Material guide: musk ketone — four of its five siblings are banned; it survives on a purity specification

Five nitro musks were once industry workhorses. From the IFRA 51st Amendment index:

Material	CAS	Standard	Published
Musk ambrette	83-66-9	Prohibition	2006
Musk moskene	116-66-5	Prohibition	2008
Musk tibetene	145-39-1	Prohibition	2008
Musk xylene	81-15-2	Prohibition	2009
Musk ketone	81-14-1	Specification	2010

Four prohibited, one still standing. How it stayed standing is worth looking at.

The short version

• Its IFRA Standard is a Specification, not a restriction. The content: it may be used only if it contains less than 0.1% musk xylene.
• That specification exists because musk xylene was banned for environmental reasons, not dermal ones. The Standard records the driving risk as vPvB — very persistent, very bioaccumulative.
• Vapour pressure is 0.000012 mmHg, extremely low. It is the extreme case of the line drawn in the previous article: it barely enters the air at all.
• The database records longevity as "400 hours @ 20% in DPG" — a diluted measurement rather than a neat one, the same problem as the 400-hour ceiling.

The basics

CAS	81-14-1
Chemical name	4′-tert-butyl-2′,6′-dimethyl-3′,5′-dinitroacetophenone
Formula	C₁₄H₁₈N₂O₅
Molecular weight	294.31
Type	Synthetic; the database records it as not found in nature
Odour	Fatty, musk, soapy, dry, floral, powdery
Odour family	musk
Strength	Medium
Longevity	400 hours @ 20% in DPG (not a neat value, see below)
Appearance	Yellow powder
Boiling point	395 °C
Flash point	100 °C
Vapour pressure	0.000012 mmHg @ 25 °C (est)
logP	3.70 (est)
Natural occurrence	Not found in nature
IFRA	Specification (45th Amendment, 2010): must contain less than 0.1% musk xylene
Implementation	New creations 11 January 2011; existing creations 11 January 2012
Suppliers	43
Corpus rank	29th (84 of 953 formulas, 8.8%, median dose 4.00%)

What that specification governs

The IFRA Standard states it plainly: musk xylene (CAS 81-15-2), prohibited for use in fragrance compounds for environmental reasons (vPvB), can be present in musk ketone as an impurity. Musk ketone should therefore only be used if it contains less than 0.1% musk xylene.

The structure is unusual. Most IFRA Standards govern how much of a material you may use. This one governs how much of a banned material may be present inside it. The reason is that their synthesis routes are close enough that musk xylene arises as a process impurity.

Practically: buying musk ketone means asking for an analysis, and the line to read is residual musk xylene. A generic "purity 98%" figure does not answer the question the specification asks.

Worth noting that the musk xylene prohibition records its driving risk as vPvB. That is rare across this series: almost every material we have covered is regulated for skin sensitisation or phototoxicity. This one is regulated because it does not go away.

The zebrafish study

Carlsson and colleagues, in Marine Environmental Research in 2000, provide a concrete example of what the environmental evidence looks like.

Female zebrafish were exposed to musk ketone through their diet before spawning, at two dose levels, for 8 weeks, then spawned with unexposed males.

The exposed females showed reduced body weight and length, and reduced liver and gonad somatic indices. The reproduction study found a dose-dependent reduction in fecundity, increased early life-stage mortality, and reduced median survival time.

A separate embryo and larval toxicity test used newly fertilised eggs from unexposed parents, exposed to a concentration series through the water, giving a NOEC of 10 µg/L and a LOEC of 33 µg/L.

The authors conclude that musk ketone clearly affects reproduction and early life-stage survival in zebrafish.

This is fish, not people, and it is dietary and waterborne exposure. It is a different question from what a spray on skin does to you. What it explains is why this family is regulated on environmental grounds: those molecules travel from wastewater into water bodies, and then they accumulate.

It is still in your household dust

Chen and colleagues, in Ecotoxicology and Environmental Safety in 2023, analysed indoor dust from Korean homes for 19 siloxanes and 12 synthetic musks (polycyclic, macrocyclic and nitro), across samples spanning 2011 to 2021.

Eighteen siloxanes and ten synthetic musks were detected in every dust sample, indicating widespread and long-term contamination. The dominant compounds included linear siloxanes, HHCB (galaxolide), musk ketone and AHTN.

Two trends are worth keeping. First, concentrations of siloxanes and synthetic musks rose from 2011 to 2021. Second, and most relevant here: the synthetic musk profile shifted from nitro musks toward polycyclic musks.

That shift is the industry's substitution visible in dust. With four nitro musks prohibited, the role passed to polycyclics like galaxolide. The authors also note that for indoor dust, estimated daily intake by ingestion exceeded that by dermal absorption.

Why it barely diffuses

Vapour pressure 0.000012 mmHg. Dropped into the quartile table from the previous article, it sits almost two orders of magnitude below the median of the least volatile quarter (0.001 mmHg).

It is the textbook fixative: it barely enters the air, so it is not itself something you smell across a room, while it stays on skin and fabric for a long time and extends how long other things are perceived.

In the pairing analysis it belongs to the chypre and moss-wood cluster, co-occurring with oakmoss absolute (lift 5.21), vetiveryl acetate (5.34) and sandalwood oil (3.78). That is the standard issue of a mid-twentieth-century chypre structure.

Read that "400 hours @ 20% in DPG" record carefully. It is not a neat value. A material that passes 400 hours at 20% dilution and a material recorded at 400 hours neat look identical in a numeric column and mean different things — which is precisely the subject of the 400-hour ceiling.

When you smell it

• It is a yellow powder. For handling solids, see the cinnamic alcohol article: make a 10% stock first, weigh on a boat, watch for caking.
• Smelling it alone disappoints. Fatty, soapy, dry, powdery — none of those descriptors is attractive, and that is what a fixative looks like.
• Run an A/B. Two versions of a small formula, one with 3% and one without. The difference sits in the body and duration of the back half, not in the opening.
• Note that it dates a formula. Combined with oakmoss and vetiver it carries a distinct period feel, which may be exactly what you want, or not.

Buying and storage

Forty-three suppliers. Two things to handle:

Ask for residual musk xylene data. This purchasing requirement is specific to this material. A generic purity spec does not answer what the IFRA specification asks.

Confirm your market. IFRA Standards bind members and the signatory supply chain, and local law is separate. Is this material still legal has the lookup procedure.

Regulatory and safety

The database's GHS field is empty, as is its register listing field. Acute toxicity is generous: oral rat LD50 above 10,000 mg/kg.

That is the point worth taking away. Acute toxicity is very low and nothing obvious happens on skin, and yet four of its siblings are prohibited and this one remains tied to a specification — for reasons on an entirely different axis. How risky is DIY perfumery deals with your skin and your lungs; this material is the reminder that assessment has a dimension you can neither smell nor feel.

→ Musk ketone in the database: full physical data, 43 suppliers and suggested blends. → Search by odour: try "musk powdery soapy".

References

G. Carlsson et al., The impact of musk ketone on reproduction in zebrafish (Danio rerio), Marine Environmental Research, 50(1-5), 237–241 (2000). PMID 11460697.

W. Chen et al., Occurrence, time trends, and human exposure of siloxanes and synthetic musk compounds in indoor dust from Korean homes, Ecotoxicology and Environmental Safety, 266, 115538 (2023). PMID 37806134. doi:10.1016/j.ecoenv.2023.115538

IFRA Standard, Musk ketone (45th Amendment, 2010) and Musk xylene (44th Amendment, 2009). Checked 2026-08-27.