Chapter One

Fragrance is everywhere—but what is it?

We breathe it, wear it, wash in it, and clean with it. Fragrance surrounds us—so why do we barely notice?

Watercolor illustration of fragranced personal care products
  • Perfume, cologne, body spray
  • Soaps, lotions, deodorant
  • Hair and skin products
Watercolor illustration of fragranced cleaning products
  • Laundry products
  • Cleaners and disinfectants
  • Dish soap, trash bags
Watercolor illustration of air fresheners and ambient scenting products
  • Plug-ins, room sprays
  • Scented candles, wax melts
  • Car air fresheners
  • Ambient or “signature” scenting

Olfactory Habituation and Adaptation

Constant exposure to fragrance can make us “nose blind.”

A scent can fade from awareness1—but the chemicals may still remain.

An Example:

You can’t smell your own perfume or detergent anymore—

—but others still can. You may even use more as your perception fades.

Chemical Sensitivity

Some people may not be able to tune a scent out.

In one study, people with chemical sensitivity showed less habituation, different brain-response patterns, and intensity ratings that did not decline over time.2

Genetic Differences

Some people can't smell certain fragrance chemicals at all.

Inherited differences in olfactory receptors can make certain fragrance chemicals—including some synthetic musks—undetectable to some people.38 No scent does not mean no exposure.

Not Just a Scent

What does "fragrance" expose us to? Often, a complex chemical formula.

Ingredients may be natural or synthetic. Some create scent; others help it dissolve, disperse, last, or remain stable.

Watercolor illustration of scent ingredients.
Fragrance ingredients in focus.

"Fragrance" ingredients are often not disclosed.

Under U.S. cosmetic labeling law, one word—“fragrance” or “parfum”—may represent dozens or hundreds3 of trade-secret ingredients.4

Most U.S. cosmetics require no FDA premarket approval.4

Worldwide, "fragrance" formulas are treated as proprietary; no jurisdiction requires their full disclosure.3

A Fragmented Regulatory Landscape

Fragrance Regulation:
What is in the product—
—and what enters the air.

Different authorities govern ingredients, labeling, chemicals, and emissions. Regulation varies by jurisdiction.

Personal care Cleaning products Air fresheners
What can be in the product

Ingredient Safety + Restriction

Which materials may be used, restricted, or prohibited.

  • USFDA — cosmetics + personal care, FD&C Act5
  • EUEuropean Commission, SCCS6,7 — prohibited (Annex II) and restricted (Annex III)
  • CANHealth Canada3 — Cosmetic Ingredient Hotlist
  • CALIOEHHA, exposure warnings: Proposition 658
Chemical law

Chemical Oversight + Risk Management

How broader chemical laws assess and manage chemicals—including some used in fragrance.

  • EUECHA9 — REACH registration & CLP classification
  • USEPA10 — Toxic Substances Control Act (TSCA)
  • CANECCC + Health Canada11 — CEPA / Chemicals Management Plan
What must be on the label

Allergen Disclosure + Labeling

Which fragrance allergens must be named for consumer awareness.

  • EUEuropean Commission12 ~80 named allergens, Reg. (EU) 2023/1545
  • EUEU Detergents and Surfactants Reg. (EU) 2026/40513
  • USFDA5 — fragrance-allergen labeling under MoCRA; no final federal allergen list as of July 2026.
What the product releases

Emissions + Indoor Air Quality

How VOCs affect indoor air.

  • CALICARB14 — VOC limits for air fresheners, cleaners, and selected personal care; Consumer Products Regulation
  • USEPA15 — VOC guidance; antimicrobial air-sanitizer claims fall under FIFRA
Globally Harmonized System of Classification and Labeling of Chemicals

Global systems support shared hazard terms and OECD test data,16,17 but each jurisdiction sets its own laws. The sections below address ingredients; Chapter Two covers emissions.

Ingredient regulation is inconsistent.

Industry standards, national laws, and state laws don't always align — the same ingredient may be allowed in one system and prohibited in another.

Industry self-regulation

What about IFRA?

IFRA is a global industry group—not a regulator. Its standards are voluntary — “IFRA compliant” does not mean government-approved.

IFRA does not replace local laws; brands remain responsible for safety and compliance.

European Union

The EU regulates more fragrance ingredients.

The EU prohibits or restricts more cosmetic ingredients and requires broader fragrance-allergen disclosure than the U.S.6,12

United States

U.S. federal regulation remains limited.

