DINP (Diisononyl Phthalate): Properties, Uses in Plastics and Regulatory Status

DINP (diisononyl phthalate, CAS 28553-12-0) is a high-molecular-weight ortho-phthalate used as a general-purpose primary plasticizer for flexible PVC, and it is the phthalate that replaced DEHP across flooring, cable and film. Because DINP is an ortho-phthalate but is not classified and not a Substance of Very High Concern, its regulatory position is regularly confused with that of DEHP, which raises the question of what is actually restricted.

DINP has no harmonised classification under the CLP Regulation, is not on the REACH Candidate List, is restricted under REACH Annex XVII entry 52 only in toys and childcare articles that a child can place in the mouth, carries an EU food-contact group restriction of 1.8 mg/kg shared with DIDP, and has been listed under California Proposition 65 for cancer since 20 December 2013. DINP is one of 56 plasticizer pages in our directory of plastic additives, each carrying the same identity, dosage and regulatory fields.

This page holds the identity data behind the two CAS numbers, the plasticization mechanism, the measured physical constants, the dosage range in PVC and its conversion from phr, the 6 application areas, the performance indicators and their test standards, the dated regulatory matrix across the EU, the United States, Canada and Japan, the health findings on both sides of the record, the comparison with DOTP, DINCH, DIDP, DPHP and DEHP, and the producers who sell it.

Table T1. DINP identity card.

Footnote: identity and physical data from PubChem CID 590836 and ECHA registration dossier 14959; regulatory entries from the EU, US, Canadian and Japanese legal texts cited in each section. Status as of 22 September 2026.

What Is DINP (Diisononyl Phthalate)?#

DINP is the di-isononyl ester of ortho-phthalic acid (benzene-1,2-dicarboxylic acid), a primary plasticizer that softens PVC on its own without a second plasticizer. Both ester groups sit in the ortho position, on adjacent carbons of the aromatic ring, and each one carries a branched nine-carbon chain supplied by isononyl alcohol. The systematic names encode that composition directly: 1,2-benzenedicarboxylic acid, di-C8-10-branched alkyl esters, C9-rich in the inventory form, and bis(7-methyloctyl) benzene-1,2-dicarboxylate in the single-isomer form. Which substances, then, does the name DINP actually cover?

A primary plasticizer is defined by function rather than by chemistry. ASTM D883 defines a plasticizer as a substance incorporated into a plastic or elastomer to increase its flexibility, workability or distensibility, and a primary plasticizer is compatible enough with the resin to do that alone, unlike a secondary plasticizer or extender. As a primary plasticizer, DINP belongs to the largest additive family by weight, and the hub on plasticizers for plastics compares all classes of them, from phthalates and terephthalates to cyclohexanoates, trimellitates, adipates, citrates and epoxidised esters. DINP took the general-purpose position in that family as DEHP left it, with the formula C26H42O4 and a molecular weight of 418.6 g/mol.

What does DINP stand for?#

DINP stands for diisononyl phthalate, where "isononyl" means a branched nine-carbon alcohol chain rather than a straight n-nonyl chain. The name is written di-isononyl phthalate as often as diisononyl phthalate on supplier paperwork, and chemical inventories use the longer forms 1,2-benzenedicarboxylic acid, di-C8-10-branched alkyl esters, C9-rich and bis(7-methyloctyl) benzene-1,2-dicarboxylate for the same product.

Why does DINP have two CAS numbers?#

DINP carries two CAS numbers because it is a UVCB substance, a mixture of branched C9 esters rather than a single molecule: 28553-12-0 and 68515-48-0 both designate commercial DINP, and Regulation (EU) No 10/2011 lists both under FCM substance 728. A UVCB, a substance of unknown or variable composition, is defined by the process and the feedstock that make it rather than by one structural formula, so two registrations can describe the same commercial product with slightly different alcohol specifications. Each CAS number carries its own EC number, 249-079-5 for 28553-12-0 and 271-090-9 for 68515-48-0.

The practical consequence is a documentation one. A certificate of analysis, a safety data sheet and a declaration of compliance for the same delivery can each print a different one of the two numbers, and neither is wrong. Reconciling a specification against the food-contact entry means checking FCM 728, which covers both.

Is DINP one molecule or a mixture of isomers?#

DINP is a mixture, not a single molecule: the isononyl alcohol used to make it is 40 to 45 % dimethyl heptanols, 35 to 40 % methyl octanols, 5 to 10 % methyl ethyl hexanols and 0 to 10 % n-nonanol. PubChem records that isomer distribution for the C9 alcohol feed, and every ester carries two of those chains.

