Don’t take our word for it. Here’s every fact on this site, with its evidence grade, its caveats, and a link to the source, so you can check us.
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 / Measured in people or real products
The protective association between bleach cleaning and reduced allergy/asthma risk was abolished in households with parental smoking; in that subgroup, bleach use was instead linked to a higher rate of recurrent bronchitis (adjusted OR for the smoking-by-bleach interaction, 2.03, 95% CI 1.12-3.66).
Moderate evidence: Subgroup/interaction analysis from a single cross-sectional study; the recurrent-bronchitis outcome is parent-reported, not medically confirmed.
Source: Nickmilder, Carbonnelle & Bernard 2007, Pediatric Allergy and Immunology Link to this fact
Children and pregnancy / Other evidence
Fragrance contact allergy is not rare in children: in a study of 1200 Danish school children aged 12-16, 1.6% of girls and 2.1% of boys tested positive to the fragrance mix, and one in three of them already had clinical symptoms.
Moderate evidence: Single study (secondary citation); the primary (Mortz 2002) is not yet in our evidence base.
Source: Johansen 2003, Am J Clin Dermatol 4(11):789-798, American Journal of Clinical Dermatology Link to this fact
Children and pregnancy / Measured in people or real products
In a UK cohort of 1,303 infants (the EAT study), each additional weekly infant moisturizer application at 3 months of age was associated with an 18-20% higher adjusted odds of developing challenge-confirmed food allergy by age 3 (adjusted OR 1.20, 95% CI 1.13-1.27).
Moderate evidence.
Caveats
Single observational cohort; moisturizer frequency is parent-reported and not randomized, so confounding by indication (e.g., subclinical dry skin) cannot be fully excluded, though sensitivity analyses reduced this concern.
Source: Perkin 2021 (EAT cohort), Journal of Allergy and Clinical Immunology Link to this fact
Children and pregnancy / Measured in people or real products
The moisturizer-frequency/food-allergy association held both in infants with visible eczema at 3 months (adjusted OR 1.20, 95% CI 1.11-1.31) and in infants with no visible eczema at all (adjusted OR 1.18, 95% CI 1.07-1.30), and survived a reverse-causation sensitivity analysis that excluded infants with any parent-reported history of eczema or dry skin (adjusted OR 1.16, 95% CI 1.01-1.33).
Moderate evidence.
Caveats
Adjusted for study group, sex, siblings, family eczema history, ethnicity, eczema severity (SCORAD), filaggrin mutation status and TEWL, but exposure is still self-reported and non-randomized.
Source: Perkin 2021 (EAT cohort), Journal of Allergy and Clinical Immunology Link to this fact
Children and pregnancy / Measured in people or real products
In the same cohort, bathing frequency at 3 months — despite being strongly correlated with moisturizing frequency — showed no association with later food allergy (adjusted OR 0.95, 95% CI 0.83-1.08), unlike moisturizing frequency itself.
Moderate evidence: A negative-control comparison within one cohort; does not rule out that bathing and moisturizing share some unmeasured common cause.
Source: Perkin 2021 (EAT cohort), Journal of Allergy and Clinical Immunology Link to this fact
Children and pregnancy / Measured in people or real products
In the same trial, infants given daily preventive emollient had a nonsignificant increase in confirmed food allergy to milk, egg, or peanut at age 2 (7% vs 5%, adjusted RR 1.47, 95% CI 0.93-2.33) and food sensitization (12% vs 9%, adjusted RR 1.36, 95% CI 0.94-1.95), measured by oral food challenge (21 of 70 cases) or a masked expert panel using a validated EAT-trial-derived algorithm (49 of 70 cases).
Moderate evidence.
Caveats
Neither the food-allergy nor the sensitization result reached statistical significance; the trial was powered to detect an eczema effect, not a food-allergy effect, so it is likely underpowered for this secondary outcome.
Source: Chalmers et al. 2020 (BEEP trial), The Lancet Link to this fact
Fragrance is everywhere / Measured in people or real products
A lab analysis of 59 soaps, surface cleaners, laundry and dish-washing products from four European countries found the citrus-scent chemical limonene in 78% of them, linalool in 61%, and citronellol in 47%; all three are fragrance chemicals linked to skin allergy.
Moderate evidence: Products c. 2000, EU only; parent terpenes measured, not the allergenic oxidized forms; Unilever co-author.
