Are products containing cyclopentadimethylsiloxane (D5) safe?

Are products containing cyclopentadimethylsiloxane (D5) safe?
Since D5 has been restricted by the European Union for use in rinse-off products, many people are concerned that the use of D5 in leave-on products will also be restricted in the future. (Leave-on products: Products such as lotions, essences, emulsions, creams, etc. that stay on the surface of the skin during use and do not need to be rinsed off after use. (As opposed to wash-off products, which need to be rinsed off after use.)
How should we use the residual products? Should we look for alternative ingredients to D5 in the future?

I. Introduction of cyclopentadimethylsiloxane (D5)
Cyclopentadimethylsiloxane (D5) is used in cosmetics as an emollient and skin/hair conditioning agent due to its good skinfeel, as well as its conditioning and evaporation properties.
A search of EWG’s product database and Beauty Practice reveals a large number of applications, which are very common and widely used, and are present in formulations at low levels. The majority of these products are in the categories of color cosmetics, sun care, skin care and hair care.
Because D5 is so widely used, the question is actually troubling to many cosmetic manufacturers.
Is D5 safe? Is D5 safe and will it be limited to use in stay-in-place products in the future?
Skin Care believes that the use is based on safety. Let’s take a look at the global safety evaluation of D5.
Second, the safety evaluation of D5
EWG (U.S. Environmental Working Group)
The EWG’s raw material rating for D5 is 3. The following safety recommendations have been made based on publicly available literature or regulations worldwide.
Persistent and bioaccumulative in wildlife [1].
Organ system toxicity (non-reproductive): classified as toxic or hazardous [2].
Tumor: Tumor formation has been observed at moderate doses in one or more animal studies [3].
Endocrine Disruption: one or more animal studies have shown that endocrine disruption has been observed at moderate doses [4].
Neurotoxicity: shown to produce effects at moderate doses in one or more animal studies [5].
Ecotoxicity: suspected environmental toxin, persistent or bioaccumulative [6].
CIR (Cosmetic Ingredient Review)
The U.S. CIR considers cyclodimethylsiloxanes (D4, D5, D6, D7) to be safe in the forms and concentrations in which they are currently used in products.
SCCS (European Union Scientific Committee on Consumer Safety)
The SCCS considers D5 to be safe at current cosmetic use concentrations. However, the product forms do not include hair styling aerosols and sunscreen spray products. This is because the SCCS believes that when these two types of products are used, D5 is atomized and tends to accumulate in the air above safe concentrations, leading to toxicity. Also the above safety conclusion for D5 does not include oral care products.

Trace amounts of D4 carried in D5 are reproductively toxic. Therefore, it is necessary to strictly control the content of D4 impurities and keep it as low as possible.
In addition, SCCS has been made aware of a proposal to restrict D4 and D5 in personal care products based on environmental concerns under the Reach (Registration, Evaluation, Authorization and Restriction of Chemicals) regulation [7]. The opinion does not address the potential environmental impacts of D5.

III. Conclusion
The above assessment opinions are synthesized:
Both the CIR and the SCCS consider D5 to be safe for humans at existing cosmetic use concentrations. In particular, SCCS considers that the above safety conclusions do not include products such as hair styling aerosols, sunscreen sprays, and oral care.
Based on the potential adverse environmental impacts of D5, it has been suggested that the SCCS place restrictions on the use of D5 in personal care applications. The current restriction is that the content of cyclotetramethylsiloxane (D4) and cyclopentamethylsiloxane (D5) in wash-off cosmetics must be less than 0.1%.
Finally, back to the original question, do we still use D5? Will it be further restricted in the future?
Skincare’s suggestion is that for domestic products, based on product usage and cost control. If D5 is to be used in non-special use cosmetics, it should be used. Special use cosmetics due to the approval of a longer period of time, to avoid the emergence of still in the test and approval, D5 regulatory changes such as further restrictions on the use of the “embarrassment”, please use discretion. If you can replace it, try to replace it, if you can’t replace it, you can still use it, after all, it will take some time for a new regulation to come into effect.