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 / Journalism
The first press coverage of a 2011 study finding 133 undisclosed chemicals in 25 best-selling scented products, in the US government's environmental-health journal, quoted no manufacturer or industry group; the underlying numbers should be cited from the study itself (Steinemann 2011).
Weak evidence: Media-coverage note only; all product numbers belong to the primary src-2011-fragranced-consumer-products-chemicals-emitted-ingredients-unlisted.
Source: Potera 2011 (EHP news), Environmental Health Perspectives Link to this fact
The industry / Review of other studies
The fragrance industry's answer to autoxidation is to add antioxidants to linalool and linalool-rich natural extracts, but the Gothenburg researchers say that protection is hard to control.
Weak evidence: Industry practice via personal communication from a RIFM scientist (A. M. Api) in a RIFM co-funded paper; no data on effectiveness.
Source: Hagvall 2008, Contact Dermatitis Industry-funded Link to this fact
The industry / Animal study
Two common fragrance ingredients, hexyl and benzyl salicylate, may test positive in the mouse skin-allergy assay not because they are true human sensitizers, but because of a mouse-specific irritant/pharmacological effect, similar to a known false-positive detergent (sodium lauryl sulfate).
Weak evidence.
Caveats
A hypothesis proposed by structural-alert absence and analogy only; the paper offers no direct evidence (e.g., a biomarker distinguishing true haptenation from irritant-driven lymph node activity) and the underlying data are RIFM's own unpublished proprietary dataset.
Source: Roberts & Api 2018, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
The industry / Review of other studies
The detergent industry's own risk assessment for esterquat fabric softeners sets a margin of exposure of about 8,100 (NOAEL 300 mg/kg bw/day vs. an aggregate consumer exposure estimate of 36.9 micrograms/kg bw/day) and concludes esterquats in fabric conditioner are safe for consumer use.
Weak evidence.
Caveats
Every number comes from the industry's own unpublished, unnamed studies with no independent citation trail; the exposure model covers only dermal and minor oral routes (no inhalation route at all, despite fabric conditioner being used in heated dryers); no carcinogenicity study and no multigeneration reproductive study exist for esterquats — the 'safe' conclusion infers these endpoints are unnecessary from adjacent negative results rather than testing them directly.
Source: HERA Project 2008 (A.I.S.E./CEFIC) Industry-funded Link to this fact
Information, not medical advice. See also: myths we won’t tell you.