Transitioning Away from D4, D5, D6 Silicones: Shifting Trends and Regulatory Framework
Silicones are a diverse group of synthetic compounds that contain silicon, oxygen, carbon, and hydrogen. They have, however, been both popular and controversial in the market. Silicones can be found in a variety of forms, including fluids, elastomers, resins, and oils. They are primarily used in cosmetics as emollients, which help in moisturizing and softening the skin while also improving the texture and spreadability of products. Silicone chemistries like Dimethicone, Dimethiconol, Cyclomethicone, Dimethicone Copolyol, Silicone Resins, Siloxane Copolymers, and others are frequently used in primers, foundations, moisturizers, shampoos, conditioners, and other skin and hair care products. They function as emollients, humectants, film formers, anti-foaming agents, anti-static agents, or binding agents in these products. Although silicone-based ingredients are derived from natural silica sources, synthetic processes have been used to create desired formulations that end up tampering with the ingredients’ native properties.
In the past few years, cyclic methyl siloxane-based silicone chemistries, such as octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), have become an emerging concern. These ingredients can be found in the environment for long periods of time, bioaccumulate in living organisms, and have the potential to harm human health and the environment. Furthermore, they are frequently distinguished by their resistance to degradation inside the body, ability to travel long distances through air and water, and accumulation in fatty tissues. As a result, it has alarmed researchers and environmentalists, come under high scrutiny, and faced certain restrictions in cosmetics applications due to bio-accumulative persistence.
Actions taken by regulatory bodies
It is worth noting that regulatory bodies like the European Union’s Scientific Committee on Consumer Safety (SCCS) and the United States Food and Drug Administration (FDA) have conducted extensive studies on the safety of D4, D5, and D6 in cosmetic products. These studies concluded that the levels of D4, D5, and D6 found in finished products pose no significant risks to human health when used as intended in cosmetics.
However, under REACH, these have been identified as substances of very high concern due to their Persistent, Bioaccumulative, and Toxic (PBT) properties. As a result, they are already restricted in wash-off cosmetic products with a permissible limit of 0.1% concentration by weight, and the concentration is further limited in leave-on cosmetic products.
The European Chemical Agency (ECHA) recently announced plans to reduce the concentration of these ingredients in cosmetics in order to reduce the use of persistent organic pollutants (POP). It is also worth noting that regulations and guidelines vary by region, and some jurisdictions may have specific restrictions or limitations on the use of cyclic silicones in cosmetic formulations.
The personal care and cosmetic industry have been exploring alternatives to these ingredients that have lower persistence in the environment. Formulators are exploring natural alternatives to these ingredients, such as plant-derived oils (e.g., jojoba oil, argan oil, or coconut oil), shea butter, cocoa butter, and other natural emollients.
These ingredients have moisturizing and softening properties similar to D4, D5, and D6-based silicones. It is important to note that the performance and properties of these alternatives may differ from those of D4, D5, and D6 silicones. Formulators carefully select and formulate alternatives based on the desired properties and intended applications of their products, taking sensory attributes, stability, and efficacy into account.
LexFeel WOW (Triheptanoin and C13-16 Isoparaffin) and WOW DT (C13-16 Isoparaffin and Heptyl Undecylenate) ingredients from INOLEX are derived from plant-based sources such as coconut, castor bean, and sugar cane and are marketed as next-generation silicone alternatives.
For the past decade, INOLEX has been ahead of the curve in providing natural solutions to brands and, ultimately, consumers in several major categories like squalene and silicones. Based on their expertise, these ingredients represent the next generation of innovation, being 100% plant-based and exhibiting exceptional performance and sensory characteristics.
Similarly, in 2022, OQ Chemicals introduced Neopentyl Glycol Diheptanoate, an emollient with skin conditioning and viscosity-increasing properties. It is created by combining neopentyl glycol (a film-forming agent and solvent) and heptanoic acid (a grape-derived fatty acid). It is regarded as a viable alternative to silicones because it is light and velvety on the skin and has excellent spreadability. It has excellent properties such as low surface tension, high lubricity, and low viscosity, which allow for fluid formulations offering a silky, non-oily feel.
Haltermann Carless developed a renewable iso-dodecane through a distillation and complex purification process based on plant-based feedstock. Isododecane is a key ingredient in the cosmetics industry. The most suitable isomer for cosmetic formulations is 2,2,4,6,6-pentamethylheptane (2,2,4,6,6-PMH), which produces an excellent skin texture due to its strong branching. The products’ low viscosity, density, and relative volatility provide good spreadability and smooth applicability.
Isododecane, particularly isododecane derived from bio-based resources, is regarded as an excellent substitute for cyclosiloxanes or silicones.
Citropol® V5, a bioderived and patented alternative to volatile silicones, was introduced by P2 Science, Inc. in 2020. This is the third commercial product developed by P2 from its proprietary Citropol® series.
Silicone formulations and regulations are evolving at a rapid pace. But because the impact of silicone is not immediately visible, people are unconcerned. As a result, the hype is limited. The industry is evolving and prioritizing sustainability; ongoing research and development efforts are underway to identify and optimize silicone alternatives that provide effective performance while having a low environmental impact. It would be very interesting to witness how this trend shapes up and if more developments or wagons come down the road.