At a glance
| Chemical family | Phthalate ester — high-molecular-weight PVC plasticizer (diisodecyl ester of phthalic acid) |
| CAS number | 26761-40-0 |
| Classification | IARC Group 3 (not classifiable as to carcinogenicity, Monographs Vol. 101, 2013). Not classified as a reproductive toxicant by the EU (unlike DEHP/DBP/BBP). Less readily absorbed than lower-MW phthalates |
| Where you encounter it | PVC flooring; cable insulation; coated fabrics; automotive interior trim; some flexible PVC consumer products; house dust (concentrations increasing as DEHP is replaced) |
| Sleep micro-environment relevance | Increasing in house dust as it replaces DEHP. Present in PVC flooring in bedrooms. Lower toxicological concern than DEHP but contributes to cumulative phthalate exposure |
Regulatory & certification status
| European Union | REACH registered. Not on the SVHC candidate list. Not classified as Repr. under CLP (unlike DEHP/DBP/BBP). Not subject to REACH Annex XIV authorisation. REACH Annex XVII Entry 51 restricts DIDP (alongside DINP) in toys and childcare articles that can be placed in the mouth. Regulatory |
| United States | CPSIA Section 108 included DIDP in the interim ban pending CHAP review. The CHAP (2014) did not recommend permanent restriction for DIDP. EPA phthalate action plan. Regulatory |
| Canada | Not restricted in children's products. Under assessment as part of the phthalate group. Regulatory |
| International | IARC Group 3 (not classifiable, Monographs Vol. 101, 2013). Not classified as a reproductive toxicant. CPSC CHAP did not recommend permanent restriction. Regulatory |
What it is
DIDP is a branched-chain phthalate ester with a molecular weight of approximately 446 g/mol — substantially higher than DEHP (390 g/mol). This higher molecular weight is toxicologically significant: larger phthalate molecules are absorbed less efficiently through the gastrointestinal tract and skin, and the metabolites produced are less biologically active. IARC evaluated DIDP in 2013 as part of Monographs Vol. 101 and classified it as Group 3 — the evidence for carcinogenicity was inadequate in both humans and animals. The EU does not classify DIDP as a reproductive toxicant, unlike the lower-MW phthalates DEHP, DBP, and BBP that carry Repr. 1B classification. The CPSC Chronic Hazard Advisory Panel (2014) recommended that DIDP not be permanently restricted in children's products, concluding it did not warrant the same concerns as the lower-MW phthalates.
Where it shows up in bedding
DIDP is not a mattress ingredient. It enters the bedroom through PVC flooring (where it serves the same function DEHP formerly did — making vinyl flexible) and from other PVC products in the room. As the product stock transitions from DEHP-plasticised to DIDP-plasticised PVC, DIDP concentrations in house dust have been rising. During sleep, DIDP exposure occurs through the same dust ingestion and inhalation pathways as other phthalates. The lower toxicological concern associated with DIDP means that the transition from DEHP to DIDP represents a genuine risk reduction, though total phthalate exposure remains a consideration.
Citations
- IARC (2013). Some Chemicals Present in Industrial and Consumer Products, Food and Drinking-water. IARC Monographs Vol. 101. Source Peer-reviewed
- CPSC Chronic Hazard Advisory Panel (2014). Report on Phthalates and Phthalate Alternatives. Source Regulatory
- ECHA. Diisodecyl phthalate — Substance Information. Source Regulatory
Frequently asked questions
Is DIDP safer than DEHP?
Yes, by several measures. DIDP has lower absorption through the gut and skin, produces metabolites with lower anti-androgenic potency, and is not classified as a reproductive toxicant by the EU. IARC classifies both as Group 3, but the EU classifies DEHP as Repr. 1B while DIDP has no reproductive classification. The transition from DEHP to DIDP in PVC products represents a genuine reduction in phthalate-related risk.
Should I be concerned about DIDP in vinyl flooring?
DIDP in vinyl flooring is lower concern than DEHP-plasticised flooring. It contributes to total phthalate exposure through house dust, but at lower toxicological significance than the restricted phthalates. If you want to minimise phthalate exposure, hardwood, tile, or certified phthalate-free vinyl are alternatives.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-08. If you find a factual error, contact us.