Although D5 has performed well in the field of personal care, its environmental residues and potential risks have attracted widespread attention, especially under the regulatory restrictions of the European Union and other places, its use faces challenges.


Environmental residues and ecological risks
Pollution pathways:


D5 enters the environment through wastewater (40%) and air volatilization (90%), with a concentration of up to 10,900 μg/kg in sewage treatment plant sludge, and diffuses to the polar regions with atmospheric circulation.


The concentration of D5 in the aquatic environment can reach 339 ng/L. Although it does not reach the toxicity threshold, long-term accumulation may affect the nervous system of invertebrates.


Bioaccumulation: D5 is fat-soluble and persistent, but studies have shown that it has a high metabolic rate, and it shows a biological dilution rather than amplification effect in the food chain, and the overall ecological risk is low.


Global regulatory trends
EU REACH Regulation: From 2020, the concentration of D5 in rinse-off cosmetics will be restricted to ≤0.1%, and will be extended to D6 and resident products in 2023.


Controversy and standard setting: China is promoting the group standard of "Determination of D4/D5/D6 Residues in Silicone Oil", using headspace gas chromatography to improve detection accuracy.


Future Outlook
Although the short-term human safety of D5 is recognized, its environmental persistence has prompted the industry to accelerate the development of alternatives. For example, the application of polyether modified silicone oil (PEMS) in agricultural adjuvants has gradually increased to reduce ecological impact.