What an ingredient scanner can and cannot tell you

What a list gives you, and what it leaves out

A cosmetic label gives you two things: the identity of each ingredient, by its standard name, and a rough order by amount. Most of what decides how a product behaves on skin is not on it.

Hazard and risk are different questions

The EU's Scientific Committee on Consumer Safety (SCCS) describes four steps. Hazard identification asks what a substance can do in itself: whether it has the potential to damage health. Exposure assessment works out how much of it people meet, from the amount in each type of product and how often it is used. A dose-response assessment relates the amount to the effect, and risk characterisation brings the steps together.⁴

The SCCS gives a plain example. A substance that is corrosive in itself is not necessarily excluded from cosmetics: potassium hydroxide is one, and whether it corrodes depends on its final concentration, the pH, what else in the formula neutralises it, and how it is used.⁴ The name Potassium Hydroxide on a label tells you it is there. It cannot tell you any of the rest.

What a hazard classification means

EU chemicals law gives many substances a harmonised classification. A hazard class describes "the nature of the physical, health or environmental hazard", and it is assigned to the substance itself. The same law does not apply to cosmetic products in their finished state.⁶

Linalool, a common fragrance ingredient, shows how the two fit together. As a substance it is classified as a skin sensitiser, with the hazard statement "May cause an allergic skin reaction".⁶ In cosmetics, the EU's answer is labelling: linalool must be named on the list above 0.001% in a leave-on and 0.01% in a rinse-off product³, so that people who are already allergic to it can avoid it.⁵

So a hazard flag repeats a fact about the pure substance. It matters most to someone who already knows they react to that substance, and on its own it says nothing about a product in which the amount is unknown.

How a product is checked before sale

In the EU, before a cosmetic product goes on the market, the company responsible for it must have it assessed and keep a cosmetic product safety report. The assessment must take into account the product's intended use and the expected exposure to each ingredient in the final formula.³

The report starts from information no label carries: the quantities of every ingredient, the purity of each substance, the stability of the product, and exposure worked out from where it is applied, over what area, in what amount, and how long and how often. A qualified assessor, with a university qualification in pharmacy, toxicology, medicine or a similar discipline, signs the conclusion.³

In the US, the person responsible for a product must keep records supporting its safety substantiation, though neither the law nor FDA regulations require specific tests.⁷

What a scanner can and cannot do

A good scanner works with what the label gives. It can:

• Identify each name, including US names, common names, Latin plant names and CI numbers, and match it to the official EU name.
• Explain what each ingredient does, from the functions recorded for it in the EU's CosIng database.
• Repeat what an official source says: that an ingredient is banned or restricted in EU cosmetics, or has a hazard classification as a pure substance, with the source named.
• Match your own preferences by showing groups such as fragrance, essential oils, silicones or drying alcohol, so you can find what you choose to avoid.

It cannot:

• Give a verdict or a score. Without amounts, a score would be a guess presented as a number.
• Predict an allergy, or rule one out. If you know you react to a named substance, its name is what to look for. A list that says only Parfum cannot confirm that a particular scent substance is absent, because allergens need to be named only above set levels.¹⁵
• Read amounts the label does not give, or tell apart two formulas with the same names.
• Replace advice. If you react to a product, speak to a doctor or pharmacist.

What to look for on the label

• The names you already know you react to, including fragrance substances named after Parfum.
• Flagged ingredients, as a prompt to read the rule behind the flag, not as a judgement on the product.
• The order, as a rough guide to amount. See cosmetic ingredient list order for what position can and cannot show.

The ingredient checker is built on these limits: it shows every name, its role and any official flag with its source, and never turns them into a score. The methodology page explains the data behind it.