This is the reason why we don’t use it.
For years, diethyl phthalate (DEP) has been widely used in perfumery.
It is odorless.
It is technically effective.
It is permitted in cosmetic formulations.
And yet, at The Today Project, we chose not to use it.
Not out of fear.
Not for marketing.
Not because of trends.
But because of scientific reflection.
Is DEP an Endocrine Disruptor?
This is where nuance begins.
DEP belongs to the phthalate family. Some members of this family — such as DEHP and DBP — have demonstrated anti-androgenic and endocrine effects in animal studies and are now restricted in the European Union.
DEP does not carry the same level of conclusive evidence.
And that matters.
In toxicology, we cannot automatically extrapolate risk based on chemical family alone.
Molecular structure matters. Molecular weight matters. Metabolism matters.
However — and this is equally important — there is also no definitive body of evidence that proves complete long-term safety across all exposure scenarios.
Scientific literature shows:
Limited to moderate evidence of reproductive or developmental effects in animal models
Inconsistent epidemiological findings in humans
Data gaps in chronic dermal exposure
Incomplete understanding of endocrine mechanisms
Several systematic reviews conclude:
There is insufficient evidence to confidently rule out potential adverse effects.
For us, that sentence is decisive.
The Paraben Lesson
For years, parabens were considered safe within regulated concentrations.
Science showed that short-chain parabens exhibited extremely weak estrogenic activity — orders of magnitude lower than endogenous estradiol.
Yet the market progressively eliminated them.
Why?
Because risk perception outpaced nuanced toxicological discussion.
At The Today Project, we do not formulate based on public pressure.
But we do observe a principle:
When a chemical family contains members with proven endocrine activity, scientific prudence requires
heightened scrutiny for all related compounds — even those with weaker evidence.
DEP belongs to that family.
The Real Question Is Not “Is It Banned?”
The deeper questions are:
Are there unresolved data gaps in long-term dermal exposure?
Has combined exposure (“cocktail effect”) been sufficiently evaluated?
Do we have complete mechanistic clarity?
Is the ingredient technically indispensable?
The answer to the last question is clear:
Alternative solvent and fixation systems exist.
And when an ingredient is not essential — and scientific uncertainty remains — our philosophy is simple:
We choose intelligent precaution.
We do not claim toxicity.
We do not engage in alarmist language.
We do not build narratives on fear.
We make formulation decisions based on scientific coherence.
Our Position as Formulators
The Today Project was born from cosmetic science.
But also from a vision of conscious luxury.
We do not formulate merely to meet regulatory thresholds.
We formulate to anticipate where science is still evolving.
When literature states:
“Evidence is limited.”
“Data are insufficient.”
“Further research is required.”
We listen.
Not because we know it is harmful.
But because we do not know, with certainty, that it is universally harmless under all real-life exposure patterns.
And in perfumery — where application is repeated, dermal, and inhalatory — that distinction matters.
This is not an attack on DEP.
It is an explanation.
Responsible cosmetics are not built on viral blacklists or simplified narratives.
They are built on critical evaluation of evidence — including its gray zones.
When science contains uncertainty, we choose clarity.
That is our standard.
That is our invisible luxury.
Scientific Conclusions on Diethyl Phthalate (DEP)
What the Literature Actually Says
1️⃣ U.S. Consumer Product Safety Commission (2010)
What the report states:
This is a comprehensive toxicological assessment prepared for the U.S. Consumer Product Safety Commission (CPSC). It evaluates available data on DEP including toxicokinetics, acute and chronic toxicity, reproductive and developmental toxicity, carcinogenicity, and exposure scenarios.
Key findings regarding DEP:
Repeated oral exposure in animal studies produced systemic toxicity, particularly affecting the liver and kidneys.Some animal studies reported effects on reproduction and development, including changes in gestation parameters and reproductive outcomes.Based on available animal evidence, the report identifies DEP as producing adverse effects at sufficiently high doses.Acceptable Daily Intake (ADI) values were derived for oral exposure based on animal toxicity data.However, the report explicitly notes insufficient data to establish ADIs for inhalation or dermal exposure routes, which are relevant for cosmetics and perfumery.Evidence for carcinogenicity was considered inadequate or insufficient.
Conclusion regarding DEP:
The CPSC review does not conclude that DEP is unequivocally safe. It confirms evidence of toxicity in animal models and clearly identifies data gaps for dermal and inhalation exposure, meaning long-term safety for those exposure routes cannot be fully characterized based on available data.
2️⃣ Kay, V.R. et al. (2020)
Systematic Review of the Toxicity of Diethyl Phthalate
Environmental Health Perspectives
https://pubmed.ncbi.nlm.nih.gov/32958228/
What the study states:
This is a systematic review evaluating toxicological studies of DEP, primarily in animal models, using structured evidence grading methods.
Key findings regarding DEP:
Evidence suggests that DEP exposure may induce:Male reproductive toxicity, including effects that appear independent of classic anti-androgenic mechanisms.Developmental toxicity in some experimental models.Liver toxicity in repeated-dose studies.Evidence for female reproductive toxicity was described as limited and less consistent.The authors emphasize that the overall database contains limitations and uncertainties, including study design variability and dose relevance.
Direct conclusion from the review:
The authors state that:Further research is required to fully evaluate and strengthen confidence in the toxicity database for DEP.In other words, the review does not conclude safety, but rather highlights evidence of biological effects in animals and the need for additional research before definitive conclusions can be made.
3️⃣ Keller, L.H. et al. (2021)
What the article discusses:
This publication reviews mechanistic data regarding phthalates and endocrine-related pathways. While not exclusively focused on DEP, it analyzes how different phthalates may interfere with hormonal systems.
Key points relevant to DEP:
Not all phthalates act through identical mechanisms.Some phthalates exert endocrine effects through:Altered steroidogenesisDisruption of hormone synthesis pathwaysModulation of nuclear receptorsThe article highlights that mechanistic understanding varies significantly between individual phthalates.For lower molecular weight phthalates such as DEP, mechanistic data remain incomplete and less robust compared to more extensively studied compounds like DEHP.
Conclusion regarding DEP:
There is no definitive mechanistic consensus confirming endocrine safety. Instead, the literature reflects mechanistic uncertainty, particularly regarding how lower molecular weight phthalates interact with hormonal pathways.
Overall Scientific Position Based on These Three Sources
Across these documents:DEP demonstrates adverse effects in animal models at certain doses.Evidence in humans is limited and less conclusive.There are important data gaps, particularly regarding:Chronic dermal exposureInhalation exposureLong-term endocrine mechanismsNone of these sources definitively declare DEP universally safe under all real-world exposure scenarios.Multiple sources explicitly call for additional research to strengthen confidence in safety assessments.
