Nanomaterial

In cosmetics, a nanomaterial is an insoluble ingredient with particles at the nanometre scale — small enough that regulators treat it as a distinct case rather than as the same substance in ordinary form. Under EU rules such ingredients must be listed with the word nano in brackets after the name.

The reason particle size gets its own rule is that it changes behaviour. Finely divided zinc oxide and titanium dioxide scatter less visible light, which is why nano grades leave far less white cast, and they distribute more evenly in a formula. Whether that smaller size changes what happens biologically is the question the labelling requirement exists to keep visible.

• Assessments by EU scientific committees have supported the use of certain nano-scale UV filters on intact skin.
• Spray and powder formats are treated more cautiously, because inhalation is a different exposure route from application to skin.
• The bracketed word on a label is a disclosure, not a warning.

This is an area where the science is genuinely still being added to, and blanket statements in either direction outrun the evidence. Anyone weighing it up for damaged skin, for a child, or in a spray format has a reasonable question for a pharmacist or dermatologist rather than for a label.