At a glance
| Chemical family | Phthalate ester — lowest-molecular-weight phthalate in widespread commercial use |
| CAS number | 84-66-2 |
| Classification | Not classified by IARC; not on US CPSC permanent ban list for children's products (which covers DEHP, DBP, BBP, DnOP, DiNP, DiBP); EU restrictions in some cosmetic categories; California Prop 65 not listed |
| Where you encounter it | Fragrance fixative in personal care products (perfumes, deodorants, lotions, shampoos, scented soaps); scented candles, air fresheners, plug-ins; some pharmaceutical excipients; indoor air during/after PCP use; indoor dust at low concentrations |
| Sleep micro environment relevance | Transfers from skin and hair to pillowcases and bedding via sweat and direct contact; the primary metabolite MEP is detected in nearly 100% of urine samples from US adults in CDC NHANES biomonitoring, confirming widespread low-level exposure |
| Activated carbon capture | Moderate to high — DEP's vapor pressure and molecular size are within the favorable range for granular activated carbon and activated carbon fiber adsorption |
Regulatory & certification status
Where Diethyl Phthalate (DEP) stands across the major regulatory systems and the certifications a bedroom product might carry. Each row links to the governing instrument; where a jurisdiction has no specific measure, that is stated plainly rather than left blank.
| European Union | REACH: diethyl phthalate (84-66-2) is not on the SVHC Candidate List, not on the Authorisation List (Annex XIV), and not restricted under Annex XVII. The Annex XVII phthalate restrictions name other esters: entry 51 covers DEHP, DBP, BBP and DIBP, and entry 52 covers DINP, DIDP and DNOP — DEP is in neither. CLP: no harmonised classification for DEP was identified in Annex VI, so any hazard classification would rest on self-classification by registrants. Regulatory — EUR-Lex · ECHA |
| United States | Federal: DEP is on the TSCA inventory but has no completed EPA TSCA Section 6 risk evaluation; its EPA IRIS assessment was discontinued, and DEP is not among the phthalates permanently banned by the CPSC for children's toys and child-care articles (that list covers DEHP, DBP, BBP, DINP, DIBP, DnHP and DCHP). California: diethyl phthalate (84-66-2) is not on the Proposition 65 list — verified against the OEHHA list, which carries DEHP, DBP, BBP, DnHP, DIDP and DINP but not DEP. Regulatory — OEHHA · US EPA IRIS |
| Canada | Under the Phthalate Substance Grouping work concluded by Environment and Climate Change Canada / Health Canada (final screening assessment published 5 December 2020), only DEHP was concluded to meet the section 64 CEPA toxicity criteria; the other phthalates assessed, including diethyl phthalate, were not. DEP is therefore not on CEPA Schedule 1. (Note: DEP was handled among the additional phthalates considered for cumulative assessment, not within the core 14-substance grouping, which did not include DEP.) Regulatory — Government of Canada · Canada Gazette |
| Australia | DEP has been assessed under the Australian industrial chemicals scheme (NICNAS, now AICIS), including a human-health hazard assessment and coverage within a phthalate-esters environment assessment, but no AICIS/IChEMS prohibition or specific restriction on DEP was identified. No ban or restriction found; the existence and exact scope of the cited assessment documents were not independently re-verified here. Regulatory — AICIS |
| United Kingdom | UK REACH and GB CLP inherited the pre-Brexit EU position, under which DEP was not restricted or classified. No DEP-specific GB restriction, UK REACH Candidate List entry, or GB CLP harmonised classification was identified. The current UK REACH Candidate List was not read in full to confirm DEP's continued absence, so this is reported conservatively. Regulatory — HSE |
