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.
Health effects / Animal study
Two fragrance musks, AETT and musk ambrette, damaged the nervous system of rats in industry-sponsored studies and were withdrawn; musk ambrette was also barred from skin products because it caused allergic reactions in sunlight.
Moderate evidence.
Caveats
Both primaries now read directly: Spencer 1979 (AETT) is a small, single-lab, single-route dietary study (N=16); Spencer 1984 (musk ambrette) is a large, dual-route, dose-ranging study (N=220) that alone would meet the bar for 'strong'. Because the claim bundles both compounds and the AETT sub-claim rests on one small single-lab study, the combined claim stays at moderate per the grading rule (one small study keeps a claim at moderate; a claim with any weaker bundled part stays below strong). Musk ambrette's photosensitization ground for its skin-product ban is independently documented (Cronin 1984, Giovinazzo 1980) and distinct from the neurotoxicity finding.
Source: Ford 1994 (RIFM) Industry-funded Link to this fact
Health effects / Animal study
AETT, a musk fragrance once common in soaps, deodorants, and cosmetics, caused progressive nerve-fiber demyelination and irreversible pigment build-up in the brains of rats fed the compound for 12-20 weeks; the fragrance industry voluntarily withdrew it from cosmetics in 1978 on the strength of its own data.
Moderate evidence: Small single-lab study (N=16 rats), one route (dietary), one dose pair (25/50 mg/kg/day); AETT was withdrawn from cosmetics in 1978 and is not a current fragrance ingredient.
Source: Spencer 1979, Science Industry-funded Link to this fact
Health effects / Review of other studies
Underarm body odor is mostly made by skin bacteria, not by sweat itself: apocrine-gland secretions are odorless when released, and only turn into the characteristic musk/urine smell after aerobic Corynebacteria metabolize odorless steroid precursors into 16-androstenes, or after bacteria break the goat-like acid 3-methyl-2-hexenoic acid free from its carrier proteins.
Moderate evidence: Review synthesis of older primary biochemistry literature, not this paper's own new data.
Source: Kippenberger 2012, Experimental Dermatology Link to this fact
Health effects / Other evidence
For the synthetic musk fragrance ingredient musk xylol, chemical still sitting in human skin 24 hours after a single application did not stay put: when an FDA lab extended testing to a full week, about three-quarters of the 24-hour skin reservoir had disappeared, while roughly 14-16% of the original applied dose had moved into the fluid representing the bloodstream side of the skin barrier.
Moderate evidence: Single FDA lab, in vitro excised human-skin model with only two human subjects in the extended-study cohort; not a living-human in vivo measurement.
Source: Hood 1996, Food and Chemical Toxicology Link to this fact
Health effects / Other evidence
Hairless guinea pig skin is substantially more permeable than human skin to musk xylol, especially for how much reaches circulation: in vitro, over half of the absorbed dose in guinea pig skin reached the receptor fluid within 24 hours, versus under 5% in human skin, even though both skin types absorbed a similar total amount into the skin itself.
Moderate evidence: Single FDA lab, in vitro excised-skin model; relevant to how much animal skin-absorption data can be extrapolated to humans for fragrance ingredients.
Source: Hood 1996, Food and Chemical Toxicology Link to this fact
Health effects / Other evidence
In 2009 the FEMA authors reported that eight flavor ingredients had lost FEMA GRAS status over the program's life (including calamus, brominated vegetable oil, and musk ambrette) and that a ninth, cinnamyl anthranilate, was abandoned by industry then banned by FDA; FDA also prohibits coumarin and safrole in food, and neither is FEMA GRAS.
Moderate evidence.
Caveats
Industry-reported list; reasons for each revocation are not given in this paper. Written by two FEMA employees and supported by FEMA (the flavor industry trade association); it is the industry's own account of its own program.
Source: Hallagan 2009, Food and Chemical Toxicology Industry-funded Link to this fact
Health effects / Lab study (cells or chemistry)
The same fragrance musks also blocked the androgen receptor at about 3 µM and one subtype of the estrogen receptor (ERβ) at about 2-6 µM, with no sign of acting as a hormone-like agonist in these cells.
Moderate evidence: In vitro only; the authors say effect concentrations are high, have not been found in the environment, and that in-vivo studies are needed before any health conclusion.
Source: Schreurs 2005, Toxicological Sciences Link to this fact
Information, not medical advice. See also: myths we won’t tell you.