Source: Rastogi 2001, Contact Dermatitis Industry-funded Link to this fact
Fragrance is everywhere / Measured in people or real products
A 2015 survey of 817 unique detergent products from 131 German households found limonene and linalool — the two fragrance chemicals most often linked to skin allergy when oxidized — named on 23.1% and 20.1% of product labels, more than any of the other 24 EU-declarable fragrance allergens.
Moderate evidence: Label-declaration frequency above the EU's 0.01% threshold, not a chemical measurement; Northern Germany, 2015, convenience sample, not representative.
Source: Wieck 2018, Regulatory Toxicology and Pharmacology Link to this fact
Fragrance is everywhere / Review of other studies
Burning, stinging, or itching sensations in the eyes, nose, and throat from airborne chemicals are caused by a specific, receptor-mediated nerve reflex (activation of TRPV1, TRPA1, TRPM8, and related channels on trigeminal nerve endings), not by allergy or immune response.
Moderate evidence.
Caveats
This is established sensory-irritation physiology synthesized from many primary studies the review cites, not new data from this paper; it describes the receptor mechanism, not whether any specific product or exposure reaches an irritating dose.
Source: Nielsen & Wolkoff 2017, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
Fragrance is everywhere / Measured in people or real products
Besides the fragrance-mix allergens, 14 other common fragrance materials (including linalool, benzyl acetate, and hedione) were found in 40-97% of the 73 deodorants tested in 1996; for three of them (hedione, linalyl acetate, alpha-isomethyl ionone) no published human contact-allergy case existed at the time despite their widespread use.
Moderate evidence.
Caveats
Absence of published reports as of 1998 is not the same as absence of risk; testing history for these three substances specifically was not systematically reviewed by the authors beyond a literature check.
Source: Rastogi et al. 1998, Contact Dermatitis Link to this fact
Fragrance is everywhere / Measured in people or real products
Because most cosmetics contain fragrance, the dermatologists noted that fragrance allergy is not limited to fragrance products: fragrance ingredients were the commonest allergen group even though perfumes and colognes were only 7% of reactions.
Moderate evidence.
Caveats
Authors' inference from a selected series; 39 reactions were to unspecified fragrance and 77 to individually identified fragrance ingredients, with the 77 not reproducible from the printed table.
Source: Eiermann 1982, Journal of the American Academy of Dermatology Link to this fact
Green, natural and unscented / Animal study
'Natural' doesn't mean allergy-free: essential oils oxidize too; in mouse tests lavender oil exposed to air for 45 weeks became about 8 times more potent as a sensitizer (EC3 36% fresh, 4.4% aged), and oxidized alpha-terpinene from tea tree oil was the most potent of all.
Moderate evidence.
Caveats
Mouse LLNA (groups of 3-4 mice; one 45-week sample) from the primary Hagvall 2008, lab open-flask exposure; aged oil reached 'moderate', not 'strong', potency. Human support: 4/4 oxidized-linalool-allergic patients reacted to oxidized lavender oil (elicitation, n=4). Earlier evidence base figure '11% -> 4.4%' was a misreading.
Green, natural and unscented / Review of other studies
Many products sold as "fragrance free" in natural-product stores are free only of synthetic fragrance and still contain essential oils, which make up 80 of the 162 fragrance ingredients documented to cause skin allergy.
Moderate evidence.
Caveats
80/162 is a count of documented allergens (de Groot), not a risk comparison; the store claim is unquantified. Klaschka 2016 supports the mechanism (supplier SDSs: orange oil ~95% limonene, lavender ~40% linalool) but counted no 'fragrance-free'-labeled products, and in its EU sample 58/100 products did declare natural-origin allergens, so on EU labels the ingredient list often shows them.
Green, natural and unscented / Government agency
Allergy UK's Product Endorsement Scheme is run by Allergy Research Ltd, a private limited company that is a legally separate trading subsidiary of the charity British Allergy Foundation (which operates publicly as Allergy UK); ARL donates its profits to the charity.
Moderate evidence: Organizational/legal fact stated plainly on the page itself; not independently verified against Companies House or charity filings.
Source: Allergy UK 2026 Link to this fact
Green, natural and unscented / Government agency
On the page describing its Product Endorsement Scheme, Allergy UK publishes no fragrance-specific criteria: the word "fragrance" does not appear anywhere on the page, and the only stated assurance is that a product has been "scientifically tested by Allergy UK to confirm its claims," with no ingredient list, protocol, or threshold given.
