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.
The industry / Lab study (cells or chemistry)
The lab tests that replaced animal testing for setting cosmetic and fragrance allergy safety limits explain only about 62% of how strongly a chemical causes allergy.
Strong evidence.
Caveats
Regression R2 against mouse LLNA, not human outcomes; industry-authored. Natsch 2023 (same author) retrains against human-anchored data: the 62% figure survives on a blended human+LLNA composite (63.4%, n=139), but against strictly human data (n=62) accuracy drops to 32-45%, and even the LLNA itself only reaches 43% predicting human potency — so '62%' should not be read as human-relevant accuracy. Api, Basketter & Lalko 2014 (RIFM's own earlier LLNA-vs-human validation, 57 fragrance chemicals) independently corroborates, by a different metric (categorical concordance, not R2) and seven years earlier, that the LLNA itself is an imperfect human proxy: 76% agreement within half an order of magnitude, but up to ~790-fold mispredicted for salicylates and ~26-42-fold for trans-2-hexenal/methyl-2-nonanoate. Roberts & Api 2018 (same fragrance dataset, direct LLNA-vs-human regression) reports a much higher R2=0.784, but only for a 35-chemical subset that already excludes those 14 known outliers a priori — demonstrating that domain-restricted R2 figures like this one can substantially overstate accuracy on unselected chemistry, a caution that applies to curated NAM training/case-study sets generally, not only to this specific figure.
Source: Natsch & Gerberick 2022, ALTEX Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
Accuracy has not improved: a 2015 model predicted allergy potency about as well as the 2022 one.
Strong evidence.
Caveats
Confirmed by reading the 2015 primary directly, not just inferred from one comparison line in the 2022 paper: Natsch 2015 Equation 7 gives R²(adj)=62.3% (Results, not the abstract's rounded 60%), matching 2022's 62% and 2023's 59-65%.
Source: Natsch & Gerberick 2022, ALTEX Industry-funded Link to this fact
The industry / Review of other studies
The cosmetics industry's own safety panel judged PGME 'safe' only for nail products and calculated only skin absorption; it did not estimate how much users or nail-salon workers breathe in, and relied on the smell to limit inhalation.
Strong evidence: Verdict probably right for occasional home users; the weakness is in the reasoning, not a demonstrated harm.
Source: CIR 2008, International Journal of Toxicology Industry-funded Link to this fact
The industry / Review of other studies
The Cosmetic Ingredient Review is funded by the cosmetics industry trade association, and the use data, exposure survey and safety-margin calculation behind its 2008 PGME verdict were unpublished industry submissions.
Strong evidence: Much of the underlying toxicology is peer-reviewed; industry funding does not by itself make the conclusion wrong.
Source: CIR 2008, International Journal of Toxicology Industry-funded Link to this fact
The industry / Review of other studies
The fragrance industry's own standard caps this one ingredient at 0.003% in lip products and 0.02-0.05% in typical leave-on skin products – about 30 parts per million in the strictest category.
Strong evidence: IFRA Standards are voluntary; the limits apply to rose ketones individually or in combination.
Source: Lalko 2007 (RIFM), Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Review of other studies
For this fragrance ingredient there was no data at all on absorption, repeat-dose toxicity, developmental effects, genetic damage or cancer – the whole safety file is skin testing, and 8 of its 11 studies are unpublished company reports that outsiders cannot check.
Strong evidence: As of the 2006 literature search; later RIFM re-evaluations may have added data.
Source: Lalko 2007 (RIFM), Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Review of other studies
Much of the evidence behind the fragrance industry's 'safe as used' verdict on salicylates is unpublished: about 65 of the cited studies are internal RIFM reports, several submitted by fragrance companies, and no modern cancer bioassay exists for any of the 17 chemicals.
Strong evidence: Counted from the paper's reference list; 'no modern bioassay' means untested, not shown to be carcinogenic.