The 4 recorded components of the isononyl alcohol feed are listed below.

• Dimethyl heptanols, 40 to 45 % of the alcohol
• Methyl octanols, 35 to 40 %
• Methyl ethyl hexanols, 5 to 10 %
• n-Nonanol, 0 to 10 %

Batch-to-batch variation in that distribution is what the UVCB designation records, and it is why constants such as the melting point are reported over a range.

Is DINP a high-molecular-weight phthalate?#

Yes: European Plasticisers defines high-molecular-weight phthalates as those with 7 to 13 carbon atoms in the alcohol-chain backbone, and DINP's branched C9 chains put it in that group together with DIDP, DPHP, DIUP and DTDP. The low-molecular-weight group is defined by the same trade body as 3 to 6 backbone carbons, and it contains DEHP, DBP, BBP and DIBP.

The grouping matters because it predicts the legal treatment better than the structure does. All 4 ortho-phthalates restricted in every EU article under REACH Annex XVII entry 51, namely DEHP, DBP, BBP and DIBP, sit in the low-molecular-weight group, and none of the high-molecular-weight esters does. The split that matters for compliance runs through the class itself, and phthalate plasticizers sets out which esters fall on each side of it.

How Does DINP Plasticize PVC?#

DINP plasticizes PVC by placing its ester molecules between the polymer chains, weakening the dipole and van der Waals forces between them and lowering the glass transition temperature. The branched C9 ortho-diester solvates PVC chains well enough to act alone, which makes it a primary plasticizer rather than an extender. How does DINP compare with DEHP in solvating power? DINP has slightly lower solvating power than DEHP and slightly lower volatility, a pairing that costs a little gelation speed and returns a little permanence.

Compatibility is a solubility-parameter question: a polymer and a plasticizer stay compatible when their solubility parameters lie within about 1.5 (cal/cm3)^0.5 of each other, and DINP sits inside that window for PVC. The effect has a lower bound as well, because below roughly 15 phr antiplasticization reverses the result and the compound becomes stiffer than the unplasticised resin.

The 4 classic plasticization theories are listed below.

• Lubricity theory: the plasticizer acts as a lubricant between polymer chains and reduces internal friction.
• Gel theory: the plasticizer masks the gel points at which PVC chains attach to one another.
• Free volume theory: the plasticizer increases the free volume between chains and allows segmental motion at lower temperature.
• Mechanistic theory: a dynamic solvation and desolvation equilibrium keeps ester molecules exchanging between chain sites.

The four are explained with solubility parameters on how plasticizers work. DINP is dissolved in the PVC matrix rather than bonded to it, and that single fact makes migration, extraction and volatility the properties every downstream regulation measures.

What Are the Physical and Chemical Properties of DINP?#

The measured constants for DINP are collected in the table below, each temperature in degrees Celsius and degrees Fahrenheit and each value labelled with its condition.

Table T2. DINP physical and chemical properties.

DINP is an oily, colourless liquid with a slight ester odour, a boiling point of 252 °C (485.6 °F) measured at 5 mm Hg, a relative density of 0.98 and a closed-cup flash point of 221 °C (429.8 °F). Two melting points are on record, -48 °C (-54.4 °F) and -43 °C (-45.4 °F), and both are printed here as reported values because the melting behaviour of a UVCB depends on the isomer distribution of the grade. The boiling point is a reduced-pressure measurement taken at 5 mm Hg and is not an atmospheric boiling point, which matters whenever a distillation or devolatilisation step is specified.

Values on this page follow PubChem (CID 590836). The USCG figure of 172 °F at 760 mm Hg that appears in some data sheets is erroneous and is not used here. The recorded density of 0.972 g/cm3 at 20/20 °C puts DINP below the density of water at the same temperature.

Which Polymers Use DINP, and at What Dosage?#

DINP is used almost entirely in flexible PVC, where total plasticizer content ranges from 5 to 65 wt% depending on the target hardness (about Shore A 50 to 90), and it serves as an ester softener in nitrile rubber. Each recorded use level and the evidence behind it is set out in the table below.

Table T3. DINP dosage by polymer and use.