Moderate evidence: Absence of published criteria on this page is not proof the underlying testing process lacks criteria internally; it is only what the public page discloses.
Source: Allergy UK 2026 Link to this fact
Health effects / Measured in people or real products
Standard allergy tests did not predict who reacted to fragrance; people with sensitive airways (including non-allergic asthma) were 2-4 times more likely to react, pointing to airway irritation rather than classic allergy.
Moderate evidence.
Caveats
Predictors measured 4-5 years before outcomes; association not causation. In clinic patients the reactive trait can be sensory rather than bronchial: Millqvist 1999's 11 perfume reactors were all methacholine-negative and 10/11 skin-prick negative, and Millqvist & Lowhagen 1996's 9 patients (an earlier, blinded, placebo-controlled challenge) were likewise all methacholine-negative yet still reacted significantly to unsmelled perfume with zero objective airway change. So 'sensitive airways' in this literature should not be read as bronchial hyper-reactivity when applied to clinic-referred sensory-hyperreactivity patients; Elberling's population-level BHR association may instead mark co-morbid asthma. A related but distinct 2007 study from the same Gentofte group (Elberling 2007, dermatology-clinic patients, not this population cohort) found a candidate non-IgE, non-neural mechanism in parallel: increased basophil histamine release to perfume, unrelated to atopy, contact allergy, or asthma status. 'Airway irritation' (a neural/sensory account) may not be the whole mechanistic story; BHR, sensory/capsaicin hyperreactivity, and basophil hyperreactivity have not been measured together in the same patients.
Source: Elberling 2005, Clinical and Experimental Allergy Link to this fact
Health effects / Measured in people or real products
The eye irritation from perfume vapor was not an allergy: people patch-test allergic to the very same perfume were no more likely to react than those who were not.
Moderate evidence.
Caveats
21 patients, 10 patch-test positive; small sample. A related 2007 study from the same group, clinic, and challenge perfume found the same pattern in a different assay: basophil histamine release to perfume was not associated with contact-allergy patch-test status either (Table 4, all P > 0.05, n=17 patients). This is modest corroboration from the same research program (same lab/clinic/perfume), not independent replication, so the grade is unchanged.
Health effects / Review of other studies
Fragrance can cause skin allergy without touching your own products: from a partner's toiletries (consort dermatitis), from soap residue carried on the hands to the eyelids, and through the air, as in a small case series of a ride-share driver and four passengers whose airborne facial/eyelid dermatitis (all patch-test positive for fragrance mix I and/or balsam of Peru) was linked to car fragrance diffusers, with the driver's rash clearing when his diffuser was removed.
Moderate evidence.
Caveats
Mechanisms from case reports and a systematic review of consort ACD cited by the review; the airborne example is now confirmed against its primary (Perper 2017, now ingested): actually 5 total patients (1 driver + 4 passengers), not just the driver, published in a Contact Dermatitis section the journal states is exempt from mandatory peer review, with no chemical/air testing, no controls, and diffuser-removal resolution documented only for the driver. Kept at moderate, not raised to strong, per the single-small-uncontrolled-study rule; no prevalence data.
Health effects / Measured in people or real products
Some people whose breathing problems are set off by scents do not have asthma or allergy: in a Swedish clinic study, 11 such patients had normal lung function, negative methacholine and allergy tests, and asthma medicines had given most of them little relief.
Moderate evidence: Clinic referrals selected for scent-triggered complaints; n=11; describes a phenotype, not its prevalence.
Health effects / Measured in people or real products
The extra coughing in multiple chemical sensitivity patients was not explained by asthma or classic allergy: patients tested negative on standard allergy skin-prick and methacholine airway-reactivity tests, and lung function (FEV1) did not change after capsaicin, pointing to an oversensitive airway nerve response rather than an allergic or asthmatic reaction.
Moderate evidence.
Caveats
Small single-center sample; several patients used asthma/allergy medication for symptom control (withheld before testing), so baseline airway status over time is not fully independent of treatment.
Source: Ternesten-Hasséus 2002, Journal of Occupational and Environmental Medicine Link to this fact
Health effects / Measured in people or real products
The excess basophil reactivity to perfume in symptomatic patients was not explained by allergy antibodies in the blood (a passive-serum-transfer test found no difference between groups) and did not track whether a patient also had a skin (contact) allergy, an inhalant allergy, or asthma.