Modernization of Cosmetics Regulation Act of 2022 (MoCRA) requires the FDA to establish fragrance allergen-labeling, but specifics are pending.5

Thank You California

U.S. states like California are moving ahead.

California is moving toward EU standards: it requires disclosure of certain hazardous fragrance ingredients and allergens and, in 2027, will ban lilial and several nitro musks and restrict musk ketone.18

The U.S. and EU regulate ingredients differently.

Cosmetic regulatory entries prohibited or restricted6
U.S.
11
EU
~2,100

Counts cover all cosmetic substances, not only fragrance. U.S.: 8 prohibited and 3 conditional entries. EU: 1,736 prohibited and 362 restricted entries; 64 restrictions are labeling-only.

Fragrance allergens that must be named on the label12,5
U.S.
0
EU
24 → ~80

After July 31, 2026, cosmetics newly placed on the EU market must label ~80 fragrance allergens, up from 24.

Counts are regulatory entries, not unique chemicals; one EU entry may cover a substance group. Data as of July, 2026.6

Beyond Europe and the United States

Canada, Japan, China, and ASEAN countries also regulate cosmetics through restrictions, labeling, and safety rules. Requirements differ by jurisdiction. 19

A Few Examples

Fragrance ingredients of concern.

Allergens, persistence, toxicity, indoor-air chemistry, and environmental harm; regulation varies by jurisdiction.

3,691 2025 IFRA Transparency List

Industry’s “perfumer’s palette” = 3,312 scent + 379 functional ingredients.20

50–250 Ingredients per blend

Industry estimate cited in 2020 for the number of ingredients in a single proprietary blend.21

Natural Scent Ingredients

Plant-Derived Terpenes

Terpenes are plant-derived scent chemicals found in essential oils and “natural” fragrances—but natural does not always mean safe.

  • limonene
  • α-pinene
  • β-pinene
  • linalool
  • geraniol
  • citronellol
  • citral
  • Concerns: VOC reactivity, allergens, and ozone-driven secondary pollutants such as formaldehyde.22,23,24
  • Regulation: In the EU, certain fragrance allergens must be disclosed above product-specific thresholds.12

Other Natural Fragrance Allergens

Some allergens occur naturally in spices, flowers, balsams, and lichen extracts. They can sensitize or irritate some people:12,7

  • eugenol
  • isoeugenol
  • cinnamal
  • cinnamyl alcohol
  • coumarin
  • benzyl alcohol
  • benzyl benzoate
  • benzyl salicylate
  • hydroxycitronellal
  • amyl cinnamal
  • hexyl cinnamal
  • oakmoss extract
  • tree moss extract
  • atranol
  • chloroatranol
  • Concerns: Well-documented contact allergens.
  • Regulation: Oak moss and treemoss extracts come from different lichens and may contain atranol and chloroatranol. The EU restricts and requires labeling of the extracts and prohibits the two potent allergens.25

Scent Ingredients

Synthetic Musks

Most musk notes are now synthetic; natural deer musk is largely avoided for animal-welfare concerns.

  • Concerns: Persistence, bioaccumulation, and potential endocrine, neurological, liver, and aquatic effects.26
  • Regulation: Some musks are prohibited, some concentration-limited, and others allowed.
Musk Group Examples Why it Matters
Nitro Musks musk ambrette musk tibetene musk moskene musk xylene musk ketone California bans intentionally added musk ambrette, tibetene, moskene, and xylene in cosmetics beginning January 1, 2027. Musk ketone is subject to product-specific limits.18
Polycyclic Musks tonalide galaxolide Aquatic-toxicity concerns. The EU limits tonalide and requires labeling for galaxolide. ECHA’s risk committee has recommended classifying galaxolide as a Category 1B reproductive toxicant — presumed to harm the unborn child; European Commission adoption is pending as of July 2026.6,27
Macrocyclic Musks habanolide ambrettolide exaltolide A newer generation of synthetic musks, increasingly replacing older musks; independent health data remain limited.