| Certifications | CertiPUR-US: certified foam is made without the phthalates regulated by the U.S. CPSC; DEP is not among the CPSC-regulated phthalates, so it is not specifically named (the public CertiPUR-US criteria reference the CPSC-regulated phthalates as a group rather than listing DEP). OEKO-TEX Standard 100: restricts phthalate content in certified textiles and DEP is conventionally among the phthalates screened, though its inclusion in the criteria was confirmed only via secondary sources here, not the OEKO-TEX limit-values document itself. GREENGUARD / GREENGUARD Gold: a low-VOC emissions certification that does not screen for an individual additive such as DEP by name. Industry — CertiPUR-US · OEKO-TEX |
| The 72-hour test window | Largely missed, with a caveat. DEP is the most volatile of the common phthalates (vapour pressure roughly 0.1 Pa at 25 C), so a short emissions test may register a little more of it than heavier phthalates like DEHP. But it is still a semi-volatile additive that mainly partitions into house dust rather than off-gassing, so a ~72-hour VOC chamber test does not reliably capture it. Inferred — from the compound's volatility/emission profile versus the VOC focus of short chamber tests |
What it is
DEP — diethyl phthalate, CAS 84-66-2 — is the lowest-molecular-weight phthalate in widespread commercial use (molecular weight 222 g/mol). The molecule is the diester of phthalic acid with two ethyl groups, giving it short side chains compared with heavier phthalates like DEHP (di-2-ethylhexyl phthalate, MW 391) or DBP (di-n-butyl phthalate, MW 278). The short ethyl chains matter for two reasons: they make DEP volatile enough to function as a fragrance solvent, and they make it too short to plasticize PVC effectively. Heudorf, Mersch-Sundermann & Angerer 2007 covered the structural-use relationship across the phthalate family in their foundational toxicology and exposure review. Peer-reviewed
DEP's commercial role is overwhelmingly in fragrance applications. The compound dissolves a wide range of aromatic molecules and evaporates slowly enough to extend the lifetime of an applied fragrance, which is why perfumers and cosmetic chemists use it as a carrier and fixative. It also appears as a denaturant in industrial ethanol, an excipient in some pharmaceutical formulations, and a plasticizer in cellulose-based plastics (though not the more common PVC). The ATSDR Public Health Statement for diethyl phthalate documents the regulatory framing and exposure overview. Regulatory
Where you encounter it
From personal care products
Anything labeled "fragrance" or "parfum" on a US personal care product can contain DEP. Federal labeling rules treat fragrance as a proprietary formulation, so individual compounds inside the fragrance blend are not required to be disclosed. Hauser & Calafat 2005 reviewed the human health and exposure literature on phthalates and identified personal care products as the dominant route for DEP specifically — distinct from the food-contact-material pathway that dominates DEHP exposure. Peer-reviewed
The product categories where DEP is most commonly identified, when fragrance ingredient disclosures are available: perfumes, colognes, body sprays, deodorants, antiperspirants, hairspray, hair styling products, lotions, body wash, scented soaps, scented laundry detergent, fabric softener, dryer sheets, and the broader category of fragranced household products including candles, air fresheners, and plug-in diffusers.
From CDC NHANES biomonitoring
The primary metabolite of DEP — monoethyl phthalate (MEP) — is the most consistently detected phthalate metabolite in US population biomonitoring. Silva and colleagues 2007 established the analytical methodology for measuring 22 phthalate metabolites including MEP in human urine; the method has anchored CDC's NHANES phthalate biomonitoring program ever since. Peer-reviewed Samandar et al. 2009 demonstrated that urinary MEP is temporally stable enough to make spot-urine measurements valid biomarkers of exposure. Peer-reviewed
MEP is detected in essentially 100% of US adult urine samples — a detection rate that reflects the ubiquity of synthetic fragrance in consumer products rather than any single dominant exposure source. The biomonitoring data does not distinguish between exposure routes, but the population-level distribution of MEP urine concentrations tracks reported personal care product use patterns more closely than it tracks dietary intake.