Moderate evidence.
Caveats
Same research group, clinic and perfume as the 2006 eye-challenge study, so this corroborates rather than independently replicates that program's earlier 'not classic allergy' findings.
Source: Elberling 2007, Clinical and Experimental Allergy Link to this fact
Health effects / Measured in people or real products
An individual's sensitivity to a given dose of an irritant gas (sulfur dioxide) was highly reproducible when the same person was retested 1-7 weeks later (r=0.85 across all subjects, r=0.82-0.74 within asthmatic subgroups), even though that sensitivity could not be predicted well from a clinical asthma diagnosis, allergy skin testing, or serum IgE level.
Moderate evidence: Single-lab study, n=85 total; reproducibility was much weaker for exercise responses measured in clean air alone.
Source: Linn et al. 1987, American Review of Respiratory Disease Link to this fact
Health effects / Measured in people or real products
Atopic (allergic, IgE-sensitized) volunteers without asthma were essentially as unresponsive to sulfur dioxide exposure as non-atopic normal volunteers; airway hyperreactivity (asthma), not IgE-mediated allergy/atopy, was what predicted reaction to this irritant gas.
Moderate evidence.
Caveats
Single-lab study, n=21 atopic subjects; sulfur dioxide is a non-allergenic irritant gas, so this speaks to the general atopy-vs-hyperreactivity question rather than to any allergic mechanism for SO2 itself.
Source: Linn et al. 1987, American Review of Respiratory Disease Link to this fact
Health effects / Measured in people or real products
In a small Swedish clinic study, people whose breathing symptoms were triggered by scents and chemical irritants — but who had normal lung function and negative allergy and asthma tests — coughed much more after inhaling capsaicin (the hot-pepper compound) than either people with verified asthma or healthy volunteers (93 vs 23 average coughs at the highest dose, P<0.001).
Moderate evidence.
Caveats
Small (n=10 per patient group, n=28 healthy controls), single-clinic study; capsaicin dosing was open-label (patients not told doses would increase) rather than placebo-blinded, so it is a correlational patient-vs-comparator design, not an intervention.
Source: Millqvist, Bende & Löwhagen 1998, Allergy Link to this fact
Health effects / Measured in people or real products
The extra coughing in these chemically sensitive patients could not be explained by asthma: their lung function, methacholine reactivity, and skin-prick allergy testing were all normal, yet they still coughed dose-dependently to inhaled capsaicin, and even to a plain saline control, while a separate group of people with verified asthma did not cough more than healthy volunteers.
Moderate evidence.
Caveats
Single small clinic sample (n=10 per patient group); normal methacholine and skin-prick tests were inclusion criteria for the chemically sensitive group, not an independent finding in an unselected population.
Source: Millqvist, Bende & Löwhagen 1998, Allergy Link to this fact
Health effects / Self-reported survey
Among the same scented-candle users, respiratory-specific complaints in the past 12 months included waking with chest tightness (36.0%), waking from a coughing attack (33.1%), nasal allergy/hay fever (25.0%), a diagnosed respiratory illness (16.3%), a shortness-of-breath attack on waking (17.2%), wheezing (14.6%) and an asthma attack (9.5%).
Moderate evidence: Self-reported, non-clinically-confirmed symptoms in a non-representative convenience sample; no comparison group of non-candle-users was asked the same respiratory questions.
Source: Al Khathlan et al. 2023, BMC Public Health Link to this fact
Health effects / Other evidence
The 1988 Nature experiment claiming diluted antibody still triggers allergy cells was judged an artifact of observer bias by an investigative team, and independent labs reportedly failed to replicate it.
Moderate evidence: Secondhand and compressed account; Grimes also lists Belon 1999 as a failure although its title reports an inhibition effect; see the Maddox and Davenas pages.
Source: Grimes 2012, Focus Altern Complement Ther, Focus on Alternative and Complementary Therapies Link to this fact
Health effects / Other evidence
Exercise, painkillers (NSAIDs) and alcohol can lower the threshold at which a food triggers anaphylaxis: in 74 cases of cofactor-enhanced food allergy NSAIDs were involved in 58%, exercise in 52.7%, and alcohol in 12.2%.