How do phr values convert to weight percent? A phr figure is divided by the total phr of the whole recipe and multiplied by 100, so 50 phr DINP in a compound of 100 phr PVC plus 50 phr DINP gives 50 / 150 x 100 = 33.3 wt%. Real compounds also carry stabilizers, fillers and lubricants, so the total used in the denominator has to be the full formulation total rather than resin plus plasticizer alone. Compound recipes give DINP in PHR (parts per hundred resin), which converts to weight percent with that full total.

DINP in flexible PVC compounds#

DINP replaces DEHP in flexible PVC compounds at close to the same loading: its typical substitution factor is 1.04 against DEHP's reference value of 1.00, so about 52 phr DINP matches 50 phr DEHP at equal hardness. The substitution factor is a typical figure from a single secondary source rather than supplier data, and it is quoted with that qualifier every time it appears. Within the flexible PVC range of 5 to 65 wt%, the practical consequence of a 1.04 typical factor is a 4 % higher ester charge per unit of softness. DINP competes with DOTP, DINCH and DIDP across the plasticizers for PVC range.

Ronja Klotz and colleagues (Environmental Science & Technology, 2024) describe the historical switch in Swiss flooring as close to a one-to-one substitution, which is consistent with a typical substitution factor near unity. The lower bound of the useful range is set by antiplasticization: below about 15 phr the compound stiffens rather than softens, so DINP is not used as a minor flexibility adjustment in a rigid recipe.

DINP in PVC plastisols#

DINP is a general-purpose plastisol plasticizer rather than a fast fuser, so formulators pair it with fast-fusing esters such as dipropylene glycol dibenzoate or TXIB when gelation speed matters. The fast fusers recorded for PVC plastisol are DBP, DIBP, BBP, DIHP, dipropylene glycol dibenzoate and TXIB, and a plastisol gels and fuses between 140 and 220 °C (284 and 428 °F) depending on the resin and the ester package.

BASF's technical information for Hexamoll DINCH reports that DINCH gives a lower initial plastisol viscosity and better viscosity stability than DOP and DINP, which is the only direct viscosity comparison in this reference. No DINP plastisol viscosity figure, gelation temperature or fusion curve is recorded here, and none is estimated. Fast-fuser blends and viscosity behaviour are compared on plasticizers for PVC plastisol.

DINP in rubber compounds (NBR)#

DINP also serves as an ester softener in nitrile rubber, where Hallstar's comparison of 34 % ACN NBR at 20 pphr found a weight loss of 4.2 % after 70 hours at 125 °C (257 °F), against 9.2 % for DOP. DIDP lost 3.8 % and the polymeric esters 610P and 711P lost 3.3 % and 4.4 % under the same conditions. Those figures describe an NBR matrix and are not transferable to PVC. Ester softeners for nitrile and chloroprene are covered on plasticizers for rubber and elastomers.

What Is DINP Used For? 6 Applications in Plastics#

DINP is used in 6 main application areas: vinyl flooring, wire and cable, garden hose and tubing, coated fabrics, adhesives and sealants, and non-mouthable parts of toys. The 6 recorded application areas are listed below.

• Vinyl flooring and wallcovering, where DINP took over from DEHP
• Wire and cable insulation and sheathing, 70 to 90 °C temperature classes
• Garden hose, flexible tubing and profiles
• Coated fabrics, including tarpaulins and synthetic leather
• Adhesives and sealants, outside this site's plastics scope and named here only because it is where the US EPA found unreasonable risk to workers
• Toys and childcare articles, restricted in the EU to non-mouthable parts

Flooring and wallcovering#

Vinyl flooring is the market where DINP took over from DEHP: Ronja Klotz and colleagues (Environmental Science & Technology, 2024) describe the switch as close to a one-to-one substitution. Their substance-flow analysis traces how the ortho-phthalate stock in installed floor coverings turned over as the newer esters entered the recipe. Complete flooring recipes, including the stabilizer and filler package, are on flexible PVC formulations.

Wiesinger and colleagues at ETH Zürich (Environmental Science & Technology, 2024) analysed 151 new PVC floorings on the Swiss market: 16 % contained regulated chemicals above 0.1 wt%, mainly lead and DEHP linked to recycled content, while 29 % contained other ortho-phthalates, principally DINP and DIDP, above 0.1 wt%. That 29 % figure is a measurement, not a compliance failure, because Annex XVII entry 52 applies to mouthable toys and childcare articles and not to floor coverings.

Washington State takes a different line, restricting ortho-phthalates as a class, the class DINP belongs to, in vinyl flooring under chapter 173-337 WAC from 1 January 2025. That vinyl-flooring restriction is one of several covered under US state laws on plastic additives.

