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.
Green, natural and unscented / Measured in people or real products
'Natural' is no protection: lavender oil's own components form skin allergens when exposed to air.
Strong evidence.
Caveats
Primary is Hagvall 2008 (lab open-flask air exposure, 10-45 weeks): the oil oxidized at the same rate as a synthetic mix of its terpenes; 3.3% linalyl acetate-OOH + 0.48% Lin-OOH at 10 weeks; mouse LLNA EC3 36% fresh -> 4.4% at 45 weeks (weak -> moderate); 4/4 oxidized-linalool-allergic patients reacted to oxidized oil (elicitation only, no fresh-oil control). Real-bottle oxidation rates not measured. Lavender oil ~40% linalool (Klaschka 2016).
Source: Bråred Christensson 2016, Contact Dermatitis Industry-funded Link to this fact
Green, natural and unscented / Review of other studies
Fragrance allergens turn up in "fragrance-free" moisturizers and personal-care products across at least four independent surveys: Scheinman named ten US "fragrance-free" products with fragrance ingredients in 1999 (benzyl alcohol in 5 of 10), dermatologists named nine more major-brand examples containing benzyl alcohol in 2007 (including a baby lotion) — two of Scheinman's own named products (Cetaphil Moisturizing Cream, Moisturel Therapeutic Lotion) reappear on this list — a 2016 survey of best-selling US body moisturizers found 18 of 40 labeled "fragrance free" (45%) listed at least one ingredient dermatologists flag for fragrance-allergic patients, and a 2015 survey of 187 US pediatric personal-care products found that of the 52 labeled "fragrance free," 42 (80.8%) contained at least one contact allergen from the standard NACDG screening tray (55.8% had >=2).
Strong evidence.
Caveats
Four independently compiled surveys (1999, 2007, 2016, 2015) across adult and pediatric products now agree that 'fragrance-free'-labeled products commonly contain contact allergens. Hamann 2015's screening tray is broader than fragrance chemicals alone (also preservatives, surfactants; preservatives were in fact its largest allergen category), so its 80.8% is not a pure fragrance-allergen count like Xu 2017's CAMP cross-reactor tally, but the direction and scale match. Still label-based, not chemical analysis; don't name current products without checking today's labels.
Green, natural and unscented / Review of other studies
In the US, "fragrance free", "unscented" and "free and clear" have no legal definition, so each company picks its own meaning; some "unscented" products contain a masking fragrance added to hide the product's smell.
Strong evidence.
Caveats
Expert review; the legal-definition point is not itself quantified, but the practical consequence now is: Hamann 2015 found 42 of 52 (80.8%) US pediatric products labeled 'fragrance free' contained >=1 NACDG-tray contact allergen, converging with Xu 2017's 45% (18/40) for adult moisturizers (narrower CAMP cross-reactor definition). Two independent, systematically screened surveys across different age populations now confirm the practical failure of the 'fragrance free' label; masking fragrance specifically remains unmeasured (see Scheinman 1999 for the one documented case). Strong because the absence of a legal definition is a regulatory fact. Hamann's 80.8% counts any NACDG allergen (mostly preservatives), not fragrance; use Xu 2017's 45% for fragrance-related allergens.
Green, natural and unscented / Industry source
Even the fragrance industry's safety institute said natural fragrance is not safer: "There is no link between the natural origin of fragrance materials and their safety."
Strong evidence: An opinion with no data in the chapter; it agrees with independent emission tests of 'green' products.
Source: Ford 1994 (RIFM) Industry-funded Link to this fact
Green, natural and unscented / Government agency
Health Canada's current guidance (accessed 2026-09-27) states that a cosmetic labeled 'unscented' or 'fragrance-free' may contain a masking agent added to hide other odors, confirming a 2010 secondhand quote of the same policy word for word.
Strong evidence.
Caveats
Confirmed directly against Health Canada's current (2025-03-17/2026-04-24) guidance and its Cosmetic Regulations s.21.4(3) legal basis; no longer resting on a 2010 secondhand NGO quote alone. Does not measure how often masking actually occurs in Canadian products.
Green, natural and unscented / Measured in people or real products
'Natural' oils get no special protection from air: in lab tests, lavender oil's main scent chemicals oxidized just as fast as a synthetic copy made only of those chemicals, and formed the same allergenic hydroperoxides.
Strong evidence: Lab chemistry, neat oil in open flasks over 10-45 weeks; one oil type (lavender), two batches.
Source: Hagvall 2008, Contact Dermatitis Industry-funded Link to this fact
Green, natural and unscented / Government agency
FDA states that products labeled "unscented" may still contain fragrance ingredients, because a manufacturer may add just enough fragrance to mask the smell of other ingredients without giving the product a noticeable scent.
Strong evidence: FDA gives no formal regulatory definition of "unscented" or "fragrance-free" anywhere on the page; this is the only statement it makes about either term.
Source: FDA 2026 (Fragrances in Cosmetics) Link to this fact
Green, natural and unscented / Government agency
In Canada, a cosmetic labeled 'unscented' or 'fragrance-free' can legally still contain a fragrance ingredient added specifically to mask another smell, declared only as 'parfum' or 'fragrance' on the ingredient list.
Strong evidence.
Caveats
Health Canada's own current guidance (accessed 2026-09-27) and the Cosmetic Regulations s.21.4(3) legal basis; confirms and dates a 2010 secondhand quote of the same policy (David Suzuki Foundation 2010). It does not measure how often masking actually occurs in Canadian products; no Canadian product-testing study of this specific question is in our evidence base.
Source: Health Canada 2026 Link to this fact
Green, natural and unscented / Other evidence
The National Eczema Association's Seal of Acceptance requires products to be fully fragrance-free — "there should be no discernable/strong scent or anything aromatic in nature in the final product" — with no stated exemption for masking fragrance, and NEA directly checks a physical product sample for absence of scent as part of the review.
Strong evidence.
Caveats
This describes NEA's written rule and process, not a chemical measurement of any Seal-holding product; a more detailed 'clinical testing requirements' PDF is referenced but was not captured on this page.
Source: NEA 2026 Link to this fact
Green, natural and unscented / Other evidence
Seal of Acceptance products must also exclude a named 34-ingredient Ecz-clusion List (including cinnamic alcohol, cinnamic aldehyde, coumarin, eugenol, farnesol, geraniol, hydroxycitronellal, isoeugenol, oak moss absolute and several citrus extracts), chemical UV absorbers other than titanium/zinc/iron physical sunscreens, and formaldehyde releasers, in any amount.
Strong evidence: Ingredient-list exclusion, verified by NEA's own review, not independent chemical assay of finished products.
Source: NEA 2026 Link to this fact
Information, not medical advice. See also: myths we won’t tell you.