Moderate evidence: Clinic case series without matched controls; the review reports them and does not re-analyze them.
Source: Skypala 2019, Frontiers in Immunology Link to this fact
Health effects / Other evidence
Daily sunscreen use did not increase skin cancer risk in this 4.5-year randomized trial; the main complaints were contact allergy or skin irritation in 25 of about 800 users, greasiness and sweat interference.
Moderate evidence: Cancer was the safety endpoint studied; no absorption or systemic toxicity was measured; allergen causing the 25 reactions not identified; the sunscreen was supplied by industry.
Source: Green 1999, The Lancet Industry-funded Link to this fact
Health effects / Other evidence
A European allergy-society expert panel says asthma starting within hours of a single very high irritant exposure, such as a chlorine or chloramine cloud from mixing bleach with acids or ammonia, can be attributed to the exposure with a high level of confidence.
Moderate evidence: Expert consensus, not a systematic review; exposure concentrations in the underlying cases were mostly estimated, not measured.
Health effects / Other evidence
Irritant-induced asthma is not an allergy: a single high exposure can trigger it without a sensitization latency period, and affected people do not react to low re-exposure of the same agent, though their airways can stay hyperresponsive for years afterward.
Moderate evidence: Expert consensus; rare cases of true sensitization after accidental exposure to a sensitizer are acknowledged.
Hidden ingredients / Animal study
The regulatory endocrine dossier on linalool tested 99.7%-pure, freshly handled material, not the air-oxidized linalool that forms in an opened bottle and that accounts for almost all of linalool's known allergy risk. Nobody has tested whether oxidized linalool is hormonally active.
Moderate evidence: This is standard and correct practice for a REACH dossier; it is a limit on what the result covers, not a flaw in the study.
Source: Hareng 2024, Archives of Toxicology Industry-funded Link to this fact
Hidden ingredients / Other evidence
Several flavor chemicals in this review (menthol, carvone, camphor, borneol, terpineol, ionones, damascones and the musks muscone, and civettone) are also fragrance materials, but the FEMA review assesses them only as swallowed food ingredients; it gives non-oral data 'less weight' and has no inhalation or skin-allergy assessment.
Moderate evidence: The paper says some inhalation data may substitute when flavor exposure is far smaller than inhaled exposure; it does not claim any airborne or skin risk from these substances.
Source: Adams 1996, Food and Chemical Toxicology Industry-funded Link to this fact
Hidden ingredients / Other evidence
Textile-dye allergy often looks atypical (purpuric, hives-like, prurigo-like, eczema away from skin contact points) and a high index of suspicion is needed, so it can be missed.
Moderate evidence: Based on case reports and case series; no frequency of atypical presentations across all patients.
Source: Malinauskiene 2013, Contact Dermatitis Link to this fact
Hidden ingredients / Animal study
In a Dutch government study, isoeugenol was the only one of five skin-allergy fragrance chemicals to stimulate the lymph nodes of mice that breathed it (about 7-fold more cell growth after 6 hours a day for 3 days), while limonene and linalool did not.
Moderate evidence.
Caveats
Mice (6 per group), one lab, nose-only at 75 mg/m3, an unvalidated assay tested mostly on strong sensitizers; a hazard signal, not human disease. Government-funded (NVWA), no industry money declared.
Source: ter Burg 2014, Inhalation Toxicology Link to this fact
Hidden ingredients / Other evidence
Methylisothiazolinone allergy became an epidemic after MI alone was approved as a preservative at higher concentrations in the early 2000s, and a patch test with only the MCI/MI mix can miss it; hidden sources include moist toilet paper, makeup-remover wipes, paint, and homemade slime.
Moderate evidence: Narrative review; the 'up to 8%' MCI/MI contact-allergy figure has no stated population in the text.
Source: Militello 2020, Dermatologic Clinics Link to this fact
Hidden ingredients / Other evidence
The flavor panel's food assessment is silent on skin allergy, inhalation, and cosmetic use: the words allergy, sensitization, and atranol do not appear in the assessment, and the abstract excludes 'dietary supplements or any products other than food'; so food-GRAS status of oak moss or jasmine says nothing about their behavior as fragrance allergens.
Moderate evidence: Absence of a topic in an industry review is not evidence of harm; it is a scope limit the paper states for supplements only by name and by 'any products other than food'.
