Silicone lowdown
The cyclosiloxanes commonly known as cyclotetrasiloxane (D4) and cyclopentasiloxane (D5) are used for their anti-static, emollient, humectant, solvent, viscosity-controlling and hair conditioning properties in cosmetic products.

However, concerns have been raised about their toxicity and effects on the environment, and now it is recognised that cyclotetrasiloxane (D4) is toxic to human reproduction systems.

It also accumulates in the environment with unpredictable long term effects.

Cyclopentasiloxane (D5) can also be harmful to the environment and in January 2018 the EU commission published an update amending Annex XVII to Regulation (EC) No 1907/2006 of REACH.

After 31 January 2020, the concentration of D4/D5 in cosmetic products placed on the market that are rinsed off after application should be less than 0.1% by weight of either substance. This has now been amended to include cyclohexasiloxane (D6) and it is expected that this restriction will be extended to include leave-on products.

Because of these restrictions most silicone alternatives have been designed to replace D4/D5. It is not necessary to exclude silicone products and Innospec suggests that Volasil 8100 (INCI: Dimethicone, trisiloxane) provides the right combination of volatility, lubricity and spreadability to impart a dry, smooth application to hair and skin products.

It has a similar volatility to D4, and is recommended for antiperspirants and hair sprays requiring a fast drying time. Volasil DM-1.5 is a dimethicone that is slightly more volatile than D5; it imparts a dry, smooth application to hair and skin products.

Dimethisil DM-5 and Dimethisil DM-6 from Innospec are suggested as replacements for D6 in hair and skin products, and as a solvent for active ingredients, as well as a diluent for silicone gums and elastomers.