Q
Quaternary ammonium compounds A large family of ingredients which can be used as antimicrobials, preservatives, surfactants (for their cleansing power) and to adjust the texture and viscosity of cosmetics. These synthetic compounds can cause contact dermatitis in some individuals.

Quaternium-18 bentonite The Quaternium family contains ingredients used for antistatic and antimicrobial purposes, as preservatives and as surfactants – as well as thickening agents. In this case, Quaternium-18 is derived from Bentonite clay. One particular member of the Quaternium family – the preservative Quaternium-15 – is considered extremely problematic (NB it does not appear in any products in The Green Beauty Bible): it has caused skin rashes and allergic reactions and is one of the most frequent sensitisers in cosmetic use.

Quaternium-18 hectorite See above, derived from a mineral called Hectorite.

Quaternium-80 See above.

Quaternium-90 bentonite See above.