Functional Ingredients

Phthalates

Phthalates can act as fragrance solvents and stabilizers. DEP has historically served as a solvent and fixative; FDA says it appears to be the only phthalate still commonly used in cosmetics.28,29

  • diethyl phthalate (DEP)
  • dibutyl phthalate (DBP)
  • di(2-ethylhexyl) phthalate (DEHP)
  • Concerns: DEHP and DBP carry stronger reproductive or carcinogenic concerns. DEP remains permitted and appears less potent, but it is still relevant because of its fragrance use and biomonitoring findings.28
  • Regulation: California banned DBP and DEHP in cosmetics on January 1, 2025. DEP remains permitted.30

Scent Ingredients

Other Restricted + High Concern Ingredients

Restricted for allergen, reproductive-toxicity, or carcinogenic concerns.12,7

  • Lyral/HICC
  • Lilial/p-BMHCA
  • Amyl Salicylate
  • Methyleugenol
  • Lyral/HICC: Prohibited in EU cosmetics; it is a strong sensitizer.25
  • Lilial/p-BMHCA: Prohibited in EU cosmetics as a Category 1B reproductive toxicant,31 SCCS opinion concluded that aggregate cosmetic exposure at proposed uses could not be considered safe,32 and California bans it beginning January 1, 2027.18
  • Amyl Salicylate: Subject to EU individual-labeling thresholds.12
  • Methyleugenol: NTP lists it as reasonably anticipated to be a human carcinogen. The EU bans intentional addition and limits naturally occurring amounts.33,34

Functional Ingredients

Fragrance Encapsulation + Synthetic Polymer Microparticles (SPMs)

Some fragranced products (e.g., laundry care) seal fragrance inside synthetic polymer microcapsules. The shell holds scent that releases over time through wear, moisture, rubbing, or friction.

  • synthetic polymer microparticles (SPMs)
  • Concerns: Non-biodegradable SPMs can contribute to persistent microplastic pollution.
  • Regulation: EU Regulation 2023/2055 restricts intentionally added SPMs to reduce microplastic emissions. Sales bans phase in by product category starting in 2027 through 2035.35

A fragranced product can change air chemistry —

Ingredient regulation is only part of the story. When a fragranced product is used indoors, these questions become relevant:

Indoor Chemistry

What about secondary pollutants?

Some fragrance chemicals can react with indoor ozone and form new pollutants.

Cumulative Exposure

Who is looking at total exposure?

Fragrance from many products and people can accumulate in the same indoor air.

Right to Know

Can businesses add fragrance or scent to shared air without notice?

Ambient scenting devices can intentionally add fragrance or scent to shared air, making exposure hard to avoid.

