Every fact on this site, with its evidence grade, its caveats, and a link to the source.
We start you on the strong ones: findings that have been replicated or come from one large, well-controlled study. Moderate and weak facts are here too, labeled for what they are. Use “Link to this fact” to share a single card.
Children and pregnancy / Government agency
The European Commission's 2018 endocrine disruptor framework names fetal development and puberty as the exposure periods of greatest concern, stating that exposure during these windows may cause permanent effects and raise disease susceptibility later in life.
Moderate evidence.
Caveats
This restates the 2012 UNEP/WHO consensus report rather than presenting new data of its own; the underlying 'no safe threshold'/non-monotonic dose-response evidence behind that consensus is itself disputed by a later industry-funded critique (see the WHO/UNEP 2012 source page).
Source: EU Commission 2018 Link to this fact
Fragrance is everywhere / Review of other studies
Of 83 chemicals the EPA had flagged as priorities for safety review (TSCA Work Plan), 65 (over 80%) were known to be in consumer products.
Moderate evidence: Not fragrance-specific.
Source: Goldsmith 2014, Food and Chemical Toxicology Link to this fact
Fragrance is everywhere / Measured in people or real products
A silicone ingredient in everyday deodorants, lotions, and hair products (D5) shows up in city outdoor air on a clear morning schedule tracking when people shower and dress for work, peaking around 6-7 AM and fading over the following several hours.
Moderate evidence.
Caveats
Diurnal emission-rate profile derived for one mid-sized US city (Boulder, CO, winter 2015/2017); Toronto ground-site data (2009) show a similarly timed morning peak in concentration, but the emission-rate model itself is Boulder-only.
Source: Coggon 2018, Environmental Science & Technology Link to this fact
Green, natural and unscented / Review of other studies
Most 'natural' or herbal deodorant actives described in this review (essential oils such as tea tree and usnic acid, and dozens of herbal extracts) work the same way synthetic actives like triclosan and silver compounds do: by killing or inhibiting the skin bacteria that cause odor, not through some fundamentally gentler mechanism.
Moderate evidence: Based on antibacterial potency (MIC/MBC) data only; this review does not compare skin-irritation or sensitization rates between herbal actives and synthetic anti-microbial salts.
Source: Kanlayavattanakul & Lourith 2011, International Journal of Cosmetic Science Link to this fact
Green, natural and unscented / Measured in people or real products
Not all fragrance-based odor masking works the same way: Iso E Super, a common deodorant fragrance chemical that barely blocked the malodor receptors in lab dish tests, still reduced how strong a sulfur malodor smelled to people, but less effectively than beta-ionone, suggesting this masking runs mainly through the brain blending two smells together rather than through receptor blocking.
Moderate evidence: Central-processing explanation is the authors' inference from a negative in-vitro result, not directly tested; based on the same single-lab, single-cohort study.
Source: Fukutani et al. 2023, Current Biology Industry-funded Link to this fact
Health effects / Self-reported survey
About 1 in 7 Danish adults (14%) reported fragrance-triggered symptoms at least weekly, and 5% had changed where they shop, how they travel, or how they work because of them.
Moderate evidence: Self-report.
Source: Elberling 2005, Clinical and Experimental Allergy Link to this fact
Health effects / Review of other studies
Cleaning products were the suspected exposure in 236 of 1,915 (12%) confirmed work-related asthma cases across California, Massachusetts, Michigan, and New Jersey (1993-1997); in California, janitors and cleaners had roughly double the confirmed-case rate of all other occupations combined (4.3 vs 2.3 per 100,000 workers).
Moderate evidence.
Caveats
Now traced to its primary source (Rosenman 2003), not a secondary citation. But the underlying surveillance system's own authors say it misses 53-87% of true cases (Michigan capture-recapture) and that up to 37% of confirmed cases in such systems may not be truly work-related (Malo et al., cited by Rosenman); 'cleaning products' is a broad, mostly unspecified chemical category (36% of named agents never identified further than 'cleaning compound'), not fragrance-specific (limonene only 2/300 exposure counts).
Source: Nazaroff & Weschler 2004, Atmospheric Environment Link to this fact
Health effects / Measured in people or real products
In a Toronto clinic for work-related breathing problems, about 1 in 10 referred workers had an irritable larynx (throat) syndrome rather than asthma; perfumes and cleaning agents, bleaches and air fresheners were among the named triggers.
Moderate evidence.
Caveats
Single referral clinic, retrospective, n=30; perfume named by 5/30 and cleaning agents/fresheners by 4/30; 10% of referrals, not of workers. Morrison 1999, the founding case series behind the diagnostic criteria Hoy applied, independently found perfume was a named trigger in only 26% (10/39) of its own ILS cohort, behind reflux (72%) and other airborne irritants (51%) — the syndrome is not fragrance-specific at its point of origin either.
Health effects / Measured in people or real products
About 80% of workers with scent- and irritant-triggered irritable larynx syndrome were women, versus 24–52% of workers with occupational asthma at the same clinic.
Moderate evidence: N=30, one clinic; referral and care-seeking may differ by sex.