Wire and cable#

DINP is a standard plasticizer for PVC cable insulation and sheathing in the 70 to 90 °C temperature classes, the range it shares with DIDP. DOTP has replaced DINP and DIDP in many cable compounds, and PVC cable insulation carries a minimum limiting oxygen index of 26 vol % O2 in the recorded specification. Which ester covers which temperature class is tabulated on plasticizers for wire and cable.

No UL temperature rating is stated here for DINP or for any other plasticizer, because the rating claims in circulation for this substance class are unverified in this reference. A cable compound is a package rather than a single additive: the plasticizer works alongside a heat stabilizer, a flame retardant and a filler, and the full insulation package is set out on additives for wire and cable compounds.

Garden hose, tubing and coated fabrics#

Garden hose, flexible tubing and coated fabrics are the consumer-facing DINP applications, and they are the ones that carry a Proposition 65 warning in California. These are extruded and calendered goods where the plasticizer level sets the hand and the cold flexibility of the finished article, and where the ester stays mobile in the matrix for the life of the product.

A California warning on a hose or a coated fabric records that DINP is on the Proposition 65 list, not that the article breaches a limit, and the mechanics are set out in the supplementary section below. This reference records no glove application for DINP.

Toys and childcare articles#

DINP is allowed in toys in the EU only where the part cannot be placed in the mouth, and it is prohibited above 0.1 % in any accessible plasticised component of a US children's toy or child care article. REACH Annex XVII entry 52 sets the EU limit at 0.1 wt% of the plasticised material in toys and childcare articles that can be placed in the mouth, while 16 CFR 1307.3(b) applies the US limit without a mouthability test.

Canada and Japan restrict by mouthability as the EU does, and the jurisdiction-by-jurisdiction detail follows in the regulatory section below. Every additive family's limits for this market are listed under additives in toys and childcare articles.

Medical tubing and DEHP-free PVC#

DINP appears in DEHP-free PVC medical tubing: Aurélie Bernard and colleagues (PLoS One, 2018) measured 34.9 to 48.7 wt% DINP in French PVC infusion lines, the highest loading of the four plasticizers they analysed. The same study measured TOTM at 30.3 to 41.0 wt%, DEHT at 26.7 to 37.5 wt% and DINCH at 30.2 to 44.3 wt% in comparable devices, which shows that a DEHP-free line still carries roughly a third of its weight as plasticizer.

DINP is not a recommended medical plasticizer in this reference. The European Pharmacopoeia list of DEHP alternatives for PVC blood containers names DINCH, BTHC, TOTM and DEHT, and DINP is not on it, so the Bernard measurements record what was on the French market in one study rather than a pharmacopoeial endorsement. The four European Pharmacopoeia alternatives are compared on plasticizers for medical devices.

How Does DINP Perform in PVC?#

DINP is slightly less efficient than DEHP: its typical substitution factor is 1.04, meaning about 4 % more DINP gives the same hardness as DEHP (reference 1.00). The same typical scale places DOTP at 1.03, TOTM at 1.11 and DIBP at 0.92, and every one of those figures is a typical value from a single secondary source rather than a supplier measurement. Substitution factors for 15 plasticizers are listed on plasticizer efficiency and substitution factors.

Does DINP stay in the compound better than DEHP? DINP has slightly lower volatility than DEHP as well as slightly lower solvating power, a qualitative relationship recorded here without a PVC volatility figure. The only measured comparison is in nitrile rubber: in Hallstar's Table III, NBR at 34 % ACN with 20 pphr plasticizer lost 4.2 % of its weight with DINP after 70 hours at 125 °C (257 °F) against 9.2 % with DOP. That test matrix is NBR, not PVC, and the numbers do not transfer.

Hardness follows loading in the expected direction. One patent example records semi-rigid PVC with 25 wt% DINP measuring Shore A 94, above the flexible PVC window of Shore A 50 to 90. The test methods for the three permanence properties are named in the table below, and ASTM D1203, ISO 177 and ASTM D1239 are explained on plasticizer migration. No DINP value is printed against any of them, because none is recorded here, and a missing value is not a zero.

Table T4. DINP performance indicators.

How Does DINP Interact with Other Plasticizers and Additives?#

DINP is usually blended rather than used alone in demanding compounds: formulators combine it with a fast fuser such as TXIB for plastisol speed, with an aliphatic diester for low-temperature flexibility, and with ESBO as a co-stabilizer. The 3 recorded interaction routes are listed below.