Source: RIFM Expert Panel / Belsito 2007, Food and Chemical Toxicology Industry-funded Link to this fact
The industry / Self-reported survey
The study most often cited to call lavender and tea tree oils 'safe' for children was part-funded by the Australian Tea Tree Industry Association, the Tisserand Institute and an aromatherapy association, while declaring no conflicts of interest.
Strong evidence: Funding is documented in the paper itself; funders are stated to have had no role. The paper's weakness is its power and design, not only its funding.
Source: Hawkins 2021, International Journal of Pediatrics and Adolescent Medicine Industry-funded Link to this fact
The industry / Review of other studies
The tea tree oil industry's trade association (ATTIA) challenged the lavender/tea tree case reports in a medical journal, and the same association later helped fund a survey that called the oils safe for children.
Strong evidence: Documents who argued what; says nothing about whether the oils cause breast growth.
Source: Ramsey et al. 2020 (JCEM reply); Hawkins et al. 2021, The Journal of Clinical Endocrinology & Metabolism Link to this fact
The industry / Animal study
The two molecules that give lavender oil its scent, linalool and linalyl acetate, were put through the full regulatory endocrine test battery (OECD guideline cell assays plus rat uterotrophic, Hershberger and one-generation reproductive studies) and came back negative on estrogen and androgen endpoints — in a study written, run and entirely funded by BASF, the company that manufactures both chemicals, with all five authors BASF employees.
Strong evidence.
Caveats
Guideline designs with working positive controls, so the negative is real; the conflict of interest is disclosed in the paper and should be stated whenever the result is cited. Scope: two constituents, not lavender or tea tree oil.
Source: Hareng 2024, Archives of Toxicology Industry-funded Link to this fact
The industry / Animal study
Nothing in the industry's endocrine testing program covers tea tree oil, whose main constituent, terpinen-4-ol, was never tested.
Strong evidence: A statement about the study's scope, not about tea tree oil's safety either way.
Source: Hareng 2024, Archives of Toxicology Industry-funded Link to this fact
The industry / Review of other studies
The fragrance industry's safety system is self-run: by its own 2003 description, companies fund the Research Institute for Fragrance Materials through dues, its expert panel reviews ingredient safety, and conclusions go to the industry's trade body IFRA, which sets voluntary standards for those same companies. No regulator appears in the loop.
Strong evidence: Industry's own description (2003); panel members are required to be independent of the industry; later governance changes not covered.
Source: Bickers 2003 (RIFM Expert Panel), Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Review of other studies
By the industry's own figures, about 60% of fragrance goes into soaps, fabric softeners, cleaners and detergents, yet its 2003 method for estimating people's exposure counted only 10 personal-care products applied to skin, and breathing fragrance in was not part of the calculation.
Strong evidence: Describes the 2003 process; later RIFM aggregate-exposure work may differ. Shows the route was not assessed, not that it causes harm.
Source: Bickers 2003 (RIFM Expert Panel), Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Other evidence
By 1994 the fragrance industry itself had banned or restricted 82 fragrance materials, most because they cause skin allergy and a dozen because they cause skin reactions in sunlight.
Strong evidence: Counts restrictions, not harm rates; limits not printed.
Source: Ford 1994 (RIFM) Industry-funded Link to this fact
The industry / Government agency
In 2000 the EU's scientific advisers recommended banning 36 fragrance materials from cosmetics, and the list they endorsed was the fragrance industry's own list of materials it had already prohibited (IFRA); the committee added no testing of its own and deferred all industry restrictions to later.
Strong evidence: Describes the 2000 procedure; later EU opinions (SCCS 2012) did independent hazard classification.
Source: SCCNFP 2000 Link to this fact
The industry / Review of other studies
A trade consortium of 11 French essential-oil companies funded and employed the authors of the journal letter disputing the lavender breast-growth case reports; together with the tea tree oil trade association's letter, the published rebuttals to those case reports came from industry.