Health effects / Measured in people or real products
Over 20 years (1993–2012), California's work-related asthma surveillance confirmed 270 cases linked to perfume or air fresheners at work, 3.8% of all confirmed cases; perfume was the 9th most common workplace asthma exposure.
Moderate evidence: Surveillance count of physician-diagnosed, reported cases; misses >=2/3 of cases; no objective testing required; excludes fragranced cleaners.
Health effects / Measured in people or real products
94% of workers with fragrance-related work asthma in California were women, mostly in offices, health care, and schools, and most cases came from perfume worn by others.
Moderate evidence: Authors attribute the sex skew to occupation and exposure, not susceptibility; care-seeking bias possible.
Health effects / Self-reported survey
Of all personal care product types, perfumes and colognes had the highest hazard ratings in the Environmental Working Group's Skin Deep database, and adults aged 18–39 used the highest-rated ones (average 7.2 of 10, vs 5.9 for those 60 and over).
Moderate evidence: EWG hazard ratings from listed ingredients, not measured toxicity or exposure; 39% of perfumes used could not be rated.
Source: Barrett 2025, Journal of Exposure Science & Environmental Epidemiology Link to this fact
Health effects / Review of other studies
A systematic review of workplace irritants found that people with pre-existing airway sensitivity (atopy plus non-specific bronchial hyper-responsiveness) can develop new-onset asthma from chronic, repeated exposure to an irritant at concentrations below the official occupational exposure limit.
Moderate evidence.
Caveats
General occupational-irritant literature (solvents, isocyanates, dusts, gases), not fragrance-specific; the below-OEL pattern is narrative synthesis over 3 older sources plus compiled case-series examples, not an independently SIGN 2+-graded finding.
Source: Baur, Bakehe & Vellguth 2012, Journal of Occupational Medicine and Toxicology Link to this fact
Health effects / Measured in people or real products
Cleaning products were the suspected exposure in 236 of 1,915 (12%) confirmed work-related asthma cases across California, Massachusetts, Michigan, and New Jersey, 1993-1997; most were new-onset asthma (80%) and about a fifth were consistent with reactive airways dysfunction syndrome, an irritant-induced, non-allergic asthma type.
Moderate evidence.
Caveats
This is a primary surveillance source, not a population prevalence estimate: the authors' own capture-recapture analysis found the surveillance system misses 53-87% of true work-related asthma cases in Michigan, and up to 37% of confirmed cases in such systems may not be truly work-related (Malo et al., cited by the authors). Fragrance/limonene was a minor named agent (2 of 300 exposure counts); bleach, acids, disinfectants, and quaternary ammonium compounds dominate.
Source: Rosenman 2003, Journal of Occupational and Environmental Medicine Link to this fact
Health effects / Measured in people or real products
In California, janitors and cleaners had roughly double the confirmed work-related asthma rate of all other occupations combined (4.3 vs 2.3 per 100,000 workers).
Moderate evidence.
Caveats
Single-state comparison using SENSOR case counts against 1990 census occupation denominators; not adjusted for other confounders; occupations with the highest overall work-related-asthma rates (firefighters, correctional officers) were not cleaning-related, so elevated rate alone does not isolate cleaning-product causation.
Source: Rosenman 2003, Journal of Occupational and Environmental Medicine Link to this fact
Health effects / Measured in people or real products
In a 2021 audit of 50 stores across 8 Boston neighborhoods, stores in lower-income Roxbury and Mission Hill were more than twice as likely to stock a hair product with a high (7-10) Environmental Working Group hazard score than stores in higher-income, predominantly White Beacon Hill (risk ratio 2.3 for both).
Moderate evidence.
Caveats
Retail-shelf audit of what stores stock, not what people buy or use; EWG hazard score is a derived ingredient-label rating, not a measured chemical concentration; only 2 of 6 neighborhood comparisons reached statistical significance, and Chinatown was excluded for 94% missing scores.
Source: Chan 2023, Environmental Health Perspectives Link to this fact
Health effects / Measured in people or real products
People with mild asthma performed a concentration task significantly less accurately than healthy people during a 3-hour ozone-limonene chamber exposure, despite working faster.
Moderate evidence: Single study, no unexposed control arm, so it is not established that the chemistry (rather than general chamber occupancy or task load) caused the accuracy difference.
Health effects / Review of other studies
Quaternary ammonium compounds such as benzalkonium chloride (BAC) and didecyldimethylammonium chloride (DDAC) have been linked to occupational asthma, contact dermatitis, and urticaria in healthcare workers, professional cleaners, and hairdressers with heavy, repeated exposure to disinfectants, antiseptics, and cosmetic preservatives.
Moderate evidence.
Caveats
Evidence is case reports, small cohorts, and a few specific-inhalation-challenge studies of occupational/disinfectant/cosmetic exposure, not laundry products; two cited cohort studies of QAC and healthcare-worker asthma directly disagree (see contradictions).
Source: Peyneau 2022, Frontiers in Toxicology Link to this fact
Health effects / Self-reported survey
Among 543 healthcare workers in 7 French hospitals/clinics, occupational exposure to quaternary ammonium compounds (QACs, e.g. benzalkonium chloride) was linked to about 7.5x higher odds of reported physician-diagnosed asthma (adjusted OR 7.56, 95% CI 1.84-31.05) and about 3.2x higher odds of nasal symptoms at work (adjusted OR 3.21, 95% CI 1.42-7.22), after adjustment for age, gender, smoking, BMI, and atopy.