Next: Fragrance Affects Indoor Air + Health

References
  1. Sinding, C., et al. (2017). "New determinants of olfactory habituation." Scientific Reports. "Habituation is the fundamental mechanism that allows filtering of the constant stream of information that reaches our sensory receptors. In doing so, it frees up processing resources for attentive processes." "...For example, it is common to experience a rapid fading of the smell of sweat when entering a crowded place." ↩
  2. Andersson, L., et al. (2009). “Attention bias and sensitization in chemical sensitivity.” Journal of Psychosomatic Research, 66(5), 407–416. Sample size of 21 CS subjects [self-reported chemical sensitivity] and 17 controls. "Results: ERP [event-related potentials] patterns indicated that CS subjects did not habituate to the same extent as the controls and had difficulties ignoring the chemical exposure. CS subjects had faster overall RT [reaction times], and the perceived intensities for the chemosomatosensory stimuli did not decrease with time in the CS group, which was the case for the controls." ↩
  3. Health Canada. "Cosmetic advertising, labelling and ingredients." Accessed July 17, 2026. Ingredients section, Disclosure of certain fragrance allergens. "The Cosmetic Regulations allow the use of the term "parfum" at the end of the list of ingredients to indicate that a fragrance ingredient, or a fragrance mixture is present in the cosmetic. Disclosure of all ingredients of a fragrance mixture used in a cosmetic could result in a product label that is hundreds of ingredients long and impractical with respect to legibility." Ingredients section, Disclosure of certain fragrance allergens. "...Globally, fragrance ingredients and mixtures are considered proprietary information. There are no jurisdictions that require the entire fragrance composition of a cosmetic on the labels." Ingredients section, Disclosure of certain fragrance allergens. "Canada's new requirements will align with the European Union with respect to the disclosure of fragrance allergens within the list of ingredients on cosmetic labels and will also maintain consistency with any future changes to the list of fragrance allergens in the E.U., ensuring future alignment."
    Health Canada. "Cosmetic Ingredient Hotlist: Prohibited and Restricted Ingredients." Accessed August 2026. "The Cosmetic Ingredient Hotlist (Hotlist) is an administrative tool that Health Canada uses to communicate to manufacturers and others that certain substances may be prohibited or restricted for use in cosmetics." ↩
  4. U.S. Food and Drug Administration (FDA). "Fragrances in Cosmetics." Accessed August 2026. (Labeling of Fragrance Ingredients) The FDA requires ingredient lists on consumer cosmetics under the Fair Packaging and Labeling Act, but that law cannot force disclosure of trade secrets. Fragrance and flavor formulas — complex mixtures of many chemicals — qualify as trade secrets, so they may be listed simply as “Fragrance” or “Flavor” and the individual fragrance ingredients are not required to be listed or disclosed separately. (Safety Requirements) "The law does not require FDA approval before they [cosmetics] go on the market, but they must be safe for consumers when they are used according to labeled directions, or as people customarily use them." ↩
  5. U.S. Food and Drug Administration (FDA). "Federal Food, Drug, and Cosmetic Act (FD&C Act)." Accessed August 2026. The Federal Food, Drug, and Cosmetic Act and subsequent amending statutes are codified into Title 21 Chapter 9 of the United States Code.
    "Modernization of Cosmetics Regulation Act of 2022 (MoCRA)." Accessed August 2026. MoCRA requires FDA to establish regulations for, among other things, fragrance allergen labeling requirements. As of July 11, 2026, the U.S. has no finalized list of regulated fragrance allergens requiring label disclosure.
    USC TITLE 21—FOOD AND DRUGS, §364e. Labeling, (b) Fragrance allergens (p. 487), (regarding MoCRA). Includes language requiring notice of proposed rulemaking within 18 months of MoCRA enactment (December 29, 2022): "...(b) Fragrance allergens The responsible person shall identify on the label of a cosmetic product each fragrance allergen included in such cosmetic product. Substances that are fragrance allergens for purposes of this subsection shall be determined by the Secretary by regulation. The Secretary shall issue a notice of proposed rulemaking promulgating the regulation implementing this requirement not later than 18 months after December 29, 2022, and not later than 180 days after the date on which the public comment period on the proposed rulemaking closes, shall issue a final rulemaking. In promulgating regulations implementing this subsection, the Secretary shall consider international, State, and local requirements for allergen disclosure, including the substance and format of requirements in the European Union, and may establish threshold levels of amounts of substances subject to disclosure pursuant to such regulations." ↩
