You made a candle from wax, a wick and a fragrance oil, and the label calculation handed back an exclamation mark, or a dead tree and fish. Customers ask whether the candle is dangerous. It isn't dangerous to burn, but the pictograms aren't a mistake either. Here's where the three most common candle hazard statements come from, and why a small change in fragrance load can add or remove a pictogram.

The wax isn't the reason

Refined paraffin, soy and rapeseed wax carry no EU hazard classification, so they add nothing to the label. Every pictogram on a scented candle comes from a handful of substances inside the fragrance oil. Under CLP, the finished candle is a mixture, and its classification depends on how much of each of those substances ends up in the candle. That's the fragrance's composition multiplied by your load.

H317: the exclamation mark

H317 "May cause an allergic skin reaction" comes from skin sensitisers, and most fragrance oils contain some. It brings the exclamation mark pictogram (GHS07) and the signal word "Warning". The allergy risk is from touching the wax or oil, not from the scent in the air, but the rule classifies the product as sold.

These are the harmonised EU classifications, as recorded by ECHA, for some sensitisers you'll find on almost any fragrance SDS:

Linalool: Skin Sens. 1B.
Limonene: Skin Sens. 1B (plus Skin Irrit. 2, Asp. Tox. 1 and Aquatic Chronic 3).
Citral and geraniol: Skin Sens. 1.
Cinnamal and isoeugenol: Skin Sens. 1A, each with a specific concentration limit of 0.01%.

The candle is classified H317 when any single sensitiser reaches its limit in the finished candle:

1% for a Skin Sens. 1 or 1B substance such as linalool or limonene.
0.1% for a Skin Sens. 1A substance.
Its specific concentration limit, if it has one: 0.01% for cinnamal and isoeugenol.

Sensitisers aren't added together. Each one is checked against its own limit. Below that limit, a sensitiser at a tenth of it or more doesn't trigger a pictogram but still has to be named on the EUH208 "Contains… May produce an allergic reaction" line. That's why a label can have an allergen line and no exclamation mark.

H411 and H412: the environment pictogram

These come from substances that are toxic to aquatic life with long-lasting effects. For candle fragrances the usual source is a synthetic musk. Galaxolide (HHCB), common in "clean" and musky scents, has a harmonised classification of Aquatic Chronic 1, the most severe long-term aquatic category.

The finished product's category decides what appears on the label:

H410 (Aquatic Chronic 1): environment pictogram (GHS09) and "Warning".
H411 (Aquatic Chronic 2): environment pictogram, no signal word.
H412 (Aquatic Chronic 3): no pictogram and no signal word. Just the hazard statement "Harmful to aquatic life with long lasting effects" and its precautionary statements (P273 avoid release to the environment, P501 dispose of contents properly).

That last point confuses people. H412 is a real classification that goes on the label, but it's the one aquatic category CLP deliberately leaves without a symbol. A candle can therefore carry an environmental warning in words and no dead-tree pictogram.

Why load decides H411 or H412

Unlike sensitisers, aquatic hazards are added together, using CLP's summation method, and the more toxic categories count ten times as much at each step. For a substance classified Aquatic Chronic 1 with an M-factor of 1 (ECHA's entry for galaxolide lists no higher one), the thresholds in the finished candle work out as:

2.5% or more → the candle is Aquatic Chronic 2: H411 with the pictogram.
0.25% to under 2.5% → Aquatic Chronic 3: H412, no pictogram.
Under 0.25% → nothing from this substance on its own.

An Aquatic Chronic 2 ingredient counts ten times less: H412 from 2.5%, H411 only from 25%. An Aquatic Chronic 3 ingredient such as limonene needs 25% before it gives H412 on its own, so in a candle it only adds a little to the total.

A worked example

Take a hypothetical musky fragrance oil whose SDS lists 25% galaxolide and 15% linalool:

At a 10% load, the candle holds 2.5% galaxolide and 1.5% linalool. Galaxolide reaches the 2.5% line, so the candle is H411 with the environment pictogram. Linalool is over 1%, so it's also H317 with the exclamation mark and "Warning". That's two pictograms.
At an 8% load, it's 2.0% galaxolide and 1.2% linalool. The aquatic hazard drops to H412: no pictogram. H317 stays.
At a 6% load, it's 1.5% galaxolide and 0.9% linalool. Still H412, and linalool is now under 1%, so H317 and the exclamation mark disappear. Linalool moves to the EUH208 "Contains…" line.

Same oil, same wax, and the label goes from two pictograms to none just by changing the load from 10% to 6%. A real fragrance has more components and needs the full calculation, including other sensitisers, other aquatic ingredients and any M-factors above 1. But the mechanism is always this one.

What to do with this

Don't copy the fragrance SDS's pictograms onto your candle. The oil is classified at 100%. Your candle is diluted, so it usually carries fewer pictograms, and occasionally different ones.
Don't drop H412 because it has no pictogram. The statement and its precautionary phrases still belong on the label.
If you want fewer pictograms, look at the load before the fragrance. A point or two of load often changes the label more than switching wax does.

Molekule reads each component from your fragrance's safety data sheet, checks it against ECHA's live classifications, runs these calculations for your candle and shows the load at which each pictogram appears. See which pictograms your candle needs in Molekule.

Candle hazard pictograms: H317, H411 and H412 explained