Source: Guengerich 2026 (FEMA Expert Panel), Food and Chemical Toxicology Industry-funded Link to this fact
Hidden ingredients / Other evidence
The hydroperoxides that cause this allergy are not listed on labels, so patients can only look for limonene and linalool, two of the 26 EU-declarable fragrance allergens.
Moderate evidence: Authors' statement about labeling in the EU; limonene and linalool on a label show the parent chemical, not whether any hydroperoxide is present.
Source: Dittmar & Schuttelaar 2019, Contact Dermatitis Link to this fact
Hidden ingredients / Review of other studies
Sulfites, a preservative that can cause skin allergy, are found in many medicines you would not suspect: topical steroids, antibiotics, antifungals, hemorrhoid creams, local anesthetics, catheter gel, and 3.8% of 264 ophthalmic medications checked.
Moderate evidence: Narrative review; the 3.8% figure comes from a single analysis of prescription eye products, and the other medicines are case reports, not prevalence.
Source: Choi 2024, Cutis Link to this fact
Hidden ingredients / Other evidence
Three studies found 28%, 17% and 23% of skin creams labeled incorrectly against the specific legislation, and 46% of allergic participants had difficulty reading cosmetic labels, so an ingredient list does not guarantee that a preservative allergy can be avoided.
Moderate evidence: Older, small Scandinavian and Korean product surveys; the review does not say what the errors were.
The industry / Lab study (cells or chemistry)
The fragrance industry's own data show its main explanation for how fragrance chemicals cause allergy doesn't cover most of them: 34 of 62 ingredients (55%) sensitize despite having no predicted protein-binding alert.
Moderate evidence.
Caveats
Structural-alert software limitation; metabolic activation explains some. Roberts & Api 2018 (different 57-chemical fragrance dataset, no direct overlap confirmed with this claim's 62-chemical set) adds two further indirect-activation routes the alert software here evidently does not capture — slow autoxidation of tertiary allylic/benzylic C-H compounds to allergenic hydroperoxides/epoxides, and a proposed bio-sulfation route for benzylic alcohols — which could explain part of the unexplained 55% for chemicals with those structural motifs. The same paper separately proposes that some LLNA-positive, alert-free fragrance chemicals (hexyl/benzyl salicylate) may be LLNA false positives rather than true sensitizers at all, which would pull in the opposite direction (shrinking, not explaining, the true no-mechanism fraction) if any such chemicals are present in this claim's 62-ingredient set — not checked here, so the net effect on the 55% figure is unresolved and the grade is left unchanged.
Source: Lee 2024, Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
Those models underestimated allergy potency by more than fivefold for 18% of the 188 chemicals tested, and more than tenfold for 11%.
Moderate evidence.
Caveats
Prediction error, not a safety-limit error; worst outliers are non-fragrance chemicals. Natsch 2023 (same author, human-anchored retraining) shows this outlier structure is not simply an artifact of fitting to mouse data: only 6/139 chemicals (4.3%) shift by more than 3.3-fold when the same models are retrained against human-anchored potency values instead of LLNA.
Source: Natsch & Gerberick 2022, ALTEX Industry-funded Link to this fact
The industry / Industry source
The industry's standard safety package for a fragrance ingredient in 1994 covered acute poisoning and skin effects (irritation, allergy, sun reactions); breathing it in was not tested, because the industry judged inhalation 'not a route of toxicological concern'.
Moderate evidence.
Caveats
As of 2024, RIFM/Creme Global's aggregate exposure model (Lee 2024) does now include a full inhalation-TTC branch across ~3,000 fragrance ingredients (99% below the inhalation TTC), so the industry itself has since closed this specific 1994 scope gap methodologically — though whether ingredients assessed only under the older dermal-only dossiers were individually revisited is not stated. The gap's closure was gradual, not a single 2024 event: Comiskey et al. 2017 (Phase 2 of the same RIFM/Creme model) added the model's first-ever inhalation branch, 23 years after this 1994 dismissal, but only for air-care and personal-care spray products — household cleaning and laundry products were explicitly still excluded and named as future work in 2017, closing only in the 2024 paper.
Source: Ford 1994 (RIFM) Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
When the same lab-dish tests that replace animal testing are checked against real human allergy-test panels instead of mouse data, they explain only about 32-45% of how strongly a chemical causes allergy in people, and the mouse test itself does barely better, explaining only 43%.