  6. U.S. Food and Drug Administration (FDA). "Prohibited & Restricted Ingredients in Cosmetics". Accessed August 2026. FDA regulations specifically prohibit or restrict the use of certain ingredients in cosmetics; FDA provides the listing at this link: eight (8) are prohibited, and three (3) are conditional (one is a labeling qualification for sunscreen ingredients). See also: Title 21 Food and Drugs, Chapter I, Subchapter G, Part 700, Subpart B—Requirements for Specific Cosmetic Products
    European Chemicals Agency (ECHA). "Cosmetic Products Regulation, Annex II - Prohibited Substances." EU Prohibited Substances: Annex II, Regulation 1223/2009/EC on Cosmetic Products, as amended by Regulation (EU) 2026/78, OJ L of 13 January 2026. Page accessed July 11, 2026: 1,736 prohibited entries (Annex II).
    European Chemicals Agency (ECHA). "Cosmetic Products Regulation, Annex III - Restricted Substances." EU Restricted Substances: Annex III, Regulation 1223/2009/EC on Cosmetic Products, as amended by Regulation (EU) 2026/78, OJ L of 13 January 2026. Page accessed July 11, 2026: 362 restricted entries (Annex III). Tonalide is listed in EU Annex III with Maximum Thresholds indicated by cosmetic product type, reflecting maximum concentrations in "ready for use" preparation. Galaxolide is listed in EU Annex III with the following Restriction: "The presence of the substance must be indicated in the list of ingredients referred to in Article 19(1)(g) when its concentration exceeds: 0.001% in leave-on products and 0.01 % in rinse-off products." ↩
  7. Scientific Committee on Consumer Safety (SCCS). "About the Scientific Committee on Consumer Safety (SCCS)." Accessed August 2026. "The Committee provides Opinions on health and safety risks (chemical, biological, mechanical and other physical risks) of non-food consumer products (e.g. cosmetic products and their ingredients, toys, textiles, clothing, personal care and household products) and services (e.g. tattooing, artificial sun tanning)."
    "Opinion on Fragrance Allergens in Cosmetic Products." SCCS/1459/11. December 2011. Paper discusses fragrance contact allergens, oxidation products of terpenes, household and occupational exposure routes, and references "well-recognized" fragrance allergens including amyl cinnamal, amylcinnamyl alcohol, benzyl alcohol, benzyl salicylate, cinnamal, cinnamyl alcohol, coumarin, citral, eugenol, geraniol, hydroxycitronellal, isoeugenol, and others including benzyl benzoate, citronellol, d-limonene, hexyl cinnamaldehyde, linalool, oak moss, tree moss. ↩
  8. California Office of Environmental Health Hazard Assessment (OEHHA). "Proposition 65." Accessed August 2026. California's Safe Drinking Water and Toxic Enforcement Act requires warnings for exposures to listed chemicals known to the state to cause cancer or reproductive harm; a number of fragrance-related substances appear on the list, search the linked page for “fragrance” to find them. ↩
  9. European Chemicals Agency (ECHA). "Understanding REACH"; "Understanding CLP (Classification, Labelling & Packaging)." Accessed August 2026. REACH governs registration of chemical substances placed on the EU market; CLP governs their hazard classification and labeling. Fragrance chemicals are covered under both. ↩
  10. U.S. Environmental Protection Agency (EPA). "Summary of the Toxic Substances Control Act (TSCA)." Accessed August 2026. TSCA gives EPA authority to require reporting, record-keeping, testing, and restrictions relating to chemical substances, including many used in fragrance. ↩
  11. Government of Canada. "Canada's approach to chemicals management (CEPA & the Chemicals Management Plan)." Date modified: 2025-02-28. Environment and Climate Change Canada (ECCC) and Health Canada assess and manage chemical substances under the Canadian Environmental Protection Act (CEPA) and the Chemicals Management Plan. ↩
  12. European Commission. Commission Regulation (EU) 2023/1545. 26 July 2023. Amends Regulation (EC) No 1223/2009. Relates to labeling of fragrance allergens in cosmetic products, including disclosure thresholds for leave-on and rinse-off products and an expanded allergen-labeling framework. ~80 Annex III (restricted) entries; requires each allergen to be individually named when present above 0.001 % (leave-on) or 0.01 % (rinse-off). The EU has required individual allergen labeling since 2005; the expanded list applies to products placed on the market from July 31, 2026 (sell-through of existing stock until July 31, 2028). The widely cited '26 allergens' (Directive 2003/15/EC) became 24 after Lyral (HICC) (Reg. 2017/1410) and Lilial (butylphenyl methylpropional) (Reg. 2021/1902) were prohibited outright and moved to Annex II. Expands the list of fragrance allergens that must be individually named above specified concentration thresholds; newly added substances include amyl salicylate and methyl salicylate. ↩
  13. European Union, EUR-Lex. Regulation (EU) 2026/405 of 11 February 2026 on detergents and surfactants and repealing Regulation (EC) No 648/2004. Modernizes and replaces the EU’s earlier detergent framework. Regulation (EU) 2026/405 on detergents and surfactants, Annex V, Part A, point 1(h)(iv). Requires labeling of fragrance allergens listed in Annex V, Part D when intentionally added above 0.01% by weight — applies September 23, 2029, per Article 37. ↩
