Material guide: Lyral (HICC) — the database calls it leerall, the EU banned it, and the supplier field still says 40

Short version: a once-ubiquitous muguet material, banned in the EU for contact sensitisation. It gets an entry because it is still in 50 published formulas at a median 4.57%, and you will run into it building from them.

This is not regulatory advice. What follows describes EU cosmetics; IFRA and national rules are separate systems.

The fields

Field	Value
Database name	leerall
Head synonym	lyral (IFF)
Chemical name	Hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC)
CAS	31906-04-4
Formula	C13H22O2, MW 210.32
Assay	97–100% (sum of isomers)
Appearance	Colorless to pale yellow clear viscous liquid (est)
Odour type	Floral
Odour	Floral, muguet, cyclamen, rhubarb, woody
Strength	Medium (rank 2)
Substantivity	400 hours at 100%
Boiling point	318.65 °C @ 760 mmHg (est)
logP	1.70 (est)
Water solubility	184.6 mg/L @ 25 °C (est)
Shelf life	24 months
Suppliers	40
GHS	H302 harmful if swallowed, H316 causes mild skin irritation, H320 causes eye irritation
Oral toxicity	Rat LD50 3,250 µL/kg
Dermal toxicity	Rabbit LD50 11,300 µL/kg

Why it was banned

Because someone measured it.

In 2017, Engfeldt and colleagues ran a five-centre study for the Swedish Contact Dermatitis Research Group. 2,118 dermatitis patients were consecutively patch tested with fragrance mix II at two strengths (14% and 16.5% pet.) and duplicate preparations of HICC 5% pet.

Test	Positive
Fragrance mix II (14%)	3.2%
HICC	1.5%
Overall prevalence with duplicate HICC applications	1.9%
Detected by HICC alone (no concomitant mix reactivity)	0.3%

The paper's research question was methodological: does raising HICC in the mix from 2.5% to 5% detect more? The answer was no — the stronger version gave rise to no more irritant reactions or signs of active sensitization, and separate HICC testing did not detect a sufficient proportion of patients reacting only to it.

But that 1.5% to 1.9% is the background against which this material was removed from the Swedish baseline series in 2014 and later banned in the EU.

In 2022, Sukakul and colleagues updated the picture for southern Sweden: 3,539 dermatitis patients, 2016 to 2020. Overall fragrance contact allergy prevalence was 13%. And one sentence bears directly on this material:

"Unlike hydroxyisohexyl 3-cyclohexene carboxaldehyde, there was no decreasing trend of CA to Evernia prunastri (oakmoss) extract after the EU regulation came into force."

Read the other way: HICC contact allergy did show a decreasing trend after the regulation.

Within one dataset, a banned material shows a decrease and a restricted one does not. That is a rare contrast.

To be clear: both studies are of dermatitis outpatients, not the general population, and these percentages cannot be read as general allergy rates. One of Sukakul's authors declares membership of the Expert Panel for Fragrance Safety, which advises the fragrance industry.

And its GHS field has no sensitisation

This field deserves its own look.

The leerall record's GHS classification reads:

H302 - Harmful if swallowed H316 - Causes mild skin irritation H320 - Causes eye irritation

No H317 (may cause an allergic skin reaction).

A material banned in the EU for contact sensitisation carries no sensitisation classification in this record's GHS field.

I am not going to explain that gap, because I do not know the source or date of this GHS data. Several things could account for it: GHS classification and cosmetics regulation are independent systems; the record may not have been updated; or the supplier-declared classification simply never included it. What can be said is: do not use the GHS field to judge whether a fragrance material can go on skin.

This series has measured something related: of 36 musk records with ten or more suppliers, 23 have no GHS field at all. Neither the coverage nor the currency of that field was designed for this use.

The natural occurrence field contradicts itself

Another field:

not found in nature; salvia officinalis oil england @ 0.10%

One field holding both "not found in nature" and a specific natural source with a concentration.

This series handles database contradictions by flagging them plainly and not guessing. Later data may have been appended without clearing the earlier line, or that sage oil detection may have been something else. Do not use this field.

(Incidentally, if the 0.10% is real it changes nothing. Ten parts in ten thousand does not make a material synthesised in bulk since the 1960s into a natural.)

What it does in the corpus

It appears in 50 of 954 formulas (5.2%), at a median dose of 4.57%, with one formula at 28.2%.

4.57% is not a trace. This is a material used structurally.

The supplier description explains why:

"Soft delicate floral, lily, cyclamen, lilac note reminiscent of hydroxycitronellal. Extraordinary tenacity and diffusivity. A powerful blending agent giving richness throughout all dryout phases of a perfume composition."

"Richness throughout all dryout phases" plus 400 hours of substantivity gives its role away. It is not a note; it is the thing holding the perfume together. Which is why removing it drops part of the structure.

The database's notes field even keeps a small accord built on it:

"waxy floral fruity accord: 0.05 leerall / 0.01 aldehyde C-14 / 0.05 aldehyde C18 10% / 0.01 musk gx / 0.01 raspberry ketone 10% / 0.01 aldehyde C-16 10%"

This round's beginner article measures the scale of the issue: 331 corpus formulas (34.7%) contain at least one now-banned or severely restricted material, and Lyral accounts for 50 of them.

That name

This site's database files it under leerall.

lyral (IFF) sits in the head synonym field. The chemical name sits in the synonyms.

Search this site for "Lyral" and you get nothing — the same problem the last material guide (sotolon) recorded, by the same mechanism: the database's name field holds a name you would never search for.

This time I found it by CAS. The rule stands: check the CAS, not the name. And if you do not know the CAS, try the chemical name, the trade name and the plausible variant spellings, and remember that the name field is not the only field holding names.

(The same search turned up Lilial filed as lilyall, CAS 80-54-6, 37 suppliers. This is a naming convention, not an accident.)

Whether to buy it

• If you are making something for the EU market, do not. It is banned.
• The 40 suppliers in the field do not mean you can buy it. Records update more slowly than markets; that field reflects history.
• But you will hit it in published formulas (50 of them, median 4.57%), so it is worth knowing what it is and what it does there.
• What it does is richness and blending, not just a muguet note. Replacing it takes more than finding one muguet material; you also have to replace 400 hours of blending.
• This article does not tell you what to substitute. That takes actual trials, and I have not run them.

What this doesn't establish

• The regulatory status is written from public information, not a legal opinion. EU cosmetics regulation and IFRA standards are separate systems, national rules differ, and all of them change.
• I have not explained the missing sensitisation classification in the GHS field. I do not know that data's source or date.
• I have not resolved the contradiction in the natural occurrence field. Flagged plainly, not guessed at.
• Both papers studied Swedish dermatitis outpatients. 1.5%, 1.9% and 13% are rates within that group, not general population allergy rates.
• Sukakul 2022's "HICC decreased, oakmoss did not" is that study's observation in its own data. Cited as a contrast, not as proof of causation.
• I have not smelled it. This piece rests on database fields, supplier notes and corpus statistics.
• The 50 corpus formulas were found by name matching, and trade-name variants can be missed. Given this article's subject, that sentence is worth reading twice.