Moderate evidence.
Caveats
Single cross-sectional cohort (not replicated by an independent group); the asthma outcome relies on self-report plus doctor confirmation, not spirometric testing; the confidence interval's lower bound (1.84) shows a wide range of plausible effect sizes; healthy-worker survivor bias could have caused an underestimate, especially among cleaners.
Source: Gonzalez 2014, Clinical & Experimental Allergy Link to this fact
Health effects / Measured in people or real products
Only 6.5% of tested healthcare workers (32 of 494) had detectable specific IgE antibodies to quaternary ammonium compounds, and this was not significantly associated with reported asthma, new-onset asthma, or nasal symptoms — despite QAC exposure itself being strongly associated with those same outcomes. The study authors read this pattern as pointing to an irritant, not an IgE-mediated allergic, mechanism.
Moderate evidence.
Caveats
Absence of an IgE signal does not rule out a non-IgE immunological mechanism; specific IgE was only tested against a general quaternary ammonium radical, not against every specific QAC compound (e.g. benzalkonium chloride vs. didecyldimethylammonium chloride) separately.
Source: Gonzalez 2014, Clinical & Experimental Allergy Link to this fact
Health effects / Self-reported survey
Reported physician-diagnosed asthma prevalence varied sharply by healthcare occupation: 16.1% among nurses, 16.7% among auxiliary nurses, 7.7% among cleaners, 5.1% among other healthcare workers, and 3.4% among administrative staff (overall 11.2%, p=0.003).
Moderate evidence.
Caveats
Descriptive prevalence from a single cross-sectional cohort; differences between nurses and cleaners may partly reflect a healthy-worker survivor effect (cleaners with severe asthma more likely to have left the job) rather than only differences in true exposure or risk.
Source: Gonzalez 2014, Clinical & Experimental Allergy Link to this fact
Health effects / Review of other studies
Benzalkonium chloride (BAK), the preservative in most glaucoma eye drops, accumulates in the trabecular meshwork and other deep ocular tissues after chronic topical use and has a tissue half-life of about 20 hours in the corneal/conjunctival epithelium.
Moderate evidence: Accumulation is well documented; a causal link between that accumulation and disease progression is not established by these detection studies alone.
Source: Rasmussen et al. 2014, Journal of Ocular Pharmacology and Therapeutics Industry-funded Link to this fact
Health effects / Other evidence
BAK-exposed trabecular meshwork tissue and cells share the same qualitative cellular and molecular damage signature — cell loss, apoptosis, increased reactive oxygen species, extracellular matrix accumulation, decreased outflow, fibronectin upregulation, and cellular senescence — seen in the trabecular meshwork of primary open-angle glaucoma patients.
Moderate evidence.
Caveats
This shared signature is correlational. The review states explicitly that the causal hypothesis (BAK worsens glaucoma, rather than merely resembling it) is unproven and was, at the time of writing, only beginning to be tested in a nonhuman-primate model. See C324.
Source: Rasmussen et al. 2014, Journal of Ocular Pharmacology and Therapeutics Industry-funded Link to this fact
Health effects / Self-reported survey
Weekly use of disinfectant/cleaning sprays at work was associated with worse asthma control in US nurses (OR 1.50, 95% CI 1.16-1.94 for poorly controlled; OR 1.38, 95% CI 1.00-1.92 for very poorly controlled), and the association held even among nurses who used sprays less than once a week.
Moderate evidence.
Caveats
Self-reported spray use; the paper attributes the effect to higher inhalation potential from spray application rather than to a specific chemical, since sprays covered multiple product types (surface, patient care, air-refreshing).
Source: Dumas 2017, European Respiratory Journal Link to this fact
Health effects / Review of other studies
The same authors' own worked example for ammonia — comparing a mouse near-zero-effect threshold (42 ppm) to the human no-effect level, then adding a further factor to account for ordinary variation between people — lands on a combined safety margin of about 4 to 5, not the smaller factor of about 2 that a later 2024 review attributes to this paper for protecting sensitive groups.
Moderate evidence.
Caveats
Single worked example for one chemical (ammonia); the 'about 2' figure the authors separately cite is explicitly for age/sex/lifestyle/disease combined in a general population, not derived fresh in this paper, and not tested against moderate or severe asthma/allergy.
Source: Nielsen & Wolkoff 2017, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
Health effects / Lab study (cells or chemistry)
BAK's ocular toxicity is proposed to work partly through mitochondria: because BAK is positively charged and mitochondria are the only negatively charged compartment inside cells, cell studies cited in this review found BAK triggers oxidative stress and can inhibit mitochondrial function by more than 90%.
Moderate evidence: Mechanism drawn from in vitro/cell-culture studies cited by the review, not measured directly in intact human eyes.
