkyl chains

123	with an average chain length of nine. The following sections present the general physical and chemical

124	properties of DINP.

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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 chemical properties of DINP for the
purposes of the draft risk evaluation.

2.1 Final Selected Physical and Chemical Property Values for DINP

Table 2-1. Summary of D

NP's Physical and Chemical

'roperty Information

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

OO

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

The EPA extracted and evaluated 11 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.
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 for the Risk
Evaluation of 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

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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

The 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; DeLorenzi 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 for the Risk Evaluation of DINP
(U.S. EPA. 2021).

2.2.4 Vapor Pressure

The EPA extracted and evaluated eleven 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 for the Risk Evaluation of 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 for the Risk Evaluation of 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
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; ECHA.
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).

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2.2.7 Log Octanol/Water Partitioning Coefficient

The EPA extracted and evaluated 13 data sources containing DINP octanol-water partition coefficient
(Kow) 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; EC HA.
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 for the Risk Evaluation of DINP (U.S. EPA.
2021) was a value calculated in EPI Suite™ from the vapor pressure and water solubility of DINP and
was 2,08/10 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 9.14x 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 9.14x 10~5 atnrmVmol 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

The 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 for the Risk Evaluation of 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
for the Risk Evaluation of 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). The EPA selected an autoflammability temperature of
400 °C for DINP (ECHA. 2016) for this risk evaluation.

2.2.11 Viscosity

In the Final Scope for the Risk Evaluation of 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). The 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 scoping
value.

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

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233	the associated references. In some instances where no data were available, or there was a wide range of

234	data that generally, but did not consistently agree with one another, models such as EPI Suite™ were

235	used to estimate the value for the endpoint (octanol water partitioning coefficient and organic carbon

236	partitioning coefficient) and cross checked with reported data from systematic review.

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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],

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http://www.chemspider.com/Chemical-Stmcture.513622.html

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-isononvl-phthalate-
final-scope.pdf

U.S. EPA. (2024a). Draft Risk Evaluation for Diisononyl Phthalate (DINP) - Systematic Review
Protocol. Washington, DC: Office of Pollution Prevention and Toxics.

U.S. EPA. (2024b). Draft Risk Evaluation for Diisononyl Phthalate (DINP) - Systematic Review

Supplemental File: Data Quality Evaluation and Data Extraction Information for Physical and
Chemical Properties. Washington, DC: Office of Pollution Prevention and Toxics.

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