• Fast fusers: benzoates such as dipropylene glycol dibenzoate, and TXIB, raise gelation speed in plastisols where DINP alone fuses too slowly.
• Co-stabilizers: ESBO (epoxidized soybean oil) acts as a co-stabilizer at 1 to 2 wt% in DINP compounds and as a main plasticizer at 25 to 45 wt%, as Czogała and colleagues record (Materials, 2021).
• Compatibility limits: a blend partner stays compatible with PVC when its solubility parameter lies within about 1.5 (cal/cm3)^0.5 of the resin.

One combination is prohibited outright rather than merely inadvisable. Regulation (EU) No 10/2011, as amended by Regulation (EU) 2023/1442 in force since 1 August 2023, states that DINP must not be used in combination with FCM substances 157 (DBP), 159 (BBP), 283 (DEHP) or 1085 (DIBP) in food-contact plastics, even where each individual substance would satisfy its own limit.

What Is the Regulatory Status of DINP?#

DINP is REACH-registered, is not a Substance of Very High Concern and has no harmonised CLP classification, but it is restricted in mouthable toys in the EU, in children's products in the US, and it is listed under California Proposition 65 for cancer (status 22 September 2026). The full matrix across the EU, the United States, Canada and Japan is set out in the table below.

Table T5. DINP regulatory matrix, as of 22 September 2026.

Two entries in that matrix do the most work in practice, and they are the two most often confused. Entries 51 and 52 of Annex XVII cover different substances with different scopes, and they are set out side by side on REACH Annex XVII restrictions.

Is DINP banned in the EU?#

No, DINP is not banned in the EU: REACH Annex XVII entry 52 limits it to 0.1 % of the plasticised material only in toys and childcare articles that a child can put in the mouth, and it is neither on the Candidate List nor on the Authorisation List. Entry 52 has applied since 16 January 2007, carried over from Directive 2005/84/EC and consolidated by Regulation (EC) No 552/2009, and it covers DINP, DIDP and DNOP.

The restriction people confuse with it is entry 51. Entry 51 covers DEHP, DBP, BBP and DIBP at 0.1 % by weight individually or combined in the plasticised material of articles, and since 7 July 2020 it has applied to all articles rather than to toys alone, under Regulation (EU) 2018/2005. DEHP has been on the SVHC Candidate List since 28 October 2008; DINP has never been added to it.

DINP also carries no harmonised classification under the CLP Regulation. ECHA's Committee for Risk Assessment examined a reproductive-toxicity proposal and concluded in 2018 that no classification is warranted, which is why flooring, hose, cable and coated fabric containing DINP reach the EU market without a restriction threshold on the article.

Is DINP allowed in food-contact plastics?#

Yes, in both the EU and the US, but with conditions: Regulation (EU) No 10/2011 lists DINP as FCM substance 728 with no individual SML and a group restriction 26 limit of 1.8 mg/kg for DINP plus DIDP combined, down from 9 mg/kg since Regulation (EU) 2023/1442. DINP also falls under group restriction 32, which caps a group of plasticisers at 60 mg/kg, and the overall migration limit of 10 mg/dm2 (60 mg/kg for articles intended for infants) applies to the finished material.

The permitted uses are narrow: plasticiser in repeated-use articles, plasticiser in single-use articles contacting non-fatty foods other than infant formula, follow-on formula and baby food, or technical support agent at up to 0.1 % of the final product, and DINP must not be combined with FCM 157, 159, 283 or 1085. Group restrictions 26 and 32 and the overall migration limit are explained on EU 10/2011.

In the US, DINP is one of the 8 ortho-phthalates that remained authorised as food-contact plasticizers after the FDA final rule of 20 May 2022 (87 FR 31080), and 21 CFR 178.3740 caps it at 43 wt% of the vinyl chloride polymer in food types I, II, IV-B and VIII at room temperature maximum, in film no thicker than 0.005 inch. FDA opened a post-market review on 27 May 2026 proposing a cumulative-assessment group of DEHP, DCHP, DIOP and DINP under docket FDA-2026-N-5776, a proposal that changes nothing until it is finalised. Which 21 CFR sections cover plasticizers is set out on FDA food contact rules.

Is DINP allowed in toys and childcare articles?#

The answer depends on the jurisdiction and on whether the part is mouthable: the EU and Canada restrict DINP only in mouthable parts, while the United States prohibits more than 0.1 % in any accessible plasticised component of a children's toy or child care article. The four recorded jurisdictions are compared in the table below.