From indoor air and dust
DEP is volatile enough to enter indoor air directly from fragranced products during use. Concentrations spike during and immediately after PCP application — perfume application, lotion use, candle burning, air-freshener spraying — and decay over hours as ventilation removes the airborne fraction. The compound also partitions to indoor dust at lower concentrations than DEHP but at detectable levels. Bornehag and colleagues 2004 in the foundational Swedish phthalate-dust-asthma study measured DEP among the phthalates in residential indoor dust samples. Peer-reviewed
From sweat-mediated bedding deposition
Personal care products applied during the day transfer to skin and hair, and from there to pillowcases, sheets, and clothing through direct contact, sweat, and skin oil migration. The body partly excretes absorbed DEP through sweat as well as urine, meaning bedding accumulates DEP residue over use periods between washes. The general phthalate sweat-excretion pathway has been documented in the broader phthalate literature; DEP-specific sweat measurements are less developed than for DEHP/MEHP. Inferred from the broader phthalate sweat-excretion literature; DEP-specific direct measurement is less well-characterized
What the research says
Endocrine activity
DEP shows endocrine activity in laboratory and animal studies, but the potency is meaningfully lower than DEHP or DBP for the most-studied endpoints. Latini et al. 2006 reviewed the male reproductive effects literature across the phthalate family and placed DEP at the lower end of the documented concern spectrum. Peer-reviewed Latini, Verrotti & De Felice 2004 covered the broader phthalate endocrine disruption case with the same comparative framing. Peer-reviewed
The relative lower potency of DEP versus DEHP/DBP does not mean DEP is inactive — it means the same exposure produces a smaller effect. Combined with the ubiquity of DEP exposure (essentially every adult tested), the population-level burden remains meaningful even at lower per-molecule activity.
Population biomonitoring and exposure assessment
Wittassek et al. 2007 quantified the daily intake of phthalates including DEP across a German children cohort using urinary metabolite measurements. Peer-reviewed Koch and colleagues 2003 developed the foundational internal exposure assessment methodology that paired urine metabolite measurement with intake reconstruction. Peer-reviewed The two methodology papers together established how the population-level DEP exposure picture was built.
Respiratory and allergic outcomes
The Bornehag 2004 nested case-control study in Sweden documented associations between phthalates in house dust and asthma/allergic symptoms in children. Peer-reviewed The strongest associations were with DEHP and BBP rather than DEP, but DEP was part of the broader phthalate exposure measured. The mechanistic story for asthma is less direct for DEP than for the heavier phthalates.
Mixture effects and total phthalate burden
Real-world exposure is to multiple phthalates simultaneously — DEP from fragrance, DEHP from food packaging and PVC, DBP/DiNP/DiBP from various consumer goods. The mixture-toxicology question — whether multiple phthalates at low individual doses sum or interact for combined effects — is an active research area. The European Food Safety Authority has shifted toward group-based assessment of phthalates with similar mechanisms, reflecting the increasing recognition that single-compound exposure assessment understates real-world risk. Speculation — the mixture-effect framework is established conceptually; quantitative human dose-response is still developing
The practical implication for residential exposure assessment is that DEP-specific intervention (switching to fragrance-free personal care products) reduces the DEP contribution but does not address the heavier-phthalate components of the mixture from food packaging, vinyl flooring, and PVC tubing. The sleep-bedroom focus is narrower: bedding-mediated DEP transfer is the addressable fraction of total daily DEP exposure that an individual can meaningfully shift through product choices. The broader phthalate-load reduction question requires food-storage choices (less plastic, more glass and stainless steel) and material choices (avoiding vinyl flooring and PVC) that sit outside the sleep-micro-environment frame this Atlas focuses on. See the methodology page for how Embr frames the boundary between addressable bedroom-specific exposures and the broader chemical environment.
Skin absorption pathway
DEP penetrates skin at a non-trivial rate compared with the heavier phthalates. The shorter ethyl side chains improve the molecule's diffusion through the stratum corneum, which is why DEP serves as a dermal-penetration enhancer in some cosmetic formulations — a property that is both an intended function and an exposure pathway. Topical application of a fragranced product results in measurable DEP appearance in plasma within hours and urine within the same window, with the metabolite MEP rising correspondingly. The bedroom relevance is direct: lotions, oils, and creams applied as part of an evening routine deliver DEP through skin during the early sleep window, with the dermal absorption continuing for hours after application. Inferred from established DEP percutaneous absorption literature; the specific contribution of evening-routine PCP application to overnight exposure has not been directly measured
What helps reduce exposure
Buy fragrance-free, not unscented. "Fragrance-free" means no added fragrance compounds. "Unscented" typically means a masking fragrance has been added to neutralize the smell of other ingredients — which can still contain DEP. The two labels are different and the difference matters for this specific compound.
Skip scented candles, plug-ins, and air fresheners. These are concentrated DEP sources, and they release into bedroom air for hours after use. The marketing positions them as ambient air quality improvements; the chemistry says the opposite for households trying to reduce phthalate burden.
