The conditioner you used this morning almost certainly contained one of them. So did the hair serum you smoothed through before blow-drying, and the primer you reached for afterward. Cyclic silicones — D4, D5, and D6 — have been the invisible workhorses of conventional hair and face products for decades, creating that effortlessly slippery, velvet-smooth finish that makes you feel like a product is working. The problem is that after they rinse off your hair and run down the drain, they don't stop. The European Union formally restricted D4 and D5 in wash-off products in 2018 — and as of June 2026, they will be restricted in leave-on products too. That restriction isn't a bureaucratic footnote. It's an acknowledgment that something you've been applying to your body has been accumulating in rivers, sediment, and aquatic organisms every single time you've used it. Women across Saudi Arabia, the UAE, and throughout the Gulf reach for these very products every single day — often without knowing what's in them.
The Mechanism: How Cyclic Silicones Persist Long After the Rinse
Cyclic silicones are ring-shaped organosilicon molecules. D4 (cyclotetrasiloxane), D5 (cyclopentasiloxane), and D6 (cyclohexasiloxane) each contain four, five, and six silicon-oxygen units respectively. What makes them so appealing to formulators is exactly what makes them problematic in the environment: they are chemically inert, thermally stable, and slow to degrade. They evaporate from your hair quickly — which is why serums feel weightless — but that volatility doesn't mean they disappear. They enter the atmosphere and waterways, and their resistance to biological breakdown means they accumulate. A landmark study published in Environmental Science & Technology found D5 concentrations in lake sediment near urbanised areas at levels consistent with ongoing bioaccumulation — Kierkegaard et al., 2006.
The European Chemicals Agency (ECHA) formally classified D4 as toxic to aquatic life with long-lasting effects, and identified D4, D5, and D6 as very persistent and very bioaccumulative (vPvB) substances. These are not contested findings — they are the regulatory science behind a restriction affecting every conventional shampoo, conditioner, and hair serum sold in Europe after mid-2026.
What Conventional Hair and Face Products Actually Contain
Scan the ingredient lists of mainstream hair serums, leave-on conditioners, and face primers and you will find Cyclopentasiloxane listed near the top — often as the second or third ingredient by volume. It is there because it creates an immediate, impressive sensory result: slip, smoothness, frizz control, a blurred-pore finish. On skin, D5 gives primers their camera-ready texture. In hair masks, D4 and D5 provide that just-left-the-salon feel without weighing strands down. The EU's restriction (Commission Regulation (EU) 2018/35 for wash-off products; extended to leave-on products in May 2024 with enforcement from 6 June 2026) limits concentrations to 0.1% — EUR-Lex Regulation 2018/35.
The challenge for the consumer is that ingredient lists can run 30–40 items. Cyclic silicones can appear under multiple names — Cyclotetrasiloxane, Cyclopentasiloxane, Cyclohexasiloxane — and even a committed label-reader may miss them. This is precisely the gap that third-party certification is designed to close: COSMOS prohibits all cyclic silicones outright, which means the audit has already been done before the product reaches you.
Conventional vs. COSMOS Certified: What the Formulas Actually Look Like
| Category | Conventional Hair & Face Products | Born to Bio — ECOCERT COSMOS Certified |
|---|---|---|
| Silicone type | D4, D5, D6 cyclic silicones (Cyclotetrasiloxane, Cyclopentasiloxane, Cyclohexasiloxane) | Zero silicones of any kind — prohibited by COSMOS standard |
| Environmental risk | vPvB (very persistent, very bioaccumulative) — ECHA classification; detected in lake sediment and aquatic organisms | Plant-derived emollients (argan, shea, monoï) — fully biodegradable |
| Fragrance disclosure | Often listed simply as "Parfum" — no breakdown of constituent ingredients required | Natural fragrance sources disclosed; synthetic fragrance ingredients prohibited |
| Preservatives | Parabens, formaldehyde releasers, or synthetic broad-spectrum preservatives commonly used | Only COSMOS-approved preservatives (e.g. benzyl alcohol, dehydroacetic acid from natural sources) |
| Certified by | No independent third-party certification required; "natural" or "organic" claims self-declared | ECOCERT COSMOS — independent annual audit of every ingredient and supplier |
| Safe for | Adults without known sensitivities — but EU is restricting D4/D5/D6 due to environmental persistence | All hair types, sensitive scalps; formulated to biodegrade safely in GCC wastewater systems |
What ECOCERT COSMOS Actually Certifies — and Why It Matters More Than "Natural"
ECOCERT COSMOS is not a marketing label. It is a technical auditing standard managed by five European certification bodies — ECOCERT, BDIH, Cosmebio, ICEA, and the Soil Association — that evaluates every ingredient, every process, and every supplier before a formula can carry the seal. To achieve COSMOS Organic status, a product must contain at least 95% of plant-derived ingredients from organic farming, and a minimum of 20% of all ingredients (or 10% for rinse-off products) must be certified organic by weight. Cyclic silicones, petrochemical derivatives, GMOs, parabens, and synthetic colorants are all explicitly prohibited — not discouraged, prohibited. This is not a brand promise. It is an annual audit with supplier traceability requirements that go all the way back to the field.