The US rule of 27 October 2017 added DINP, DIBP, DPENP, DHEXP and DCHP to 16 CFR 1307.3(b) and lifted the interim restrictions on DIDP and DNOP, while DEHP, DBP and BBP remain permanently prohibited under 1307.3(a). The 8 restricted phthalates and the exempt polymers are listed on CPSIA phthalate limits. One EU change is scheduled but not yet operative: Toy Safety Regulation (EU) 2025/2509 bans CMR substances and endocrine disruptors in toys from 1 August 2030, and DINP has no harmonised CMR classification while its ECHA evaluation for endocrine-disrupting and PBT properties has no established outcome.

What did the US EPA conclude in its TSCA risk evaluation of DINP?#

The US EPA concluded in January 2025 that DINP presents an unreasonable risk to workers under 4 conditions of use, all of them spray applications of adhesives, sealants, paints and coatings that account for about 3 % of US volume. The Federal Register notice of availability for the final risk evaluation is dated 15 January 2025 (90 FR 3828), and the evaluation itself was manufacturer-requested in December 2019.

The three findings that matter to a compounder are listed below.

• What EPA found: unreasonable risk to workers from 4 conditions of use, all spray-applied adhesives, sealants, paints and coatings, representing about 3 % of US DINP volume.
• What EPA did not find: no unreasonable risk to consumers, no unreasonable risk to the general population and no unreasonable risk to the environment.
• What comes next: a TSCA section 6(a) risk-management rule is pending, and DINP was included in EPA's cumulative risk analysis of six phthalates, namely DEHP, DBP, BBP, DIBP, DCHP and DINP.

The 2016 Chemical Data Reporting volume for DINP is 200 to 500 million pounds, which places the 3 % spray-application slice against the flooring, cable and film volumes that carry no unreasonable-risk finding. How a risk evaluation turns into a section 6(a) rule is explained on TSCA and plastic additives.

Is DINP listed under California Proposition 65?#

Yes: DINP has been on the California Proposition 65 list for cancer since 20 December 2013, with a No Significant Risk Level of 146 micrograms per day set by OEHHA and last revised on 1 April 2016. The current OEHHA list edition is dated 31 July 2026 and the listing has not changed. For contrast, DEHP is listed for cancer since 1 January 1988 and for developmental and male reproductive toxicity since 24 October 2003, DIDP is listed for developmental toxicity since 20 April 2007, and DOTP, DINCH, ATBC, DIBP and DCHP are not listed at all. Listing dates and safe-harbour levels for all plasticizers are on California Proposition 65.

Is DINP Safe? Health, Safety and Environmental Profile#

DINP has no harmonised hazard classification under the EU CLP Regulation, and ECHA's Committee for Risk Assessment concluded in 2018 that no classification for reproductive toxicity is warranted. At the same time DINP sits on the California Proposition 65 list for cancer, and this page states both records rather than one. The 3 strands of the record are listed below.

• Classification: no harmonised CLP entry; ECHA's classification and labelling inventory records DINP as not classified, and 895 of the 901 notifying companies report that it does not meet the GHS hazard criteria.
• Assessments: ECHA's RAC found no reproductive-toxicity classification warranted in 2018, the US EPA found unreasonable risk to workers only in January 2025, California OEHHA listed DINP for cancer on 20 December 2013 with an NSRL of 146 µg/day, and EFSA's CEP Panel set a group tolerable daily intake covering DBP, BBP, DEHP and DINP as DEHP equivalents in its 2019 opinion.
• Exposure: diet dominates exposure to the high-molecular-weight phthalates, and Ami Zota and colleagues (Environmental Health Perspectives, 2016) associated higher fast-food consumption with higher DEHP and DINP metabolites in NHANES participants.

Human exposure to DINP is measured through its urinary metabolites MINP and MCOP. Phthalate biological half-lives are under 24 hours, so a single spot urine sample reflects recent exposure rather than a long-term body burden. This page states no LD50, no NOAEL and no mechanism of action for the Proposition 65 listing, because none is established here, and it applies no unqualified label such as "safe" to DINP or to any alternative. How exposure and health evidence are assessed across the group is summarised on phthalates: health effects.