Read deodorant, hairspray, and styling product labels. These three product categories are routinely high-DEP per gram of product applied. Disclosed-ingredient brands that publish fragrance composition let you make informed choices. Brands that hide behind "fragrance" treat the omission as a feature.
Ventilate during and after PCP use. Opening a window or running a bathroom fan during morning/evening PCP routines reduces the bedroom air concentration of DEP after the routine ends. The effect is real and immediate.
Wash bedding regularly. Bedding accumulates DEP from sweat-mediated transfer over use periods. Weekly hot-water washing reduces the accumulated bedding load.
Reduce overall PCP application before bed. The fewer fragranced products on skin and hair going into the sleep window, the less DEP transferring to bedding overnight.
What does NOT help
- "Natural fragrance" claims. "Natural fragrance" has no regulatory definition in the US. The composition is just as proprietary as conventional "fragrance" — and natural-fragrance formulations commonly contain phthalates including DEP as solvent and fixative. The label tells you nothing about phthalate content.
- Generic "non-toxic" or "clean beauty" labels. These terms are unregulated. Brands using them set their own internal standards, which may or may not exclude DEP. Look for independent ingredient disclosure or third-party certifications (MADE SAFE, EWG Verified) rather than self-declared marketing claims.
- Organic certifications. USDA Organic and similar standards address agricultural inputs and processing — they have no bearing on synthetic fragrance, which is independent chemistry. An organic-certified body wash can still contain DEP.
- Air purifiers at typical residential concentrations. HEPA-only air purifiers do not capture DEP (it's a vapor, not a particle). Activated-carbon air purifiers reduce DEP airborne concentrations but the dominant exposure routes are dermal contact and PCP-direct application rather than ambient air — so air filtration addresses a smaller fraction of the total exposure.
- Showering off scented products. Showering reduces accumulated skin residue but the typical pattern is to reapply scented products after showering. The exposure pathway resets every morning.
Open research questions
- Lower-dose endocrine effects of DEP specifically (as distinct from the heavier phthalates) in human populations at typical exposure levels. Speculation — animal evidence is established at higher doses; the residential low-dose human response is the active research area
- Phthalate mixture toxicity at real-world exposure profiles, where DEP is one component of a multi-phthalate exposure rather than the dominant species. Speculation
- The contribution of pillowcase-deposited DEP to total daily exposure relative to direct PCP application and indoor air. Speculation
- The toxicological profile of replacement compounds (DINCH, DEHT, ATBC) that are being introduced as DEP/DEHP alternatives in some product categories. The replacements have less complete safety data than the compounds they replace. Inferred from the general regrettable-substitution pattern documented in flame retardants and PFAS; DEP-replacement-specific data is sparse
Citations
- Heudorf U, Mersch-Sundermann V, Angerer J (2007). Phthalates: toxicology and exposure. International Journal of Hygiene and Environmental Health, 210(5):623-634. DOI 10.1016/j.ijheh.2007.07.011 Peer-reviewed
- Hauser R, Calafat AM (2005). Phthalates and human health. Occupational and Environmental Medicine, 62(11):806-818. DOI 10.1136/oem.2004.017590 Peer-reviewed
- Latini G, Del Vecchio A, Massaro M, Verrotti A, De Felice C (2006). Phthalate exposure and male infertility. Toxicology, 226(2-3):90-98. DOI 10.1016/j.tox.2006.07.011 Peer-reviewed
- Latini G, Verrotti A, De Felice C (2004). DI-2-Ethylhexyl Phthalate and Endocrine Disruption: A Review. Current Drug Targets — Immune, Endocrine & Metabolic Disorders, 4(1):37-40. DOI 10.2174/1568008043340017 Peer-reviewed
- Wittassek M, Heger W, Koch HM, Becker K, Angerer J, Kolossa-Gehring M (2007). Daily intake of di(2-ethylhexyl)phthalate (DEHP) by German children — A comparison of two estimation models based on urinary DEHP metabolite levels. International Journal of Hygiene and Environmental Health, 210(1). DOI 10.1016/j.ijheh.2006.11.009 Peer-reviewed