Source: Goldstein 2022, Eye Industry-funded Link to this fact
Health effects / Lab study (cells or chemistry)
Exposing primary human bronchial epithelial cells (air-liquid interface culture) to a disinfectant-concentration (0.4%) benzalkonium chloride aerosol for 24 h produced 2,810 differentially expressed genes (1,475 up, 1,335 down), mapping onto DisGeNET disease networks for asthma, COPD, and pulmonary fibrosis; IL1RL1 and IL6R (upregulated) are independently reported as elevated in human asthma patients.
Moderate evidence.
Caveats
Single cell-culture model, one lab, no animal or human validation of the transcriptomic findings; the authors themselves call the existing evidence that BKC causes respiratory disease in humans 'insufficient' and frame this as hypothesis-generating.
Source: Kim et al. 2025, Ecotoxicology and Environmental Safety Link to this fact
Health effects / Government agency
An international expert working group convened by the World Health Organization and UN Environment Program concluded that close to 800 chemicals are known or suspected to interfere with hormone receptors, hormone synthesis, or hormone conversion, but only a small fraction of them have been tested for whether they actually cause overt endocrine effects in an intact organism.
Moderate evidence.
Caveats
This is a 2012 expert-consensus count covering every kind of suspected endocrine disruptor (industrial chemicals, pesticides, plastics, cosmetic ingredients, natural compounds), not a fragrance-specific count, and the report is now well over a decade old.
Source: WHO/UNEP 2012 Link to this fact
Health effects / Government agency
Benzophenone's oxidative metabolite 4-hydroxybenzophenone, which is estrogenic in vitro (MCF-7 cells, ERalpha binding) and in vivo (rat uterotrophic assay), can also be formed by ultraviolet or sunlight irradiation of benzophenone itself, not only by enzymatic metabolism; the Working Group noted this matters because benzophenone has been used as a UV filter in cosmetics.
Moderate evidence.
Caveats
Photochemical formation and estrogenic activity of the photoproduct are drawn from cited primary studies (Hayashi et al. 2006, Nakagawa & Tayama 2001/2002) summarized in the monograph, not independently re-verified here; this describes the parent compound's own photoproduct, not a sunscreen-derivative UV filter's photoproduct.
Source: IARC 2013 Link to this fact
Health effects / Other evidence
In a British birth cohort followed from birth to age 42, people who had ever worked as hairdressers, barbers, or beauticians had 88% higher odds of adult onset asthma than office workers (OR 1.88, 95% CI 1.24-2.85), adjusted for sex, smoking, childhood social class, and childhood hay fever.
Moderate evidence: Occupational, not fragrance-specific: exposure is the job title, not a measured product or chemical; single UK cohort, not yet independently replicated.
Health effects / Other evidence
Four cleaning occupations (unspecified cleaners, domestic helpers and cleaners, helpers/cleaners in offices and hotels, and hand-launderers) were associated with adult onset asthma in this cohort, with odds ratios from 1.58 to 2.26; the offices/hotels cleaning code (OR 1.82, 95% CI 1.34-2.48) and home-based personal care workers (OR 1.94, 95% CI 1.40-2.69) remained significant after correcting for testing 61 occupations.
Moderate evidence: Job-title-level exposure, not product-level; the lowest estimate (unspecified cleaners, OR 1.58) did not reach significance on its own (p=0.078).
Health effects / Other evidence
People who went on to develop adult onset asthma spent less time working in the jobs linked to asthma than people who did not develop asthma (e.g., home-based personal care workers: 1.88 years vs 3.18 years, p=0.016; domestic helpers and cleaners: 1.08 years vs 3.14 years, p=0.022), consistent with a 'healthy worker effect' in which people leave jobs that cause or worsen their disease.
Moderate evidence: This pattern supports the cohort's occupational associations being real rather than reverse-caused, but does not rule out all residual confounding.
Health effects / Self-reported survey
59.4% of autistic adults reported losing workdays or a job in the past year because of fragranced-product exposure in the workplace, versus 7.6% of non-autistic adults.
Moderate evidence: Self-report; the comparable item in sibling Steinemann surveys may count 'became sick' without lost time, so this is plausibly an upper bound.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
Health effects / Measured in people or real products
Among hotel workers directly handling cleaning products, bleach, and laundry chemicals, the average estimated excess lifetime cancer risk from inhaled VOCs (4.1 in 100,000) was about 40 times the EPA's 1-in-a-million screening threshold, driven more than two-thirds by formaldehyde (then chloroform and benzene), even though measured VOC concentrations were at the low end of those reported in US buildings generally.
Moderate evidence: Preliminary/screening-level risk estimate extrapolated from short-term (6-9h) measurements to a 40-hr workweek; small sample (2 hotels); not a measured cancer incidence.
Health effects / Measured in people or real products
Despite directly and repeatedly handling cleaning products and bleach all shift, hotel housekeepers', laundry, maintenance, and office workers' calculated non-cancer hazard ratios for VOC exposure all fell below the standard threshold of 1 (ranging 0.3-0.5 across worker groups), though all remained above the more conservative 0.1 margin-of-safety benchmark the authors mention; formaldehyde contributed most of the hazard for every group except the single maintenance worker, where a lubricant-derived alkane (n-nonane) contributed slightly more (54% vs 46%).
Moderate evidence: Preliminary screening-level estimate from short-term sampling; maintenance-worker group size n=1.