When you see the ECOCERT COSMOS seal on a Born to Bio shampoo or hair mask, it means a third party — not the brand — has verified that there are no cyclic silicones, no D4, no D5, no D6, and no ingredient that would fail the standard's environmental persistence criteria. You don't have to read a 38-ingredient list and cross-reference the ECHA registry. The work has been done. Read the full documented science →
Why Certified-Organic Hair Care Costs More — and What You're Actually Paying For
Born to Bio formulas are manufactured in France under pharmaceutical-grade conditions. The price reflects what goes into the bottle — cold-pressed argan certified by organic cooperatives in Morocco, fair-trade shea from West Africa, monoï from Tahitian gardenias macerated in coconut oil — not a brand premium. Organic ingredient supply chains are shorter, more traceable, and far more expensive per kilogram than the synthetic alternatives they replace. COSMOS certification itself requires annual third-party audits that add a compliance cost most conventional brands simply don't carry. The result is a formula that costs more to make, not more to market.
Made in France
Manufactured under French pharmaceutical-grade quality controls — every batch tested, every supplier traced.
Every Ingredient Vetted
COSMOS audits each raw material independently — not just the finished product. The standard prohibits cyclic silicones by name.
Oils That Actually Condition
Argan, shea, and monoï penetrate the hair fibre rather than coating it — no buildup, no clarifying shampoo needed to reset.
What most formulas include
- Cyclopentasiloxane (D5) — often the 2nd or 3rd listed ingredient
- Cyclotetrasiloxane (D4) — vPvB classified, EU restriction 2020
- Dimethicone and dimethiconol for surface coating
- Synthetic fragrances listed only as "Parfum"
- Preservative blends including parabens or formaldehyde donors
What Born to Bio eliminates
- All cyclic silicones — D4, D5, D6, and linear silicones
- Petrochemical-derived slip agents and film formers
- Synthetic fragrance compounds hidden under "Parfum"
- Parabens, formaldehyde releasers, and EDTA chelators
- PEG-based emulsifiers and sulphate surfactants
Silicone-Free Hair Care — Certified, Made in France
✔ Free delivery in Saudi Arabia on orders over 249 ﷼ · Ships to UAE, Kuwait, Bahrain, Oman & Qatar
Share this with someone who needs to read it
What to Look For on Any Label
Cyclic silicones appear on ingredient lists under three INCI names: Cyclotetrasiloxane (D4), Cyclopentasiloxane (D5), and Cyclohexasiloxane (D6). If you see any of these near the top of the list, the product is built around a silicone the EU has now restricted. The simplest verification shortcut: look for the ECOCERT COSMOS Organic seal — it means the certification body has already audited the formula and confirmed no cyclic silicones are present. Any brand making an "organic" or "natural" claim without a third-party seal has not been independently verified.
Frequently Asked Questions
What exactly is the EU restriction on D4, D5, and D6 — and when does it apply?
The first restriction (Commission Regulation EU 2018/35) banned D4 and D5 in wash-off cosmetics at concentrations above 0.1% from January 2020. An extended restriction adopted in May 2024 covers D4, D5, and D6 in leave-on products — including hair serums, conditioners, and face primers — with enforcement beginning 6 June 2026. D6 is also under ongoing review for further restriction.
I rinse my conditioner off — does that mean D5 washes away harmlessly?
No. The EU's original 2018 restriction was specifically for wash-off products precisely because rinsing sends D4 and D5 directly into wastewater systems. Studies detected D5 in activated sewage sludge at concentrations that persist after standard water-treatment processes. Rinsing does not neutralise a vPvB substance — it routes it into the environment.
Will a silicone-free shampoo or conditioner perform as well as a conventional one?
Yes — with the right replacement ingredients. Cyclic silicones create the impression of conditioning by coating the hair shaft. Cold-pressed argan and shea actually penetrate the cortex and reduce moisture loss. The result with a well-formulated organic shampoo is comparable slip and smoothness, without the product buildup that silicones cause over repeated use. Most people who switch report needing clarifying treatments far less often.
What is the difference between ECOCERT COSMOS certification and a brand simply saying "natural"?
"Natural" is an unregulated marketing claim — any brand can use it without independent verification. ECOCERT COSMOS is an annual third-party audit that evaluates every ingredient, every supplier, and every manufacturing process against a published technical standard. The standard explicitly prohibits cyclic silicones, petrochemical derivatives, GMOs, parabens, and synthetic colorants. There is no self-certification — the seal can only be used after an accredited body approves the full dossier.
Are all silicones banned under COSMOS — including the non-cyclic ones?
Yes. The COSMOS standard prohibits silicones as a category — not just cyclic variants. This is more stringent than EU cosmetics regulation, which restricts D4, D5, and D6 specifically while permitting other silicone types such as dimethicone. If a product carries the COSMOS seal, it contains no silicones at all — cyclic or otherwise.
Sources
- European Chemicals Agency (ECHA) — Cyclosiloxanes: D4, D5, D6 restriction overview
- EUR-Lex — Commission Regulation (EU) 2018/35 restricting D4 and D5 in wash-off cosmetics
- Kierkegaard et al. (2006) — Decamethylcyclopentasiloxane (D5) in lake sediment: Environmental Science & Technology
- COSMOS Standard — Technical standard for organic and natural cosmetics (v3.0)
- Genualdi et al. (2011) — Cyclic siloxanes in biosolids: Chemosphere