Origin and provenance
Castoreum is the secretion held in the castor sacs, a pair of cavities under the beaver's skin between the pelvis and the base of the tail. Both sexes carry them, and both sexes separately carry a pair of anal glands, which are a different organ.
Confusing the two is the most widespread error about this material, including in otherwise serious writing. Castor sacs are not, strictly speaking, glands at all.
Two species supply the material, the Eurasian beaver Castor fiber and the North American beaver Castor canadensis. Collection is a byproduct of fur trapping, which explains volumes that are small and irregular.
Olfactory profile
Castoreum is leathery, smoky, animalic and honeyed at once. It reads as dry hay, blond tobacco, a phenolic facet close to birch, and a leathery sweetness that appears on dilution.
Its smell comes from the beaver's diet of bark and leaves, whose phenolic compounds concentrate in the secretion. It is an animal material that tastes of burnt vegetation, which sets it clearly apart from musk and civet.
In a formula it works as a binder. It gives leather its depth and tobacco its roundness, without ever taking the foreground.
Production and extraction
The sacs are removed, dried, then either macerated in alcohol to yield a tincture or extracted to yield a resinoid and an absolute. Drying is decisive: it sets the leathery facet and strips the harshness of the fresh material.
The volumes involved are minute on an industrial scale. The safety assessment published by Burdock in 2007 puts American dietary consumption in fractions of a microgram per kilogram of body weight per day, far below the thresholds FEMA established.
Regulatory status, as of 8 September 2026
United States. 21 CFR 182.50, headed Certain other spices, seasonings, essential oils, oleoresins, and natural extracts, lists castoreum among substances generally recognized as safe, naming both source species, Castor fiber L. and C. canadensis Kuhl. FEMA assigns it number 2261.
IFRA. No IFRA Standard covers castoreum. The index of IFRA Standards, fifty-first amendment, does not mention it. The common claim that IFRA banned it during the 1990s rests on no text at all.
Conservation. The IUCN has listed Castor fiber as least concern since its 2008 assessment, the European population having recovered through reintroduction programs.
What that means. Of the five animal materials, castoreum is the least constrained by law. Its retreat from perfumery comes down to availability, cost and commercial reluctance about animal origin, not to a ban.
History in perfumery
Castoreum has structured the great leather register since the nineteenth century. Paired with birch tar, it builds the accord known as Russian leather, of which Cuir de Russie, composed by Ernest Beaux for Chanel in 1927, remains the archetype.
It then runs through the chypres and fougeres of the twentieth century as a base note, where its honeyed facet rounds off oakmoss and labdanum.
Reconstructions largely displaced it from the 1980s onward, not through regulatory pressure but because a reconstructed base offers a consistency that a trapping byproduct cannot.
Notable perfumes
The Russian leather register is castoreum's own territory. Cuir de Russie holds the archetype, with the birch and castoreum accord set under a floral aldehyde.
The leather family of the Societe Francaise des Parfumeurs classification names three sub-families, leather, floral leather and tobacco leather. Castoreum appears in all three, but tobacco leather is the one its honeyed facet defines best: the nomenclature there names woody, honeyed and hay accords explicitly.
Why this material matters in niche perfumery
Castoreum is the material that teaches you to read a pyramid. It almost never appears as a declared note, and yet it decides how deep a leather goes. Its presence shows in an effect, not in a listing.
It is also the best argument for verification. Two claims circulate everywhere about it, the anal gland origin and the IFRA ban, and both are false. An encyclopedia that repeats them forfeits the right to be cited on anything else.