EU REACH Restricts D4 / D5 / D6 Cyclic Siloxanes — The Reformulation Race

TL;DR

EU REACH Annex XVII Entry 70 — entered into force in stages from January 2026 — caps cyclic siloxanes (D4, D5, D6) at 0.1% (w/w) in rinse-off cosmetic products and at lower limits in other consumer goods. The restriction applies to D4 (octamethylcyclotetrasiloxane) and D5 (decamethylcyclopentasiloxane) immediately, and to D6 (dodecamethylcyclohexasiloxane) from 2027. Global personal-care formulators, antiperspirant manufacturers, and silicone-fluid suppliers face an urgent reformulation race — switching from volatile cyclic-siloxane carriers to volatile linear silicones, hydrocarbon esters, and water-based alternatives. The Chinese silicone industry is positioned to benefit if it can scale up production of volatile linear silicones (V-PDMS) and food-grade dimethicone alternatives.

Background

D4, D5, and D6 cyclic siloxanes have been the workhorse "feel-modifying" ingredients in personal-care formulations for 35 years. They evaporate after application (D5 evaporates in 90 seconds), leaving behind a non-greasy "second-skin" sensation that consumers prefer. Antiperspirants, sunscreens, color cosmetics, hair conditioners, and skin lotions all rely on D5 (and to a lesser extent D4 and D6) as primary carrier solvents.

Environmental concerns about cyclic siloxanes have been mounting since 2008. The compounds are persistent (resist environmental degradation), bioaccumulative in fatty tissues, and reach measurable concentrations in surface waters near wastewater treatment plants. EU REACH Annex XVII Entry 70, the regulatory response, restricts cyclic siloxane content in consumer products to mitigate environmental release.

What the Restriction Does

The restriction (REACH Annex XVII Entry 70, applying to substances on the candidate list of substances of very high concern):

Notable exemptions and details:

• "Rinse-off" includes shampoos, conditioners, body washes, scrubs — products where the cyclic siloxane is washed into the wastewater stream
• "Leave-on" products (skin moisturizers, antiperspirants, color cosmetics applied to skin) are addressed by complementary EU regulations and may have less-strict limits
• Industrial applications (silicone manufacturing intermediates, rubber-curing diluents) are not directly captured by Entry 70

The 0.1% threshold is so low that it essentially prohibits use of cyclic siloxanes as primary functional ingredients; limits below 0.1% are achievable only as residual unreacted monomer in linear silicone products.

Reformulation Pathways

Global formulators are pursuing three replacement strategies:

1. Volatile Linear Silicones (V-PDMS)

Volatile linear PDMS (e.g., 1.5 cSt PDMS, Dow Xiameter PMX-200, Wacker AK 0.65) provides similar evaporation behavior to D5 but is not cyclic — and so not subject to the restriction. The trade-off is that V-PDMS evaporates 30-60% slower than D5, requiring formulation adjustments. Cost is comparable but supply is concentrated among Western and Japanese producers.

2. Hydrocarbon Esters

Caprylic/capric triglyceride, isodecyl neopentanoate, isohexadecane, and similar hydrocarbon esters provide non-greasy feel without silicon chemistry. These are widely available, lower cost, but produce different sensory profiles. Many premium brands have rejected hydrocarbon esters as "feeling waxy."

3. Water-Based and Microemulsion Approaches

Some categories (sunscreens, hair conditioners) have moved toward water-based formulations using PEG-modified silicones, silicone microemulsions, or aqueous polymers. Performance is generally inferior to cyclic-siloxane-based, but environmental positioning is stronger.

Industry Players Affected

The reformulation race affects every personal-care category but with differential urgency:

Chinese Silicone Industry Opportunities

The reformulation race is positive for Chinese silicone suppliers if they can scale up:

• Volatile linear PDMS (1-3 cSt grades): currently dominated by Wacker, Dow, Shin-Etsu. Chinese producers (Hubei Huifu, Tongcheng) are investing in V-PDMS capacity 2025-2027.
• Phenyl-modified silicones: alternative to cyclic D5 for foundation and primer applications.
• Polyether-modified silicones: bridge between hydrocarbon and silicone phase formulations.

The Chinese export window for V-PDMS (1 cSt and 1.5 cSt grades, particularly) is 2026-2028.

Implications for Buyers

For personal-care formulators sourcing from China:

1. Audit current formulations: identify D4, D5, D6 in current European products
2. Validate V-PDMS suppliers: 1-3 Chinese sources can meet volatile linear silicone specifications
3. Reformulation timing: 18-month window from formulation lock-in to market launch (typical regulatory + retail cycles)
4. Ingredient labels: reformulated products may need new INCI nomenclature (e.g., "Dimethicone" or "Caprylic/Capric Triglyceride" replacing "Cyclomethicone")

Outlook

By 2028, expect:

• D4/D5/D6 use in EU rinse-off cosmetics: ~5-10% of 2024 baseline (replacement product reformulated)
• D6 use in EU leave-on cosmetics: 20-30% of 2024 baseline (limit applies later, slower transition)
• V-PDMS demand: 2-3x 2024 baseline (driven by reformulation)
• Chinese V-PDMS production capacity: 30,000-50,000 tonnes/year by 2027 (from below 10,000 in 2024)
• Other regional restrictions (Canada, possibly US) likely to follow EU lead by 2030

Related Reading

Personal care industry guide for cyclic siloxane application context. Silicone oil category for V-PDMS grade selection. Cosmetics silicone oil grade for personal-care formulation. Geopolitics insights for the related EU regulatory framework.