- Koch HM, Rossbach B, Drexler H, Angerer J (2003). Internal exposure of the general population to DEHP and other phthalates — determination of secondary and primary phthalate monoester metabolites in urine. Environmental Research. DOI 10.1016/s0013-9351(03)00083-5 Peer-reviewed
- Bornehag CG, Sundell J, Weschler CJ, Sigsgaard T, Lundgren B, Hasselgren M, Hägerhed-Engman L (2004). The Association between Asthma and Allergic Symptoms in Children and Phthalates in House Dust: A Nested Case-Control Study. Environmental Health Perspectives, 112(14). DOI 10.1289/ehp.7187 Peer-reviewed
- Silva MJ, Samandar E, Preau Jr JL, Reidy JA, Needham LL, Calafat AM (2007). Quantification of 22 phthalate metabolites in human urine. Journal of Chromatography B. DOI 10.1016/j.jchromb.2007.10.023 Peer-reviewed
- Samandar E, Silva MJ, Reidy JA, Needham LL, Calafat AM (2009). Temporal stability of eight phthalate metabolites and their glucuronide conjugates in human urine. Environmental Research. DOI 10.1016/j.envres.2009.02.004 Peer-reviewed
- Agency for Toxic Substances and Disease Registry. Diethyl Phthalate — Public Health Statement (ATSDR Toxicological Profile). atsdr.cdc.gov Regulatory
Frequently asked questions
What is DEP used for?
DEP is a fragrance fixative and solvent in personal care products — perfumes, colognes, deodorants, hairspray, lotions, soaps, scented candles, and air fresheners. Unlike heavier phthalates that plasticize PVC, DEP's commercial role is in fragrance applications because of its high solvency for aromatic compounds and slow evaporation rate.
Is DEP banned?
No. The US CPSC permanently banned six other phthalates (DEHP, DBP, BBP, DnOP, DiNP, DiBP) above 0.1% in children's toys and child-care articles, but DEP is not on that list. The EU has not banned DEP in cosmetics. Some manufacturers have voluntarily removed it. It remains legal in essentially all consumer product categories.
How is DEP different from other phthalates?
DEP is the lowest-molecular-weight phthalate in widespread use (MW 222). The short ethyl chains make it volatile enough to function as a fragrance solvent but too short to plasticize PVC. DEHP and DBP have longer chains, plasticize plastics, and show stronger endocrine activity in laboratory studies. DEP's health profile is real but less concerning per unit of exposure than DEHP.
Can you avoid DEP exposure?
Largely yes through product choice. Look for fragrance-free labeling on personal care products, deodorants, soaps, lotions, and laundry detergents. "Unscented" can mean a masking fragrance is added — "fragrance-free" is the more reliable label. Avoid plug-in air fresheners, scented candles, and reed diffusers. Background exposure from environmental sources continues even with these choices.
Is DEP in baby products?
Yes if the baby product contains fragrance. Baby lotions, baby shampoos, baby wipes, and baby laundry detergent commonly contain DEP under the "fragrance" umbrella term. Fragrance-free versions of all major baby product categories exist; the certified-fragrance-free designation is the most reliable filter.
What is MEP and why does it matter?
MEP (monoethyl phthalate) is the primary metabolite of DEP — the form your body produces after exposure. MEP is what CDC and other biomonitoring programs measure in urine to estimate population-level DEP exposure. MEP is detected in essentially all US adults sampled, indicating ubiquitous low-level DEP exposure across the population.
Is DEP an endocrine disruptor?
DEP shows weaker endocrine activity than DEHP or DBP in laboratory studies. It has documented anti-androgenic effects in animal models at higher doses, but the human evidence for reproductive or developmental impacts at typical residential exposure levels is more limited than for the heavier phthalates. The full mixture-effect question across all phthalates simultaneously is an active research area.
Related compounds
Phthalate family
Every claim on this page is evidence-tagged — see our methodology for how we evaluate evidence and apply tags. For broader context on bedroom chemistry, see the non-toxic bedroom guide and how long mattress off-gassing actually lasts.
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Our work on the personal-care-residue pathway focuses on capture at the sleep-surface interface, where fragrance-derived phthalates including DEP deposit on bedding from skin contact and sweat. Research and product development in progress.
Last reviewed 2026-05-25. If you find a factual error, contact us.