Moderate evidence: The strictly-human comparison dataset (n=62) is small and the author flags it as biased/non-representative; a larger human dataset might do better.
Source: Natsch 2023, ALTEX Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
Neither the animal test nor its lab-dish replacements are strong predictors of real human allergy thresholds; they are about equally weak, shown independently in 2015 and again in 2023.
Moderate evidence: Both comparisons reuse overlapping historical human patch-test literature (HRIPT/HMT), not independent new human data.
Source: Natsch 2023, ALTEX Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
Whether a chemical is irritating to cells in a dish, not just whether it reacts with proteins, drives a lot of the mouse allergy test's readout in ways that don't reflect real human allergy.
Moderate evidence: Statistical inference from regression coefficients across three chemical subsets, not a direct mechanistic experiment.
Source: Natsch 2023, ALTEX Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
The fragrance industry's own 2007 safety review of benzyl salicylate assessed allergy, toxicity, and cancer risk in detail but never tested it for hormone-like activity at all; the first test came two years later, from an independent lab with no fragrance-industry funding.
Moderate evidence.
Caveats
The independent test found only a weak, partial effect, at concentrations well above the industry's own worst-case exposure estimate, so this closes a testing gap rather than reversing the 2007 review's 'safe as used' conclusion.
Source: Charles & Darbre 2009, Journal of Applied Toxicology Link to this fact
The industry / Measured in people or real products
In RIFM's own comparison of 57 fragrance chemicals, the mouse test used to set fragrance skin-allergy safety limits agreed with real human sensitization thresholds within about 3-fold for 76% of the chemicals tested, but was off by up to nearly 800-fold for others, including hexyl and benzyl salicylate.
Moderate evidence.
Caveats
Single paper/author group (RIFM staff plus an industry consultant), though a large (57-chemical), systematically protocolled primary dataset; the authors themselves call the outlier groups 'an alert for consideration, rather than… a general rule' given only 7 materials populate each. Corroborates, from a different metric and era, the LLNA-human accuracy gap C230 documents for the newer non-animal replacement tests.
Source: Api, Basketter & Lalko 2014, Cutaneous and Ocular Toxicology Industry-funded Link to this fact
The industry / Measured in people or real products
The study's own authors note that current diagnostic patch-test concentrations for oxidized linalool allergy are more than 500 times higher than the hydroperoxide levels they actually found in consumer products.
Moderate evidence: Industry-funded interpretation; does not itself prove patch tests over-diagnose, since already-sensitized skin can react to much lower doses than the diagnostic test threshold.
Source: Kern 2014, Analytical and Bioanalytical Chemistry Industry-funded Link to this fact
The industry / Measured in people or real products
Despite thousands of positive allergy-test reactions to oxidized limonene and linalool reported worldwide, the fragrance industry's own market-testing program concluded that where people are actually getting exposed to these allergens "remains elusive" — the industry itself has not identified the real-world consumer-product source of a widely documented skin allergy.
Moderate evidence.
Caveats
This is the industry's own conclusion, from an industry-funded study; it does not mean the allergy is not real or not caused by fragrance chemicals — only that the specific consumer-product exposure route has not been chemically confirmed even by the party with the strongest incentive to find an innocuous explanation.
Source: Natsch 2019, Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Review of other studies
When RIFM's own scientists switched from mainly human patch-test data (their 2017 categorization) to a full weight-of-evidence approach that also folds in animal, computer-model, and lab-dish data, the assigned allergy-potency category changed for 29% of the same 82 fragrance chemicals — moving to a weaker category for 20.5% of them and a stronger one for 8.5%.
Moderate evidence.
Caveats
Same authors and institution comparing their own two categorization schemes; independent validation of either scheme against real-world human sensitization rates is not addressed in this paper.
Source: Na et al. 2022, Dermatitis Industry-funded Link to this fact
The industry / Other evidence
The fragrance industry lowered its recommended limit for isoeugenol in consumer products from 0.2% to 0.02% in 1998, in response to documented high and rising rates of contact allergy to it.
Moderate evidence.
Caveats
A single documented industry guideline change; the review notes it is unknown whether this will actually reduce isoeugenol sensitization, since chemically similar substitutes can cross-react.