Strong evidence: Documents who argued what (disclosed in the letter); says nothing about whether the oils cause breast growth.
Source: Giroux & Orjubin 2020 (JCEM letter; Consortium Huiles Essentielles), The Journal of Clinical Endocrinology & Metabolism Industry-funded Link to this fact
The industry / Review of other studies
In 1997 the cosmetics industry's own safety panel (CIR) formally asked for inhalation-toxicity data on benzyl alcohol, benzoic acid and sodium benzoate, received none, and still published a 2001 "safe" conclusion that explicitly excludes any product where inhalation is a route of exposure (colognes, hairsprays, deodorants, aerosol fixatives).
Strong evidence: The gap is documented in the report's own text (Notice of Insufficient Data, no comments received); no later CIR report closing it was found in this pass.
Source: Nair 2001 (CIR Expert Panel), International Journal of Toxicology Industry-funded Link to this fact
The industry / Lab study (cells or chemistry)
The lab tests that replaced animal testing for fragrance and cosmetic allergy limits have been stuck at explaining about 62% of allergy potency since 2015 — the 2015 model and the 2022 model perform the same.
Strong evidence: Regression R2(adj) against mouse LLNA potency, not human outcomes; industry-funded (Givaudan).
Source: Natsch 2015, Toxicological Sciences Industry-funded Link to this fact
The industry / Measured in people or real products
The independent dermatologists who ran this study concluded deodorants should contain cinnamal at less than 0.01% to protect people already sensitized, a stricter limit than the fragrance industry's later 0.05% IFRA standard.
Strong evidence: Authors' own recommendation, not a regulatory outcome; the 0.05% IFRA cap was set afterward using the induction NOEL, not this elicitation data.
Source: Bruze et al. 2003, Journal of the American Academy of Dermatology Link to this fact
The industry / Review of other studies
The fragrance industry's own risk-assessment methodology (QRA1, then QRA2) has set enforceable safety limits for fragrance materials since 2008, but by its own authors' admission has never been tested against real-world clinical outcomes.
Strong evidence: Industry-authored methodology paper; the paper itself calls for the longitudinal clinical studies that would settle this, and states they have not been done.
Source: Api 2020 (RIFM/IFRA), Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Review of other studies
The industry's fragrance safety-limit system (QRA/IFRA Standards) is explicitly designed to prevent new fragrance allergies from developing, not to protect people who are already allergic from reacting to a compliant product.
Strong evidence.
Caveats
Confirmed as the framework's own stated design intent (Section 2.2), not inferred from a single ingredient's numbers; does not itself test whether existing limits provoke reactions in sensitized people.
Source: Api 2020 (RIFM/IFRA), Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Government agency
A population study widely treated in dermatology literature as independent, EU-style evidence that confirmed dermatologists' fragrance-allergy estimates over the industry's own claims was itself funded by the fragrance industry's own research body, the Research Institute for Fragrance Materials (RIFM) — a funding fact omitted by every earlier secondhand citation of this study.
Strong evidence.
Caveats
The industry-funded study still confirmed the higher, consumer-relevant estimate (1.9% clinically relevant, up from a disputed 'up to 2%') over industry's own 2000 'far lower' claim — the funding did not appear to weaken the result in this case.
Source: Diepgen 2015 (EDEN), British Journal of Dermatology Industry-funded Link to this fact
The industry / Government agency
The EU guidance that defines what 'free from' and 'hypoallergenic' cosmetic claims are allowed to mean was jointly agreed by the European Commission, all EU/EFTA member states, the main EU cosmetics trade body (Cosmetics Europe) and the fragrance industry's own trade association (IFRA).
Strong evidence: Stated on the document's own cover page (footnote 1); this describes who wrote the guidance, not an independent audit of its content.
Source: EC Technical Document on Cosmetic Claims 2017 Industry-funded Link to this fact
Information, not medical advice. See also: myths we won’t tell you.