What Are the Alternatives to DINP?#

The 4 main alternatives to DINP in flexible PVC are DOTP (DEHT), DINCH, DIDP and DPHP, while DEHP is the ortho-phthalate that DINP itself replaced. Two of the four sit outside the phthalate class entirely, in the group of non-phthalate plasticizers, and all six esters are compared in the table below.

Table T6. DINP compared with its 4 alternatives and with DEHP.

Footnote: SF values are typical figures from one secondary source, not supplier data. Blank or "not established" cells mean the value is not in our source library, not that the value is zero.

Full property data for all five sit on the plasticizer comparison page. The four comparisons below take each candidate in turn, in the order of the table.

DINP vs DOTP (DEHT)#

DOTP is the better choice wherever an ortho-phthalate label or a Proposition 65 cancer warning is a problem, because it is a terephthalate with no Annex XVII restriction, no Prop 65 listing and an individual EU food-contact SML of 60 mg/kg, at a near-identical typical substitution factor (1.03 against DINP's 1.04). DOTP carries CAS 6422-86-2 and a molecular weight of 390.6 g/mol, and its ester groups sit in the para position rather than the ortho position, which is why phthalate screening methods that report the ortho class do not return it.

DINP keeps two advantages. It is the long-established general-purpose grade with the broadest supply base, and it holds an explicit FDA allowance of 43 wt% of the vinyl chloride polymer under 21 CFR 178.3740, a broader single-regulation clearance than DOTP, whose US food-contact route runs through 21 CFR 177.1210(b)(5) for closure sealing gaskets plus five food contact notifications that bind only their own notifiers. DOTP / DEHT (dioctyl terephthalate) carries an individual food-contact SML of 60 mg/kg and no Prop 65 listing, and the choice is usually decided by which of those positions matters more to the customer.

DINP vs DINCH#

DINCH is DINP with the aromatic ring hydrogenated: BASF makes Hexamoll DINCH by hydrogenating diisononyl phthalate, which turns the benzene ring into a cyclohexane ring and takes the product out of the phthalate class entirely. The resulting cyclohexane-1,2-dicarboxylate carries CAS 166412-78-8 (US product CAS 474919-59-0), EC 431-890-2, the formula C26H48O4 and a molecular weight of 424.7 g/mol, six hydrogen atoms heavier than its parent.

The regulatory consequence of those six hydrogens is large. DINCH is listed in Regulation (EU) No 10/2011 as FCM 775 with no individual SML under group restriction 32, it is not restricted under REACH Annex XVII, it is not on Proposition 65, and it is used at up to 40 wt% in PVC for medical devices, toys and food packaging. BASF's technical information also reports a lower initial plastisol viscosity and better viscosity stability than DOP and DINP. DINCH (Hexamoll DINCH) is made by hydrogenating DINP, which is why the two esters behave so similarly in a compound and so differently on a declaration of compliance.

DINP vs DIDP and DPHP#

DIDP and DPHP are the two C10 phthalates that sit one chain length above DINP: both trade a little plasticizing efficiency for lower volatility, which is why they appear in cable and roofing compounds. DIDP carries CAS 68515-49-1 (also 26761-40-0), the formula C28H46O4 and a molecular weight of 446.7 g/mol, a C10 branched UVCB as DINP is a C9 one. DIDP (diisodecyl phthalate) shares REACH Annex XVII entry 52 and EU 10/2011 group restriction 26 with DINP, so the two are treated as one pair for the 1.8 mg/kg SML(T), while its Proposition 65 listing is for developmental toxicity from 20 April 2007 rather than for cancer.

DPHP is the odd member of the group. It carries CAS 53306-54-0, EC 258-469-4 and the same formula and molecular weight as DIDP, and its C10 chains come from 2-propylheptanol; typical use levels in plastic materials run from 10 to 35 wt%. DPHP (dipropylheptyl phthalate) is not listed in Annex I of Regulation (EU) No 10/2011, so it cannot be used in EU food-contact plastics at all, while DINP and DIDP can under group restriction 26. It is also absent from Annex XVII entries 51 and 52.

DINP vs DEHP (DOP): why DINP replaced it#

DINP replaced DEHP because DEHP carries a harmonised Repr. 1B classification (H360FD), an SVHC listing since 28 October 2008 and a REACH authorisation requirement, none of which apply to DINP, and because the swap is close to one-for-one in flooring compounds. DEHP sits on REACH Annex XIV as entry 4, with a latest application date of 21 August 2013 and a sunset date of 21 February 2015, it falls under Annex XVII entry 51 at 0.1 % in all articles since 7 July 2020, and its EU food-contact SML is 0.6 mg/kg against DINP's 1.8 mg/kg shared group limit.