Hidden ingredients / Self-reported survey
About two-thirds (64.6%) of US adults did not know fragrance ingredients don't have to be listed on the label, and more than half would prefer fragrance-free workplaces (53.2% vs 19.7% against) and health care (54.8% vs 22.4%).
Moderate evidence: Opinion survey.
Source: Steinemann 2016, Air Quality, Atmosphere & Health Link to this fact
Hidden ingredients / Measured in people or real products
Most healthcare workers using disinfectants did not know whether the products they used contained quaternary ammonium compounds: 99 of 543 subjects (18.2%) could not be classified by exposure status from self-report alone, and researchers had to independently review Material Safety Data Sheets with 3 experts to determine actual product ingredients.
Moderate evidence.
Caveats
This describes a French occupational healthcare-worker population in 2006-2007, not consumers; it does not measure how well consumers can identify QACs in household cleaning products from labels today.
Source: Gonzalez 2014, Clinical & Experimental Allergy Link to this fact
Indoor air / Measured in people or real products
In a real working primary school, mopping a classroom with a limonene-containing detergent produced bursts of tens of thousands of tiny new particles per cubic centimeter within minutes, but only when ozone was present in the air; a plain water-only mop produced no such burst.
Moderate evidence.
Caveats
One school, one detergent; particle number not mass. Classroom mopping peak ~35,000/cm3; matched controlled lecture-theater trials with the same detergent confirmed peaks up to ~68,500/cm3.
Source: Morawska 2009, Environmental Science & Technology Link to this fact
Indoor air / Other evidence
The 25 mg/m3 total-VOC chamber dose that produced a measurable lung-function decline in asthmatics is, in the authors' own framing, a maximal concentration seen in new houses but only a moderate one in the work environment — not a typical existing-home level.
Moderate evidence: This is the paper's own characterization of the dose, not a broad survey of home VOC levels for our cross-paper comparison.
Source: Harving et al. 1991, American Review of Respiratory Disease Link to this fact
Indoor air / Measured in people or real products
Not noticing a chemical or fragrance smell in your home or workplace anymore does not mean it is gone: electro-olfactogram recordings show peripheral smell receptors stay measurably responsive to a steady background odor even after conscious perception of it has faded, because habituation happens mainly in the brain, not the nose.
Moderate evidence.
Caveats
Evidence is from small human electrophysiology studies of perception, not from measurements of continued chemical absorption, dose, or health effect; this paper does not address whether continued unnoticed exposure is harmful.
Source: Pellegrino 2017, Physiology & Behavior Industry-funded Link to this fact
Indoor air / Other evidence
Across 10 real, working New York City nail salons, total VOC levels (measured in real time with a photoionization detector) averaged almost 10 times higher (32 ppm) when indoor CO2 exceeded the ANSI/ASHRAE ventilation target of 850 ppm than when the target was met (4.1 ppm).
Moderate evidence: Small (n=10), non-random convenience sample skewed toward larger, 'upscale' Manhattan salons; TVOC is an unspeciated PID sum, not a specific chemical measurement.
Source: Pavilonis, Roelofs & Blair 2018, Journal of Occupational and Environmental Hygiene Link to this fact
Indoor air / Other evidence
Mean total VOC levels measured in 10 NYC nail salons (12 ppm, median 4.0 ppm, range 0.035-67 ppm) were, in the study authors' own assessment, many times higher than would be considered acceptable in homes or office workplaces.
Moderate evidence: The paper does not give a specific numeric residential/office comparison value in text, only a qualitative 'many times greater' statement; TVOC is unspeciated.
Source: Pavilonis, Roelofs & Blair 2018, Journal of Occupational and Environmental Hygiene Link to this fact
Indoor air / Other evidence
Nail technicians' whole-blood toluene and ethyl acetate rose significantly over a single work shift (toluene 0.16→0.36 µg/L; ethyl acetate <0.16→0.51 µg/L) and post-shift levels significantly exceeded U.S. general-population (NHANES) levels for female nonsmokers.
Moderate evidence: Single small pilot study (n=10); one small cohort does not establish generalizability across the nail-salon industry.
Indoor air / Measured in people or real products
In a field study of two Michigan hotels, hotel housekeepers' and other staff's personal breathing-zone VOC exposure while working (57 ± 36 µg/m3 total target VOCs) was nearly twice the level measured by stationary indoor-area monitors in the same hotels (28 ± 15 µg/m3), and both were far above outdoor levels (mostly below detection).
Moderate evidence: Small sample (2 hotels, 22-23 personal samples); short 6-9 hour sampling shifts; not generalizable to other hotels.
Indoor air / Other evidence
During real COVID-19 disinfection at a hotel, repeated use of a quats-based disinfectant raised fine-particle levels by 5.5 to 14.2 micrograms per cubic meter in the lobby, elevator, and a public bathroom, exposing cleaning staff to repeated particle bumps throughout a work shift.
Moderate evidence.
Caveats
One day of field measurement, one hotel; cleaning protocol there also deviated from the product label (solution left on surfaces rather than wiped off) to reduce staff vapor exposure.
