Material guide · 131
Material guide: β-damascone — two records under one FEMA number, and only the obscure one carries the sensitisation warning
· 18 min read
The database holds two β-damascone records: (E)-β-damascone (#11165, 41 suppliers) and β-damascone (#11159, 11 suppliers). They share FEMA 3243, the same formula, the same 200 °C boiling point and the same logP of 3.50. But substantivity reads 264 hours on one and 191 on the other; storage says refrigerate on one and cool dry place on the other; toxicity gives an oral LD50 of 2920 mg/kg on one and 'not determined' on the other. The striking one is GHS: the record with 11 suppliers carries H317, may cause an allergic skin reaction, and the record with 41 suppliers has an empty GHS field. Giménez-Arnau and colleagues' 2002 case only identified α-damascone as one of the culprits by taking a bottle of perfume apart — the standard fragrance mix patch test was negative.
About a 5 minute read.
The short version
- Name: β-damascone, FEMA 3243; the database holds two records
- Odour type: fruity; odour: fruity, floral, black currant, plum, rose, honey, tobacco
- Strength: high (evaluate at 1% or less), rank 3; substantivity 264 or 191 hours depending which record
- Suppliers: 41 (the (E)- record) / 11
- Only the 11-supplier record carries the H317 skin sensitisation warning
- It is what you get when an enzyme cuts a carotenoid in half
The two records first
| (E)-β-damascone #11165 | β-damascone #11159 | |
|---|---|---|
| CAS | 23726-91-2 | 35044-68-9 |
| FEMA | 3243 | 3243 |
| Formula / MW | C13H20O / 192.30 | identical |
| Boiling point | 200 °C | 200 °C |
| logP | 3.50 | 3.50 |
| Specific gravity | 0.928–0.936 | 0.925–0.932 |
| Substantivity | 264 hours | 191 hours |
| Storage | Refrigerate | Cool, dry place |
| Oral toxicity | LD50 2920 mg/kg (1975) | Not determined |
| GHS | (empty) | H303, H317 skin sensitisation |
| Suppliers | 41 | 11 |
Sharing a FEMA number means the regulator treats them as the same substance (one specifies E geometry, one does not).
And on that basis, every field that ought to be a measurement differs — substantivity by 38%, opposite storage instructions, toxicity data on one and none on the other.
The last two rows are the ones that matter. The skin sensitisation warning sits on the record with 11 suppliers; the record you are more likely to be buying from — 41 suppliers — has an empty GHS field.
Empty does not mean safe. It means that record was not filled in. I measured the same phenomenon in the storage field article: this database's fields arrive with each record's source, not from one person filling them consistently.
And the sensitisation has a case behind it
What Giménez-Arnau and colleagues published in Contact Dermatitis in 2002 was one case and one method:
A 50-year-old woman presented with a pruriginous, erythematous eruption, characterized by papules, vesicles, exudation and crusting over the neck and chest. With the suspicion of fragrance allergy, patch testing was performed. Initially, the only positive reaction observed was with her own eau de toilette … The TRUE Test fragrance mix patch test was negative.
The standard screen missed it. So they fractionated the perfume concentrate chemically and worked backwards with sequenced patch testing and structure-activity studies:
Benzophenone-2, Lyral, alpha-hexyl cinnamic aldehyde and alpha-damascone were found to be responsible for the patient's contact allergy to the commercial product. These substances contain chemical structural alerts giving them antigenic ability.
Three of those four culprits have their own articles here: Lyral, α-hexyl cinnamaldehyde, benzophenone. The fourth is damascone.
Their conclusion is worth keeping: new chemicals keep going into fragrances, and the number of patients sensitive to them but negative on the fragrance mix keeps growing.
(Note: that paper tested α-damascone, not β-. I cite it because it establishes that damascones sensitise and that the standard screen misses them, not because it tested this material.)
Where it comes from: one enzymatic pair of scissors
Huang and colleagues, in Phytochemistry in 2009, were answering a biochemical question: where do rose oil's key aroma molecules come from?
Several of the key flavor compounds in rose essential oil are C13-norisoprenoids, such as β-damascenone, β-damascone, and β-ionone, which are derived from carotenoid degradation.
They cloned a carotenoid cleavage dioxygenase gene from Rosa damascena (RdCCD1), expressed it in E. coli, and fed it a range of carotenoids:
The RdCCD1 protein was able to cleave a variety of carotenoids at the 9-10 and 9'-10' positions to produce a C14 dialdehyde and two C13 products, which vary depending on the carotenoid substrates.
The rose does not "make" damascone. It makes carotenoids, and cuts them at a fixed position with an enzymatic pair of scissors. What the C13 fragment turns out to be depends on which carotenoid went in.
Which explains why β-damascone, β-damascenone and β-ionone look so alike — same scissors, different substrates, siblings.
(It also explains why it turns up everywhere. The occurrence field lists apple, grapefruit juice, rose, tea leaf, tobacco, olive at up to 0.5 mg/kg. Any plant with carotenoids and this kind of enzyme can produce it.)
The notes field contains a one-line formula
notes reads:
Blends well with moss notes. Drakkar is allyl amyl glycolate, rose oxide, β-damascone and dihydromyrcenol.
Four materials in one sentence, and all four have articles here: allyl amyl glycolate, rose oxide, β-damascone (this article), dihydromyrcenol.
It is not a formula, obviously — it is a four-word skeleton. A commercial fragrance has dozens to hundreds of components. But it is a useful hook: put these four together and you head in that direction.
The odour fields differ between the two records too
| The (E)- record | The other | |
|---|---|---|
| Odour | fruity, floral, berry, plum, black currant, honey, rose, tobacco, woody, minty | fruity, floral, black currant, plum, rose, honey, tobacco |
The (E)- record adds "woody" and "minty." Mosciano's evaluation reads "fruity, woody and berry with a minty note"; Luebke's 1987 entry has no mint in it.
One material, two evaluators, one smelled mint and the other did not. I measured how common that is when I looked at who signs the odour field.
How to use it
- Trace amounts. Rank 3, evaluate below 1%, and it runs past two hundred hours.
- It is the core of the black currant/plum line, and the source of the fruity edge in rose.
- Pair it with moss. The notes field says so, and fougère/chypre is its home ground.
- Assume it sensitises. H317 sits on the obscure record, but the two share a FEMA number. Do not read the empty GHS field on the one you bought as an all-clear.
- Check IFRA. Damascones are restricted.
What this doesn't establish
- I have not smelled it. This is fields, whole-database statistics, and two papers.
- Giménez-Arnau 2002 tested α-damascone, not β-damascone. I have no patch test data for β-.
- That paper is a single case and a methodology, not a prevalence study, so it says nothing about how many people react to damascones.
- Attributing the two records' differences to different sources is an inference. The database records no source, and I did not compare supplier specification sheets.
- "An empty GHS field does not mean safe" is a general rule, not something I verified for this record.
- Huang 2009 is an in vitro enzyme activity study; I did not confirm the actual flux inside a rose.
- The "Drakkar is these four" line is the notes field's claim, with no independent source and no proportions.
- I did not check the current IFRA restriction text for damascones.