Source: Johansen 2003, Am J Clin Dermatol 4(11):789-798, American Journal of Clinical Dermatology Link to this fact
The industry / Government agency
In February 1992, the Business Council on Indoor Air (an indoor-air industry trade association) told HUD that the American Medical Association, American Association of Allergy and Immunology, American College of Physicians, and American College of Occupational and Environmental Medicine had all stated (December 1991) that there was "inadequate scientific evidence to establish the existence of MCS as a disorder," and asked HUD to correct guidance that recognized MCS as a handicap.
Moderate evidence.
Caveats
Reported via the trade association's own letter and white paper, not read directly from the cited medical-society statements; BCIA is an interested industry group asking a housing regulator to narrow disability protections, which does not by itself make its scientific summary wrong but is a relevant interest to disclose.
Source: BCIA letter (1992) Link to this fact
The industry / Lab study (cells or chemistry)
A 2022 skin-absorption study of linalool, funded by the fragrance industry's own safety institute (RIFM) and run by RIFM's long-term contract lab, tested only fresh linalool and did not report the test material's oxidation state or test air-oxidized linalool, the form clinical studies link to skin allergy.
Moderate evidence: Industry-funded (RIFM); the gap mirrors the same undisclosed-oxidation-state pattern documented in RIFM's separate 2003 sensitization dossier for linalool.
Source: Brain et al. 2022 (An-eX/RIFM), International Journal of Pharmaceutics Industry-funded Link to this fact
The industry / Journalism
The Skin Deep database draws on about 60 sources including IFRA and the industry's own Cosmetic Ingredient Review panel, the EU banned-fragrance list, and the SCCNFP fragrance-allergy opinions, with reference dates running to about 2009; the page does not state whether sources are refreshed.
Moderate evidence: Source list from the page's own references; the live database may use newer data.
Source: EWG Skin Deep methodology page (2026 capture) Link to this fact
The industry / Other evidence
The main safety data set the oxybenzone sunscreen maker offered against clinic reports of oxybenzone allergy is 64 of its own unpublished studies, written up by its employees and former employees; the authors argue clinic-based literature overstates risk because clinic patients already have skin disease.
Moderate evidence.
Caveats
The authors' point about clinic selection is fair, but their healthy-volunteer design cannot measure risk in the photosensitive people where oxybenzone photoallergy is reported. 'Meta-analysis' here means pooling the sponsor's studies, with no search or inclusion criteria.
Source: Agin 2008 (oxybenzone HRIPT), Photodermatology, Photoimmunology & Photomedicine 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
Multiple chemical sensitivity has no dedicated diagnostic code and is instead coded, when coded at all, under nonspecific ICD-10 codes for unspecified respiratory conditions from inhaled fumes/gas/chemical vapors (J68.9) or unspecified allergy/hypersensitivity/idiosyncrasy (T78.4); some countries and agencies (US EPA, US ADA, Germany, Austria) have given the condition some form of recognition, while Italy's health ministry has declined to recognize it as a rare disease due to diagnostic-nosology difficulty.
Moderate evidence.
Caveats
Regulatory-recognition landscape as of this review's 2015 search cutoff and largely focused on Italy; recognition status in individual US states, agencies or other countries may have changed since, and the review does not cite the specific EPA/ADA source documents establishing "recognition.".
Source: Rossi 2018, Journal of Occupational & Environmental Medicine Link to this fact
Laws and loopholes / Government agency
For loose food and food packed at the buyer's request, EU law makes allergen information mandatory (Art. 44(1)(a)) but lets each Member State decide how it is provided, citing evidence that most food-allergy incidents trace to non-prepacked food (recital 48).
Moderate evidence: Recital 48 is the legislator's stated premise, not a measured figure in the regulation; national rules were not reviewed.
Source: EU Reg 1169/2011 (OJ L 304) Link to this fact
Laws and loopholes / Other evidence
In 2014 the Danish EPA said disperse dyes, which can cause allergy and cancer, were not regulated by REACH or other legislation; limits came from voluntary labels (Oeko-Tex, EU Ecolabel) and company restricted-substance lists.
Moderate evidence: Agency's 2014 statement about Denmark/EU; the regulatory position may have changed, and the report notes REACH does restrict azo dyes that release 22 listed amines (30 mg/kg).
Source: Danish EPA 2014, Survey of Chemical Substances in Consumer Products No. 129 Link to this fact
Information, not medical advice. See also: myths we won’t tell you.