The technical cost of the switch is small: the typical substitution factor moves from 1.00 to 1.04, about 4 % more ester for the same hardness. DEHP (DOP, dioctyl phthalate) carries a harmonised Repr. 1B classification and needs REACH authorisation; DINP needs neither, and the medical-device derogation that keeps DEHP legal in the EU runs only to a latest application date of 1 January 2029 and a sunset date of 1 July 2030 under Regulation (EU) 2023/2482.

Who Manufactures DINP? Grades and Suppliers#

DINP is produced by the major plasticizer makers, including BASF (Palatinol N), Evonik (Vestinol 9) and ExxonMobil (Jayflex DINP). Two further trade names are recorded without an owner in this reference, Sansocizer DINP and Plastomoll DINP, and they are listed as names rather than attributed to a producer. More producers and their locations are in the directory of plasticizer manufacturers.

Table T7. DINP producers and trade names.

No grade designations, plant locations or certifications are printed beyond the trade names above, because none is established here. Buyers should request the supplier's technical data sheet and safety data sheet and, for EU food-contact work, a declaration of compliance referencing FCM 728 with the group restriction 26 value of 1.8 mg/kg. Price drivers for DINP are tracked on plasticizer prices, and the trade measures that move them are summarised below.

How Do High-Molecular-Weight Phthalates Fit into the Plasticizer Family?#

DINP is the leading high-molecular-weight ortho-phthalate, the group that European Plasticisers puts at about 85 % of Western European ortho-phthalate production and that sits beside terephthalates, cyclohexanoates, trimellitates and adipates in the plasticizer family. Global plasticizer consumption runs at about 8.4 million tonnes per year, and European Plasticisers reports that more than 85 % of plasticizer use in Europe goes into flexible PVC, which is why a PVC-first reading of this family is the accurate one. Where each class sits is set out on the hub for types of plasticizers.

Low-molecular-weight vs high-molecular-weight ortho-phthalates#

The regulatory line inside the phthalate class runs between low- and high-molecular-weight esters: all 4 ortho-phthalates restricted in every EU article under Annex XVII entry 51 are low-molecular-weight, and none of the high-molecular-weight ones is. The two groups and their treatment are compared in the table below.

Table T8. LMW and HMW ortho-phthalates compared.

A label that says phthalate-free removes both groups at once, which is a marketing claim about a class rather than a statement about a restriction. What the label on a finished product actually covers is examined on phthalate-free plastics.

DINP trade: tariffs and capacity#

DINP trade is shaped by tariffs rather than antidumping duties: ResourceWise's 2025 market review records a 15 % US tariff on Evonik Oxeno's DINP exports and new DINP capacity at Deza in the Czech Republic. DOTP is the ester that carries US antidumping duties, on Turkish, Malaysian, Taiwanese and Polish origin, while DINP imports are affected by tariff measures instead. ResourceWise also records that ExxonMobil gained share and that the 2026 outlook is ample supply against flat demand. Tariff lines and duty orders by origin are listed under plastic additive trade. No HS code for DINP is printed here, because none is established.

Is DINP the same as DINCH?#

No: DINCH (CAS 166412-78-8) is the ring-hydrogenated form of DINP, a cyclohexane-1,2-dicarboxylate rather than a phthalate, and it is not restricted under REACH Annex XVII. DINCH carries the formula C26H48O4 and a molecular weight of 424.7 g/mol against DINP's C26H42O4 and 418.6 g/mol, and it is listed separately in Regulation (EU) No 10/2011 as FCM 775.

Does a product containing DINP need a Proposition 65 warning?#

A warning is required only when a knowing and intentional exposure exceeds the safe-harbour level, which for DINP is the No Significant Risk Level of 146 micrograms per day. The obligation under California Proposition 65 falls on businesses with 10 or more employees, which must give a clear and reasonable warning before such an exposure to a listed chemical. This is a description of how the rule operates and not legal advice, and country-by-country rules are compared on phthalate restrictions worldwide.

Does DINP need an SDS?#

Yes: suppliers provide a safety data sheet for DINP as for any traded chemical, even though 895 of the 901 companies that notified it to ECHA report that it does not meet the GHS hazard criteria. A safety data sheet records handling, storage, transport and disposal information regardless of classification outcome, so its existence is not evidence of a hazard classification.