Decamethylcyclopentasiloxane (D5)
- Silicones
- CAS 541-02-6
- IUPAC: 2,2,4,4,6,6,8,8,10,10-decamethyl-1,3,5,7,9,2,4,6,8,10-pentaoxapentasilecane
Decamethylcyclopentasiloxane (D5) (CAS 541-02-6) appears in 21 of the 1,812 car-care products CarCareTruth tracks (as of June 2026). It is classified as a VOC.
Low acute human toxicity — H227 (combustible) is the only GHS code. No carcinogenicity, reproductive toxicity, or sensitization classifications. Environmental persistence (PBT/vPvB) is the primary concern, not personal health.
Decamethylcyclopentasiloxane (D5) is a cyclic volatile methylsiloxane (cVMS) used as a carrier solvent in auto-care glazes, silicone polishes, and trim coatings. It evaporates quickly from surfaces, delivering active ingredients and leaving behind a film.
Environmental concern: D5 is classified PBT (persistent, bioaccumulative, toxic to aquatic environments) and vPvB under EU REACH. It does not biodegrade and accumulates in aquatic sediments. EU regulations restrict D5 in wash-off cosmetics above 0.1%. For leave-on automotive products, aquatic exposure is primarily through atmospheric deposition of vapors rather than direct drain discharge. Products containing D5 at significant concentrations (>10%) receive environmental score penalties.
Human health: Low acute toxicity — the only GHS code is H227 (combustible liquid). No carcinogenicity, sensitization, or confirmed reproductive toxicity in humans. The PBT/environmental concern, not personal health risk, is the main issue with D5.
Health & environment profile
- VOC
- yes
- Prop 65 listed
- no
- Asthmagen
- no
- EPA Safer Choice
- no
- Aquatic toxicity
- yes
- Biodegradable
- no
- Bioaccumulative
- yes
- Persistent
- yes
- Ozone depleting
- no
- Microplastic
- no
- PFAS
- no
- Env. score
- 2/5
Common questions about Decamethylcyclopentasiloxane (D5)
- What is Decamethylcyclopentasiloxane (D5) used for in car care?
- Volatile carrier solvent; delivers active glaze/silicone ingredients to the surface, then evaporates
- Is Decamethylcyclopentasiloxane (D5) a VOC?
- Yes. Decamethylcyclopentasiloxane (D5) is classified as a volatile organic compound (VOC).
- Is Decamethylcyclopentasiloxane (D5) on California's Proposition 65 list?
- No. Decamethylcyclopentasiloxane (D5) is not on California's Proposition 65 list.
21 products contain this
303 Products 303 Graphene Nano Spray CoatingProp 65ceramic-spray-wax
3M Perfect-It EX Ultrafine Machine Polish (06068)Prop 65finishing-polish
Adam's Polishes Advanced Graphene Ceramic CoatingProp 65ceramic-coating
Adam's Polishes Advanced Graphene Ceramic Spray Coatinggraphene-coating
Prop 65
Adam's Polishes Adam's Buttery WaxProp 65liquid-wax
Adam's Polishes Glass Sealant 2.0rain-repellent
Adam's Polishes Graphene Ceramic Spray CoatingProp 65graphene-coating
Adam's Polishes Graphene Glass CoatingProp 65glass-coating
Adam's Polishes H2O Guard & Glosssio2-booster
Adam's Polishes Spray Waxspray-wax
Adam's Polishes Adam's UV Ceramic Spray CoatingProp 65ceramic-spray-wax
Adam's Polishes UV Graphene Ceramic CoatingProp 65graphene-coating
Adam's Polishes Waterless Wash (16oz)waterless-wash
CarPro ECH2O Waterless Wash & Clay Lubricant Concentrateclay-lubricant
Ethos Car Care Ethos Graphene Coating PRO V2.0Prop 65graphene-coating
Malco Epic Revive Nu Plastic Trim & Cladding RestorerProp 65exterior-dressing
Optimum Gloss-Coatceramic-coating
Torque Detail Mirror Shinehybrid-ceramic-spray
Related
Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.