Source: Souza 2025, ACS Earth Space Chem, ACS Earth and Space Chemistry Link to this fact
The industry / Measured in people or real products
In a French fragrance-and-flavor factory, the company's own measurements found the butter-flavor chemical diacetyl (linked to 'popcorn lung' in US factory workers) in workers' breathing air at 0.05–9 ppm during short tasks; 29 of 31 samples were above the 15-minute limit of 0.1 ppm recommended by the EU's scientific committee on occupational limits.
Moderate evidence.
Caveats
Limit comparison is our (paper makes none); samplers on clothing, respirator use per task not reported; flavor chemical, factory workers, not consumers; industry-funded (V. Mane Fils).
Source: Angelini 2016, PLoS ONE Industry-funded Link to this fact
The industry / Measured in people or real products
The standard EU (REACH) screening tool for estimating workers' chemical exposure predicted lower levels than were actually measured in 61% of 431 measurements in a fragrance-and-flavor factory, sometimes by more than 100-fold.
Moderate evidence: One plant; evidence base count from the paper's S4 table (paper: 37% of tool predictions were above the measurement); short task samples.
Source: Angelini 2016, PLoS ONE Industry-funded Link to this fact
The industry / Industry source
Even after this 2017 update, the fragrance industry's own aggregate exposure model still explicitly excluded household cleaning and laundry products — the product category the industry's own 2003 safety-process paper says accounts for about 60% of fragrance volume — and named their inclusion as future work.
Moderate evidence.
Caveats
Single industry methods paper describing its own model's scope; the gap was closed industry-wide only in a later 2024 paper (Lee et al.), which this claim's caveat should be read alongside.
Source: Comiskey 2017 (RIFM/Creme Global), Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Industry source
To build this exposure model, the fragrance industry combined three surveys that were never designed to work together — a 7-day product diary, a monthly recall survey, and a categorical daily-frequency questionnaire — by matching subjects only on age and gender and assuming they share the same habits for entirely unrelated products.
Moderate evidence.
Caveats
The paper's authors are explicit about this assumption's uncertainty and do not test it directly; a companion validation paper (Safford et al. 2017) is not yet in this evidence base to check how much this integration step affects final exposure estimates.
Source: Comiskey 2017 (RIFM/Creme Global), Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Review of other studies
All three named authors of this inhalation-TTC methodology paper were Unilever employees at Unilever's own research center (Colworth Science Park, UK), and the paper states 'The authors declare that there are no conflicts of interest' even though the work was industry research explicitly aimed at reducing inhalation-toxicology testing requirements on the authors' own company's aerosol consumer products under REACH and the EU Cosmetics Directive's 2013 animal-testing ban.
Moderate evidence.
Caveats
A self-declared 'no conflicts of interest' statement from an industry-employed author group performing industry-funded research aimed at reducing regulatory testing burden on their own company's products.
Source: Carthew, Clapp & Gutsell 2009, Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Review of other studies
After a separate 'exception letter' sent in March 2015 by the National Candle Association, the original study's authors deleted a sentence reporting that formaldehyde in three scented-candle types (925, 1022, and 2098 ppb) exceeded workplace TLV (325 ppb) and PEL (730 ppb) limits, and softened a paper highlight from 'exposure levels of some species are high enough to exceed guideline values' to 'can approach or exceed certain guideline values.'
Moderate evidence.
Caveats
This is a documented instance of a trade association prompting language softening and deletion of a specific hazard finding in an academic paper's corrigendum; it does not mean the underlying revised emission-factor numbers (which went up, not down) are wrong.
Source: Kim et al. 2016, Journal of Hazardous Materials Link to this fact
The industry / Self-reported survey
The cosmetics industry generated its own dataset for how much lipstick, body lotion, and face cream people actually use, written by staff of the cosmetics trade association (CTFA), the fragrance industry's safety institute (RIFM), a contract statistics firm, and personal-care manufacturers including P&G, Unilever, Avon, Johnson & Johnson, Mary Kay, L'Oreal, Bath & Body Works and Takasago.
Moderate evidence.
Caveats
No funding statement is printed in the paper, but every author's affiliation is a cosmetics/fragrance trade body or personal-care manufacturer; absence of a disclosure is not evidence of independence.
Source: Loretz 2005, Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Other evidence
Using the cosmetics industry's own recommended default values, a typical fragrance pump-spray application works out to a systemic inhalation exposure dose of about 1.5×10^-6 mg per kg body weight per day for a substance present at 0.5% of the formula.
Moderate evidence.
Caveats
Every input is a literature-derived default, not a direct measurement of a real consumer's breathing-zone air; treat as an industry worst-case-to-realistic model output, not a measured exposure.
Source: Steiling et al. 2025, Toxicology Letters Industry-funded Link to this fact
Laws and loopholes / Review of other studies
History shows removing the exposure works: as industrial turpentine use fell from 94.5% of US supply as a solvent in 1935 to 4.5% in 1975, turpentine skin allergy declined with it.
Moderate evidence: Ecological historical correlation.
Source: Karlberg & Lepoittevin 2021, Contact Dermatitis Link to this fact
Laws and loopholes / Review of other studies
Official limits for the same gas odorant differed about 280-fold in 2009: Germany allowed 50 ppm at work, a Dutch health agency derived 0.18 ppm, and the US had no limit.
