“May contain”: the colour lists at the end of an ingredient list

Flip over a lipstick or an eyeshadow and the ingredient list often ends with a strange tail: “±” or “may contain/peut contenir”, followed by a row of codes like CI 77891, CI 77491, CI 42090. It looks like the company couldn’t make up its mind. In fact, it’s a deliberate labelling shortcut, and once you know how it works, the tail tells you quite a lot.

One label for twenty shades

Makeup is usually sold as a range: the same foundation in 30 skin tones, the same polish in a wall of colours. Each shade has a slightly different mix of colourants, but printing a separate ingredient list for every one would be impractical.

Canada’s Cosmetic Regulations solve this in section 21.2(2). For makeup and nail polish or enamel sold in a range of colour shades, all the colouring agents used across the range may be listed together if they are preceded by “+/–”, “±” or the phrase “may contain/peut contenir”.

So the list after “±” is the palette for the whole range, not the recipe for your shade. Your lipstick contains some of those colourants, on purpose. It almost certainly doesn’t contain all of them.

Health Canada’s labelling guide adds a recommendation: when “±” or “may contain” is used, the colouring agents should be the last ingredients listed, to avoid confusion about what the phrase covers. That’s why the colour tail is almost always at the very end.

Where colours sit in the list

The regulations also give colourants a special place in the ordering. Ingredients must normally be listed in descending order by weight. But section 21.4(2) says that ingredients at 1% or less, and all colouring agents regardless of their concentration, may be listed in any order after the ingredients above 1%.

In practice, that means you can’t judge how much of a colourant is present from its position. A colour at the end of the list might be a trace or a meaningful amount.

What a CI number is

CI stands for Colour Index, an international classification of dyes and pigments. It’s maintained by the Society of Dyers and Colourists, a UK-based society, and has been running since 1924. The Index gives each colourant two labels: a generic name that describes its use and hue, and a constitution number, a five-digit code tied to its molecular structure.

On cosmetic labels, you mostly see that constitution number, written as “CI” plus the code. A few you’ll meet often, as listed in the European Union’s cosmetics colourant list:

• CI 77891: titanium dioxide, a white pigment
• CI 77491, CI 77492, CI 77499: iron oxides, in red, yellow and black
• CI 77007: a blue pigment, listed as lazurite
• CI 42090: a blue dye, known in the US as Blue 1

The same number means the same colourant in any product, anywhere the system is used, which makes CI numbers a handy way to pin down exactly which colourant you’re looking at.

Why the same colour can have two names

You may see “CI 42090 (Blue 1)” or “CI 15985/Yellow 6”. Health Canada’s guide explains that colouring agents often have more than one INCI name (INCI being the international naming system for cosmetic ingredients). A label may use the CI number, the colour name or both, as long as it’s clear they’re the same ingredient. Brackets or a slash show that pairing; here, unlike elsewhere in the list, a slash doesn’t mean two ingredients reacted together.

The colour names come from the US system. The Food and Drug Administration explains that its certified colours carry a prefix, FD&C, D&C or External D&C, plus a colour and a number, and that these colours are made mainly from petroleum and must be batch-certified. Colours from mineral, plant or animal sources, such as iron oxides, are exempt from that certification. Health Canada’s guide notes that the “FD&C” prefix isn’t part of the INCI name, so Canadian labels should say “Blue 1”, not “FD&C Blue 1”.

Where the shortcut doesn’t apply

The “may contain” rule has limits. Health Canada’s guide says it can be used for makeup, hair mascara and temporary coloured hair sprays that rinse out, but it does not apply to hair dye colourants. A permanent or semi-permanent hair dye must list the colourants it actually contains.

Colourants aren’t a free-for-all either. Health Canada’s Cosmetic Ingredient Hotlist, its list of prohibited and restricted cosmetic ingredients, names specific colourants that can’t be used, such as Basic Green 4 (malachite green). In the EU, the colourant list also sets conditions of use for some colours, such as “rinse-off products” only or “not to be used in eye products”.

What the list can’t tell you

The shortcut has a real drawback if you react to a specific colourant. A “may contain” list tells you what might be in your shade, not what is. If a doctor has told you to avoid a particular colourant:

• Look for its CI number and its colour name, since either may be used.
• If it appears after “±”, you can’t tell from the label whether your shade contains it.
• Contact the company listed on the label and ask about your specific shade; the contact information is a required part of every Canadian cosmetic label.
• Keep the packaging of any product that caused a reaction, so the exact shade can be traced.

If a product makes your lips, eyelids or skin red, itchy or swollen, stop using it, and see your doctor or pharmacist if it doesn’t settle within two weeks.

The thing to remember: “±” or “may contain” introduces the colour palette for the whole range, and your shade uses part of it. CI numbers are universal codes for each dye or pigment, colour names like “Blue 1” are their aliases, and neither tells you how much is inside. When it matters, ask about your exact shade.