  14. California Air Resources Board (CARB). "Fragrance Use in Consumer Products." Accessed August 2026. CARB's Consumer Products Regulation sets VOC limits for numerous product categories — including personal fragrance, air fresheners, and cleaning products — to reduce smog-forming emissions. For additional reading, refer to "CARB's Efforts to Reduce Fragrance Emissions" on the page provided by the link. ↩
  15. U.S. Environmental Protection Agency (EPA). "Volatile Organic Compounds' Impact on Indoor Air Quality"; "Efficacy Data and Labeling Requirements: Air Sanitizers." Accessed August 2026. EPA provides VOC guidance for indoor air quality; air sanitizers and certain deodorizing sprays that claim to control airborne microorganisms are regulated as antimicrobial pesticides under FIFRA. Requirements apply to products with label claims for the treatment of air to reduce the numbers of airborne microorganisms. ↩
  16. United Nations Economic Commission for Europe (UNECE). "Globally Harmonized System of Classification and Labelling of Chemicals (GHS)." Accessed August 2026. A UN framework that standardizes hazard classification and communication; countries adopt it into their own laws, with variations. ↩
  17. Organisation for Economic Co-operation and Development (OECD). "Chemical Safety and Biosafety." Accessed August 2026. OECD Test Guidelines and Mutual Acceptance of Data support internationally comparable chemical hazard testing. ↩
  18. California Legislative Information. SB 312, Leyva. Cosmetic Fragrance and Flavor Ingredient Right to Know Act of 2020. Senate Bill No. 312, CHAPTER 315; Approved by Governor and filed with Secretary of State September 30, 2020. An act to add Section 111792.6 to the Health and Safety Code, relating to cosmetics. "This bill would, commencing January 1, 2022, require a manufacturer of a cosmetic product sold in the state to disclose to the Division of Environmental and Occupational Disease Control a list of each fragrance ingredient or flavor ingredient that is included on a designated list, as defined, and a list of each fragrance allergen that is present in the cosmetic product in specified concentrations. The bill would, commencing January 1, 2022, require the division to post on its existing database of cosmetic product information a list of those fragrance ingredients and flavor ingredients in the cosmetic product and its associated health hazards."
    California Legislative Information. AB-496 Cosmetic safety (2023-2024), Chapter 441; Approved by Governor and signed by the Secretary of State on October 08, 2023. An act to amend Section 108980 of the Health and Safety Code, relating to public health. Act lists ingredients banned starting in 2025, updated for additional ingredients banned starting in 2027, including Lily aldehyde (CAS 80-54-6).
    California Legislative Information. AB-60 Cosmetic safety (2025-2026), Chapter 432, the Musk Reduction Act; Approved by Governor and signed by the Secretary of State on October 07, 2025. "This bill, the Musk Reduction Act, would expand that prohibition by adding musk ambrette, musk tibetene, musk moskene, and musk xylene to the list of banned ingredients. The bill would also, beginning January 1, 2027, prohibit the use of musk ketone in cosmetic products in excess of specified amounts, including 1.4% in fine fragrance products, and oral products, as defined." ↩
  19. Japan Ministry of Health, Labour and Welfare. "Standards for Cosmetics"; "Method for Displaying All Cosmetic Ingredients." Accessed August 2026.
    China National Medical Products Administration. "Catalogue of Raw Materials Banned for Cosmetics"; "Registration and Notification Dossier Requirements"; "Cosmetic Safety-Assessment Requirements." Accessed August 2026.
    Singapore Health Sciences Authority. "ASEAN Cosmetic Directive." Last updated June 30, 2026. The directive harmonizes cosmetic requirements among ASEAN countries and includes annexes identifying prohibited and restricted cosmetic ingredients.
    ASEAN Cosmetic Committee. "Annexes of the ASEAN Cosmetic Directive." Version 2026-1, June 22, 2026. The annexes include controls on fragrance substances, including musk ambrette (listed as prohibited) and other restricted fragrance allergens. ↩
  20. International Fragrance Association. "About the IFRA Transparency List"; "IFRA Code of Practice." Accessed August 2026. "The 2025 edition of the IFRA Transparency List includes 3,691 ingredients, comprising: 3,312 fragrance ingredients used for their odor properties or to cover malodors; and 379 functional ingredients used to support the functionality and/​or stability of a fragrance ingredient or mixture." ↩
  21. Breast Cancer Prevention Partners. "Fragrance." Accessed August 2026. Includes BCPP’s reference to "IFRA estimates these 4,000 ingredients are used by 900 expert perfumers to create the 60,000 to 80,000 unique proprietary fragrance blends made up of between 50 and 250 ingredients that they create each year." footnoted as: [1] International Fragrance Association. "IFRA Transparency List." Accessed November 4, 2020. ↩
  22. National Toxicology Program (NTP), U.S. Department of Health and Human Services. "Report on Carcinogens, Fifteenth Edition, Formaldehyde CAS No. 50-00-0". For table of contents: https://ntp.niehs.nih.gov/research/assessments/cancer/roc. Accessed August 2026. "Formaldehyde is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans and supporting data on mechanisms of carcinogenesis." ↩
