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.
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distinguishing true haptenation from irritant-driven lymph node activity) and the underlying data are RIFM's own unpublished proprietary dataset.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 / Other evidence
The authors suggest BAK use may have increased as manufacturers replaced methylisothiazolinone and formaldehyde releasers after the methylisothiazolinone allergy epidemic (peak in Australia about 2015, legislation from 2017), which could be part of why BAK allergy rose.
Weak evidence: Hypothesis only; timing fits but the paper provides no data on which products changed preservatives.
Information, not medical advice. See also: myths we won’t tell you.