Moderate evidence: Regulatory values as reported by the paper (2009); may have been revised since.
Source: Baur & Bittner 2009, American Journal of Industrial Medicine Link to this fact
Laws and loopholes / Measured in people or real products
Workers with fragrance-related asthma were twice as likely as other work-asthma cases to still be exposed at work (50% vs 26%) and more often had workers' compensation claims denied (30% vs 21%), though ER visit and hospitalization rates were the same.
Moderate evidence: Interviewed cases only (~58% of fragrance cases); unadjusted.
Laws and loopholes / Review of other studies
A fragrance-and-flavor company reported that about half of the chemicals it handles are classified hazardous, and that few of the more than 3,000 flavoring substances in use have workplace exposure limits.
Moderate evidence: Industry self-description, no inventory published; flavor materials at one company.
Source: Angelini 2016, PLoS ONE Industry-funded Link to this fact
Laws and loopholes / Review of other studies
A 2015 CMAJ editorial (Flegel & Martin, CMAJ 187:1187, DOI 10.1503/cmaj.151097) states hospital environments free from artificial scents 'should become a uniform policy, promoting the safety of patients, staff and visitors alike'; the US CDC's own workplace policy separately says fragrance 'is not appropriate for a professional work environment' (CDC wording still unverified against a primary CDC source).
Moderate evidence.
Caveats
CMAJ quote now verified against the primary editorial, now in our evidence base (src-2015-artificial-scents-no-place-hospitals): exact wording is 'should become a uniform policy' (ASEQ-EHAQ's paraphrase drops the article 'a', not a substantive misquote). The editorial is opinion/commentary, not a study — its own cited prevalence numbers (30% scent sensitivity, 27% of asthmatics worsened) are the same Caress & Steinemann survey figures used elsewhere in our evidence base. CDC portion remains unverified; the CMAJ editorial itself never mentions the CDC.
Source: ASEQ-EHAQ 2020 (quoting CMAJ 2015 and CDC) Link to this fact
Laws and loopholes / Self-reported survey
MCS is legally recognized as a disability in Canada, but in a national survey most people with MCS who asked for a workplace or housing accommodation before the pandemic (85% of 119) were refused at least once (the paper's own figure: 'at least 78%').
Moderate evidence.
Caveats
Self-reported, cross-sectional, community-based convenience sample of 119 recruited substantially through an MCS advocacy charity's own channels (ASEQ-EHAQ, which also funded the study and paid some authors); over-represents Quebec; likely under-represents the most severely affected.
Source: Diallo 2026 Link to this fact
Laws and loopholes / Measured in people or real products
A 2026 primary measurement study of cosmetic spray products concluded that current cosmetic safety assessment lacks any framework for inhalation exposure, stating there is an urgent need for regulatory frameworks targeting inhalation exposure from cosmetic sprays.
Moderate evidence.
Caveats
This is the authors' stated policy conclusion, not a dose-response or health-outcome finding; it extends, but does not resolve, our existing C178 (no inhalation branch in fragrance/cosmetic safety review processes).
Source: Dai et al. 2026, ACS Environmental Au Link to this fact
Skin allergy / Review of other studies
Atopic dermatitis skin has a weakened barrier that allows topical drugs up to about 800 Dalton (tacrolimus 822 Da, the ascomycin derivative SDZ ASM 981 811 Da) to work, whereas the same molecules and larger ones (cyclosporine, 1202 Da) are not effective applied topically to normal skin.
Moderate evidence: Narrative synthesis of separately published clinical trials, not a new experiment; treated by the authors as the named exception to their own 500 Dalton rule.
Source: Bos & Meinardi 2000, Experimental Dermatology Link to this fact
What you can do / Self-reported survey
About twice as many Australians would prefer fragrance-free workplaces (42.8%) as fragranced ones (22.2%), and over three times as many prefer unscented flights (57.7% vs 16.3%).
Moderate evidence.
Source: Steinemann 2017, Preventive Medicine Reports Link to this fact
What you can do / Self-reported survey
Most people would rather have fragrance-free spaces: 65% prefer fragrance-free airplanes, 61% hotels, 51% health care, and 48% workplaces, against 16-22% who prefer them fragranced.
Moderate evidence: Preference survey, adults 18-65.
Source: Steinemann 2019, Air Quality, Atmosphere & Health Link to this fact
What you can do / Self-reported survey
People with asthma back fragrance-free spaces by wide margins: 66.2% vs 16.1% for fragrance-free workplaces and 72.1% vs 14.8% for fragrance-free health care.
Moderate evidence.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
What you can do / Self-reported survey
More UK adults prefer fragrance-free over fragranced workplaces (44.7% vs 23.3%), health care (43.3% vs 26.7%) and airplanes (61.9% vs 18.4%).
Moderate evidence: Pluralities, not majorities, for workplace and health care; preference, not health benefit.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
What you can do / Review of other studies
Occupational lung specialists treating irritable larynx syndrome recommend a 'low-scent' workplace policy or respiratory protection to limit exposure to triggers.
Moderate evidence: Clinical recommendation, not tested as an intervention.