  23. Horvat, T., Pehnec, G., & Jakovljević, I. (2025). "Volatile Organic Compounds in Indoor Air: Sampling, Determination, Sources, Health Risk, and Regulatory Insights." Toxics, 13, Article 344. https://doi.org/10.3390/toxics13050344. Open access under a Creative Commons Attribution license. "Monoterpenes readily undergo chemical reactions with airborne oxidative agents, such as OH•, NO3, or ozone, producing dangerous secondary pollutants such as organic acids, formaldehyde, and SOA [129]." (p. 14 of 36) "Terpenes are used as active solvents in some cleaning products and perfumed agents in consumer products. These substances produce formaldehyde, hydrogen peroxide, hydroxyl radical and SOA in reaction with ozone [185–187]. According to Bello et al. [188], ten-minute cleaning sessions with glass and bathroom cleaners raised overall VOC concentrations for up to 20 min after the cleaning operation ended. Singer et al. [189] investigated concentrations of limonene and showed that it can be found in 10 to hundreds of milligrams per cubic meter in air and persist for many hours after cleaning." (p. 22 of 36) ↩
  24. Sharmeen, J. B., et al. (2021). "Essential Oils as Natural Sources of Fragrance Compounds for Cosmetics and Cosmeceuticals." "Among natural fragrances, essential oils, which are complex mixtures of terpenes and other aromatic or aliphatic compounds, produced as secondary metabolites in specialized secretory tissues of aromatic plants [4], are the most popular." Table 5 lists 26 possible allergenic fragrances (from 2021), 18 of the 26 can be found as ingredients of essential oils. Safety of Essential Oils; "...essential oils are challenging to standardize because of the variable growing conditions, genetics, and harvesting of botanicals." ↩
  25. European Commission. Commission Regulation (EU) 2017/1410, amending Annexes II and III to Regulation (EC) No 1223/2009 on cosmetic products. 2 August 2017. Amends the EU Cosmetics Regulation to prohibit HICC, atranol, and chloroatranol in cosmetic products after SCCS allergen-safety concerns. "(4) The SCCS indicated in its opinion of 26-27 June 2012 that atranol and chloroatranol are natural components of oak tree moss (Evernia prunastri) and treemoss (Evernia furfuracea) extracts regulated in entry 91 and 92, respectively, of Annex III to Regulation (EC) No 1223/2009." Added HICC (Hydroxyisohexyl 3-Cyclohexene Carboxaldehyde), atranol, and chloroatranol to the EU cosmetics prohibited-substances list. Products containing them could no longer be placed on the EU market after August 23, 2019, or made available after August 23, 2021. ↩
  26. Wang, T., Zou, H., Li, D., Gao, J., Bu, Q., and Wang, Z."Global Distribution and Ecological Risk Assessment of Synthetic Musks in the Environment." Environmental Pollution, vol. 331, 2023, article 121893. doi:10.1016/j.envpol.2023.121893. Author-accepted manuscript hosted by Empa/Lib4RI. Accessed August 9, 2026. Overview of synthetic musk categories—including nitro musks such as musk xylene and musk ketone and polycyclic musks such as galaxolide (HHCB) and tonalide (AHTN)—and their environmental occurrence, persistence, bioaccumulation and ecotoxicity. The review also notes studies reporting endocrine activity and reproductive, developmental, neurotoxic and hepatotoxic effects for some musks, primarily in experimental organisms and laboratory systems. ↩
  27. French Agency for Food, Environmental and Occupational Health & Safety (ANSES). "ANSES proposes classifying galaxolide as toxic for reproduction in the European CLP Regulation." March 4, 2025. ANSES proposed classifying galaxolide (HHCB) as a Category 1B reproductive toxicant under the CLP Regulation, citing potential effects on fertility and development. ECHA opened the scientific dossier for public consultation on January 27, 2025.
    European Chemicals Agency (ECHA). "Harmonised Classification and Labelling Process—Galaxolide (HHCB/hexamethylindanopyran)." CAS 1222-05-5; EC 214-946-9; Index 603-212-00-7. RAC adopted its final opinion in December 2025 and published it in March 2026, recommending classification as Repr. 1B, H360D (“May damage the unborn child”), based on developmental toxicity. As of July 2026, the recommendation has not been incorporated into CLP Annex VI. Commission adoption and application of an Annex VI entry remain necessary. Once applicable, the classification would generally prohibit the use of HHCB in EU cosmetic products under Article 15, subject to applicable exemptions and transition provisions. The ECHA record provides access to the RAC opinion and supporting background document. ↩
  28. U.S. Food and Drug Administration (FDA). "Phthalates in Cosmetics." Content current as of: May 19, 2022. Explains phthalate uses in cosmetics, including their role as solvents and stabilizers in perfumes and fragrance preparations, and notes DEP’s historic use as a fragrance solvent and fixative. FDA states that per its latest survey of cosmetics conducted in 2010, dibutylphthalate (DBP), used as a plasticizer in products (e.g., in nail polishes, to make them less brittle); and dimethylphthalate (DMP), used in hair sprays (to allow for a flexible film on the hair) are both used rarely. DEP appears to be the only phthalate still commonly used in cosmetics. ↩
