You can read every word on the back of a perfume bottle and still not know what is in it. One word on that label — "fragrance," or "parfum" on European packaging — is legally allowed to stand in for the entire scent formula. Behind it sits a menu of roughly 3,700 chemicals that the manufacturer never has to name.
That is not a loophole somebody discovered. It is written into the rules.
The one word that hides the formula
Federal cosmetics labeling law is actually pretty strict. Under 21 CFR 701.3(a), the label on a cosmetic has to declare each ingredient in descending order of predominance — "except that fragrance or flavor may be listed as fragrance or flavor."
That exception is the whole ballgame. The FDA's own explainer is blunt about why it exists: fragrance and flavor ingredients "do not need to be listed individually" because they are the ingredients most likely to be trade secrets. The preservative gets named. The dye gets named. The scent — which in a perfume is most of the product — gets one word.
How much can hide under it? The International Fragrance Association publishes a Transparency List of everything its industry actually uses. The 2025 edition runs to 3,691 ingredients: 3,312 used for scent, plus 379 functional ingredients like solvents and stabilizers. When the Environmental Working Group last wrote about this the number was around 3,100. The pool keeps growing. The disclosure requirement has not moved since 1973.
What a lab found when it actually looked
Nobody has to guess about this, because someone paid to open the bottles.
The Campaign for Safe Cosmetics commissioned Analytical Sciences, an independent lab in Petaluma, California, to test 17 name-brand fragrances. EWG then analyzed the results against government and industry hazard data and published them as Not So Sexy. The tally:
- 91 chemical ingredients across the 17 products.
- 51 of them were disclosed on labels.
- 38 were found only in testing — never listed anywhere.
- The average product carried 14 secret chemicals, roughly one hidden ingredient for every one disclosed.
- American Eagle Seventy Seven carried 24 secret chemicals, the most of any product tested. Chanel Coco had 18. Britney Spears Curious and Giorgio Armani Acqua Di Gio had 17 each.
- The average product contained 10 sensitizers — chemicals that can trigger allergic reactions, asthma, or contact dermatitis — and 4 chemicals with hormone-disrupting potential.
The part that gets skipped in the social-media version of this study is the safety-assessment gap. Of those 91 ingredients, the industry's own review bodies had published assessments for a minority: the Cosmetic Ingredient Review had assessed 19, and IFRA and the Research Institute for Fragrance Materials had assessed 27 across the previous 25 years. So it is not simply that consumers cannot see these chemicals. In a lot of cases nobody has publicly checked them either.
Diethyl phthalate, and why it shows up in urine
One name came up over and over: diethyl phthalate, or DEP. It appeared in 12 of the 17 products, at concentrations from 30 ppm up to 32,000 ppm in Eternity for Women. DEP is not there for the smell — it is a solvent that keeps scent from flashing off your skin.
Phthalates are the class of chemicals most people have heard of in the "endocrine disruptor" conversation, and DEP is one of the most widely detected: EWG cites biomonitoring finding it in 97 percent of Americans.
Here is the part that makes fragrance different from most exposure stories. It is measurable, in people, on a timescale of hours.
A Harvard School of Public Health team led by Susan Duty studied 406 men and matched their urinary phthalate metabolites against a questionnaire about which personal care products they had used. Men who had used cologne within the prior 48 hours had median monoethyl phthalate — the breakdown product of DEP — of 265 ng/mL, versus 108 ng/mL in men who had not. Aftershave users came in at 266 versus 133. Each additional product type used was associated with a 33% increase in MEP (95% CI: 14–53%). That study, Personal Care Product Use Predicts Urinary Concentrations of Some Phthalate Monoesters, ran in Environmental Health Perspectives in 2005.
The same group had published earlier that in 168 men, an interquartile-range increase in urinary MEP was associated with a 3.6 µm increase in sperm DNA comet extent — the first human data tying MEP at ordinary environmental levels to DNA damage in sperm. Notably, the other phthalate metabolites they measured were not significantly associated.
Two honest caveats, because this is where the internet version of this story overreaches. These are observational human studies showing association, not proof that your cologne caused a specific outcome. And within the phthalate family, the strongest anti-androgenic evidence — the testosterone and reproductive-development findings — sits with DEHP and DBP, not DEP. What DEP has is near-universal exposure, a clear route from the bottle into your body, and a documented association with sperm DNA damage. That is enough to want it on the label.
You are also inhaling it
Skin absorption is only half of it. Every spray is an aerosol you breathe.
Anne Steinemann's lab analyzed emissions from 37 fragranced consumer products and found 156 volatile organic compounds. Of those, 42 were classified as toxic or hazardous under US federal law, and every single product emitted at least one of them. Fewer than 3% of the VOCs detected were disclosed on any label, safety data sheet, or website.
And the "green" and "organic" versions? Emissions of carcinogenic hazardous air pollutants were not significantly different from the conventional products.
There is a second-order effect on top of that. Common fragrance VOCs react with ozone in indoor air to generate secondary pollutants, including formaldehyde and ultrafine particles. The thing you spray is not the only thing you end up breathing.
The rules are changing — slowly here, faster in Europe
United States. The Modernization of Cosmetics Regulation Act of 2022 was the first real update to US cosmetics law in 80-plus years, and it directed the FDA to propose a rule requiring fragrance allergens to be disclosed on labels. The statutory deadline for that proposed rule was June 29, 2024. The FDA missed it, and missed the follow-on date as well. The Unified Agenda has since pushed the proposed rule into 2026, which means a final rule realistically lands no earlier than 2027.
European Union. Already done. Commission Regulation (EU) 2023/1545 expands the list of fragrance allergens that must be individually named on the label from 26 to 82. New products placed on the EU market must comply by 31 July 2026; stock already on shelves has until 31 July 2028. The same brand can sell you the same perfume with a longer ingredient list in Berlin than in Boston.
California. The Cosmetic Fragrance and Flavor Ingredient Right to Know Act of 2020 (SB 312) was the first US law to crack the fragrance exemption. Since January 1, 2022, companies selling cosmetics or professional salon products in California have had to report any fragrance or flavor ingredient appearing on one of 23 designated hazard lists to the state's Safe Cosmetics Program, which publishes it in a public database. It is not full disclosure — only flagged chemicals get reported — but it is the closest thing Americans currently have to reading the formula.
What to actually do about it
You do not have to smell bad to avoid this. You have to be able to see the label.
"Fragrance-free" and "unscented" are not the same claim. Unscented often means masking fragrance was added to cover the smell of the base ingredients. Fragrance-free is the one you want.
Look for brands that publish the full fragrance breakdown. A growing number list every scent component instead of hiding behind the collective term. That is a real signal — a brand that discloses is a brand that thinks the formula survives being read.
Check the California database for a product you use daily. If a flagged ingredient is in there, the state has it.
Watch the dose, not just the product. The exposure evidence scales with how many scented products you use and how recently. Cologne, aftershave, lotion, body spray and scented deodorant stack.
This is exactly the gap we built Tallow for. Scan a barcode and Tallow breaks down what is really in a product — ingredients named line by line, additives rated, and independent lab testing attached where it exists — so "fragrance" is not the end of the conversation. Know what is really inside.
This article summarizes published academic and government sources for consumer-information purposes. Product-level test results described here are those reported by the Campaign for Safe Cosmetics and EWG in 2010 and reflect the formulations tested at that time; they are not a current test of any named product and are not a legal determination against any brand. Sources: EWG / Campaign for Safe Cosmetics, FDA, eCFR, IFRA, Environmental Health Perspectives, Steinemann via NIH, EUR-Lex, and California CDPH.