What you can do / Measured in people or real products
The California Department of Public Health recommends enforced fragrance-free workplace policies, no air fresheners or fragranced cleaners, and better ventilation instead of odor masking.
Moderate evidence: Recommendation from a public-health agency based on surveillance, not an intervention trial.
What you can do / Self-reported survey
A fragrance-free sign is not enough on its own: Canadians with chemical sensitivities described workplaces and hospitals with 'scent-free' policies where staff still wore scents and scented cleaners stayed in use.
Moderate evidence: Qualitative focus groups, n=60 self-selected MCS/IAQ-affected Canadians; advocacy-funded.
Source: Roy 2026 Link to this fact
What you can do / Review of other studies
Smell scientists reviewing the evidence found that scenting workplaces to boost mood or productivity is not well supported, and noted that a chemically intolerant employee can react to a fragranced workplace.
Moderate evidence: Short narrative review; the positive-scent literature it weighs is small; no primary data.
Source: Dalton & Jaén 2010, Current Opinion in Allergy and Clinical Immunology Industry-funded Link to this fact
What you can do / Self-reported survey
Support for fragrance-free health care and workplaces is not limited to people with symptoms: in Germany roughly 70% of those who backed them reported no fragrance-related health effects themselves.
Moderate evidence: Our arithmetic from Table 5; preference, not outcome; German workplace support was only 33.2% (30.6% against, 35.3% unsure).
Source: Klaschka 2020, Environmental Sciences Europe Link to this fact
What you can do / Government agency
Workplace accommodations for fragrance sensitivity do not have to be a building-wide ban: the US Labor Department's Job Accommodation Network lists scent-free meeting rooms, moving a worker away from air fresheners and vents, telework, air purifiers, signage, and staff education.
Moderate evidence: List of options, not tested for effectiveness.
What you can do / Measured in people or real products
Being below a standard occupational exposure limit does not mean an irritant gas is safe for someone with asthma: chamber studies found severe asthma attacks from sulfur dioxide and sulfuric acid at concentrations at or below typical workplace limits for those substances.
Moderate evidence: Occupational limits are set for healthy workers by design; this is not itself an argument that the limits are wrong, only that they don't protect people with asthma.
Source: Johansson 2016, Critical Reviews in Toxicology Link to this fact
What you can do / Review of other studies
When relying on a workplace, clinic, or school's fragrance-free policy, check whether it (1) defines what's covered beyond perfume, especially cleaning and laundry products, (2) sets a default fragrance-free expectation rather than a complaint-triggered one, (3) controls what cleaning/laundry products the institution buys, and (4) names a real consequence for non-compliance — a 2026 scoping review of 63 such policies found these structural features present in well under half of cases.
Moderate evidence: Based on a gray-literature document review of North American policies; individual policies may vary, and having these features on paper does not guarantee enforcement.
What you can do / Review of other studies
Aluminum-salt antiperspirants (aluminum chlorohydrate and related salts) work by two combined mechanisms: they physically plug sweat ducts by polymerizing into a gel at skin pH, and they directly inhibit the growth of odor-causing skin bacteria; fragrance is not the active mechanism.
Moderate evidence: Mechanism review synthesizing older primary studies; does not itself measure sweat reduction or bacterial counts in a new trial.
Source: Kanlayavattanakul & Lourith 2011, International Journal of Cosmetic Science Link to this fact
What you can do / Government agency
EPA's official framework for improving indoor air quality ranks three strategies in order: (1) source control (remove or reduce the pollutant source), (2) increased ventilation, and (3) air cleaners, which EPA says are far more effective for particles than for gaseous pollutants.
Moderate evidence: Agency guidance/assertion, not a controlled comparison of the three strategies.
Source: US EPA, "The Inside Story" Link to this fact
What you can do / Measured in people or real products
If a constant smell at home or work has faded for you but a visitor still notices it, that is a normal habituation effect on your part, not proof the smell is gone or that the visitor is being oversensitive.
Moderate evidence: Based on general human olfactory-habituation evidence reviewed in this paper, not a study of visitor/resident comparisons specifically.
Source: Pellegrino 2017, Physiology & Behavior Industry-funded Link to this fact
What you can do / Other evidence
Hairdressers, salon workers, and professional or domestic cleaners can reduce workplace asthma risk with ventilation, gloves, and lower-irritancy products or application methods where available, since this population-based cohort found both hairdressing and cleaning occupations, and reactive cleaning/disinfecting chemical exposure specifically, associated with higher adult-asthma risk.
Moderate evidence.
Caveats
The study cannot identify which specific chemicals within 'hairdressing' or 'cleaning/disinfecting' exposure are responsible, so this is general occupational-hygiene advice, not a product-specific recommendation.
What you can do / Self-reported survey
65.5% of autistic adults would support a fragrance-free workplace policy and 77.2% would prefer fragrance-free health care facilities and professionals, compared with 46.1% and 45.8% support among non-autistic adults.
Moderate evidence: Stated preference, not an intervention study; self-report survey.
Source: Steinemann 2018, Air Quality, Atmosphere & Health Link to this fact
Information, not medical advice. See also: myths we won’t tell you.