  29. Breast Cancer Prevention Partners (BCPP). "Right to Know: Exposing Toxic Fragrance Chemicals in Beauty, Personal Care and Cleaning Products". 2018. BCPP’s report; includes testing discussion behind the 338 detected fragrance chemicals and 99 chemicals linked to at least one health concern. BCPP's product testing identified diethyl phthalate (DEP) to be "one of the most common chemicals found." ↩
  30. California Legislative Information. AB-2762 Toxic-Free Cosmetics Act. Chapter 314, Date Published: 10/02/2020. An act to add Chapter 14 (commencing with Section 108980) to Part 3 of Division 104 of the Health and Safety Code, relating to cosmetics. Approved by Governor and filed with Secretary of State September 30, 2020. Prohibits 24 intentionally added ingredients in cosmetics beginning January 1, 2025, including dibutyl phthalate (DBP) and diethylhexyl phthalate (DEHP). ↩
  31. European Commission. Commission Regulation (EU) 2021/1902 , amending the EU Cosmetics Regulation "as regards the use in cosmetic products of certain substances classified as carcinogenic, mutagenic or toxic for reproduction." Added Butylphenyl Methylpropional (p-BMHCA/Lilial) to Annex II following its classification as toxic to reproduction, Category 1B. The prohibition applied from March 1, 2022. ↩
  32. Scientific Committee on Consumer Safety (SCCS). “The Safety of Butylphenyl Methylpropional (p-BMHCA) in Cosmetic Products — Submission II.” SCCS/1591/17, final opinion adopted May 10, 2019. "On individual product basis, Butylphenyl methylpropional (p-BMHCA) (CAS 80-54-6) with alpha-tocopherol at 200 ppm, can be considered safe when used as fragrance ingredient in different cosmetic leave-on and rinse-off type products. However, considering the first-tier deterministic aggregate exposure, arising from the use of different product types together, Butylphenyl methylpropional at the proposed concentrations cannot be considered as safe." ↩
  33. National Toxicology Program (NTP), U.S. Department of Health and Human Services. "Completed Report on Carcinogens Evaluations: Methyleugenol"; and "Toxicology and Carcinogenesis Studies of Methyleugenol." Accessed August 2026. NTP lists methyleugenol as reasonably anticipated to be a human carcinogen. Its animal studies found clear evidence of carcinogenic activity in rats and mice. NTP also identifies fragrance use in perfumes, creams, lotions, detergents, and soaps. ↩
  34. European Union. Commission Directive 2002/34/EC . The EU concluded that methyleugenol should not be intentionally added as a cosmetic ingredient. Naturally occurring content from essential oils may remain only within product-specific limits: 0.01% in fine fragrance, 0.004% in eau de toilette, 0.002% in fragrance cream, 0.001% in rinse-off products, and 0.0002% in other leave-on and oral-hygiene products. ↩
  35. European Commission Access2Markets. "Restriction of microplastics in the EU from 17 October 2023."Summarizes Regulation (EU) 2023/2055, including restrictions on intentionally added synthetic polymer microparticles (SPMs) and the transition period for synthetic polymer microparticles used for fragrance encapsulation. From the regulation: "The EU considers synthetic polymer particles smaller than 5 mm that are organic, insoluble and resistant to degradation to be microplastics." Includes, among other product types: facial scrubs and other types of cosmetics, detergents, waxes, polishes and air fresheners, etc. ↩
  36. California Department of Toxic Substances Control. "Candidate Chemicals List." Accessed August 2026.
  37. National Center for Biotechnology Information. PubChem Compound Summaries [all cited June 28, 2026]:
  38. Sato-Akuhara, N., Trimmer, C., Keller, A., Niimura, Y., Shirasu, M., Mainland, J.D., & Touhara, K. (2023). "Genetic variation in the human olfactory receptor OR5AN1 associates with the perception of musks." Chemical Senses, 48, bjac037. https://doi.org/10.1093/chemse/bjac037 Shows that inherited variation in the olfactory receptor OR5AN1 is associated with whether—and how strongly—people perceive musk compounds, with sensitivity to specific musks differing by genotype. Musk is a long-recognized example of "specific anosmia": an otherwise normal sense of smell with an inability to detect particular compounds. ↩
  39. Dalton, P., & Wysocki, C.J. (1996). "The nature and duration of adaptation following long-term odor exposure." Perception & Psychophysics, 58(5), 781–792. https://doi.org/10.3758/BF03213109 "Detection thresholds did not return to preexposure levels for most subjects until 2 weeks after removal of the odorant from their home." After two weeks of continuous odorant exposure at home, participants showed an odorant-specific reduction in sensitivity and perceived intensity; for most individuals, reduced sensitivity was still evident up to 2 weeks after the last exposure. The authors note this slow recovery distinguishes long-term, real-world adaptation from the rapid rebound seen after brief exposures. ↩